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removed from the sheet immediately after leaving the rolls, having served the temporary purpose of producing a fine surface. In order to facilitate the removal of this upper fabric it is recommended to use it damp, or to prepare one face of it with a coating which shall have the effect of preventing adhesion. At this stage the sheet is placed finally in a drying chamber, where it is left until the softening liquid is completely evaporated.

1392. An Improved Combination of Metals for the Production of a White Alloy resisting the action of Vegetable Acids. M. A. F. MENNONS, Paris. A communication. Dated June 4, 1861. (Not proceeded with.) THIS alloy is prepared by fusing together the following metals in the proportion to make 1000 parts, viz.,-banca tin 875 parts, antimony 50 parts, nickel 55 parts, and bismuth 20 parts.

It will be seen that this alloy differs from common pewter by containing bismuth in the place of lead, and nickel in addition. The employment of the last named metal may possibly counteract in a measure the tendency to corrosion by acids, but will, on the other hand, raise considerably the price of the alloy.

1861.

1397. Improvements in the Manufacture of Gas, and in the Apparatus connected therewith. A. PRINCE, Trafalgar Square, London. A communication. Dated June 4, THESE improvements are based upon the action of a current of steam passing through the gas retorts in producing a larger volume of illuminating gas from a given charge of coal. The aqueous vapour is decomposed by the highly carburetted products of the distillation of coal in such a manner as to form carbonic oxide, and at the same time furnishing an increased amount of hydrogen to the gas, and so preventing a great loss in illuminating effect by diminishing or avoiding the separation of carbon against the heated surfaces of the retort.

There is every probability of a larger yield of gas being obtained by this process, and of the illuminating power in the aggregate being considerably augmented. The poisonous character of carbonic oxide gas appears to be the great disadvantage to which this method of production is liable.

1406. Improvements in the Manufacture of Insulators for Telegraphic Wires, and in Materials and Machinery for Coating Telegraphic Wires. H. G. B. ROEBER, Silvertown, Essex. Dated June 4, 1861. (Not proceeded with.) THE insulators employed in connection with telegraphic wires and apparatus have hitherto been made of only one non-conducting material; the first part of this invention relates to their manufacture from two or more insulating substances, such as india-rubber, gutta percha, or shellac, employed conjointly with glass, earthenware, or porcelain. The principle of associating two or more non-conducting materials in the manufacture of telegraphic insulators cannot be said to have originated so recently as June last. Many of the earlier patterns were constructed in this manner; glass and shellac, earthenware and gutta percha, besides other combinations, being employed. It is a common practice in the present day to make the insulators of more than one material.

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Royal Institution. The following Lectures will be delivered in the ensuing week :-Monday, May 5, at Two o'clock, General Monthly Meeting. Tuesday, May 6, at Four o'clock, Mr. C. T. Newton, "On Ancient Art.' Thursday, May 8, at Three o'clock, Dr. Lyon Playfair, "On Progress of Chemical Arts, 1851-62." Friday, May 9, at Eight o'clock, Mr. W. Fairbairn, "On Resisting Properties of Iron." Saturday, May 10, at Three o'clock, Professor Anderson, "On Agricultural Chemistry."

CORRESPONDENCE.

Downing v. Chance.

"

To the Editor of the CHEMICAL NEWS. SIR,-Your version of the "circuit short-hand writer's ' notes, which appeared in your last week's Number, necessitates from me a reply, which in fairness I trust you will insert in your next Number.

In my letter which appeared in your Number for April 19, I quoted two versions of what (in the Number for April 5) you made me say, the accuracy of both of which I denied.

In your transcript of the circuit short-hand writer's notes, which are supposed to be "verbatim," you give a third version.

Here they are:

No. 1. "Does not remember the composition of cyanogen, for the compounds of hydrogen are so complicated." No. 2. "He could not just then refresh his memory as to which two gases cyanogen was composed of at the moment. Some of the compounds of hydrogen are so difficult." "Some of the compounds are so excessively difficult that it would be perfectly impossible, without scientific books, to enter into their composition."

No. 3.

Leaving to others to comment on these three "reports," all said to be taken in the very words used by me, I feel, Sir, that I have a right to ask you, if it is fair-is it English --to hold me up to animadversion for words spoken, three versions of which you have already given?

