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[4579.]-DUTIES OF GAS ENGINEER.-I should feel obliged if "Sigma" or some of your other correspondents would give me some information concerning the duties of a gas engineer. What books ought to be studied, &c.? Is there any drawing, and what kind ?— GRAHAM.

[4580.]-PLAN OF AVIARY.-I want to make an open aviary, so that I can divide it into two or three breeding compartments, or several smaller ones. My greatest difficulty is to feed and clean them when the divisions are I do in without having it unsightly when they are out. not mind a little trouble, as I am pretty handy at wood

or wire work.-J. H. P.

[4581.]-LINK MOTION.-Will some reader be good enough to send a sketch showing the action of the link motion?-R. W. B.

[4582.]-GOLD LEAF.-Will some of your readers kindly inform me how gold-leaf books are prepared in gilding so as to prevent the tendency of the leaf to fly about? I have seen gilders use them for out-of-door work. The leaf sufficiently adheres to the paper to make it firm until it touches the gold size, to which it immediately becomes attached, leaving the paper quite clean.-CHEMICUS.

[4583.]-HALSE'S BATTERY, &c.-Perhaps "M. D." or some other reader of "our" MECHANIC, will give a description of how this machine is made. I have also some carbon dust that I want to make into blocks for a Will some reader tell me how to Bunsen battery. proceed to make them?-NORTHUMBERLAND SUBSCRIBER. [4584.]-MANGANESE BATTERY.-Will Mr. Jarman be so kind as to state how many quart size cells of his manganese battery are equal to a one-quart Bunsen battery ?-NORTHUMBERLAND SUBSCRIBER.

[4585.]-AMBER MOUTHPIECE.-Can any reader tell me how the amber for mouthpieces is softened, so that it can be bent or made pliable?-ONE OF THE OLDEST SUBS.

[4586.)-WORKS ON COTTON.-Can any of your readers (particularly those interested in cotton spinning) give me the name and price of a good work on the cotton plant? I want something of this sort: a work that has plates of the plant, showing the leaves and flowers, also the pods in their various stages; also of different sorts of plants, such as American, Egyptian, Sea Islands, Surinam, Surat, China, &c. If it had the plates coloured, it would be better. I have seen, sometime since, somewhere a drawing of the various lengths of staples of cotton, from the longest to the very shortest, printed on paper, the paper being all black, and the cotton white, and numbered.-A COTTON SPINNER.

[4587.]-HARMONIUM.-Will Mr. Hermann Smith tell me if I can remedy the following defect in my harmonium ?-All the notes in the bottom octave, with the exception of G and B flat, are very slow in speaking, while all the rest, four octaves, are very good. It makes it very annoying when playing. The tone is remarkably sweet and good.-J. T. HILL.

[4588.]-TELESCOPE.-Will black varnishing the inside of a terrestrial telescope improve its illuminating powers, or will it do harm ?-J. T. HILL.

[4589.]-TENDER FEET.-Are there any means of making the feet less sensitive so as not to cause blisters in the course of a pedestrian tour ?-J. T. HILL.

[4590.]-TOWN GARDENING.-I have, in a large factory town, unsuccessfully endeavoured to grow geraniums and fuchsias; I attribute it to the absence of the sun's rays, and to having gas in the house, I should like to know what plants will grow and flower under these conditions-whether they are annual or not-or whether they are grown from seed or not. I also wish to grow a few hardy plants in boxes on the window-sills outside. I wish to know how to rear them from seed, and the best sorts for growing in the shade.-A FACTORY

LAD.

[4591.]-EGG-BOILER.-Will any brother reader send me a sketch of an egg-boiler fitted with steam jacket, and tell me the cost of fitting one about six horsepower?-IMPROVER.

[4593.]-PIANO PINS.-TO "W. T."-I beg to tender my thanks to "W. T." for his answer to my former query respecting piano pins, and also to ask him another. I find said piano will not "draw up" within a semitone of the pitch without breaking. Can" W. T." tell me what to do under the circumstances? Can he tell me what sizes of wire to use, and if anything else is

[4596.]JAPAN ISINGLASS. Is this substance
employed for any purpose in industry ?-J. I. G.
[4597.)-INDIAN COIN. - Will some kind brother
reader inform me from what country is the following
copper coin?-Obv.: an elephant, and above, the letter
B in Indian character. Rev.: an Indian or Arab inscrip-
The coin is rather thick and somewhat larger
than a farthing.-J. N. D. C.

tion.

[4598.] - CRYSTALS IN GREENHEART WOOD.-
What are the acicular, gold-yellow, brilliant crystals
found sometimes in Turkish oak or greenheart wood?

Might it not be Bebeerine -GREENHEART.
[4599.]-EFFECTS OF CARBONIC ACID.-I shall
be glad to learn through your columns what proportion
approximately of carbonic acid gas (the deadly product
of our coal-mine explosions) in atmospheric air is fatal
to human life? Also what smaller proportion would
have the effect of producing only insensibility in the
victim?-A. St. VINCENT.

[4600.)-PRINTING IN GOLD OR BRONZE.-Will
any reader tell me how I can print some cards with gold
or bronze ink ?-AMATEUR TYPO.

[4601.]-GILDING BOOK EDGES.-How can I gild
the edges of some books I have just bound ?-A. H. D.
[4603.]-MELTING GLUE.-Will any of our cabinet-
maker readers tell me how to melt glue properly? I mean
so that I can keep it in the glue-pot and re-melt just as I
want it.-S. N. R.

[4603.]-FISHING.-Where can I catch small fish
that will do to put in an aquarium, such as bleak, stone-
loach and gudgeon.-E. JAMIESON.

[4604.)-PICRIC ACID.-Can any of our chemical readers tell me what is pieric acid, and how I can detect its presence? It is said that it is used to give a bitter taste to beer.-S. H. B.

[4605.]-PROPELLING A VESSEL BY A WIND. MILL-May I beg some subscriber to inform me whether it is possible to propel a vessel, head to wind, by means of a windmill working a fan or screw ? A statement to this effect appeared in the Illustrated London News, some weeks since, accompanied by a drawing.THOS. C. BURTON.

[4606.]-BRONZING IRON IN PAINT. Can any of your readers inform me how to bronze ironwork in paint ?-C. H.

[4607].-ORGAN BUILDING.-Will some kind correspondent inform me how I can make wood pipes (stop diapason) speak a little louder! Also, how can I harden brass wire, so that it will be adapted to make springs for organ pallets ?-W. PORTEUS.

[4608.] FRICTION: HORSE POWER.-Will some
reader state the amount of friction (in pounds) to be over-
come by a horse in drawing a load of one ton on a level road,
made as follows?-1st. On granite pavement. 2nd. On a
broken granite surface. 3rd. On a gravel surface. The two
last supposed to be level surfaces. Also what amount of
traction (in pounds) is required to draw a ton up a
gradient of 1 in 20? Also, how many pounds of force is a
horse calculated to exert ?-W. B.

