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[4579.]—DUTIES OF GAS ENGINEER.—I should feel obliged U "Sigma" or some of your other correspondents would give me some information concerning the duties of a gas engineer. What hooka 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 tbemwhenthe divisions arc in without having it unsightlv when they aro out. I do not mind a little trouble, as I am pretty handy at wood or wire work.—J. H. P.

[4581.]—LINK MOTION.—Will some reader bo 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 mo how gold-leaf books are prepared iu gilding so as to prevent the tendency of the leaf to fly about? I havo seen gilders use tUeni for out-of-door work. Tho 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.—Cuemiccs.

[4583.]— HALSE'S BATTERY, Ac—Perhaps "M. D." orsome other reader of "our" Mechanic, will give adcscription of how this machine is made. I have also some carbon dust that I want to make into blocks for n , Bunsen batten,-. Will some reader tell me how to proceed to make them?—Northumberland Subscbiber.

[4581.]—MANGANESE BATTERY.—Will Mr. Jarmau be so kind as to state how many quart size cells of his manganese battery are equal to a one-quart Bunseu battery?— Northumberland Subscriber.

[4585.] —AMBER MOUTHPIECE.—Can any reader toll mo how the amber for mouthpieces is softened, so that it can be bent or made pliable?—One Of The Oldest Subs.

f45815.]_WORKS ON COTTON.—Can any of your renders (particularly those interested in cotton spinning) give me the name and price of a good work on tho cotton plant? I want something of this sort: a work that has plate* of tho plant, showing the leaves and flowers, also the pods in their various stages; also of different sorts of plants, such as America*, Egyptian, Sea Islands, Surinam, Surat, China, <fcc. 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 tho very shortest, printed on paper, the paper being all black, and tho 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 alow in speaking, while all tho rest, fouroctaves, 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 podestrian tour t—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 plauts will grow and flower under these conditions—whetherthey 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 Beed, and the best sorts for growing in the shade.—A Factory Lad.

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

[4593.] — TEETH OF CHANGE WHEELS.—Will "J. K. P." please to toll me how the teeth of change wheels are struck out? I know how to strike out the epicycloidal form of tooth for wheels that always remain the driver or tho driven, but do not know how they are formed when tho wheels have to be changed, aa on the screw-cutting Lithe.—C. C.

[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 11 ml 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 tho matter?—Man Of Necessity.

[4594.]—GOM A 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 Qoma. The ___. small seeds, enclosed in the capsule, are so rich in oil that tho 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 bo useful in textilo 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 employments. This oil can be got in Germany from MM. Secger and Maur, in Dresden." Does any brother reader know some nioro particular* about this plant, its botanical name, &c.'f I find Hoi-mwah for a Chinese name of Cannabis saliva. Might not Go-ma procoed from that word ?—Bernardis.

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

[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 inscription. The coin is rather thick and somewhat larger than a farthing.—J. N. D. C.

[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 Beheerine »—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 i=* fatal to human life? Also what smaller proportion would have the effect of producing only insensibility in tho victim?—A. St. Vincent.

[4000.]— PRINTING IN GOLD OR BRONZE.—Will any reader tell me how I can print some cards with gold or bronze ink ?—Amateur Typo.

[4001.]—GILDING BOOK EDGES.-How can I gild the edges of some books I have just bound ?—A. H. 1>.

[4603.]—MELTING GLUE.—Will any of our cabinetmaker readers tell me how to melt glue properly? I mean so that I can keep it in tho glue-pot and re-melt just as I want it.—S. N. R.

[4008.]—FISIIISG.—Where can I catch small fish that will do to put in an aquarium, such as bleak, stone loaeh and gudgeon.—E. Jamiesox.

[4604.]—PICRIC ACID.—Can any of our chemical readers tell me what is picric 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 WINDMILL.—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 tan or screw? A statement to thi* effect appeared in the Illustrated London News, some weeks since, accompanied by a drawing.— Thos. C. Burton.

[4006.]—BUONV.ING IRON IN PAlNT."^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 bo adapted to make springs for organ pallets i'—W. Portkus.

