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The English Mechanic

AND

WORLD OF SCIENCE AND ART.

IN

FRIDAY, APRIL 12, 1872.

ARTICLES.

PUDDLING MACHINES.

N the account of Danks's rotary puddling furnace, which we gave on p. 579 of our last volume, we alluded to the probability of supplementary reports being presented at the meeting of the Iron and Steel Institute, in order that a clearer idea of the whole bearing of the new invention on the iron industry might be rendered more easily obtainable than was possible from the necessarily incomplete description of the process furnished by the Commissioners on their return to this country. Mr. G. J. Snelus, one of the Commissioners, has now presented to the Institute at its recent meeting, as full a report on the scientific, practical, and commercial aspects of the process as the time at his disposal enabled him to accomplish; and from the manner in which the invention was spoken of at the meeting, a great and important change in the manufacture of iron is about to be inaugurated. In fact, it has been stated that Mr. Danks has entered into an agree

ment with a number of iron-masters, representing various districts, to permit them to put up 200 furnaces on his plan in consideration of a payment of £50,000 in six months. As few of the manufacturers intend to remove their old handpuddling furnaces, this will represent an enormous increase in the puddling power of the industry, equal to an additional make of 300,000 tons

a year.

positively known, but it is believed to unite with about once every half-minute for the first eight
the slag as sulphide of iron, or, becoming oxidised, minutes or so in order to insure the perfect action
to pass away with the gases from the furnace. of the cinder upon the molten metal. At this
In the Danks furnace, however, the whole of the stage of the process a jet of water is directed
necessary oxygen is obtained from the fettling, against the lining on the descending side, so as
and it was the failure to secure this necessary to solidify a portion of the cinder, which is thus
property in the lining of the metal bath that carried under the melted iron, and rising up
proved so great a stumbling-block to the intro- through it combines with and removes the impu-
duction of a machine for mechanical puddling; rities in a more effectual manner than has
for some years ago Mr. Menelans, who is a hitherto been the case, even with hand puddling.
most untiring experimenter in this direction, all Mr. Snelus thinks that the jet of water also has
but succeeded in producing a rotary puddling the effect of carrying off sulphur from the
furnace, being stopped solely by the difficulty of cinder. In about ten minutes after the pig iron
procuring a suitable compound for fettling pur- is all melted the cinder is run off, carrying with
poses. It was at this stage of the invention it a large portion of the products of the sulphur,
that Mr. Danks, of Cincinnati, took up the sub- phosphorus, and silicon, and the iron begins to
ject, and after numerous experiments hit upon a boil. The chamber is now made to revolve six
method of fettling with a material which gave the or eight times in a minute, and a high tempera-
desired results. The revolving chamber or ture being kept up the iron is thrown about vio-
puddling bath of his machine, which we illustrated lently till the process is complete, and the speed
on p. 579 of the previous volume, is constructed being reduced the ball begins to form. The
with longitudinal wedge-shaped recesses on its stopper hole is now opened, and the ball partially
interior face, which assist in firmly holding the solidified by means of a tool, when the head-piece
mixture forming the first or initial lining of the is
puddling chamber. This lining consists of an
ore free from silica, ground up and mixed with
lime cream, so as to form a kind of mortar, which
adheres to the plates forming the revolving
chamber, and when dried becomes refractory, and
sufficiently cohesive to allow of the fettling proper
being melted upon it without itself melting, or
separating from the plates of the furnace. On
this initial lining a quantity of ore, free from
silica, is melted and distributed over the whole
surface by slowly revolving the chamber, and

removed and the ball taken out by means of a lifting-fork, as described in the previous article.

The defect of the process as here described, however, consists in the fact that the time taken to melt the charge is actually longer than that occupied in puddling-viz., from 30 to 50 minutes for a charge of 600lb., and this time consequently represents a large consumption of fuel. It is so far satisfactory to find, nevertheless, that this defect is one the removal of which offers no insuperable difficulty; for finding that while the new puddling furnace is economical in the working of its own peculiar duty, it is a bad melter of the iron, Mr. Snelus points out that the charge must be melted elsewhere and brought to the mechanical puddler in the molten state. By the adoption of this method, he thinks that not only would a moiety of the fuel be saved, but twice the number of heats might be obtained in the same time. The arrangements for firing and regulating the blast of the furnace form an important part of the invention, and contribute largely to the success of the system as a whole. The puddler has, in fact, complete control of his fire; by means of a valve he can so regulate the blast as to urge the furnace to an intense heat or to almost stop combustion altogether. This blast also serves to prevent the entrance of air at the joint between the revolving chamber and the furnace, the full pressure inside stopping its ingress, and thus avoiding all waste of iron which might be caused by the admission of free oxygen.

