had they made their arrangements so as to exhibit an undisputed advantage arising out of its adoption, it would not have been so tardy in its progress.

It is to M. de Faber Dufaur, superintendent of the iron works at Wasseralfingen, in the kingdom of Wurtemburg, that most of the credit is due for the present method of converting pig into wrought iron, by using and burning the gases that escaped from the mouth of the blast furnace. The best idea that can be given of the manner in which the operations are conducted in the above works, and the advantages accruing therefrom, is contained in the following short extract from a letter written by M. Grouvelle to M. Dumas.

"The establishment at Wasseralfingen is supplied with ore, three-fourths of which is a hydrated oxide of iron, and the other fourth is an ore in grains. The influence of the first species of ore gave to the pig so bad a quality that it was used altogether for castings. M. Dufaur, by his processes, without altering the operations of the blast furnace, now obtains from the pig a wrought iron of superior quality.

The first gas furnace put in operation by him was a refining furnace, into which the pig metal was run as it issued from the blast furnace, where the refining was executed with the air of the hot blast. From this the most beautiful results were obtained, and it worked regularly during the year 1837. In 1838 he erected a puddling furnace; and finally in 1839 he completed his magnificent system for the fabrication of iron, by constructing a furnace for re-heating and welding."

At Wasseralfingen there are now turned out, annually, one million pounds of wrought iron in various forms, made in these new furnaces, and owing to the deficiency of moving power, all the pig cannot be worked up. This operation of refining iron by the combustion of gas, without any other fuel, has been in successful operation at the above locality for several years, and it has been followed with a great improvement in the quality of the iron, and has reduced the loss to one fourth of what it was originally.

This method of refining the pig has also been in active operation in a number of places, and whenever properly executed, is always attended with economy and success. M. d'Andelarre, in one of the departments of France, in a letter states, "Our puddling furnaces, heated altogether by the gas lost from the mouth of the blast furnace, has been attended with the most complete success, which rarely happens in the first attempts at the application of any improvement, which

most generally require long experience. We lighted up our furnace on the morning of the 5th, and put in the first charge at 11 o'clock on the morning of the 6th, and shingled the same at three-quarters past 12. The accomplishment of the results so quickly passed our expectations, resulting in

"1st. An economy of the total amount of fuel used in the refining of iron (which, in a furnace with two doors, amounted in twentyfour hours, to 6,000 pounds bituminous coal, costing twelve dollars).

iron.

2nd. Improvement in the quality of the

"3rd. The loss was very small, being 5 instead of 20 per cent., which it is by the old processes.

4th. The operations of the furnaces are much improved."

Here we see that the experience of M. d'Andelarre accords exactly with that of M. Dufaur, and already have Russia, Prussia, Sweden, and Germany, sent commissioners to Wasseralfingen, to study the processes as they are there carried on. The government of Wirtemburg have opened their works to the inspection of all who may wish to make themselves acquainted with their character.

The advantages arising from the employment of the waste gas from the mouth of the blast furnace is no longer problematical, and as some of those interested in this matter may not be acquainted with the method by which the gas is collected and employed, a few words explanatory of it will not be out of place.

The gas, as it rises through the fire-room of the furnace, containing from 60 to 80 per cent. of the combustible effect of the fuel used, is made to pass into a chamber surrounding the upper and outer part of the fire-room. Into this chamber the gas is conducted by pipes from the fire-room, and other pipes are provided for drawing off the gas from the chamber. The gas is drawn out by means of blowing cylinders, and forced into the refining, puddling, or other furnace, through a number of small orifices, alternating, with other orifices, through which a hot or cold blast of air is thrown, that serves to keep up the combustion of the gas when once united; and by regulating the supply of air, by means of stop-cocks, the maximum of heat can be obtained. In order to arrive at the maximum of heat, just sufficient air should be admitted to burn all the carbonic oxide and hydrogen contained in the gas coming from the blast furnace. If the amount of air be too small, some of the combustible gases pass out unconsumed; if too great, the excess cools the furnace, and at the same time oxidises the metals undergoing refining. The regulation of the

ment.

The differences between the reverberating furnaces worked in this way and those in which coal is used is, that carbonic oxide with a little hydrogen is the fuel, and it is burnt by a full supply of air. It is hardly necessary to say more of the advantages that are to arise out of this important change in the working of iron; for there is no expense for fuel in the refining of the pig, as the gaseous combustible issuing from the mouth of the blast furnace is more than sufficient to refine all the pig made from the furnace. The quality of iron is also improved, as none of those impurities contained in the coal and other fuel can interfere in the working of the iron.