[4609.]-AIR-GUN.—TO “T. A.”—On p. 499, Reply
4044,"T. A." gives a very clear explanation of the lock
of air-gun. Would he kindly give sketches necessary for
the construction of an air-cane, with directions showing
position of air chamber, valves, charge, &c.?-A. HUNTER.
[4610.]-SHUTTERS.-Will any of my fellow millers
tell me if the shutters in a patent sweep (on the lead
side), should be at the point or heel of the sweep, the rest
of the lead side being board? I have an idea the shutters
should come down, say two-thirds of the way, and the
rest made up as a lead board at the POINT.-ONE EYE.

[4611.] POLISHING VULCANIZED INDIA-
RUBBER.-Can any reader inform me how to get a
perfect surface on vulcanite for polishing, and what
powder, &c., will produce the finest polish on black
vulcanite? I have a lathe and circular brushes for it;
would cotton brushes be any better than hair ones?-
G. N. L.

[4615.]-SEWING MACHINE ATTACHMENT any of our readers tell me the best form of for a shuttle sewing machise; like make a marker, or creaser, as need in &c.; and how to form and fasten the I believe is attached to presser foot des cording? Diagrams would oblige.-11. [4616.]-PROBLEM.-Will C. H; din" be good enough to solve the l of 100lb. is resolved into two equal angle of 135; find magnitude of a.

AMICUS.

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[4617.)-QUERIES ABOUT OL4.1 fellow readers of the ENGLISH ME following information ?-1st. What 5 rendering linseed-oil siccative. ** litharge or other salts of lead? boil the oil with litharge, but this ina colour for my purpose. 2nd. Is pay of being transformed into as quickly dry seed, and whether it is subjected to thes linseed-oil to render it siceative? B line spirit," now sold at the oil-r purposes, the same substance as the chemists in small bottles, under the a collas," and used for cleaning, &c. I. [4618.]-MANAGEMENT OF BEESobliged if you or a brother subscriber wea on what principle, and how the feeding br.. are constructed. They are made so that the escapes from the bottle as fast as the bees I cannot find out how it is made. Ishoni if some one would tell me how or where I of the honey, and what is the price per lb der I must say I was glad to see the subject clust the MECHANIC, for I think it is a subject is many take an interest in, and if a brother

some other, would give some information on that. ment of bees in a series of letters, I think they interesting and useful to a great maLĮ SEASII THOS. POULTON.

[4619.]-HARD WHITE METAL-CD SET spondent tell me how to make the hard white w

is sometimes used for models ? I have set (Film) brackets, &c., of working models east with the m and want to cast some with it, not having the nests an do it with brass. I think it is run down in the diver the open fire. Please state if it is any as fast -HAMMERMAN.

[4620.)-EMERY STICKS.-I see te shat Will be emb emery wheels by "Matrix." shellac and mineral naphtha, but des set the pee emery sticks are made? I am told th portions nor the modus operandi sa oblige.-HAMMERMAN.

[4621]-CHLORIDE OF GOLD.-Wid numerous subscribers please inform u box the ene is manufactured, as I have some old gold I wish to a into the chloride ?-YOUNG PHOTO,

[4622.]-NITRATE OF SILVER-I have a silver st tion which I use for electro-plating. How again converted into nitrate ? Must it be erad, fused, and redissolved in nitric acid-for

[4623.]-HORNS.-I have a few specimens of polished cows' horns: would any one give me a recipe for krejang them a good gloss?—WORKING MAN.

[4624.)-PENDULUM SPRING-I feel extremely obliged to " Seconds Practical Watchmaker" if he would kindly answer the following questions, viz — How to tell the proper length and strength of a penin lum spring. How to tell the pallets and lever depths in the depth tool, and like wise to tell when they a correct when uprighted and in the frame. How to the adjustment and tell when it is correct, and bow tell when the fusee chain is the proper length-Yo

JOBBER.

[4625.]-FLUORINE.-Can "Beta" or any spondent, inform me on what grounds the table at Kensington, quoted by him, p. 449, reckons F among the normal constituents of our bodie? I d from the other thirteen in the table by notes advis to be ubiquitous in the mineral world. The B is known in the home counties, the question o if fluorine be necessary to us, whence do Lond It is remarkable that only fourteen eleme ubiquitous on earth, and thirteen of these, c the table, are necessary to man.nly one Aluminium, has not been found in his body, about the fourth most abundant in terrestrial E. L. G. and though alum is taken as medicine, and it is

[4626.]-TUNING BELLOWS FOR HAR REEDS.-Will any fellow reader be kind enoug me a description of the bellows used in tuni as requested on p. 287, ante? A diagram would be

-REED TUNER.

[4612.]-PORTABLE MILL.-I am much obliged to [4592.]-TEETH OF CHANGE WHEELS.-Will H. W. Reveley for his reply to my letter. I thank him "J. K. P." please to tell me how the teeth of change much for telling me of Smeaton's work, of which I had it ? I know how to strike out the not known. There is only one thing I need remark on wheels are struck out ? epicycloidal form of tooth for wheels that always remain in his letter. He seems to think that the slow motion the driver or the driven, but do not know how they are of the horizontal mill is a great drawback. It may be formed when the wheels have to be changed, as on the for some things, but this slow and powerful motion is screw-cutting lathe.-C. C. just what is wanted for other things, e.g., for agriculand this, as he says in his letter in the ENGLISH tural purposes, such as Mr. Vallance applied his to; MECHANIC, was capable of drawing seven ploughs, and had arms only 12ft. long. Surely this was "useful work," and yet to perform it there was needed no "formidable train of wheels and pinions." If I wanted a mill to turn millstones I should give Mr. Reveley's plan a trial; but as I want a portable mill it would not suit. While on the subject, would Mr. Reveley or any other correspondent give a plan for draining a marshy field by wind power? In "Mechanical Movements," No. 259, there is something like what I want, but the worm wheels would be difficult to get made here; and, besides, the form of buckets given would not suit, as sand and mud would have to be lifted out as well as water. to drain is near the river, from which it has been embanked; it is too flat to allow of sufficient fall for the drain. I would sink a well near the embankment, and over this mount the windmill; but whether a horizontal or vertical one would suit best I do not know. For an be best, I should think. If any practical man will endless band, with buckets attached, the vertical would kindly give me an answer I should be much obliged.

the matter ?-MAN OF NECESSITY.

[4594.]-GOMA OIL.-A German review says:-"The Japanese colony, near Pliersville, in California, has lately cultivated with success an oleaginous plant, belonging to the nettle order, and called Goma. The small seeds, enclosed in the capsule, are so rich in oil that the yield of one acre is estimated at 136 pounds of oil. The plant requires much watering, and it is hoped that by artificial irrigai on, three crops annually may be obtained. The young sprouts are excellent as salad, the flowers give a rich food for bees, and the fibrous stem will probably be useful in textile fabrics. Goma oil, well refined, is equal to the best olive oil; has a very slight tendency to become rancid, and probably might form a substitute for olive oil in all technical employ. ments. This oil can be got in Germany from MM. Secger and Maur, in Dresden." Does any brother reader know some more particulars about this plant, its botanical name, &c.? I find Hoi-mwah for a Chinese name of Cannabis sativa. Might not Go-ma proceed from that word ?-BERNARDIN.