With regard to the cost of puddled iron by the Danks process, Mr. Jones, the member of the Commission who has drawn up the supplemental report upon this part of the question, estimates a saving of 10s. 8d. a ton, but considers that this is considerably underestimated. Mr. Danks, however, claims a saving of £1 a ton, and it is probable that when the machine is brought into extensive operation, that figure will be reached if it is not exceeded. The effect of so large a rewhile this coating is in the molten state large lumps duction in the cost of producing malleable iron, of similar ore are thrown in, and being cold cause together with the ascertained fact that 12 of the melted metal to set round them and fix them Danks's rotary puddlers will turn out as much as firmly, thus producing a rough lining with & 50 of the old hand-worked furnaces, for which of largely increased surface to act upon the charge late years it has been difficult to obtain a supply of pig iron. It is absolutely necessary that these of competent men, owing to the laborious and lumps should be of such a texture that they will exhausting nature of the work, will speedily not crumble with heat, and they must be nearly make itself felt in commerce. So that taking free from silica. "6 Tap cinder"-i.e., cinder ob- into account that this new rotary puddler disThe theory of the puddling process is described tained from a heating furnace where a bath of penses with the killing labour of its human by Mr. Snelus at the opening of his report, and oxidised iron is used to protect the plates instead namesake, besides doing his work better and if we give an abstract of this, the advantages of sand is a suitable material both for the lining cheaper, it is not to be wondered at that the obtained by the employment of Danks's furnace and the lumps, but where this cannot be had, and report of the Committee has been received and will be apparent to our readers. Pig iron is the ores free from silica are difficult to obtain and ex-adopted by the Iron and Steel Institute, and metal in what may be termed its raw state; it is pensive, Mr. Snelus thinks it would pay to that arrangements are being made for the combined with sufficient carbon to render it oxidise scrap iron for the special purpose. A erection of a large number of Mr. Danks's fusible at what is comparatively a low temperature, great advantage of the mechanical puddling proand is possessed of little malleability. A few other cess is found in the larger yield of metallic iron, elements are generally found in the raw pig, such a portion of which is obtained from the lining of as sulphur, phosphorus, silicon, and manganese, the furnace; for it is obvious that if the necessary and the object of the puddling process is to oxygen for oxidising the carbon in the pig is obrender the iron malleable by removing these "im-tained solely from the oxide of iron forming the parities" and the excess of carbon. This is accomplished by submitting the iron to a process of oxidation, the oxygen for which is obtained, in the old process, partly from the "fettling" or lining of the metal bath, and partly from the air which finds its way in through the door at which the puddler introduces his rabble or stirring-rod. By this means the carbon is converted into carbonic oxide or carbonic acid, the silicon into silica, the phosphorus into phosphoric acid, and the manganese into manganous oxide, and these are either carried away or pass into the sing. What becomes of the sulphur is not

lining the latter must be reduced to the
metallic state, and so help to swell the yield of
puddled iron. It is also worth mention that
under these conditions the carbon is oxidised to
its highest point, and more pure metal is obtained
than when carbonic oxide alone is produced.

The fettling having been successfully accom-
plished, the pig iron to be puddled is introduced
in large lumps, the charge being generally about
600lb. The chamber is then slowly rotated at
intervals, so as to expose the charge equally to the
action of the flame, and when the whole is in the
molten state the chamber is made to revolve

furnaces. The opinions expressed at the meeting were unanimous in its favour, and, together with the high commendation pronounced by Mr. Menelaus, must be very gratifying to Mr. Danks.

It must not, however, be supposed that while success has thus fallen to the lot of an American, it has not been striven for, and in a measure obtained by, our own inventors. Mr. Spencer has succeeded in constructing a rotary puddling machine, in which the revolving chamber is made up of troughs. The results obtained from this machine are described as being highly successful, but as the iron is divided into comparatively small balls, although this is convenient for after operations, the general opinion was that from the greater expenditure of the fuel and the increased size of the machine itself, it was not so valuable an innovation as the Danks

machine. We may, however, give an illustration portions-viz., Cla'O". (See Odling, Becquerel, seizes on the oxygen of the chloric acid, expels the chlorine, and takes its place, thus :and description of it in a future number. In the Gmelin, &c.)