But you will probably say the circuit short-writer's notes (about whose accuracy there can be no question) states, that when Serjeant Pigott asked the question, "Will you tell me what cyanogen is?" I replied, "It is a compound of nitrogen and hydrogen."

If I had said so, pray how was it that in his next question (see "report") he asks, "Is not it an element, tell me what you say it is?"

Is it not plain from his second question that I never said it is a compound of nitrogen and hydrogen?

If I had so replied, would it not have been arrant nonsense for Serjeant Pigott to ask, "Tell me what you say it is," when I had just told him?-I am, &c.

Birmingham, April 29.

ALFRED BIRD.

[Our readers will see that the "three versions" are strictly what they profess to be. The first two being condensed accounts, and the third a verbatim report, given to prove the perfect accuracy of our former abstract. It is satisfactory to know that Mr. Bird admits there can be no question about the accuracy of the circuit short-hand writer's notes.-ED. C.N.]

Spectrum Analysis.

To the Editor of the CHEMICAL NEWS.

SIR,-On page 214 of your Number for April 19, Sir D. Brewster is stated to be the first who (in 1822) examined a coloured flame by the prism. A short investigation, however, shows that the first application of the prism to such purposes must be dated at least seventy years previous. The very paper (Trans. of the Roy. Soc. of Edinburgh, vol. ix. p. 435) in which Sir David published his examination of yellow sodium light, proposing to use it in his monochromatic lamp, contains a reference to a paper in the "Edinburgh Physical and Literary Essay," (vol. ii. p. 34,) in which we find these previous observations described. To the writer of this paper the remarkable phenomena exhibited by coloured lights when examined by the prism were well known. To show how fully he was acquainted with the

252

Correspondence-Chemical Notices.

peculiarities of yellow sodium light, it is sufficient to quote the following passage, in which he speaks of the light of burning alcohol mixed with nitre (impure?) or sea-salt:

"The proportion in which the bright yellow exceeds the other colours in this light is still more extraordinary than in the former; insomuch that the hole seen through the prism appears uniformly of this yellow, and as distinctly terminated as through a plain glass, except that there is adjoining to it on the upper side a very faint stream of green and blue. White bodies illuminated by it appear also through the prism perfectly well-defined; both which are very surprising phenomena to those who have been accustomed to the use of the prism in other heterogeneous lights, where it never fails to throw confusion on the extremities of all visible bodies."

This paper was read before the Medical, afterwards the Philosophical, Society of Edinburgh, on January 3 and February 7, 1752. Its author was Thomas Melvill, M. A., a young and talented experimentalist, who, according to a note prefixed to the printed paper (vol. ii. p. 12), died in December, 1753, at the early age of twenty-seven years. Melvill, it is added, noticing that few, if any, of Sir Isaac Newton's followers had gone one step beyond him in his researches on the spectrum, proposed to apply himself particularly to the further illustration of the theory of light and colours. The published essay, it is said, "is a specimen of what might have been expected from him, and sufficiently shows the uncommon genius of its author."

Another paper by Melvill, on the "Cause of the Different Refrangibility of the Rays of Light," is printed in the Phil. Trans., vol. xlviii. (1753), p. 261, having been transmitted to the Royal Society by its author while staying at Geneva. It exhibits equal scientific genius. It seems, then, only common justice to accord to Thomas Melvill the full honour of first entering with deliberation upon a branch of discovery which now occupies the fore most place in the scientific world. Had his life been prolonged, many beautiful and important facts concerning the spectrum, which we are only just learning, might have been given to the world more than a hundred years ago.

I am glad to find that Professor Roscoe, in the last of his three lectures, briefly noticed the claims of Thomas Melvill, which I am now urging.

In Phil. Trans., vol. lxxv. (1785), p. 190, is a paper relating to the subject by a Rev. Mr. Morgan; it is of very inferior importance.-I am, &c.

London, April 23.

Carbon in Iron.