[4595.]-HOUSES FROM STRAW AND WATERGLASS. Is it true that houses have been constructed in England the principal inaterial of which was bundles of straw impregnated with water-glass or silicate of soda? Some particulars might interest several readers. -UN ABONNE.

DERF ERRAC.

The land I want

[4613.]-TREE STUBBER.-Will some one please describe a machine for pulling out the stumps of trees? There is an American machine worked by horse-power. The principle is, I believe, a powerful screw. Particulars would oblige.-DERF ERRAC.

[4614.1-ELECTROLYSIS.-Will "Sigma," or "Ignorant Irishnan," or any other subscriber, kindly say whether electrolysis, such as electrotyping and decompo sition of other substances, can be effected by the aid of a magneto-electric machine? An answer through the MECHANIC will oblige.-TRANSPARIENT.

[4627.]-DISCOLORATION OF LEATHER-C reader give me any information on the followi have been pressing some leathers into a shape, bater remaining in the presses all night, that they may re I soak then their shape, I find them nearly black. water before pressing, and the presses are made of What I want is to get them as near to the colour pressing as they were before, also a quicker hardening them, if possible, than by allowing thent remain in the presses all night.-G. A. G.

[4628.]-COILS.-If any reader of your journal be made a coil from the instructions given in Dyer. found to arise?-W. J. P. he please state his experience and what difficulties we

[4629.]-MANGANESE BATTERIES.-I have th specification of the patent of the "Leclanche" battery and wish to ask if any of your readers can enlighten on the subject. The battery consists of two parts-th generator and accumulator-the former being really th battery, but the accumulator I cannot understand. It ha two plates of carbon, one of which is in a poronsp The patent is No. 2,623, 10th October, 1866, patented the name of Brandon. The price of the specification Sd. I also wish to ask in what number Dr. Stenc maganese battery is described.-VIATOR,

[4630.]-COACH PAINTING.-Will any of our brother readers be kind enough to inform me if there is a book

lished on coach painting, and where it is to be bought probable cost ? And if there is no such book, will e one be kind enough to give me instruction as to node of procedure in coach painting?-AN OLD SUB

BER.

631.1-LATHE QUERY.-TO "J. K. P."-I return aks to "J. K. P." for his prompt reply to my query Will he please refer to page iv. of the last number ) of the ENGLISH MECHANIC? He will there see an strated advertisement of a lathe by Greenwood thers; my head stock is like that one, and backed; the mandril running in two collars; the bed has p, with saddle and brackets, to carry screw, same as tration, with swing pite. I wish to fit it to carry saddle backwards and forwards, while the lathe is ning. Ifind there is 8in. from centre of mandril to tre of leading screw; will wheels of the 12 pitch do, en fitted, with backward and forward motion? Now, many threads to the inch, and what diameter for ding screw? The one you mention-8 threads and leftaded-would not do in this case, I should say. P.S.hould like to see his 5in. head stock, but my place of idence is 150 miles from London, which place I should is his abode.-H. WILLIAMS.

4632.]-WEIGHT OF BALL.-Would "Ferrum," in ply to my question on the weight of ball, oblige me by e working of the sum, as I think he has omitted a int in reference to obtaining the weight of a yard of 1. round wire? I don't think he will obtain it simply ɔm multiplying the square of diameter by 7854, and I nnot see that to divide 50 by 5 gives 100.-RALPH

ILLIAMS.

[4633.]-WEIGHT OF METALS.-Would J. Nash also olige me with the name and publisher of a good praccal work on the weight and strength of metals generly, and with the rules for obtaining the same? How oes he find the cubic content of the ball to be 179-5948, nd where does he get his decimal 5236 from in the 78 x 5236 x 7645 ormula ? Am I to assume that the 1728 × 16 name (Hutton) in brackets is the name of the publisher from which he gets his information; if so, would he oblige me with the price and particulars? By "Ferrum's" rule there is a difference of 31b. in the weight of cast-iron ball to that of J. Nash's, so I am not exactly in a position to decide which to accept, and would be grateful to J. Nash for information respecting the book. -RALPH WILLIAMS.

[4611.]-GAS-HOLDERS.-I have a very leaky gasholder; it leaks at the rivets and all round the angle. Can any one tell me the best cement to use that would stop the leakage, and would be lasting? I have put red and white lead round, but it is not effectual; or would it be safe to caulk it the same as boiler-makers would, while it is full ?-R. D.

[4643.]-METERS.-Can any one explain this ?When we are cleaning our purifiers our meter travels backwards. It has indicated 1,000ft. less, although we have shut the centre valve.-R. D.

[4644.]-CORN FLOUR.-Will some fellow-reader kindly inform me the process by which "corn flour" is manufactured from Indian corn (or maize), also from rice ?-JOSIAH R. NEANE.

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[4635.]-WATER COLOURS.-Can any one give me the process of making up pigments into cakes for watercolour painting ?-D. G.

4292

Friction in Steam Cylinders, 406.

4293

Millers, 406.

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[4634.]-ELECTRIC CLOCK.-May I ask Dr. Stone, who so amiably, some time ago, described the manganese battery with which his electric clock is worked, add to the obligations we are under to him, a short description of his time-piece, which, I am glad to learn, is giving him so much satisfaction? I think, a considerable time ago, a similar request was directed to your readers generally, but met with no response, except in the "Editorial Correspondence Column," in which was described an arrangement of electric clocks, under what is known as the remontoire system, and one of which was, I believe, exhibited in the Great Exhibition of 1851, but there must have been many improvements made since. I understand there is description of such clocks in the earlier volumes of your journal; but as I only go back to Vol. V., they are as hidden secrets to me. Many thanks to your learned correspondent "Sigma."- ELECTRO-MAGNET,

No. 1.

[4636.]-INCUBATOR.-I want to make an incubator. By referring back to Vol. X., No. 238, page 108, I find a sketch of one by Mr. J. Pinchen, but not having seen one of any kind, and being entirely ignorant of their principle and construction, I am unable to understand it from Mr. Pinchen's very brief description. If he, or some other correspondent, would make me understand it, I should feel greatly obliged. What is the use of the glass case E, and how is the mother D made? How many eggs does each drawer A hold, and what are they placed upon? Are they wooden or zinc drawers? Is there an opening at the end for the chicks to escape through to the mother, and do the black dots in the outer end represent air-holes? Is the lamp-chamber open all through to the glass case? Of what, and how, are the moistening-drawers constructed and connected with the egg-drawers? Is the zinc boiler entirely hid from view with the woodwork, and is there no danger of steam bursting it when corked up? What is the best kind of lamp to use, and what degree of heat is necessary? What are the dimensions of the different parts of the incubator ?-ROBIN HOOD.