=

mean time we illustrate what we may term an 121.-CHLORO-CHLORIC ACID.-Synonym: Chlo-
adaptation of Mr. Danks's principle to the exist-rate of Chlorine Trioxide. When a current
ing furnaces, the joint design of Messrs. Howson of eachlorine is passed through a series of U-
and Thomas. The object of these gentlemen is shaped tubes, cooled by a freezing mixture, this
to construct a machine which, while operating body condenses as a red fluid, while chlorine gas
on the principle of the rotary puddler, shall uti- escapes. It resembles strongly chlorine tetroxide,
lise as much of the present working plant as but differs from it, inasmuch as it does not boil
possible, so as to avoid the large expenditure of till it reaches 89-6° Fahr.1, nor explode below 70°
capital rendered necessary by the impending Fahr. The composition of this body has been
revolution in the iron trade. Experiments have given by Millon as 2C1,'O", Cl, 'O", or, what
as yet only been made under imperfect arrange amounts to the same thing, Cl'O13. Its formation
ments, but the inventors consider that with more from euchlorine may be expressed thus:---
complete details their machine will provide a
Cl18'013" 2C12'06, Cla'Os" + 7C1'.
satisfactory makeshift for the Danks's furnace,
and thus avoid the total loss of the now "old- 122.-CHLORO-PERCHLORIC ACID.-Synonym :
fashioned" plant which is still sound and good. Perchlorate of Chloride Trioxide.-On exposing
The section represents an ordinary paddling fur- chlorine trioxide to the action of light, at
nace, from which the hearth is entirely removed, a temperature of about 68° Fahr., this compound
and the revolving chamber B mounted in its place. separates as a reddish brown liquid, smelling
A is the ordinary firegrate, which, however, it somewhat like bromine, and fuming strongly in
may be advisable to slightly modify, and C is the the air. When acted on by caustic potash, a
flue leading to the uptake, which would remain in mixture of two molecules of potassium percholate,
much the same state as at present. The revolv- K'Cl'O,", and one molecule of potassium chlorate,
ing chamber, B, is of wrought iron with cast- K'Cl'O" is formed, hence its composition is sup-
iron trunnions, and is preferably constructed of posed to be
two cones, fitted base to base, for convenience in
lining. The trunnions are mounted on rollers on
a carriage which runs on wheels in a direction
across the axis of the furnace. By means of this
carriage the chamber is run out between the flue
and the firegrate for the purposes of being lined
and charged, and for removing the puddled ball.
The lining is made of bricks of ground oxide of
iron burnt very hard, and the shape of the
chamber being favourable a lining thus formed
will wear down to fin. without giving way. The
great difficulty to overcome in adapting this
chamber to the present furnace consists, of course,
124. Several oxides of bromine corresponding
in rendering harmless the cold air which finds its
way in at the gap between the chamber and the with those of chlorine are known. They present
firegrate—a gap which is obliged to be left in con- great analogy with the relative chlorine oxides ;
sequence of the expansion of the casing by heat. but as they have been little studied, and are up
This is accomplished by making the opening to the present of no practical use, we shall con-
against which the trunnion works of two cast-iron fine our attention to the three following, which
rings inclosing an annular space which communi- are the most important.
cates either with the chimney, by means of a.
separate flue, or with the fire, as shown in the
figure, by means of a pipe, E. A draught is thus
formed in the annular space, which draws away
the air leaking in at the joint, utilising it at the
most serviceable point, and reducing leakage into
the working chamber to a minimum. Screens are
provided to prevent loss of heat when the chamber

is run out, and the puddled ball is readily removed by tipping the chamber when it is drawn beyond the screens, which are perforated with holes for observation and manipulation. The chamber is worked by a steam-engine with 7in. cylinder and 7in. stroke, the gearing giving revolutions of three and six to the minute. It is probable that within the next few months great improvements will be made in the puddling process, now that so many minds will be directed to the subject, and are acquainted with what has been already accomplished; for economy in fuel alone is well worth anxious study and enterprising experiment.

LESSONS ON CHEMISTRY."
BY SELIMO R. BOTTONE.

(Late of the Istituto Bellino, Novara, Italy.)
(Continued from p. 30.)

119.

-OTHER compounds containing chlorine and oxygen exist, but their constitution is doubtful, their composition uncertain, and their very existence as definite compounds is, by many, disallowed. We will notice briefly a few of these bodies, referring the reader who may be desirous of entering into details to the works of Gmelin, Watts, and Millon.

120.-EUCHLORINE.-If a mixture of a chlorate

along with hydrochloric acid be gently heated, a bright yellow explosive gas is evolved, which is the body in question. The composition of this body is constant; but as, by exposure to cold, it resolves itself into chlorine gas and another oxide of chlorine, it is regarded by chemists as a mere mixture. Its composition would appear to be

C17, 2012'Os", Cl2'Os"; or Clis'O13". Some chemists look upon this as the missing link in the chain of oxides of chlorine, and represent its formula by a submultiple of the above pro*The right of translation and reproduction is reserved.

123. We have seen that the most stable com-
oxygen is chlorine
pound of chlorine with
heptoxide; indeed, all the others are resolved
into this by heat; hence Millon, who gave the
subject much attention, inclined to the belief that
chlorine with
the only definite compounds.
oxygen are chlorine monoxide, chlorine trioxide,
and chlorine heptoxide.

SECTION 6c.-COMPOUNDS OF OXYGEN WITH

BROMINE.

=

K'Cl'Og" + Br' K'Br'03" + CI'. From the bromate bromic acid may be prepared as mentioned at paragraph 115, substituting the bromate for the chlorate.

C. BROMINE HEPTOXIDE.-Synonym: Perbromic anhydride. Symbol: Br2'O" (?) Molecular weight: 272 (?).

131. Unknown in the free state. Combined

with the elements of water, it forms :—

c (2). PERBROMIC ACID.-Synonym: Hydrogen Perbromate. Symbol: H'Br'O". Molecular weight: 145.