W. S. JEVONS.

To the Editor of the CHEMICAL NEWS. SIR,-In a recent Number of your Journal you give an analysis of iron for carbon, taken as new from the Zeitschrift des Vereins Deutscher Ingenieurs. Permit me to say that this method is not new. It is due to Mr. Christopher Binks, who, in his paper read at the Society of Arts in 1857, states this very method as his own, and as the best way for determining both the proportion and the quality of the carbonaceous matter contained in steel. The following extract from Mr. Binks' paper shows

this:

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"Under the head of Some Evidences of the Analysis as to the Real Composition of Steel,' he says (other evidences being adduced), The best malleable iron, on the one hand, and by way of comparison with this, the same kind of iron fully converted by the usual process, were taken on trial; the steel was dissolved in a very dilute and pure hydrochloric acid, and after many trials it was found best to place the bar of steel or iron in single voltaic arrangement with platinum, and to effect the solution in the cold with the usual precaution of expelling air from the water

CHEMICAL NEWS, May 3, 1862.

employed. In this way, slowly, the steel was dissolved, and the carbonaceous flocculent matter that was left collected, carefully dried and analysed. The iron was treated in the same manner, and the comparatively very small proportion of carbonaceous residue given by it also examined. And these were compared with the residue obtained also from cast-iron. If the acid be strong, and heat be used, and the voltaic arrangement be not used, the results are very different. Gaseous nitrogen, in very minute quantity, is given off along with the hydrogen, some muriate of ammonia is formed in the solution, and but little nitrogen left in the residue.'"

Herr Weil, who announces this as his method of analysis, is not the only one (MM. Fremy, Caron, and others, for example,) who have been anticipated in this paper of Mr. Binks.

Mr. Binks' object in resorting to this, then, new mode of analysis, was to examine into the character of the previously so-called carbonaceous matter found in steel and in some kinds of iron. The result forms one of his numerous proofs of the invariable and inevitable co-operation of nitrogen as well as of carbon in the formation and composition of steel,-results that have, as you are aware, been recently confirmed by the researches of some of the French chemists.-I am, &c. JOHN STEBBING. Inverness Road, Bayswater.

Chemical Notices from Foreign Sources.

ORGANIC CHEMISTRY.

Benzyl Mercaptan and Bisulphide of Benzyl.—

When

Vogt has prepared (Annal, der Chem. und Pharm., Bd. cxix. s., 142) both of the above bodies in Kolbe's laboratory. Benzyl mercaptan, C12 He S2, is prepared as follows: in a good-sized flask, and when the evolution of hydrogen -Dilute sulphuric acid is poured on some granulated zinc is brisk some sulpho-chloride of benzyl is added. The flask and its contents are then allowed to stand for twentyfour hours, and the whole is afterwards distilled. the flask is heated the evolution of hydrogen recommences, and the new body passes over with the gas and steam, residuum in the flask contains the second body,—the bisulcondensing in the receiver as a colourless oil. The saline phide of benzyl. Benzyl mercaptan shares with the known hydrogen in the form of sulphuretted hydrogen on coming mercaptans the property of readily exchanging an atom of in contact with a metal; and in possessing a peculiar affinity for mercury. One drop placed on dry oxide of mercury gives rise to a violent reaction. The author goes on to describe the compounds which are formed by the action of this body on various metals.

Products of the Oxidation of Sulphindigotic Acid. An interesting paper on this subject, by G. and A. Schlieper, will be found in the Annalen. der Chemie, und Pharmacie, Bd. cxix. s. 1. The authors describe the formation of isato-sulphuric acid C61 NH4 O3, 2 SO3 + 4 HO, and the salts mono- and bibasic formed with the alkalies, alkaline earths, and some metals. Isato-sulphuric acid is prepared by decomposing the baryta salt. The solution is orange red, and very acid. By drying over sulphuric acid a silky crystalline mass is obtained, which remains unchanged in the air, and may be rubbed to a bright yellow powder. The four equivalents of water are lost in the drying. The acid has a strong affinity for bases, and will displace some of the strong mineral acids. It dissolves in streng sulphuric acid without change, and the solution may be heated without producing any blackening. By reducing isato-sulphuric acid with sulphide of ammonium, the authors obtained a new acid, which they have named Hydrindin schwefel saure, (and which we may translate sulphydrindic acid), C16 He NO, SO, SO, HO. Several other new compounds are described by the authors in this valuable paper.