[4608.]—FRICTION: HORSE POWER.—Will some reader state the amount of friction (in pounds) to be overcome by a horse in drawing a load of one ton on a lovelroad, made as follows ?—1st. On granite pavement. 2nd. On a broken granite surface. 3rd. On a gravel surface. The two last supposed to bo 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-eaue, with directions «bowing positioner air chamber, valves, charge, Ac?—A. Hu.NTEn.

[4610.]— SHUTTERS.—Will any of ray fellow millers tell me if the shutters in a patent sweep (on the lead side), should be at the point or heel of tbe sweep, the rest of the lead side being board? 1 have an idea tho shutters should come down, say two-thirds of tho way, and the rest made up as a lead board at the Point.—Ont: Ete.

[4611.] — POLISHING VULCANIZED INDIARUBBER.—Can any reader inform mo how to get a perfect surface on vulcanite for polishing, and what powder, Ac, 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.

[4612.]—PORTABLE MILL.—I am much obliged to H. W. Reveley for his reply to my letter. I thank him much for telling me of Smeaton's work, of which I had not known. There is only one thing 1 need remark on in his letter. He seems to think that the alow motion of tbe horizontal mill is a great drawback. It may bo for some things, but this slow and powerful motion is just what is wanted for other things, c.g., for agricultural purposes, such as Mr. Valla nee applied his to; and this, as he says in his lottor in the English Mechanic, was capable of drawing seven ploughs, and had arms only 12ft. long. Surely this was " useful work,*1 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. Rcveley's phin a trinl; but as I want a portable mill it would uot suit. While on tho subject, would Mr. Reveley or any other eorrespondontgive a plan fordrainingamarahy field by wind power? In '* Mechanical Movements," No. 259, there is something like what I want,but tho worm whecU would be difficult to got made here; and, besides, tho form of buckets given would not suit, as maud and mud would have to bo lifted out as well as water. The laud I want to drain is near tbe river, from which it has been embanked; it is too flat to allow of sufficient fall for the drain. I would sink a well ne;ir the embankment, and over this mount the windmill; but whether a horizontal or vertical one would suit best I do not know. For an endless band, with buckets attached, the vertical would bo best, I should think. If any practical man will kindly give me au auswer I should be much obligod.— Derf Errac.

[4613.]—TREE STUBIJER.—Will some one please describe a machine for pulling out tho stumps of trees? There is an American machino worked by horsepower. The principle is, I believe, a powerful screw. Particulars would oblige.—Djsrf Errac.

[1014.J — ELECTROLYSIS.—Will"Sigma," or "Ignorant Irishman," or any other siiW-ribor, kindly say whether electrolysis, such as eloctrotvpiug and dec-imposition of -.Llier substances, can be effected by the aid of a magneto-electric machine? Au answer through tbe Mkchamu will oblige,—Transpariext.

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bed cm coach painting, and where it is to be bough I rob able cost 5* Ami if there in no such book, will me be kind enough to give uie instruction as to ■le of procedure in coach pointing V—An Old Sub

I/]—LATHE QUERY.—TO "J. K. P."—I return a to " J. K. P." for his prompt reply to lny query Will he please refer to page iv. of the last number Of the English Mechanic? He will there see an fated advertisement of ft lathe by Greenwood lert*; uiv bead stock is like that one, and backd ; the mandril running in two collars ; the bed has % with saddle and brackets, to carry screw, same as jtntion, with swing p>ite. 1 wish to fit it to carry Avliile backwards and forwards, while the lathe is p&ff. Hind there is Hin. from centre of mandril to i of loading screw; will wheels of the 12 pitch do, tltted, -with backward and forward motion? Now, iiuy threads to the iuch, and what diameter for H screw? The one you mention—8 threads and leftd—would not do in this case, I should Bay. P.S.— _ uld like to see his 5in. head stock, but my place of lence is 150 miles from London, which place I should Is bis abode.—H. Williams.

163-3.]—WEIGHT OF BALL.—Would "Ferrum," in ly to my question on the weight of ball, oblige me by working of the mum, as I think he has omitted a at in reference to obtaining the weight of a yard of . ronnd wire? I don't think he will obtain it simply m multiplying tho squaro of diameter by "7864, and I unit see that to divide 60 by 6 gives 100.—Ralph

LLIAMS.