132.--PROPERTIES.-Very similar to those of perchloric acid; but its oxidising power is not so great, and its affinities are not so powerful.

133.-PREPARATION.-By adding bromine to perchloric acid as long as chlorine is evolved. The interchange is expressed by the annexed equation :—

H'Cl'O," Br' = H'Br'O," + Cl'. By this we learn, that although the affinity of chlorine for hydrogen is greater than that of bromine, yet this latter element has a stronger attraction for oxygen than chlorine has, and hence is able to expel chlorine from its oxygen compounds. SECTION 6D.-COMPOUNDS OF OXYGEN WITH

IODINE.

Several of these have been described. We shall notice the three most important.

A. IODINE MONOXIDE.-Synonym: Hypo-iodous
Molecular
Symbol: I'0" (?).
anhydride.
weight: 270 (?).
134. This body is unknown in the free state.
(2).-HYPOIODOUS ACID.-Synonym: Hydrogen
hypoiodite. Symbol: H'I'O". Molecular
weight: 144.

135.-PROPERTIES. -A pale, straw-coloured,
transparent liquid, smelling somewhat like ozone.
It first reddens and then bleaches vegetable
blaes, but the bleaching action is very tardy and
imperfect.
2

BROMINE MONOXIDE.-Synonym: Hypobro-
mous anhydrides. Symbol: Br,'0" (?) Mole-
cular weight: 176 (?).

125.-Up to the present time this body has
not been isolated. In union with the elements of
water it forms the following compound
(2). HYPORROMOUS ACID.-Synonym: Hydrogen
Hypobromite Symbol: H'Br'O". Molecular
and combining weight: 97-0.

126.-PROPERTIES.-Almost exactly those of
hypochlorous acid; but as bromine holds oxygen
with greater tenacity than chlorine does, its
bleaching powers are not so active. The hypo-
bromites are almost indistinguishable from the
corresponding hypochlorites.

127.-PREPARATION.-When an aqueous solution of bromine acts on mercury oxide it gives rise to mercury bromide and hypobromous acid. (See 101.)

136.-PREPARATION.-If a few crystals of iodine be placed in a watch-glass, under a glass bell, with a stratum of well-slaked lime surrounding the watch-glass, the iodine gradually volatilises and is absorbed by the lime, which becomes of a more brilliant white, and is found to possess properties similar to those of "chloride of lime," but not nearly so active. Care must be taken that the temperature does not exceed 60° Fahr., as in this case little or no hypoiodite is formed.

When the body thus formed (consisting of calcium iodide and hypoiodite) is distilled along with dilute nitric acid, or, better, with dilute acetic acid (1 part acid to 4 of water), hypoiodous (S. Bottone.) It is worthy acid passes over. of note that the "iodide of lime," prepared as directed above, possesses more active bleaching powers than does the free acid itself. If, in the preparation of the acid (from the hypoiodite), B. BROMINE PENTOXIDE.-Synonym: Bromic anhy-sulphuric acid be used instead of nitric, or if the dride. Symbol: Br2'O"? Molecular weight: nitric acid be too strong, iodine, together with 240 (?). hydriodic acid, and not hypoiodous acid, is liberated.

128.-Like the relative chlorine oxide this body is unknown in the separate state.

Hydrogen

B (2). BROMIC ACID.-Synonym :
bromate.6 Symbol: H'Br'03". Molecular and
combining weight: 129.

B.-IODINE PENTOXIDE.-Synonym: Iodic anhydride. Symbol: I'O". Molecular weight: 334.

137.-A white crystalline solid with a strong 129.-PROPERTIES.-A colourless, almost in- acid taste. Prepared by heating iodic acid (see odorous, oily fluid, strongly acid to the taste. It below) to a temperature not exceeding 338° Fahr. first reddens and afterwards bleaches vegetable It dissolves freely in water, and if the solution blues. In all its properties it strongly resembles be concentrated, crystallises from it, without chloric acid, but owing to the greater affinity of taking up water. bromine for oxygen it does not part with its B (2). IODIC ACID.-Synonym: Hydrogen iodate.10 oxygen so readily.

Symbol: H'I'Og". Combining weight: 176. 130.-PREPARATION.-By acting on potassium hy- 138.-PROPERTIES.-Iodic acid forms colourdroxide, K'H'O", with bromine, a mixture of a bro less, six-sided tables, very sour to the taste, and mide and a bromate is produced. From this the acid reddening litmus strongly. It is very similar to may be prepared in the same manner as recom-chloric and bromic acids. Like them it combines mended for chloric acid, or advantage may be with metals to form a class of bodies called taken of the power which bromine has of abstract- iodates, which, like the corresponding chlorates, The iodates differ ing oxygen from the oxides of chloride by the are decomposed by heat. following proceeding :-Chlorine is passed into from the chlorates, inasmuch as the iodates of a warm concentrated solution of potassium car- the heavy metals, instead of yielding oxygen bonate. Potassium chlorate is thereby formed. and an iodide, give, on heating, metallic oxides, On adding an equivalent of bromine this latter iodine, and oxygen. The iodates of the ligh metals, however, behave like the correspon

1 Gmelin.

2 Idem.

3 Hypobromous acid.

4 Hydric hypobromite.

5 Bromic acid.

6 Hydric bromate.

M

I' + H'N"O" = N" + H'I'O".