[4637.]-FLEXIBLE CEMENT.-Could any of your correspondents suggest a flexible cement, in place of the india-rubber solution, for uniting cloth and indiarubber; something that could be kept ready for use, dry quickly, and resist moisture ?--PARVUS PUER.

[4638.]-SILK WINDING.-How ought the silk of the silkworm to be wound so that it can be sold? Ought each cocoon to be wound separately, and tied up as one skein; or should the second cocoon be started where the first left off, and so on, until the skein is a large one? Or should about a dozen or so be wound together, so that the ends shall be together, and then tied up as one skein?-C. H. BOLTON.

[4639.]-DYEING WOOL AND YARNS.-Will any of your correspondents kindly inform me if there is any book on dyeing wool, &c., and scouring yarns, &c. ?— N. E. W.

USEFUL AND SCIENTIFIC NOTES.

REPAIRING LEAKY ROOFS, ETC.-The following is said to answer well in mending roofs that leak, and for similar uses:-Take two parts byweight of common pitch with one part of gutta-percha, melt together in an iron pot; it forms a homogeneous fluid much more manageable than gutta-percha alone. To repair gutters, roofs, earthy matters, slightly warm the edges with a plumber's or other surfaces, carefully clean out of the cracks all soldering iron, then pour the cement in a fluid state upon the cracks while hot, finishing up by going over the cement with a moderately hot iron, so as to make a good connection and a smooth joint. The above will repair zinc, lead, or iron, and is a good cement for aquariums.

SO CALLED "COLD GALVANIZATION" OF IRON AND CAST IRON.-The metal is first cleaned by being placed in a bath made up of water 1,000 litres; chlorhydric acid, 550 litres; sulphuric acid, 50 litres; glycerine, 20 litres. On being removed from this bath, the metal is placed in a bath containing 10 per cent. of carbonate of potassa, and is next transferred to a metallizing bath consisting of water 1,000 litres; chloride of tin, 5 kilos. ; chloride of zinc, 4 kilos.; bitartrate of potassa, 8 kilos.; acid sulphate of alumina, 4 kilos.; chloride of aluminum, 10 kilos. The metal has to be left in this mixture for from three to twelve hours, according to the thickness of the layer of zinc to be desired.

[4640.]-SOUTH KENSINGTON EXAMINATION PAPERS.-Would any of your kind readers be so kind as to tell me where I could get 4 South Kensington Ex-idea (says a local journal) has been prompted by the

amination Papers? Subjects:

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PROPOSED MUSEUM AT BURNHAM, SOMERSET. -A feeling has been expressed that it would be an advantage to provide the town of Burnham with a museum for the collection of the curiosities of the district. The fact that Mr. E. Rosser, of College-street, who has devoted his attention to geology, is willing to dispose of his collection. One large fossil possessed by Mr. Rosser This is an Icthyosaurus, which is much admired. splendid specimen of extinct animal existence was obtained from Street, near Glastonbury. He has also a very valuable ammonite. Besides these, Mr. Rosser posshells, &c. This would form a good nucleus for a sesses a good collection of minor fossils, stones, crystals, museum, and we hope means will be taken to make them the property of the town. Some Roman pottery and other curiosities dug up in the neighbourhood would doubtless be added by their owners.

A SPONTANEOUS COMBUSTIBLE GAS.-The bibromide of ethylene, when mixed with oxygen gas, takes fire spontaneously in the sunlight. The bromine appears to combine with the hydrogen in a manner analogous to the union of chlorine with hydrogen in the sunlight.

REAL AND APPARENT DEATH.-Dr. Laborde, in a paper recently read by him before the Academy of Medicine in Paris, has endeavoured to show that the effect produced on a bright steel needle inserted into the body indicates whether death has or has not occurred. When life is present, he says, the needle, generally very soon, becomes more or less tarnished by oxidation; when, on the other hand, death has taken place, the needle, even at the end of half an hour or an hour will retain its brightness. According to the British Medical Journal, M. Laborde believes that, in the first instance, the occurence of oxidation, with its attendant electric phenomena, indicates that death is only apparent; while, in the second, the complete absence of oxidation is a sign of real death. The communication has been referred to a committee, consisting of MM. Gavarret, Beclard, and Vulpiau.

PRESERVED BREAD.-This bread is proposed as a substitute for the biscuit and "hard tack" used at sea. It is easily prepared, though the process is somewhat tedious. The bread is baked in the usual way, it is then subjected to desiccation for eight to fourteen days, until it is thoroughly dry; it is then exposed for a short time to the action of steam, and afterwards squeezed into tablets under an hydraulic press for twenty-four hours. The tablets can be preserved for years in hermetically-sealed packages. Bread thus prepared retains a vitreous fracture, can be easily masticated by the teeth, is admirable for bouillon and soup, and experience has shown that 200 pounds of good flour will afford with this bread and Liebig's extract of meat would be 188 pounds of compressed tablets. An army provided prepared for any emergency that might arise. A soldier could easily carry several days' rations in his knapsack.

MUSSEL EATING.-It is surprising the quantity of mussels imported into our manufacturing towns. The working-men appear to feast upon this shell-fish with a marked preference, if we may judge by the large consumption of it. A visit to the markets of Manchester, and like towns, will reveal the fact, that mussels were largely sought after and eaten by the manufacturing class at the time of the year when some restriction should be placed upon their sale, for during the months of May, June, and July, they are a dangerous commodity, not having recovered from the effects of spawning, and We in many instances produce serious mischief. (Medical Press and Circular) have lately observed the grave results which arise from a careless indulgence in mussels, from the general rash over the surface of the body-so characteristic of unwholesome fish-to the protracted and, in some cases, fatal diarrhoea. In France, where mussel farming is cultivated with the same care as that of the oysters, and where they are placed under the operation of fishery laws, we find, during four suminer months, no mussels are sold for consumption in the markets or shops. Even if they were, they would not be so dangerous as the large, fat mussels to be found in our markets, and consumed with so much recklessness as to future sufferina by the working-men. Disease is engendered and propagated through the carelessness with which the dietary of our people is managed, and serious epidemics arise through incaution. Accordingly, we believe it should fall to the duty of inspectors of markets to prohibit the sale of unseasonable articles of food. How often do we see lobsters and crabs vended at a time when they are most baneful, and how frequently are our professional services required to minister to sufferings arising from the injurious effects of stale or unseasonable shell-fish.

CAUSE OF THE FATIGUE TO THE EYES CAUSED BY ARTIFICIAL LIGHT.-M. V. Meunier states that the great difference between sun and artificial light is due to the fact that, of the light emitted from the former, about half the quantity of rays are luminous and calorific at the same time; but, as regards our artificial light, for ordinary oil (colza oil), the amount of non-luminous, yet calorific, rays is 90 per cent.; for for white-hot platinum, 98 per cent.; alcohol flame, 99 per cent.; electric light, 80, and gas-light, 90 per cent.; while for petroleum and paraffine oils, the amount is 94 per cent.