THE CHEMICAL NEWS.

VOL. V. No. 127.-May 10, 1862.

SCIENTIFIC AND ANALYTICAL CHEMISTRY.

A New Method of Clarifying Saccharine Liquids, Juices, and Syrups, and of Revivifying the Animal Charcoal used in the Manufacture of Sugar, by H. LEPLAY and J. CUISINIER.

Of late years, most of the improvements in the manufacture of sugar have been directed to the disuse of animal charcoal. Having for many years witnessed the services which animal charcoal has rendered, and still renders, we have directed our researches in a direction entirely different. Our principal object has been to analyse the action exercised by animal charcoal on saccharine liquids at each stage of the manufacture, the duration of this action, and its exhaustion. We have sought to restore, by easy and speedy methods, the absorbing properties it loses by use, and to ascertain the cause of its various absorbing properties, on which chemistry hitherto has thrown but little light. This cause being discovered, we can, so to speak, increase it at will, and thus effect in saccharine liquids, juices, and syrups, a greater degree of purification than can be obtained by the ordinary means.

This study has led us to the discovery of a new method for refining saccharine liquids, and of revivifying animal charcoal, as shown in the following principal results in the manufacture of beet-root sugar :

1. To completely do away with the use of fresh animal

charcoal.

2. To abolish revivification at a high temperature (kilns for revivification, &c.).

3. To greatly reduce the quantity of charcoal used in the course of the work, and thus to effect a notable

economy.

4. To obtain sugars of a superior quality, with a larger yield, without changing the apparatus now in use.

5. To reduce considerably the net cost of sugar. Now, to point out this new method. In the ordinary manufacture, a filter filled with granulated charcoal lasts from twelve to twenty-four hours. The absorbing properties of the charcoal then appear to be exhausted, and have to undergo revivifying processes, the principal being calcination in a closed vessel at a high temperature. The animal charcoal thus revivified does not completely recover its primitive qualities, and its value as an absorbent is reduced one-half, and sometimes more.

In the ordinary method, all the absorbing properties of the animal charcoal are supposed to be exhausted at the same time, and the object of the revivifying process is to restore them equally and simultaneously.

The following is, on the contrary, the fundamental idea of our method:

1. Granulated charcoal plays a manifold part, and has various absorbing powers, which act independently, and do not become exhausted simultaneously.

2. In the successive revivification of the absorbing properties of animal charcoal, according as they become exhausted, by various means appropriate to the nature of the matters the charcoal has absorbed.

3. In the possibility of augmenting at will the energy of the absorbing properties of the charcoal, and thus to render its refining action on juices and syrups more complete.

4. In obviating any necessity for a temperature higher than that of boiling water or free steam.

By investigating the process of the filtration of juices and syrups, we find that the exhaustion of the absorbing properties of the charcoal can be divided into three periods, which we will examine successively.

The first series of absorbing properties is almost entirely exhausted after a few hours' filtering,—say, under ordinary circumstances, about four hours. These are the properties which affect viscous, nitrogenised, ammoniacal, sapid, and odorous matters, which injure the fluidity of syrups, their crystallisation, the hardness and consistence of the grain, the quantity and quality of the sugar, and which impart to rough sugars the odour and flavour peculiar to the produce of the beet-root. We completely re-establish the primitive absorbing properties by passing a current of steam through the granulated animal charcoal contained in the filter. The absorbing properties of animal charcoal can thus be regenerated indefinitely.

A much longer time is required to exhaust the second series of absorbing properties. They last six or eight times as long as those of the first series. The period of exhaustion varies with the alkalinity of the defecated juices and syrups. Free alkalies, lime, potash, soda, salts of lime, and other saline matters are absorbed by the series in question. These matters especially contribute to colour the juices and syrups during evaporation by destroying the sugar, and when present in large proportion prevent crystallisation. We revive these absorbing properties by pouring a weak solution of hydrochloric acid over the charcoal contained in the filter and by sufficiently prolonged washings in water.

The third series comprise the absorptive properties of charcoal for colouring matters. They last thirty or forty times as long as the first series. Moreover, the presence of colouring matters in these syrups is of no great importance when they are transparent and brilliant and hold no matter in suspension. White sugars can be obtained from coloured syrups, and when, from the tint of the products, it is deemed necessary to revivify the power of absorbing colouring matters, we make use for this purpose of a weak solution of boiling caustic alkalies.