4683.] —WEIGHT OF METALS.—Would J. Nashalso J.ge me with the name and publisher of a gowd pracol work on the weight and strength of metals genery, and with the rules for obtaining tho same? How en be find tho cubic content of the ball to be 179*5918, .d where does he get his decimal '5236 from in the

. 7* x '5236 x 7045 „ , _ . ._ . ..

rmulft yu»n it* ?Am I to assume that the

Iuic (Hatton) in brackets is the name of the publisher rom which he gets his information; if so, would he bUge me with the price and particulars? By " Fcrum'a" rule there is a difference of 81b. in the weight of ant-iron ball to that of J. Nash's, so I am not exactly n a position to decide which to accept, and would be ;rateml to J. Nash for information respecting the book. -ralph Williams.

[4634.]—ELECTRIC CLOCK.—May I ask Dr. Stone, rho so amiably, some time ago, described the manganese lattery with which his electric clock is worked, add to ho obligations we are under to him, a short description ►f his time-piece, which, I am glad to learn, is giving him Io much satisfaction 'I I think, a considerable time ago, i 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, exhibitod in the Great Exhibition of 1851, but there must have been many improvements made since. I under stand 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 secrots to me. Many thanks to your learned correspondent "Sigma." — Electro-magnet, No. 1.

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

[463C.]—INCUBATOR.—I want to make an incubator. By referring back to Vol. X., No. 238, page 108, I find a Bketch 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. Pint-hen'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? Li there an opening at tho end for the chicks to escape through to the mother, and do the black dots in the outer end represent air-holet f Is the lamp-chamber open all through to tho glass case? Of what, and how, are the moiatening-dratcers constructed and connected with the egg-drawers? Is the zinc boiler entirely hid ftom view with the w-odwork,aud 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? Wbatarethe dimensions of the different parts of the incubator ?—Robin Hood.

[1637-]— FLEXIBLE CEMENT.—Could any of your correspondents suggest a flexi ble 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?—Pabvus 1'i.kk.

[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 tho first left off, and Bo 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.J-DYEING WOOL AND YARNS.—Will any of your correspondents kindly inform me if there is any book on dyeing wool, &c, and scouring yarns, Ac. ?— N. E. W.

[4640.]—SOUTH KENSINGTON EXAMINATION PAPERS.—Would any of your kind readers be so kind as to tell me whore I could get 4 South Kensington Examination Papers? Subjects :—

Organic Chemistry—l«t, or Elementary Paper, 1
H n 2nd, or Advanced „ 1

Inorganic „ 1st, or Elementary „ S

n ii 2nd, or Advanced „ 1

I have found it an utter impossibility to get them about

thin neighbourhood—Heckmondwiko, Yorkshire. By

inserting this you will oblige a triple subscriber.—J■

[4641.]— MILI.*BILLS,—Can any one inform mo how to harden mill bills, for Icaunot get them to stand ?—

J*-. I'.

[4041.]—GAS-HOLDERS.—I have a very leaky gasholder; it leaks at the rivets and all round the angle. Can any one tell mo the best cement to use that would stop the leakage, and would be lasting? 1 June put red and white load round, but it is not effectual; or would it bo safe to caulk it the saino as boiler-makers would, while it is full ?—B. L>.

[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 tho centro valve.—R. D.

[4644.]—CORN FLOUR.—Will somo fellow-reader kindly inform mc the process by which "corn dour " is manufactured from Indian corn (or maize), also from rice?—Josiah R. Neane.

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Paris, p. 382.

Naval Architecture, 382.

Black Diamonds for Drilling, 382.

Adulteration, 3s2.

■Water-wheel, 382.

Sign Writing 882.

Harmonium Heeds, 382.

Photography, 382.

Treatment of a Chrysalis, 382.

Unnoticed Queries on Magnetism, 382.

Medical Coil, 382.

Watchmaking, 382.

Incrustation in Boilers, 382.

Wire Netting Machine, 382.

Glycerine as a Substitute for Cod Liver Oil,

Anatomical Models, 383.