It is this large quantity of caloric rays in this inconvenience may, according to the author, be artificial light which causes the fatigue to the eyes; but rays by glass, or, better yet, mica plates. The use of almost entirely obviated by intercepting the thermic these renders the light soft and agreeable to the eyes.

FLUORSPAR IN GLASS MANUFACTURE.-Herr E. Richters, of Waldenberg, Germany, states that the substitution of fluorspar for lime in the manufacture of glass allows of a great reduction in the amount of glauber salt, and greatly promotes the melting of the frit. As the result of numerous experiments conducted tion of fuel and similar length of time, the amount of on a large scale, he found that, with the same consumpglauber salt required could be diminished one half by substituting fluorspar which had previously been pulverised and calcined for the lime usually employed. In countries where fluorspar can be had in abundance its offer many important advantages. The following are introduction into glass manufacture would appear to the proportions taken:-With fluorspar: Sand, 111 44lb.; fluorspar, 27-691b.; glauber salts, 4901b.; manganese, 4.091b; charcoal, 2001b.; glass frit, 299-00lb. Sand, 116-40lb.; lime, 15:55lb.; glauber salts, 8:00lb.; manganese, 300lb. ; charcoal, 2-001b.; glass frit, 248.00lb.

With lime:

ANTIQUITY OF THE MITRAILLEUSE.-We give only a revival of an old invention, from "Grose's the following curious evidence that the mitraillense is Military Antiquities" (1801), vol. ii., p. 165:-" A patent was granted by King Charles I. to William Drummond, of Hawthornden, in 1625, for the sole making and vending, for the space of 21 years, of the following machines and warlike engines invented by him. The patent is printed in his works. The third is a sort of machine of conjugated muskets, by the assistance of which one soldier or two are enabled to oppose 100 guns, which machine from its effect, is called the thundering chariot, and vulgarly, the fiery waggon."-Spectator.

THE RIGHT AND THE LEFT HAND.-Dr. Dwight, a writer in the Journal of Psychological Medicine, main

tains that the pravalent use of the right hand in preference to the left is not merely due to habit or educaation, but is the result of a natural impulse, which he attributes to a difference in the endowments of the two lobes of the brain. He lays down, as probably true, the following propositions:-1. There is an inborn impulse to use, to excite motion, one-half of the brain in preference to the other. 2. One half the brain, the left, has a more acute perception of tactile impressions, while the other, the right, distinguishes more readily different degrees of temperature and weight. 3. This arrangement is occasionally inverted." That we shall ever know the nature and origin of this impulse to use one side in preference to the other, Dr. Dwight thinks impossible; but a step is made, he remarks, when it is admitted that it is an impulse born with us, a part of our organization and is neither due to the arrangement of the arterial system, nor is the effect of habit.

A PUZZLING POSSIBILITY.-When the RussianAmerican Telegraph is completed, the following feat will be possible: A telegram from Alaska for New York, leaving Sitka, say at 6:40 Monday morning, would be received at Nikolaef, Siberia, at 6 minutes past 1 on Tuesday morning; at St. Petersburg, Russia, at 3 mins. past 6 Monday evening; at London at 22 minutes past 4 Monday afternoon; and at New York at 46 minutes past 11 Monday forenoon. Thus, allowing 20 minutes for each re-transmission, a message may start on the morning of one day, to be received and transmitted the next day, again received and sent on the afternoon of the day it starts, and finally reach its destination on the forenoon of the first day. The whole taking place in one hour's time.

PRESERVED MILK.-If a full milk diet could be obtained for the children in every cottage, how often would the sickly infant live, the poor, ricketty child grow into an active boy, and the overgrown, consumptive-looking youth reach manhood. In fact, how much would the bone and sinew of the rising generation be strengthened, if children could have a liberal supply of milk food, instead of being brought up on washy substitutes, and kept quiet by sugar, stimulants, or opiates. The importation into this country of the pure condensed milk from Switzerland is another step in the right direction-the amelioration and condition of the poor-which modern science has taught us to take; and we also hail with hearty satisfaction the announcement that establishments for the preparation and supply of immense quantities of the condensed milk are now at work in the county Cork, Ireland. In this manner the "green pastures" of the sister isle may indeed be made to confer a substantial blessing upon the crowded and heated towns of England, whose population in infancy is stimulated into unhealthy and unnatural precocity, instead of being soothed and fed by Nature's own food during the ills to which juvenile existence is subject.WOOTZ.-In 1819, while Faraday was an assistant in the Royal Institution, he made an analysis of wootz which attracted considerable attention, as, besides carbon, it was found to contain only silica and alumina, from which the conclusion was drawn that the peculiar property of the metal was due to the presence of silicium and aluminum. The uncertain state of analytical chemistry at the time of Faraday, says the Journal of Applied Chemistry, has induced Rammelsberg to repeat the analysis of wootz, and he has communicated the results of his work to the Berlin Chemical Society. The following is Rammelsberg's analysis:-Carbon, 0-867; silicium, 0-136; phosphorus, 0099; sulphur, 0·002. It will be seen that the metal contains no trace of aluminum, and Rammelsberg doubts the existence of such a thing as aluminum steel. It is certain that the usual alloys of alluminum and iron are crystalline and brittle and not at all possessed of the properties of steel.

Food Journal.

REVERSION SPECTROSCOPE.-An important addition to the resources of spectrum analysis has been made by Zöllner's invention of a reversion spectroscope, by which extremely small changes of refrangibility, and consequently comparatively slow motions of a star or sun-flame, can be detected. It consists of a spectroscope, in which, by reflection, the spectrum of a source of light can be superposed above a reversed spectrum of the same source; so that if a white flame containing sodium be viewed, there will be seen in the upper part of the field a sodium line with the blue end of the spectrum on the one side, and underneath it a sodium line with the red end of the spectrum on the same side. The two bright lines may be made to coincide exactly by an adjustment; and if any change in refrangibility takes place, the motion of the line is doubled, and is also more exactly measured, because it is referred to itself as a standard.

A NEW INDIAN MEDICINE.-We have received from Mr. Narayan Daji, of Bombay, a paper read before the Grant College Medical Society, containing an ac count of a new Indian drug-the bark of Ailantus excelsa Roxb. This tree is common in many parts of India, and' its bark can be obtained in sufficient quantity for general use. The active principle of the bark is called ailantic acid, and its taste is purely and strongly bitter. In doses of from one to three grains ailantic acid, given internally, acts as a tonic and stomachic, exciting the appetite and promoting digestion. When given in large doses (from three to five grains), two or three times a day, its action is distinctly marked, especially in cases of torpid stages of the digestive function, attended with muscular and nervous relaxation and constipation. It is useful in watery diarrhoea, and has been found of considerable benefit in the first stage of cholera. It is administered either as decoction, infusion, extract, or tincture of the ailantus bark, and pills can be made containing the concentrated extract. The bark alone contains the active agent, in combination, as far as has yet been discovered, with lime, carbonate of lime, salts of magnesia, alumina, uncrystallizable sugar, gum, and a trace of volatile oil and lignin; its medicinal virtues depend entirely upon an azotized bitter principle possessing an acid nature, and it is this which has been called ailantic acid. The tree is figured in Dr. Wight's "Illustrated Indian Botany."