The sooner these modifications are introduced into our furnaces, the sooner shall we be able to place iron in the market at a price to compete with that coming from any other quarter of the world, and entering our ports free of duty; at the same time it will increase the value of those works whose wood-land has been diminished by a too rapid and improvident use of fuel.

I next pass on to make a few remarks about the refining furnace used in the working of iron. In these furnaces the air is thrown, by one or two tuyers, into a crucible filled with charcoal, into which the pig to be refined, along with scraps coming from previous operations, is placed in a certain relative position. The changes that take place by the reaction of the air upon the coal, is similar to what occurs in the lower part of the blast furnace, namely, the conversion of the oxygen into carbonic acid, which is immediately changed into carbonic oxide. The analyses of the gases taken from the centre of the furnace, prove that the transformation of the oxygen into carbonic acid corresponds to the position where the workmen constantly place the iron that is about to be forged, and this is just what we should expect, as it is the point of maximum temperature.

Ebelman states that the atmosphere which surrounds the melted iron contains hardly a trace of carbonic acid, either in the blast or puddling furnace; this being contrary to the opinion which is generally admitted, that the decarbonisation of the iron takes place by the action of the air during the melting of the pig: but it would appear that this reaction is attributable to the protoxide of iron covering the surface of the mass undergoing refining. In the second period of refining, in the puddling, properly speaking, is is easy to deduce from the analyses of the gas that there is oxidation of a considerable portion of the

Here again much of the fuel passes off under the form of carbonic oxide, thereby causing considerable waste. Of late years a modification has been introduced into the refining furnaces, even when the waste gases from the blast furnace are not employed; a modification by which none of the combustible is lost. A few words will suffice to explain how this is accomplished.

All the furnaces are modifications of the reverberatory furnace. The fuel is placed upon the grate and ignited by air thrown in from below the grate, by a bellows or otherwise. The air, in traversing the ignited coal, is first converted into carbonic acid, and then, if the bed of coal be thick enough, this last will be changed into carbonic oxide. As this, however, is generally not the case, a part of the carbonic acid passes beyond the upper surface of the fuel without having undergone a change, particularly if the blast from below has been strong and abundant. By this operation the chamber or bed of the furnace becomes heated, and a mixture of carbonic acid, carbonic oxide, nitrogen, and a little hydrogen is passed out at the flue. The object of the metallurgist, however, is not to permit any carbonic oxide or hydrogen to escape combustion, but to endeavour to add to the heat of the furnace the heat arising from the combustion of these two gases. This is readily accomplished by throwing in a second blast of air, through a number of small orifices just above the surface of the fuel: this blast to be regulated as required.

By this process we re-create, as it were, the maximum intensity of heat (which first shows itself at the lower part of the fuel on the grate, just where the air becomes converted into carbonic acid), and in the chamber where it is most wanted; for the amount of heat rendered latent by the reduction of the carbonic acid into carbonic oxide, is rendered sensible by the reproduction of the former.

The advantages arising from this method of burning the fuel, are important. In the first place the heat is diffused over a larger space, thereby heating more uniformly the metal than when it is placed in the midst of the fuel. Again, fuel of the most inferior quality can be made use of; and as evidence of this, in some trials made at Audincourt, it was proved that the reverberatory furnace could be heated to whiteness by burning the gas, and the pig melted and puddled, when a mixture of charcoal-dust and earthy matter was made use of as fuel.

Ebelman, whom I have so often quoted in

Thus the influence that hot air exercises, is to extend the space of fusion, which is twice as great with the air at 300° C. as it is when the air is at 0° C.

The heat of the combustion of equal volumes of hydrogen and carbonic oxide is about the same, and it can be easily deduced that the decomposition of the vapour of water by the charcoal, determines an absorption of latent heat, equal to that which is produced by the transformation of the same volume of carbonic acid into carbonic oxide. The vapour of water alone passed through the ignited coal produces all the effects just mentioned, but the absorption of latent caloric is so great as to cause the operation to cease in a few minutes. By projecting, however, a mixture of air and the vapour of water through the coal, the operation is said to be carried on advantageously.