We use these various means of revivification either in the filter itself or in a special apparatus similar to the filter.

The various methods of revivification just described restore the absorbing properties of the animal charcoal to their primitive state, but without augmenting them.

254

On the Commercial Analysis of Chrome Ores.

We have sought, in the production of a new fixed product in the charcoal itself, for the solution of the problem of augmenting the absorbing properties of charcoal.

When one equivalent of biphosphate of lime is added to one equivalent of tribasic phosphate of lime, identical with that which enters into the composition of animal charcoal, the two phosphates combine and form a third, which is a phosphate with two equivalents of base. This is explained by the following formula :

PO.3CaO+PO,. CaO.2HO= 2(PO,2CaO.HO). This new phosphate is insoluble in water, has no acid action on litmus paper, produces no inverting action on the sugar, and possesses very energetic absorbing properties.

What takes place in a test-glass with tribasic phosphate of lime is produced in the same manner in a filter filled with granulated animal charcoal when a weak solution of biphosphate of lime is poured over it. The same effect is produced with powdered animal charcoal. Charcoals treated in this way possess greater absorbing powers, which can be varied at will, and a smaller quantity of this charcoal suffices to produce a greater degree of refinement in juices and syrups.

Further, we have utilised for clarifying and purifying saccharine liquids the singular property possessed by the phosphate with three equivalents of lime, of precipitating itself in a gelatinous form, and of carrying with it all matters hindering the transparency of syrups, much more effectual than albumen, blood, and other matters used in clarification. In short, our processes are founded on attentive and inductive study of the singular and useful properties of different phosphates of lime, and of their application to the refinement of saccharine liquids, particularly beet-root juice and syrups.

The foregoing processes are in operation at two important sugar-works in the department of the Oise,-one at Fraucières, belonging to MM. Bachoux and Co.; the other at Frogers, belonging to MM. Daniel and Co. The quantity of sugar made at these two works by our processes is now about 300,000 kilogrammes. This manufacture has sufficiently shown the value of our processes and the reality of the advantages they offer. Our processes can be applied with like success to the manufacture of cane sugar as well as sugar refining.

On the Preparation of Protoxide of Nitrogen by the
Moist Way, by M. H. SCHIFF.*

VARIOUS substances, such as sulphide of ammonium,
sulphide of potassium, moist finely-divided iron, possess
the property of changing binoxide of nitrogen into
protoxide. Nascent hydrogen has the same property,
and we know that greatly diluted nitric acid disengages
protoxide of nitrogen in presence of zinc or metallic
iron. Moderately concentrated nitric acid, on the con-
trary, yields binoxide of nitrogen; but if weak sulphuric
acid is added to the mixture, the gas disengaged becomes
in a short time protoxide of nitrogen free from binoxide.
The addition of sulphuric acid, instead of intensifying,
as it generally does, the action of the nitric acid,
weakens it, a phenomenon which can be explained
only by a reaction of the nascent hydrogen on the
binoxide of nitrogen.

Protoxide of nitrogen, sufficiently pure for ordinary purposes, can be readily prepared from zinc and a mixture of part of concentrated sulphuric acid, 1 of concen

* Annalen der Chemie und Pharmacie, vol. cxviii. 84.

CHEMICAL NEWS,
May 10, 1862.

trated nitric acid, from 9 to 10 parts of water. It is advisable to pass the gas through a tube filled with pumice-stone saturated with ferrous sulphate, to prevent the admixture of a small quantity of binoxide of nitrogen.

ACCORDING to M. Balard, the best vehicle for dissolving On the Detection of Bromine, by M. FRESENIUS. bromine just displaced by chlorine is sulphide of carbon, a process long used in France for detecting iodine. M. Fresenius, who has verified this fact with his usual care, insists on the necessity of avoiding excess of chlorine, and of employing sulphide of carbon free from sulphurous and sulphuric acid.

His preference for sulphide of carbon over ether and chloroform is founded on a series of direct experiments with standard solutions containing various proportions of bromides. Solutions containing only both of bromine in the state of bromide of potassium, when treated with the requisite quantity of chlorine, do not communicate the least colour to ether or chloroform, while sulphide of carbon acquires a decided yellow tint.