Paint for Aquarium, 883.

Gold Lacquer, 383.

Cotton Spinning, p. 406.

Fixing and Colouring Prints on Glass, 406.

Water Gilding, 40ti.

Re-working Vulcanizod Rubber, 406.

Associate of Art Degroe, 406.

Chemical, 406.

Cupelling, 406.

Testing Gold, 406.

Alabaster Class. To Mr. J. Leicester, 406.

Alloys for Tin Foil, 406.

Cotton Spinniug, 406.

Force Pump for Irrigation, 406.

Friction in Steam Cylinders, 406.

Millers, 4(16.

Brewing, 406.

Silvering Clock Dials, p. 407.

Sausages, &c., 407.

Madagascar Matting, 407

Cast-Iron, 407.

USEFUL AND S0LENTIFI0 NOTES.

REPAIRING LEAKY ROOFS, Etc.—Tho following is said to answer well in mending roofs that leak, and for similar uses:—Take two parts by weight 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, or other surfaces, carefully clean out of the cracks all earthy matters, slightly warm the edges with a plumber's soldering iron, then pour the cement in a lluid state upon tho cracks while hot, finishing up by going over tho 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.—Tho 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, tho metal is placed in a bath containing 10 per cent, of carbonate of potassa, and is next transferred t-j 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 throe to twelve hours, according to the thickness of the layer of zinc to bo desired.

PROPOSED MUSEUM AT BURNHAM, SOMERSET. —A feeling has been expressed that it would be an advantage to provide tho town of Burn ham with a museum for the collection of the curiosities of tho district- The idea (says a local journal) has been prompted by tho fact that Mr. E. Rosser, of College-street, who has devoted his attention to geology, is willing to dispose of hiB collection. One largo fossil possessed by Mr. Rosser is an Icthyosaurus, which is much admired. This splendid specimen of extinct animal existence was obtained from Street, near Glastonbury. He has alBo a very valuable ammonite. Besides these, Mr. Rosser posHpsso* a good collection of miuor fossils, stones, crystals, shells, Ac. This would form a good nucleus for a museum, and we hope means will be taken to make them the property of the town. Some Roman pottery a;id other curiosities dug up in the neighbourhood would doubtless he added by their owners.

A SPONTANEOUS COMBUSTIBLE GAS.—The hibromide of ethylene, when mixed with oxygen gas, takes fire spontaneously in the sunlight. Tho broiniue appears to combine with the hydrogen in a manner analogous to tho union of chlorine with hydrogen in the sunlight.

REAL AND APPARENT DEATH.-Dr. Laborde, in a paper recently read by him before tho Academy of Modicine in Paris, has endoavoured 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 prosont, he says, the needle, generally very soou, becomes more or less tarnished by oxidation; when, on the other hand, death has taken place, tho needle, even at the end of half an hour or an hour will retain its brightness. According to the Brit'uh 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 tho second, the complete absence of oxidation is a sign of real death. The communication has been referred to a committee, consisting of MM. Gavarret, Btclnrd, and Vulplau.

PRESERVED BREAD.—This bread is proposed a3 a substitute for the biscuk and " hard tack " used at sea. It is easily prepared, though the process is somewhat tedious. The bread is baked in tho 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 timo to the action of steam, and afterwards squeezed into tablets under an hydraulic press for twenty-four hours. The tablets can bo preserved for years in hermetically-sealed packages. Bread thus prepared retains a vitreous fracture, can be easily masticated by tho teeth,is admirable for bouillon and soup, and experience has shown that 200 pounds of good flour will afford 188 pounds of compressed tablets. An armv provided with this bread and Liebig's extract of meat would be prepared for any omergency that might arise. A soldier could easily carry several days' rations in his knapsack.