It was my intention to have remarked, at length, about the effects of the hot blast, but it is now so generally admitted that the hot is to be preferred to the cold blast in reducing the iron from the ore, and bringing it to its most refined state, that anything on the subject at this time would be superfluous. All that is important to make known upon this subject is the results lately arrived at by M. Scheerer, as to how it is that hot air produces such remarkable effects in the blast furnace.

By calculations, based upon his own experiments as well as those of others, he was led to the conclusion, that the most elevated temperature that charcoal could produce in burning in air, is 2571° C., which is that at which platinum melts. This temperature is situated in the middle of the space upon which the air is projected, and it goes on diminishing towards the exterior, so as to form a space for melting, the centre of which is at 2571° C. and the exterior at 1550° C. When the hot blast is made use of, the temperature of the centre does not change, but the portion heated to 2571° C. becomes more extended. The exterior of the mass which was at 1550° C. while using the cold air, acquires when the hot blast is employed, a temperature as many degrees higher as there is difference between the temperature of the two blasts; for instance, if the temperature of the air be 280° C., that of the exterior of the heated mass will be 1830° C.-if 300° C., the latter will be 1850° C.

THE HEALTH OF CATTLE.* MR. SILVESTER presented to the Veterinary Medical Association, at one of its recent meetings, some of the urine and the bladder and kidneys of a sheep. The coats of the bladder were much inflamed, and covered, as was also the urethra, with a quantity of calcareous matter. Mr. Morton said, "that he had found the specific gravity of the urine to be 1.20; it possessed an alkaline reaction, and he had obtained traces of the presence of both albumen and bile in it. The calcareous deposits consisted of animal matter and carbonate of lime." And he entered into a theoretical explanation of the source of the deposit in connexion with the food of the animals. Mr. Simmonds added his experience on the subject, saying, that "there could be no doubt of the advantages to be derived from an application of the principles of chemistry to pathology. It was only of late years that calcareous deposits in the bladders of sheep had been so frequently observed, and in those cases the sheep had been fed on vegetables growing on land which had been recently limed; hence it was easy to account for the formation of the calculi. In the specimens submitted, the deposit of carbonate of lime was to such an amount, that the entire mucous coat of the urethra was covered more or less with calcareous matter, and within the vermiform appendage the canal was blocked up; the bladder in consequence had become greatly distended, The sheep died from long retention of urine. consequent upon calcareous deposition." Mr. Cox related an instance of a large dairy of cows being fed on turnips that had been grown on land manured with guano, and all of them became affected with nephritis. The bulbs were given with the earth upon them. The disease disappeared when the food was changed, but again returned on the turnips being allowed. Mr. Morton added-" Such an effect from such a cause was highly probable, as guanó contained several of the salts of ammonia, which, acting as diuretics, would be very like to produce nephritis."

*Lancet, and Trans. Vet. Association.

BY M. C. CALLOUD.

THE employment of iodide of iron in the state of protoiodide, (with the extent of the therapeutic value of which M. Dupasquier, of Lyons, informed us, in a memoir published in 1841), has since then been generally adopted. Preparations insuring a certain degree of stability in the ferrous salt were destined to replace the old iodide, whose variable changes were well known. Still, however, in several prescriptions, where iodide of iron was prescribed as an alcoholic tincture, no other could be employed, and we were thus reduced to the necessity of using a preparation, even then acknowledged

to be defective.

To persuade the medical man to reject the employment of so deteriorated a preparation, it became a useful task to examine it analytically, and to represent the relative quantities of the iron in combination, the iron separated, and of the iodine set at liberty, in common iodide of iron.

With this intention, several specimens of dry iodide of iron were examined, and the analysis showed, not only that the iodide had undergone a great change, but that complete decomposition had taken place. In the latter case there was the appearance of solubility in water; but this solubility was due to the accidental presence of an iodurated salt, quite distinct from iodide of iron.

The different samples of iodide examined were in the following states:-1. Recently prepared. 2. In a state of deliquescence. 3. Spontaneously dried, after having passed the period of deliquescence.

The state of change and decomposition which analysis exhibited were

1. The recently prepared, half deconposed. 2. In a state of deliquescence, decomposed to 0. 3. Dried after deliquescence, entirely decomposed.