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We have frequently been asked to devote a portion of our space to cheap or rather SMALL Wanted Advertisements, and we now propose to do so under the heading "Employment Column." Hundreds of skilled labourers are continually wanting employment, and very frequently employers are in want of skilled labour. These wants, in a great industrial country like ours, exist under a variety of forms. A brass-founder may want a foreman; or an optician an assistant; a person may want his microscope repaired, his pianoforte tuned, or his ma nu scripts edited, when in all probability there is just the person to do the work near by. But the two do not know of each other's wants. At the present time there is no national cheap and expeditious medium whereby the one who wants the work done, and the other. who is ready and able to do it, may easily place themselves in communication with each other. think the ENGLISH MECHANIC is just the organ for such a purpose. This, in most cases, may be done in a very few words. We therefore place at the disposal of all who may want it,

OUR EMPLOYMENT COLUMN.

We

As in the Sixpenny Sale Column, the charge will be sixpence for the first sixteen words, and sixpence for every additional eight words.

The following are the initials, &c., of letters to hand up to Tuesday morning, August 23, and unacknowledged, elsewhere:

C. J. Richards, F.R.C., M.D., G. Brian, W. Perryman,
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THE PYRAMIDS.-Col. Sir Henry James, in a recent
lecture on the pyramids of Egypt, stated that in the
king's chamber, inside the pyramid, some of the stones
were 30ft. long. These stones, weighing some 90 tons,
were not found in Egypt at all, but were brought down
the Nile a distance of 500 miles, and then placed in their
present position, 100ft. above the level of the ground.
With regard to their finish, these Syenite stones are of
the very hardest known, and yet they are so exquisitely
polished, and built in (to form a casing for the king's
chamber) with such superior skill, that the finest sheet
of tissue paper could not be inserted between two of
the stones, and this after a lapse of 4,000 years. Such
workmanship would excite the wonder and admiration
of the world, even in this age of science and improve-G. LUFF.-Will answer by post in a day or two.

ment.

J. HARRISON.-Your letter displays too much of the fondness of some of our earlier correspondents for calling hard names.

VIGIE. The subject was fully discussed and various expedients suggested in our last volume. FLORIST.-See back numbers.

you.

H. H.-The address counts as part of the advertisement. W. SEABORNE.-No stamps enclosed.

T. K.-Your letter is merely a record of failures. J. B. H.-You ought not to complain of space being unprofitably occupied when you fall into the same error yourself.

A PETRIFIED SEA-MONSTER.-A very beautiful A BLACKSMITH.-Mr. Binn's book would, we think, suit and interesting petrified sea-monster has, according to the White Pine Nevada News, been lately discovered about 100 miles to the south-east of Hamilton, on a high plateau of land containing an extensive deposit of marine shells and the fossil remains of a large variety of extinct species of fish. The petrifaction of this particular monster is perfect, and is estimated to weigh about ten tons. It presents a dual appearance-the head and body are that of a hump-back whale, while the extremities extend into feelers and antennæ, like the polypus or devil-fish, with the exception that they were evidently during life lined with a hard and bony substance. The eyes are set in each side of the head, which is flat and oblong, and are twenty-four inches apart. The mouth is armed with triple rows of teeth, which are sharp in front, but underneath and well into the jaw they turn nto grinders, capped by a solid osseous formation, u nning back from the widest portion of the head.

P. H. S. says on the principle that every one should help his neighbour, I venture to ask you if you would wish to insert in the ENGLISH MECHANIC one or two papers on Land Surveying." We should be glad to insert the papers if suitable.

S. R.-Yes. Cannel coal is largely used for making ornaments. It is found principally around Wigan, as well as near Manchester and in Scotland. A very fine cannel is found in Flintshire, where it is used for the distillation of coal-oil.

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L. DICKSON (Antrim).-To find the dies of chimney for a stationary boiler, maitiply thre of pounds of coal consumed under the boiler by 12, and divide the product by the square ră height of the chimney in feet, the quotient of the chimney in square inches at the smal B. B.-Yes; apply to the office for Registre signs, 1, Whitehall. You had better emp able patent agent. See advertisements. J. HARPER.-Send the drawing and descrip insertion they shall appear.

E JONES Llandudno).-The bird you mas likely the herring gull, which is commonparts of the southern and western coaste the kittiwake and the common gull t pearance; but the bill is yellow; legs: iris, light yellow, with an orange eyelid the head, neck, tail, and underparts, are p a grey mantle, and black and white prin quite a mistake to suppose that the here only on the fry of fish which swim Dear It eats both shrimps and small crabs, small birds are not safe in its presence been seen following the plough, and picat, and larvæ from the furrows. SABBAS.-Epidote is a silicate of alumin There are several varieties of it; and / granite and other igneous rocks and vac line slates.

J. T.-No. Several wires are used in subma because copper wire is liable to break There are seven conducting wires in the b cable.

S. G.-The French powder is made of 75 pas 12.5 sulphur, and 12-5 charcoal: The Prussian 1 part less sulphur, and 1 more of chares English contains 10 of sulphur, and 15 of char C. R. T.-No. It is quite a mistake. Asphaltas of hydrocarbon, produced in the interior of the by the transformation of carbonecoss A is soluble in about five times its weight of my, htt The mixture of gas tar with sand or fine is known as artificial asphalte:

F. W. GRIERSON.-Tuesday morning will be too late. J. W. asks why his "congratulatio is get in-das in the list published. Simply became be said "I bet to congratulate you," &c. We and lovemes An columns of such. Our plan bittere has been to selen racy and characteristic seaming to the ENGLISH MECHANIC from opulenta ISLA give them in clusters.

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KANSAS.-Cain is supposed to have married him. On reference to the Book of Genesis you with births of daughters not recorded until a constient later period. J. MELOME. Consult articles on Electricity now appe:

ing.

H. D. (Birmingham).-Described in back numbers NORTHUMBERLAND SUBSCRIBER-212 out of priti, other can be had.

R. Y. G.-Steam was known as a motive power. before the time of Watt-even to the ancients. JOHN FLETCHER.-Apparently there is little dif in discovering your method of secret writing." did so in two minutes. The following is the tra tion:-"This sort of thing soon uses them up there are plenty more in the labour market. W cheap as flesh and blood ? But we have forge! fine wire; now for the artist's touch." JOHN A. MACLEAN.-You will receive the paper t end of your present subscription free of fir R. G. B.-Too frivolous.

charge.

C. H.-No book ever published contained a tithe f information to be found in our back volumes practical construction of the harmonium. W. H. THORPE (Reading).-A cubic foot of wre weighs 485lb.; of cast iron, 450lb.; of g 525lb.; of rolled brass, 534lb.; of cast corp of gunmetal, 5491b.; of lead, 7101b.; of steel in J. A.-Better apply to a surgeon accustomed

treatment of the ear.