MUSSEL EATING.—It Is surprising tho 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 liko towns, will reveal the fact, that mussels were largely sought after and eaten by the manufacturiug class at tho time of the year when some restriction should be placed upon their sale, for during the mouths of May, June, and July, they are a dangerous commodity, not having recovered from the effects of spawning, and in many instances produce serious mischief. We (Medical Pre** and Circular) have lately observed tho grave results which ariso from a careless indulgence in mussels, from tho 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 samo care as that of the oysters, and where they are placed under the operation of fishery laws, we find, during four summer months, no mussels are sold for consumption in tho markets or shops. Even if they were, they would not bo so dangerous as the large, fat mussels to be found in our markets, and consumed with so much recklessness as to future suffcrina 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 fail to the duty of inspectors of markets to prohibit the sale of unseasonable articles of food. How often do we seo lobsters and crabs vended at a time when thoy are most baneful, and how frequently are our professional services required to minister to sufferiogs arising from the injurious effects of stale or unsoasonablo 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 duo to the fact that, of the light emitted from the former, about half tho quantity of rays aro 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 DO per cent, j for for white-hot platinum, 98 per cent.; alcohol flame, 99 percent.; electric light, 80, and gas-light, 90 por cent.; while for petroleum and parafhno oils, the amount is 94 per cent. It is this large quantity of caloric rays in artificial light which causes tho fatigue to the eyes; but this inconvenience may, according to tho author, be almost entirely obviiited by intercepting tho thermic rays by glass, or, better yet, mica plates. The use of theso renders the light soft and agreeable to the eyes.

FLUORSPAR IN GLASS MANUFACTURE.—Herr E. Richters, of Waldenberg, Gormauy, states that the substitution of fluorspar for lime in the manufacture of glass allows of a great reduction in tho amount of glauber salt, and greatly promotes the melting of the frit. As tho result of numerous experiments conducted on a large scale, ho found that, with the same consumption of fuel and similar length of time, the amount of glauber salt required could be diminished ono half by substituting fluorspar which had proviously been pulverised and calcined for tho lime usually employed. In countries where fluorspar can be had in abundance its introduction into glass manufacture would appear to offer many important advantages. The following are the proportions taken:—With fluorspar: Sand, lll'441b.; fluorspar, 27'69lb.; glaubor salts, 4*901 b.; inangane-e, 4-091b; charcoal, 2001b.; glass frit,299-OOlb. With lime: Sand, 116'401b.; lime, 15551b.; glaubor salts, 8'OOlb.; manganese, 3001b.; charcoal, 2-001b.; glass frit, 248-OOlb.

ANTIQUITY OF THE MITRAILLEUSE.—We give the following curious evidence that the mitrailleuse is only a revival of an old invention, from "Grose's Military Antiquities" (1801,, vol. ii., p. 165:—" A patent was granted by King Charles I. to William Drtmnnond, of Hawthornden, in 1625, for the solo making and vending, for the spaco of 21 years, of tho following machines and warlike engines invented by him. The patent is printed inhis 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 thethundering chariot, and vulgarly, the fiery waggon."—Spectator.

THE RIGHT AND THE LEFT HAND.—Dr. Dwiglit, a writer in the Journal uf Psychological Medicine^ maintains thnt (be pravalent as© of tbo right hand in preference to the left is not merely duo to habit or education, 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 tho other, Dr. D wight 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 tho 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 it inins. 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. Tho whole taking place in one hour's time.

PRESERVED MILK.—If a full milk diet could bo obtained for the children in every cottage, how often would the sickly infant live, the poor, ricketty child grow into an active boy, and tho 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 ill the county Cork, Ireland. In this manner the "green pastures" of the sister i«le may indeed be made to confer a substantial Messing 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.— Food Journal.

WOOTZ.—In 1819, while Faraday was an assistant in the Keyal Institution, he made nn 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 waa 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 analvsis:—Carbon, 0*867; silicium, 0*136; phosphorus, 0-099; sulphur, 000*2. 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.

REVERSION SPECTROSCOPE.—An important addition to the resources of spectrum analysis has been made by Zollner'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 tho spectrum on the ono wide, 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.

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 Btones 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 tho level of the ground. With regard to their finish, these Syenite stones are of the very hardest known, and yet they arc so exquisitely polished, and built in (to form a casing for the king's chamber) with snch 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. Sucli workmanship would excite the wonder and admiration of the world, even in this age of science and improvement.