In practice, however, pure nitrogen is very seldom evolved, the nitric acid being generally reduced to a lower oxide, and not to nitrogen itself. 2. If a current of chlorine be passed through water containing iodine in suspension, hydrochloric acid and iodic acid are formed. By virtue of its superior affinity for hydrogen, the chlorine combines with this element, while the iodine seizes on the oxygen thus set free.

I'+3H,'0"+5C1 = 5H'C' + H'I'O". The resulting iodic acid may be purified from the hydrochloric acid by boiling, and allowing the liquid to crystallise.

chlorates, that is to say, they give off oxygen, union takes place, or, in other words, welding what better than good honest fire-clay? The inand are converted into iodides, thus : occurs. In the Catalan process the iron falls to terior may be made of good fire-brick, the exM'I'Og" = M'I' + 30". the bottom of the furnace particle by particle, terior of some refractory material. By the term forming one spongy lump, but the particles refractory applied to clay is meant a substance 189.-PREPARATION.-Iodic acid may be pre- brought into contact during the process of ham- which has the power of resisting a high tempepared by several methods. 1. 1 part of iodine mering become firmly united into a solid com-rature without melting or softening. There must and 40 parts of nitric acid of the specific gravity pact mass, while ny slag which might be diffused be a good solid foundation, where water cannot of 15, are to be boiled together in a porcelain through it (and there always is some slag) is ex- have access. The part of the bottom immediately capsule, until all the iodine dissolves. The solu-pelled by that operation. The lump is familiarly underneath the shaft of the furnace may be made tion is then to be cautiously evaporated to dry-known as "blooms." of good fire-brick, or of good sandstone, or ness, redissolved in water, filtered through As was mentioned before, by varying the of some portions of the slag. This latter forms asbestos (while hot), and allowed to crystallise. proportion of ore and charcoal (or other carbon one of the most refractory bodies accessible to us. In this process the nitric acid loses its oxygen, used as fuel) we get a variety in the quality of Next, there must be provided the means of inwhich it gives up to the iodine, thereby converting the iron produced. The greater the quantity of jecting air, through three apertures usually-one it into iodic acid. The results of the operation charcoal used the more steely is the iron obtained, at back and one on each side. For that purpose may be seen by the following equation:- for metallic iron, when exposed to carbonaceous is provided three arched recesses large enough to matters at a high temperature, has the property allow a workman to get easily through. The which, although the iron may remain quite solid, because from that part the molten iron is tapped of imbibing or taking up a portion of that carbon, front part of the furnace is prolonged forwards, becomes diffused through the mass, and it is in out. this way that steel is produced on a large scale. growth of the iron manufacture from its rudest Let ns endeavour to trace the progress of the stages, as seen in the Hindoo and in the more advanced Catalan process. Man would try to economise fuel and labour, and probably his first idea would be to construct a furnace having a greater altitude. This is done in the "Osmund furnace," so named from the kind of iron proof the Catalan forge. In the winter time, the duced, used in Sweden. It is a step in advance Swedes, not being occupied by their agricultural operations, produce very good malleable weldable iron from the ore; but instead of the Catalan forge they employ a much deeper furnace. It is made of material capable of resisting fire, cased outside with wood, and the ore and fuel used is oxide of iron and charcoal. In many cases it is the "lake ore," or brown oxide-i.e., the peroxide combined with water. This ore is formed at the bottom of certain lakes in Sweden, near the places where the rivers supplying these lakes enter, and principally on reedy ground; it is composed of particles of various sizes, some are small-"pearl ore," others larger, " money ore; sometimes "cake ore," while a kind composed of very small particles is known as 'gunpowder ore." In the winter time, when the lakes are frozen over, holes are made in the ice, and the ore dredged up and washed. It is found that in places where the ore has been removed, in the course of about twenty or thirty years a fresh supply has been deposited. The furnace is charged with ore and charcoal, and after some hours lump of iron is formed at the bottom. This is (during which the blast is kept up by bellows) a not extracted from the top as in the Catalan process, owing to the greater height of the furnace, but a contrivance is made for extracting the metal from the bottom. At the bottom of one side a hole is made, or a part of the furnace is made removable, a hole being left for the outflow of the slag. A larger lump of iron can be made in the same time by this method than in a Catalan forge.