E. RUSSELL.-We are glad you find our
useful. We shall, as hitherto, issue ti
index to each half-yearly volume.
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information. Letters for the Queen

sorted by some trustworthy secretary, psy letter to us we don't think any comONA

yours would ever reach her.

You wi

ONE OF THE FIRM.-Assuming all you say to
you would certainly have the right to m
the articles during whatever period the pi
kept up.
Of course it will mainly depends
receipt, on which advice should be taken.
T. A.-Your letter appears unnecessary.
attacked in the letter to which you refer.
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J. B. COCKBURN.-No apology is needed. We fully cognised the purity and zeal of your intentions only regretted that the circumstances to which alluded prevented our taking advantage of th You know probably better than we do how difficul is to prevent fraud in such matters.

W. G. H.-We should be glad to receive a drawing description of the saw, and, if worth anything, insert it.

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ceased become deeply stained, and in time all the cell walls are also stained. Neither the current nor rotating granules are ever stained. The inert matter in the centre of the larger cells becomes stained, and is apparently granular. After the reagent has been applied for three or four hours, a very moderate power will enable one to see the movement of the current of protoplasm very clearly, and most rigidly to mark its bounds.

The younger cells appear to resist the test altogether. A writer in one of our scientific periodicals, some two or three years since, was of opinion that this re-agent enabled him to demonstrate an intercellular substance, which, he said, became deeply stained. Careful observation, will, I think, show this to be a fallacy. A rigid optical analysis with polariscope and most delicate focussing does not reveal more than the simplest of cell walls (consolidated sometimes, with silex), but no intercellular substance. I have further to notice that the phenomenon of cyclosis is almost entirely dependent upon the influence of light. It is most interesting to see how speedily general activity is resumed in cells that were dormant when an intense light is thrown upon the leaf by the mirror. Heat is also a necessary condition. From these considerations I think we can come to but one conclusionthat this is one of those phenomena we call vital, and that it may be regarded as analogous to the circulation of the blood through certain vessels in animals, and as being essentially related to that simultaneous removal and replacement of matter" which distinguishes "living from "dead" matter.

With a purple selenite and the proper setting of

1, 2. Portion of leaf of Anacharis alsinastrum-"a" the hollow spine. The circulating granules do not pass to the point, but make a short cut across.

3. A portion from near point of leaf, showing the more circular form of cell.

4. A cell showing a helical motion. All are magnified about 900 linear.

The leaves are narrow, and, when full grown, are usually a great class of deposits known by the about gin. in length, name of the Silurian system. This formation was though in a specimen first examined and classified by Mr. (now Sir in my aquarium this Roderick) Murchison, who, with that zeal in length is very considerthe interests of science by which he has been ably exceeded. At the margin there is but so uniformly characterised throughout his distinone layer of cells, the remainder of the leaf being guished career, investigated the whole of this incomposed of two layers of cells, somewhat teresting group, and firmly established it as an shallow, and of irregular shape and size. A independent system, both in lithological and leaf mounted in fluid or glycerine jelly, when paleontological features. In our own country it examined by polarized light appears as a narrow is found to be mostly developed in that portion of frame of light when the prisms are crossed. almost necessitates one to ascribe powers of voli-England and Wales formerly occupied by the This may or may not be from the presence of tion to the granule. These people inhaThe protoplasmic current Silures, whence the name. silex in these cells. I incline to the latter notion. which carries the granules along is somewhat bited a large portion of South Wales, and some of the counties which border on that principality; the prisms, these cells assume the peculiarly rich narrow-perhaps on an average the united cur- but the system which has been named after them crimson colour which I have usually found to be rent of two sides of an oblong cell would equal is not co-extensive with the region which they incharacteristic of simple cellulose such as, for cells apparently restricted to its path between one-third of the whole width, and is in these longer habited, and although it is found for the most example, the cells of Aralia and the paren- the cell walls and the primordial utricle of part there, still small masses, or outliers as they chymatous cells of rush, of rhubarb, or rumex; Mohl. In the more circular (and younger) cells are termed, are found distributed over the whole and it may be mentioned that the vertical cell it is common to see the whole cell contents country, and appear in places far removed from walls (separating cells in the same plane) are seen, that at which it most copiously occurs. under a high power, to exhibit precisely similar Very often currents in contiguous cells may be The Silurian system is divided primarily into For anything like a careful observation of the the more easy to demonstrate that this rotation Lower Silurians; and these groups are subdivided seen to flow in opposite directions, rendering it two groups, called respectively the Upper and phenomenon of cyclosis in this plant a power of is wholly distinct from circulation. But what is secondarily into three subgroups, namely, the not greater focus than" is absolutely neces- it? By what is it caused-Osmotic force, or, Ludlow, Wenlock, and Llandeilo series, as in the sary. A higher power would be useful, but with subjoined list. care and dexterous illumination much may be as has been suggested to me, electrical agency? done with" and a deep eyepiece. It is useful In the attempt to gain a little light upon this to begin our observations at the broad end of the matter, I have immersed leaves of the plant in leaf, and to gradually work our way up. The cut (Fig. 2) gives a fair representation of the last

phenomena of polarization.

leaf I worked at. It will be seen that the

rotate about a central axis.

various fluids of different densities.

Perhaps I cannot do better than recount my experiments.

Glycerine Jelly.-This I made of medium solidity. A leaf immersed in it in a warm and moderately fluid state was set aside for some time in an ordinary sitting-room in the month of November. wards of three hours; the whole of this time I observed it every fifteen or thirty minutes for upcyclosis went on rapidly. The next morning, how

ever,

all was still.

cells at the broader end are oblong; that in the
middle they are irregularly rhomboidal; and that
at the upper end they become nearly circular. In
the lower cells the current, so far as I have seen,
invariably travels along the full length of the
cell in a perfectly regular manner. Sometimes
towards the middle I have found the axis of
rotation to be diagonal, and at the upper end the
Glycerine. I used Price's, of commercial
rotation is not infrequently in a circle. When quality. In every case where I have used this fluid
the leaf is first severed from the stalk rotation is at the temperature of the room rotation has ceased
almost invariably suspended for a short time, lowed immersion in syrup of like density.
almost immediately. The same result has fol-
during which the chlorophyll granules con-
gregate at each end (rarely in the middle, though Iodine solution immediately stops the current.
they are often said always to do so) in the oblong but faintly coloured, also generally stops rota-
Carmine fluid, slightly alkaline with potash, and
cells, and aggregate in a confused mass in the tion. In some cases, however, the phenomenon
more circular cells. It is most interesting to
watch the gradual commencement of the move-
goes on unimpeded and the current becomes
slightly stained.

* A faithful full-size drawing would be about 30ft. long and 7 or 8ft. broad. I have therefore given portions of the leaf.

Acetate of Rosaniline.-The results with this are most interesting. It appears to stimulate the current. The cells in which the rotation has

UPPER SILURIAN.