A PETRIFIED SEA-MONSTER.—A very beautiful and interesting petrified sea-monster has, according to tho White Pine Nevada Neics, been lately discovered about 100 miles to tho south-east of Hamilton, on a high plateau of land containing an extensive deposit of marine shells and tho 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 present* a dual appearance—the head and body are thnt of a huoip-back whale, while the extremities extend into feelers and antenna?, like the polypus or devil-fish, with the exception that thev 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 polid osseous formation, u nning back from the widest portion of the head.

A NEW INDIAN MEDICINE.—We have received from Mr. Naravan IMjt, of Bombay, a paper read before the Grant College Medical Society, containing an account of a new Indian drug—the bark of Ailantus rxcelsa , Roxb. This tree is common in many parts of India, and its bark can be obtained iu sufficient quantitv for general use. The active principle of tho 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 iwcful 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 bo mado containing the concentrated extract. The bark alone contains the active agent, in combination, as tar as has yet been discovered, with lime, carbonate of lime, salts of magnesia, alumina, un cry stall izable sugar, gum, and a trace of volatile oil andngnin; 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."

ANSWERS TO CORRESPONDENTS.

*,* Ail communications should be addressed to the Editor of the English Mechanic, 81, Tavistockstreet, Covent Garden, W.C.

EMPLOYMENT COLUMN.

We have frequently been asked to devote a portion of our space to cheap or rather SMALL Wanted Advertisements, and wc now propose to do Bo under the beading "Employment Column." Hundreds of skilled labourers are continually wanting employment, and very frequently employers are in want of skilled labour. These want', 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 choap and expeditious medium whereby the ono 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. We think the English Mechanic is just the organ for such a purpose. This, in most cases, may be done in a very few words. Wo therefore place at the disposal of all who may want it,

OUR EMPLOYMENT COLUMN.

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

The following are the initials, Ac, of letters to hand np to Tuesday morning, August 23, and unacknowledged, elsewhere:—

C. J. Richards, F.R.C., M.D., G. Brian, W. Perryman, C. H. A.,G. E. Davis, J. M.. J. S., J. W. D., J. M.T., Jas. Page, C. V. Riley, E. Leywood, Payne & So:«s, Thomas Hawley, J. H., Lieut. Jas. B., F. H. S., E, H., H. M. M., G. V. M., T. Oseland, R. Brereton, T. H.( M. H. B., Sable with MSS., T. S. H., with do., W., Ask worth Bros., Esperance, with MSS., F.R.A.S., with do.. H. P., with do., Fellow of the Royal Microscopical Society, with MSS. (next week), T. L. H., A. S. C, Enquirer, 8 ♦ * * * * * r, M. G. Morgan, Coustans Lector, John Ross, F. J. Walker, J. Briggs, A. Bros., A Clergyman, Orme Bros., A. M. W., O. E. R., H. W. Henfrey, A. Tolhausen, D. D., A Carpenter, J. L. F., R. A., Mons Meg., H. Jameson, F. R. T., Billy, Student, A Mineralogist, Fortunate, R. T. Ellicslaw.

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.

G. Lcff.—Will answer by post in a day or two.

A Blackshith.—Mr. Bum's book would, wo think, suit you.

H. H.—The address counts as part of tho 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.

P. H. S. says " on the principle that every one should kelp his neighbour, I venture to ask you ifyou 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.

8. R.—Yes. Caunel coal is largely used for making ornaments. It is found principally around Wisan. as well as near Manchester and in Scotland. A very fin.1 caunel is found in Flintshire, where It is used for the distillation of coal-oil.

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AND

[KROR OF SCIENCE AND ART.

FRIDAY, SEPTEMBER 2, 1870.

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CYCLOSIS IN ANACHARIS. IE "American" or "new" waterweed is all too common to need much description. ie cut (Fig. 1) will enable any of our readers to recognise it at sight. The leaves, of pale green, grow in a whorl of three, the stem being at this point exceedingly brittle. The plant is very easily propagated. Almost the smallest piece thrown into spring water, or into a stream or pond, will rapidly grow and increase, so that the microscopist who once succeeds in obtaining a piece may ensure a constant supply, live wheresoever he may. My own acquaintance with the plant extends only over about twelve months, but during that time I have devoted to it a considerable amount of attention. The results of my observations sbiii now be given.