The iodates of the lighter metals may be conveniently prepared by dissolving iodine in a solution of the metallic oxide, and then passing a current of chlorine through the liquid. A chloride, along with an iodate of the metal employed, is the result. The following equation illustrates the interchange :

2

=

3M'0"+I+ 5C1' 5M'C' - M'I'Og". From these iodates the acid may be obtained in the mode described for chloric acid. c. IODINE HEPTOXIDE. Synonym: Per-iodic anhydride. Symbol: I'O7". Combining weight: 366. 140.-PROPERTIES. A white spongy mass, freely soluble in water. It is obtained by cautiously heating the next compound to about 320° Fahr. At a higher temperature oxygen and iodine are given off.

c (2). PER-IODIC ACID.-Synonym: Hydrogen per-iodate.12 Symbol: H'I'O". Combining weight: 192.

141.-PROPERTIES.-Per-iodic acid is a white solid, which crystallises in colourless plates, somewhat resembling potassium chlorate. The crystals are permanent in the air. At 266° Fahr. they fuse without undergoing any change. At a higher temperature they lose the elements of water, and are converted into per-iodic anhydride. The acid, as well as its compounds with metals, bears a strong resemblance to per-chloric acid and its compounds; and, although the oxygen is much more tenaciously held, yet the periodates (and iodates) deflagrate when heated with charcoal. 142.-PREPARATION. - By adding iodine to perchloric acid, when the following substitution takes place :

I' + H'CIO,"

Cl'H'I'O"".

Now we come to a furnace 16ft. or 20ft. high, in section quadrangular or circular, with the blast injected at the back by a double-acting bellows worked by men or by water-power. In the front part a space is left which can be closed or unstopped at will. In such a furnace it was found that either malleable or cast iron could be produced. When charged suitably for the production of wrought iron, a lump of metal from six to seven hundredweight might be extracted at the front part of the furnace, with great hooks and chainwork attached to a drum connected with a water-wheel. When extracted the lump is divided and subdivided till the parts are sufficiently small to be forged into bars, heating and hammering during the working as required. There is usually malleable lump-even in the Hindoo process a some cast iron accompanying the production of a small quantity occurs, and therefore the discovery would soon naturally be made that by altering the proportion of the charge malleable or cast iron could be produced at pleasure.

Now we have come from the Hindoo direct process to the modern blast furnace, though at

In front of this opening, to prevent the iron running away, is placed a strong dam of with some fire resisting substance. The lower part good thick cast-iron plate, and lined internally of the furnace is left open, the top is closed more or less during the working. The furnace shaft is bound firmly by rings of iron round it at intervals from top to bottom, and to prevent accidents from the breaking and falling of the rings chains are hung longitudinally round. A more common and to encase them in stout boiler plate. Now as to method now is to make the rings more expansive, the means of injecting the air: in each of the three openings is placed a large iron twyer. The twyer, if introduced into the furnace would burn away, so precautions are taken to protect it as much as possible by using a water twyer. It is constructed of wrought iron, and consists of two hollow truncated cones, the smaller inside the larger, coinciding at both ends and welded together. There is a clear space left round the inner cone (owing to the inequality of their sizes), and at the thicker end, away from the fire, two wrought-iron pipes communicate with this space, and it is so contrived that when the furnace is in operation a plentiful supply of cold water thus passes around the inner cone. This water twyer does not prevent altogether the burning of the iron, but it keeps it from burning so rapidly away as it would otherwise do. Round the furnace above the twyers is constructed a circular iron pipe sus(pended above them, and bent or elbow tubes run from this, the nozzle of one being placed in each of the twyers, and the elbow (containing a hole in the joint) serving to allow of inspection, or,in case blast is injected under considerable pressure-not of hot blast, of ascertaining the temperature. The less than three pounds to a square inch-and is produced by double-acting cylinders (about 14in. diameter). In order to support the lower part of the furnace, that part in which the metal accumulates, in some cases water "boshes " employed, being thick plates of cast iron, through the interior of which water is circulated. The term "bosh" is applied to the lower contracted part of the furnace, and is doubtless a corruption of the German bosche, a slope, probably introduced by the German workmen brought over by Elizabeth.

are

Now let us see what occurs in the blast furnace, and for this purpose we will suppose it is in working order, having had time to dry. To simplify matters we will also assume that the materials employed are quite pure. The fire must be made slowly, and brought up gradually; the material employed may be coal, coke, or charcoal: we will suppose it to be an easily combustible fuel of pure carbon. We must keep adding this from time to time till we have filled the structure with it, all the ime injecting air at a pressure of three or four pounds. The bottom aperture is closed so as to make the air find its way upward, and nitrogen. Hitherto we have been considering the thus we get an upward stream of carbonic oxide and fuel only; now we will put into the top of the furnace oxide of iron, no matter which kind. In the first place, the temperature of the furnace will be the highest towards the lower part, and the oxide of iron and fuel being added alternately, as the former descends, it at length reaches a place where

present only on a small scale. And first the fur the CO streaming upward is sufficiently hot to
naces were made higher and more capacious; to act upon and reduce the oxide, and so we get
some years ago a furnace 30ft, or 40ft. high was the iron in a metallic state.
considered very large, now in Middlesbrough agent in the reduction of iron ore; almost the
CO is the grand
district furnaces have been erected, with the best whole of the iron produced in the world is pro-
possible results, not unfrequently Soft. high: induced from the oxide by means of this agent. The
some cases 100ft.
similar form, some are everywhere circular in converted into carbonic acid, and this latter pro
All are not constructed of a CO, by combining with the O in the ore, becomes
section, others like two truncated cones set base duct must not be allowed to remain for one seco
to base. The furnace is constructed of a mate- in contact with the iron, or the reverse act
rial which stands a good high temperature, and would occur and the iron again be oxidised.