Five grammes of each sample of the dry iodide of the apothecaries were dissolved in distilled water; the solution, after being filtered, to separate the insoluble portion, was treated with hydrate of potash, which precipitated the remainder of the iron in combination. The calculation, deduced from the portion remaining undissolved in the water, and the oxide of iron precipitated by

* Journal de Chimie. N.S., VOL. IV.

be

These two iodides produced a clouded solution, very highly coloured, with the smell of iodine, and not comporting themselves with reagents like the persalts of iron. They are precipitated of a light blue colour by ferrocyanide of potash, and of a green colour by the alkalies.

As to the iodide, No. 3, it was entirely decomposed, and all the iron had passed into the state of oxiodide, thus forming, with the reduced iodine, a mixture absolutely insoluble in water. The portion dissolved by the water did not exhibit, on the application of the most delicate tests, any trace of iron in combination, but only manganese, which was present in a soluble combination, with iodine in the state of sesqui-iodide, fact, which has been also noticed in certain iodides of commerce, arises from the iron employed in the preparation of the iodide containing manganese, like that obtained from carbonated minerals of iron, which are always combined with manganese.

This

We thus see that the iodide of iron obtained by evaporating it to dryness, forms one of the most imperfect preparations, and that its therapeutic employment is subject to sufficiently serious variations.

In the employment of iodide of iron, in evaporating the protoiodurated solution, a disengagement of hydroiodic gas takes place, from whence results the first decomposition of the salt, and we obtain, as a product, a corresponding quantity of oxiodide, mixed with the undecomposed iodide, and this decomposition of the solution into hydroiodic

30

acid and oxiodide, does not cease until the watery vapours, which are abundantly produced, prevent the contact of the air with the salts in the solution. Although iodide of iron is not met with, with the iodide in excess, we cannot admit that it has passed into the state of sesqui-iodide, or that the half proportion of iodine in excess, is entirely combined, for as such it scarcely has the characteristics of the intermediate salts of iron. Already the smell and taste declare the presence of free iodine; and the solution rendered colourless by solid starch, is precipitated of a light blue by ferrocyanide of potash, and green by the alkalies: the iodide of iron ought therefore to correspond with ferroso-ferric oxide. The rather that, by analogy with the combinations of chlorurated iron, we must grant to the periodide more' stability than to protoiodide; but experiment does not justify this, for the iodide of iron of pharmacy, by being constantly subjected to the hygrometric and oxidating action of the air, becomes completely decomposed, even at the temperature of the atmosphere. This can be readily recognised in the manufactories of dry iodide of iron, when the naked eye can detect flakes of crystallised iodine, adhering to a bluish mass, friable, and insoluble in water, which is no other than a mixture of reduced iodine and sesquioxiodide of iron.

IODIDE OF IRON OBTAINED BY DOUBLE DECOMPOSITION.

By reducing iodide of potassium, and sulphate of protoxide of iron, into a fine powder, and triturating the mixture of the two salts, we obtain the protoiodide of iron. 1 Part sulphate of crystallised protoxide of iron ... 161.52

1 Part iodide of potassium .. 206.94 The double decomposition being produced by the assistance of the water of crystallisation of the sulphate of iron, we treat it with alcohol at 85 per cent., which only dissolves the iodide of iron that is formed. The alcoholic solution has all the characters of the protosalts of iron; and the reaction of the two salts is complete. The sulphate of potash is, in this case, in the condition of the insoluble salts.

The ferrous iodide, thus mixed with the sulphate of potash, may be employed therapeutically with undoubted advantage, for it is in a dry state, and unaltered!

The following formula may serve for certain pharmaceutical preparations, having iodide of iron for a base :

It is important to choose the sulphate of iron in small, colourless, and translucent crystals, which integrally represent the pro toxidated salt, with seven proportions of water. The iodide of potash ought to be perfectly neutral and pure; the least excess of alkali in the iodide would, also, be at once shown by the sulphate of iron, which, in this case, is a good test. To be satisfied of the purity of the substances, the mixture of the two salts being dissolved in a certain quantity of water, the latter ought not to be rendered cloudy by the green or yellow oxide of iron, which would indicate the employment of a basic iodide of potash, or a sulphate of iron, partially peroxidated.

PILLS OF PROTOIODIDE OF IRON.

The two salts being pulverised, we add a few drops of wine to the mixture, quickly triturate it, then dissolve it in the rest of the wine, and filter.

32 Grammes of the wine contain 1 gramme of ferrous iodide, besides a little sulphate of