The leaves S28 narrow, and, when full grown, are usually about gin. in length, though in a specimen in my aquarium this length is very considerably exceeded. At the margin there is but one layer of cells, the remainder of the leaf being composed of two layers of cells, somewhat shallow, and of irregular shape and size. A leaf mounted in fluid or glycerine jelly, when examined by polarized light appears as a narrow frame of light when the prisms are crossed. This may or may not be from the presence of silex in these cells. I incline to the latter notion. With a purple selenite and the proper setting of the prisms, these cells assume the peculiarly rich crimson colour which I have usually found to be characteristic of simple cellulose—such as, for example, the cells of Aralia and the parenchymatous cells of rush, of rhubarb, or rumex; and it may be mentioned that the vertical cell walls (separating cells in the same plane) are seen, under a high power, to exhibit precisely similar phenomena of polarization.

For anything like a careful observation of the phenomenon of cyclosis in this plant a power of not greater focus than J" is absolutely necessary. A higher power would be useful, but with care and dexterous illumination much may be done with f and a deep eyepiece. It is useful to begin our observations at the broad end of the leaf, and to gradually work our way up. The cut (Fig. 2) gives a fair representation* of the last leaf I worked at. It will be seen that the 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 rotation is not infrequently in a circle. When the leaf is first severed from the stalk rotation is almost invariably suspended for a short time, during which the chlorophyll granules congregate at each end (rarely in the middle, though they are often said always to do so) in the oblong cells, and aggregate in a confused mass in the more circular cells. It is most interesting to watch the gradual commencement of the move

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

1, 2. Pftrtion of leaf of Anacharia alsinastrum—" a " the hollow Bpine. Tho circulating granules do not pass to the point, but make a short cut across.

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

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

almost necessitates one to ascribe powers of volition to the granule. The protoplasmic current which carries the granules along is somewhat narrow—perhaps on an average the united current of two side s of an oblong cell would equal one-third of the whole width, and is in these longer cells apparently restricted to its path between the cell walls and the primordial utricle of Mohl. In the more circular (and younger) cells it is common to see the whole cell contents rotate about a central axis.

Very often currents in contiguous cells m ay be seen to flow in opposite directions, rendering it the more easy to demonstrate that this rotation is wholly distinct from circulation. But what is it? By what is it caused—Osmotic force, or, as has been suggested to me, electrical agency? In the attempt to gain a little light upon this matter, I have immersed leaves of the plant in various fluids of different densities. Perhaps I cannot do better than recount my experiments.

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

Glycerine.—I used Price's, of commercial quality. In every case where I have used this fluid at the temperature of the room rotation has ceased almost immediately. The same result has followed immersion in syrup of like density.

Iodine solution immediately stops the enrrent.

Carmine fluid, slightly alkaline with potash, and but faintly coloured, also generally stops rotation. In some cases, however, the phenomenon goes on unimpeded and the current becomes slightly stained.

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

ceased beco oo deeply stainod, 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 reBist 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 conclusion— that this is one of those phenomena we call vital, and that it may bo regarded as analogous to the circulation of tho 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. H. P.

THE WORLD: ITS FORMATION AND ANTIQUITY.

By Abthcr Underbill.

(Continued from page 484.)

Chapter VII.

ABOVE the strata of the Cambrian group lies a great class of deposits known by the name of the Silurian system. This formation was first examined and classified by Mr. (now Sir Roderick) Murchison, who, with that zeal in the interests of science by which he lias been so uniformly characterised throughout his distinguished career, investigated the whole of this interesting group, and firmly established it as an independent system, both in lithological and palicontological features. In our own country it is found to be mostly developed in that portion of England and Wales formerly occupied by the Silures, whence the name. These people inhabited a large portion ot South Wales, and some of the counties which border on that principality; but the system which has been named after them is not co-extensive with the region which they inhabited, and although it is found for the most part there, still small masses, or outliers as they are termed, are found distributed over the whole country, and appear in places far removed from that at which it most copiously occurs.