removal is effected by keeping up a good blast. The rapidity of reduction varies with the nature of the ore and with respect to its compactness. The iron after being thus reduced still goes on descending with the glowing carbon to a hotter part of the furnace, and when these two substances are heated very strongly in contact with each other they combine, and we get an easily fusible, comparatively speaking, "pig iron." The term "carburisation" is applied to this part of the action. Descending to still hotter parts the iron becomes perfectly melted, and owing to its high specific gravity falls down on to the hearth.

Practically, we cannot get either pure carbon or pare ore. The ores which we are obliged to use contain certain materials which are very difficult to melt, e.g., silica, which cannot be melted under ordinary conditions. We often have ores with silica or clay, and our fuel employed contains earthy matters. In this case the iron will be reduced as it descends into the furnace, being influenced somewhat by the impurities mixed with the ore; if this stuff associate with the reduced iron, that metallic iron will be intermixed with this infusible stuff, and so contact between the reduced iron and the highly heated charcoal prevented. But in order to get pig iron we must have that contact. The material existing in most of our ores and in fuel is easily converted into a glass-like, easily melted substance-slag-by lime. We, therefore, put in chalk or limestone with the ore, and the same phenomena exactly take place as before. The slag resulting from the addition of lime will contain all the silica and elayey impure matter of the ore, and the ashy matter of the fuel run together. This compound is much lighter than pig iron, and they will not mix with each other; the consequence is the slag swims at the top of the melted iron. Thus from the ore, limestone, and fuel put in alternately at the top of the furnace, we get two things at bottom -slag and pig iron. A hole is made in the side of the furnace for the slag to flow away through, and out of the dam. When the bottom part of the furnace has become nearly full of melted iron it is drawn off. A hole is there, but stopped with clay during the reduction; now with a long bar of iron the clay is broken out, and the metal allowed to run into moulds, sometimes of iron, sometimes of sand, running parallel to the furnace, and thus we get the bars commonly termed pig iron. The limestone is called the "flux."

MICROSCOPICAL NOTES.*

RTIFICIAL

AF

the conostat is shown in Fig. 2, and is characterised
by the presence of a cup or goblet-shaped en-
largement which becomes filled with air, and by
this the conostat remains floating.

When developed in the neighbourhood of one
another, the calcospherites mutally adhere and
form dumb-bells, plates, and polyhedric bodies,
recalling the structure of the shells of various
Lamelli branchiata, &c. (Figs. 3 and 4.)
In certain definite circumstances the calcium
carbonate, combined with albumen, forms very
thin curved lamina, precisely resembling the cal-
careous plates of the "bone" of the Sepia. These
concretions consist of a combination of calcium
carbonate with organic matter, which is the sole
residue when the salt is removed with an acid.
If the development has taken place in albumen,
or a liquid containing it, this fundamental organic
substance remains with the form and structure of
the calcareous body; but this fundamentalsubstance
is no longer albumen, but is albumen transformed

FIG.2

FIC.3

FIG.I

FIG. 4

They are either perfectly homogeneous or show fine fibres, sometimes disposed in a parallel manner, sometimes divergent, and concentric bands, and have precisely the conformation of the calcareous substance which constitutes the internal layer of the shell of the Lamelli branchiata and forms almost exclusively the shell of Gasteropoda. On other plates are thickened patches similar to those which exist on the external layer of the scales of osseous fishes. Under the influence of a low and constant temperature there are developed both on the calcospherites and on the plates curved spinous projections (Fig. 5). If the liquid contains in addition gelatine, these projections have a warty appearance, and they themselves have either secondary projections or they branch until they come to precisely resemble the sclerites of Alcyonaria. Similar sclerites, but different in form, are developed in cartilage, which is first impregnated with calcium chloride, and then placed in a solution of potassium carbonate mixed with a little sodium phosphate. All these calcareous formations become charged with any colouring matter contained in the liquid, and thus the coloured calcareous formations of nature may be closely imitated. Biologists will wait with impatience the publication of the author's complete memoir on this most interesting subject.