LUDLOW SERIES.-Red and green sandstones, with finely marked lamination and ripple-mark. Micaceous greyish sandstone, clayey limestone (known as Aymestry limestone).

Shale.

WENLOCK SERIES.-Limestone (known as Wenlock limestone).

Clayey shale.

Shaley lime and sandstones.
Grit, sandstone, and shales.

LOWER SILURIAN.
LLANDEILO SERIES.-Grits and shales, white
sandstone.

Dark limestone, flags, and slates.

It will be seen from the above statements that exclusively clayey, sandy, and calcareous (limey). the whole of the rocks composing this system are

The fossils of the Silurian epoch are very numerous, and there are a considerable number of species, upwards of 400 having been recorded, comprising fishes, crustaceans, annelids, several orders of molluscs and conchiferæ, crinoids and polyparia. Marine plants are also frequently

found, and the whole of the organic remains testify to the sole creation of aquatic beings, as no fossil of any terrestrial animal has ever been found in the system.

The Llandeilo group is seen principally in the county of Carmarthen, where it occurs on the banks of the Towy for a considerable distance. Its gentle but picturesque scenery renders it a pleasant change to the more wild and rugged rocks of the older formations. The little wooded hillocks, formed by the convulsions of a former age, give to the scene that quiet and peaceful beauty which excites within us an admiration of a passive, rather than of an active kind. Here we find none of those bare, hard, slaty rocks, whose jagged and rugged sides bear witness to the elemental vicissitudes to which they have been exposed; neither do we see those pointed peaks, whose appearance, at once picturesque and sublime, raise in us a sensation of admiration | akin to fear; but we have before us the gently undulating ground, rounded and beautiful, with a quiet feminine beauty, so to speak, which soothes the searcher after the sublime and picturesque, as much as the more masculine contour of the Metamorphic and Cambrian groups excite and awe him. I cannot better show the difference between the scenery of these two groups than by comparing them to a sea, which in the Metamorphic and Cambrian districts is as it were upheaved and lashed by the fury of some tropical gale, but which in the localities of the Silurian group is only stirred into a gentle swell, whose billows, wavy yet unbroken, give just enough of variety to prevent monotony, yet not sufficient to cause confusion.

This group, as found in the Caradoc range, exhibits certain peculiarities; the lime and sandstones, upheaved and dislocated by an emission of trap rock, are thrown up into elevated hills and rounded hummocks of considerable height; and the sandstone is in places turned into quartz, by reason of the contact of the molten trap, showing how greatly heat has changed the metamorphic rocks.

Immediately above the Llandeilo series lie the strata of the Wenlock group, the components of which are principally shale and limestone. This series extends from Wenlock as far as the Caradoc range, and embraces a large area of country. The strata are rich in organic remains, and the limestone affords a great proportion of that used for ornamental purposes, the richness of its fossils giving it when polished a variegated aspect most pleasing to the eye. Next in the system comes the Ludlow series, which consists of clayey limestones, grey, red, and green sandstones, and shales. This group is peculiarly interesting, owing to the variety of its strata and the great abundance of its fossils. The Aymestry

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+

The following are specimens of the formation of acids, monobasic and polybasic (di- triand tetrabasic) :—

1st.-Monobasic hydrogen nitrate (nitric acid).

molecule

+

nitrogen Two molecules hydrogen pentoxide

=

nitrate.

2nd. Dibasic hydrogen sulphate (sulphuric acid).

HO +
One

molecule
3rd.

acid).

(H2O)3 +

Water
phosphorus
three molecules pentoxide
basic acids:-
4th. The following are

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HO PO"" HO HO HO two molecules trihydrogen phosphate specimens of tetra

HO HO (HO

PO HO Hydrogen pyrophosphate.

Probably the beginner will be puzzled to know the signification of the above letters or symbols, therefore is annexed a list of the elements with their symbols and atomic weights.

PERISSADS.

[blocks in formation]

Strontium
Sulphur
Tellurium

BASES are metallic oxides which are decompose. when they come into contact with acids proper, or hydrogen salts when they yield a salt of the metal. Bases contain a metallic radicle called a basyl; thus potassium and calcium oxides contain the basyls potassium and calcium. Bases are not to be confounded with the basylons radicles which form salts by combining with chlo rous radicles. These radicles, if they are formed from a monad basyl, contain one oxygen atom; if the basyl is a dyad two atoms of oxygen exist and a triad basyl contains three oxygen atom united by half their force :

Symbol

Atomic
weight.

Molecular weight

Sb

122

488

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As

75

800

Bi

208

832

B

11

22

Br

80

160

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limestone (so called from the town near which it
mostly abounds) is useful in the industrial arts,
yielding when burnt a very celebrated lime used
as a subaqueous cement. It is in composition
clayey or argillaceous, and non-crystalline, but is
literally thronged with shells. In the sandstone
of this group have been discovered the remains of
the first created vertebrate, or backboned, animals,
in the shape of fish. These fishes belonged to
the family of sharks (Placoids), and were termed
by Sir Roderick Murchison Sphagodi (murderous
teeth), on account of the sharpness and length of
those organs: they appear to have lived upon
their weaker brethren of the ocean, and were in
fact, to use the words of the author above quoted,
without doubt the pirates of the sea of that
period." Fucoids, or sea-weeds, are very plenti-
ful in this group; and Encrinites (krinon, a lily)-
so called from their resemblance to that flower-
peopled the ocean's bed with their tiny forms.
Although from their name it may perhaps be
thought that these were vegetables, such was
not the case; they were animal organisms of the
order Radiata, and were somewhat similar to a
star-fish of the present time, anchored to the PERISSADS are those members of the group of
bottom of the sea by a long stalk-like appendage. elements which exhibit an uneven equivalency:
Sea-urchin-like creatures were also rife at this monads possessing one degree of chemical force,
epoch, in the form of Cystideans (kystos, a bladder); triads three, and pentads five. A pentad may act
curious in appearance were these little specimens as a triad, or even as a monad, by the mutual
of life on a lowly scale, somewhat resembling a saturation of its own force, which may be repre-
small spherical honeycomb perched on the ex-sented graphically in the case of nitrogen,
tremity of a waterlily's stalk. Bivalves, allied to thus :-
the oyster and mussel of our day, also flourished
in the seas of the Silurian epoch, together with
a great variety of Trilobites and other Crustaceans
of a higher order.

This system has, in common with the two succeeding ones (the Devonian and Carboniferous), been the chief repository of that all-powerful metal, which has in all ages and in all states of society

Silver..
Sodium

Tantalum
Thallium
Vanadium

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Triad bismil radicle.

SALTS are formed by the replacement of the hydrogen atoms in the acids proper by basya the haloïd salts are no exceptions, for sodiu chloride (common salt) is formed, by the repla ment of hydrogen in hydrogen chloride, by basyl sodium. It is therefore to be looked a as a salt formed from an acid, rather than direct combination of the metallic radicle with chlorous element.

As an instance of the formation of salts from acids by the successive replacement of hydrogen, we may take the tribasic acid, hydrogen ortho phosphate:

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