The Silurian system is divided primarily into two groups, called respectively the Upper and Lower Silurians; and these groups are subdivided secondarily into three fmbgronjM, namely, the Ludlow, Wenlock, and Llandeilo series, as in the subjoined list.

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 the',whole of the [rocks composing this system are exclusively clayey, sandy, and calcareous (limey).

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 conchifene, 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 Llandoilo 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 pleasaat 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 Metarnorphic 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 meta- morphic rocks.

Immediately above the Llandeilo series lie the strata of the Wenlock group, the components of which are principally Bhale and limestone. This series extends from Wenlock as far as the Caradoc range, and embraces two 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 limestone (so called from the town nearwhich it mostly abounds) is useful in the industrial arts, yielding when burnt a very celebrated lime used as a subaqueous cemont. 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 (Placoidm), and were termed by Sir Roderick Murchison Syhagodi (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 plentiful 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 bottom of the sea by a long stalk-like appendage. Sea-urchin-like creatures were also rife at this epoch, in the form of C'ystidean* (/castes,bladder); curious in appearance were these little specimens of life on a lowly scale, somewhat resembling a small spherical honeycomb perched on the extremity of a waterlily's stalk. Bivalves, allied to 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-powerfal metal, which has in all ages and in all states of society

so uniformly influenced man; truly sang Horace

Anrum per medioB ire satellites,
Et perrumpere aixutt aaxa, potentius
It in fulruineo.

Which has been translated somewhat freely—

Stronger than thunder's winged force,
All powerful gold can speed its course,
Through watchful guards its passage make,
And loves through solid stones to break.

(To be continued.)

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By George E. Davis,

Honours Certificated Teacher.

(Continued from page 507).

Chapter II.

IN our last chapter we broke off in the midst of acids, bases, and salts ; in the present we will continue the subject, including their crystallography, of which the student should possess a fair knowledge. We will then commence by showing the formation of acids.

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

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

HaO + \ O

I NO, Water one

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Two molecules hydrogen nitrate.

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Alumuiiuni ..

Barium

Cudiuium

Calcium

Carbon

Cerium

Chromium ..

Cobalt..

Copper

Didymium .

Erbium

Oluoinum

Indium

Iridium

Iron

.largonium ..

Ltuith&uuin ..

Lead

Magnesium ..

Manganese ..

Mercury

Molybdenum

Nickel

Osmium

Oxygen

Palladium

Platinum

Rhodium

Ruthenium .

Selenium

Silicon

Strontium

Sulphur

Tt 11 uiiu hi .

Thorium

Tin ..

Titanium

Tungsten

Uranium

Yttrium

Zinc ..

Zirconium .

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Water , phosphorus

three molecules youtoxide

4th.—The following basic acids :—

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The Artiads exhibit an even eqarralax-/ ef two, four, or six hexads combinm? A> k<.ni< or dyads, as in the case of sulphur :—

n a «

-S- -S- =8=

0 II

Dyad. Tetrad. Heiad. Bases are metallic oxides which are decompose when they come into contact with acids propel, or hydrogen salts when they yield a salt of the metal. Bases contain a metallic radicle called a basyl; thuB potassium and calcium oxides con- tain the basyls potassium and calcium. Basei are not to be confounded with the Wayhnu radicles which form salts by combining with chlorous 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 exiitand a triad basyl contains three oxygen atoms united by half their force:—

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Salts are formed by the replacement of tW hydrogen atoms in the acids proper by has; > the haloid salts are no exceptions, for sodru chloride (common salt) is formed, by the repW ment of hydrogen in hydrogen chloride , by basyl sodium. It is therefore to be looked s» as a salt formed from an acid, rather than a* > direct combination of the metallio radicle witi' chlorous element.

As an instance of the formation of sal tn froE acids by the successive replacement of hydrogen we may take the tribasic acid, hydrogen orth phosphate:—

Nat
Na f PO,

Na)
Tri-sodium
phosphate.

The metallic radicles which enter into combination with the acid radicle, need not of necessity, in a polybasic acid, be of the same kind. The hydrogen in the above orthophosphate inny be replaced by different radicles, as in the case of hydrogen sodium potassium phosphate (1), or in microcosinic salt (2).

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