STRUCTURE OF TENDON.-Dr. Mitchell Bruce, in an exhaustive but purely technical article on the structure of tendon, gives the following method for preparing cross sections of this tissue, which may be of value to some of our readers. The distal half of the tail is removed from the living animal (rat), the skin stripped off, and the organ placed in a 5 per cent. solution of chloride of gold for fifteen or twenty minutes, after which time it is removed and exposed to the light in distilled water until coloured. It is then placed in a one-tenth or on one-eighth per cent. solution of chromic acid for two or three days until the bones become softened, then transferred to alcohol for a quarter or half an hour and then cut into sections. The sections when cut should be washed in water and mounted in glycerine.

ILLUMINATION OF OPAQUE OBJECTS.-The following ingenious plan, which our "binocular" friends may find useful, is taken from the Lens, a new American Journal of Microscopy. A beam of light is sent down the oblique body of the binocular microscope, the prism being in position for use binocularly by a plane mirror rectangular prism or ordinary drawing camera, and is directed by the Wenham prism through the objective upon the slide. A small portion of the centre of the field will, if all the adjustments be correct, be brilliantly illuminated. This ought to be of service to diatomists.

NEW STAINING REAGENT.-Molybdate of ammonium, a concentrated solution, is diluted with two to three parts of water; to this are added as much iron filings as will lie upon the point of a knife (!) and commercial hydrochloric acid slowly added drop by drop with continual agitation till a deep blue, almost black, colour is produced. When it has acquired the desired colour it is allowed to stand for ten seconds and then filtered. Merkel recommends this for use in staining preparations of the nervous system.

CALCAREOUS FORMATIONS.-Professor Harting has been for some time engaged in researches into the origin and structure of certain organic calcareous structures, and has succeeded in imitating Nature in the manufacture of some of the more interesting forms of these structures. These results may be obtained by placing in the liquid containing the organic matter-albumen, solution of gelatine, a mixture of these, blood, bile, mucus from Arion rufus, tissue of the umbrella of Aurelia aurita, and the liquor obtained by triturating chopped-up oysters in a mortar; salts which, by their double decomposition, produce insoluble salts of calcium. These salts are, on the one hand, calcium chloride, caicium nitrate, calcium acetate, magnesium chloride, and, magnesium sulphate; and, on the other hand, sodium bicarbonate, potassium carbonate, sodium phosphate, and ammonium phosphate. The experiments occupy many weeks, owing to the extreme slowness of the reactions into a substance, the chemical reactions of which involved. The most frequently ecurring form effected by calcium carbonate in connection chitine. The author calls it calcoglobine. If a are those of conchyoline, and resemble those of with albumen, gelatine, or the other organic fragment of calcic chloride be placed in albumen substances mentioned, the Professor christens it is dissolved, and after some days the albumen calcospherites (Fig. 1, copied from the author's is transformed in calcoglobine, which also presents figure in the Quarterly Journal of Microscopical Science); when these are formed in the midst of a fibrillar structure, and after having been washed gives all its chemical reactions. the liquid and it is perfectly tranquil, they are perfectly spherical ("a") and vary from the 002 of a millimetre to 2 of a millimetre, and become larger in proportion as their formation takes place with greater tranquillity and slowness. They often contain a nucleus, and all of a certain size are seen to be formed of concentric layers and radiating lines. If the state of equilibrium of the fluid be not perfect the calcospherites undergo in the course of their development transformations in consequence of which their form is very much modified, and they become ellipsoidal, oval, or fundamental forms, which under certain definite is worth careful study by those interested in lenticular bodies. One very remarkable form, circumstances appear more or less perfectly de* Extracted and condensed from the Quarterly Journal veloped. The first form consists of plates, often of a considerable size, and more or less curved.

of Microscopical Science.

BATCERIA AND PUTREFACTION.--Professor Cohn has conducted researches into the relation between bacteria and putrefaction, and concludes that all putrefaction is accompanied by the development be prevented; it commences as soon as they are of bacteria; it is wanting if the access of these in the same ratio as these multiply, and with its present even in the smallest number; it proceeds completion ceases also their multiplication. They are then precipitated either as a powder or in gelatinous lumps (zooglea), just as yeast precipitates in completely fermented sugar solution.

There can thus be no doubt that there is the When calcium phosphate and calcium carbonate same relation between bacteria and putrefaction are liberated by the double decomposition of as between the yeast fungus and fermentation. calcic chloride and neutral sodium phosphate, They are, therefore, exciters of putrefaction or ammonium phosphate, in a solution of albumen (saprogenous), whilst the other accompaniments tion of the organic material with the two cal-only to be regarded as accompaniments (saproor gelatine, the precipitate consists of a combina- of putrefaction-mould, fungi, and infusoria-are careous salts. If the calcareous phosphate con- philous). There is no genetic relation between stitutes only a small fraction of the constituent, bacteria and mould fungi. Professor Cohn's paper calcospherites are formed, but among them are -a print of a lecture delivered before the Silesian some which form the starting point of various Society for Natural Culture, reprinted in abstract ulterior formations that may be reduced to two in the Quarterly Journal of Microscopical Science sanitary science, and especially by our medical friends. We have not space for a further reference to it.

H.P.H,