This vehicle, then, answers best for this purpose. Moreover, being heavier than water, it sinks to the bottom of the liquid with the bromine it has dissolved, and there remains.

If the bromide is accompanied by an iodide, the iodine must be previously eliminated by adding a little hyponitric acid and a drop of sulphide of carbon, which takes away the displaced iodine. After this the separation of the bromide may be proceeded with.-Zeitschrift für Analytische Chemie, i. 46.

On the Commercial Analysis of Chrome Ores. WE have received a valuable communication on this subject from Mr. C. L. Oudesluys, of Baltimore, the proprietor of extensive deposits of chrome iron ore near that city. Our correspondent writes:

"I see in your Notice to Correspondents' that you call upon me to furnish my formula. I enclose one received from a chemist here, by which he has obtained results very similar to those obtained by Dr. Genth from a part of the same sample; but Dr. Genth's formula is only known to himself. I had an interview with him yesterday. He has consented to communicate his formula to Edward Franklin, Esq., a chemist residing in London, for examination, and is willing to abide a test of a sample of fused and pulverised ore he will send to Mr. Franklin, and thinks it will agree with a test of a part of the same sample made by Genth. Dr. Genth thinks that the English formula, as stated by Charles O'Neill, of Manchester, is good (CHEMICAL NEWS, No. 123); but that he should take 7 grains for fusion instead of only 5 grains, and should fuse an hour or more instead of only half an hour. He thinks Mr. O'Neill loses chromic oxide in his solutions."

referred to by Mr. Oudesluys:-
The following is the Baltimore chemist's process

and fused in a platinum crucible with three times its
"Half a gramme of the finely pulverised ore is taken
weight of bisulphate of potash for one hour; then
allowed to cool, and the same amount of a mixture (of
equal parts of nitrate of potash and carbonate of soda)
put on the top, and again fused for another hour, then

* Qy. Frankland.

NEWS

allowed to cool, and digested in a porcelain dish for two or three hours, with water on the sand bath. Then filtered, and well washed out with boiling water. The filter is then treated with hydrochloric acid for two or three hours in a warm place until the sesquioxide of iron is dissolved; then filter, and if there is not too much undecomposed chrome remaining, it can be weighed and deducted, or if too much remains it must be again fused as before. The chromic acid solution is warmed, and carbonate of ammonia added to precipitate any alumina, silica, or lime in solution, allowed to stand an hour and filtered, then hydrochloric acid added to the solution until acid, then warmed and sulphurous acid added to reduce the chromic acid to sesquioxide, then ammonia added, and allowed to stand twelve hours, filtered, washed out by decantation, dried, burnt, and weighed."

Mr. Oudesluys remarks upon this :

"By the above method, a sample of grain ore, of which the enclosed sample is a part, gave 41°04 per cent. oxide of chrome, or 5307 chromic acid. It then contained 271 per cent. of moisture. If dry, as it is now, it should have contained 42:30 oxide or 55:38 of chromic acid. By O'Neill's analysis, as reported by him, a part of this sample analysed dry gave 46'02 acid,—a discrepancy of 9.36 per cent., thus:55.38 acid Manchester, by O'Neill, 46°02

Analysis made in Baltimore, dry

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On the Preparation of Caustic Soda, by M. WOEhler. THIS process consists simply in calcining nitrate of soda with peroxide of manganese. No chameleon is formed, as might be supposed, since the nitrate decomposes long before the mixture can reach the temperature necessary for the production of manganic acid.-Annalen der Chemie und Pharmacie, cxix. 375.

On the Preparation of Sulphur Soluble in Sulphide of Carbon, by M. L. FAUCHER.

THE works of MM. Ch. Deville, Fordos, Gélis, and Berthelot show that, besides sulphur soluble in sulphide of carbon, there exists a variety of sulphur insoluble in this liquid. Sulphurs obtained by distillation contain insoluble sulphur varying in quantity with the rapidity of the process of cooling from 2 to 3 per cent., as in roll sulphur, to 35 or 40 per cent., as in flower of sulphur.

Thus, to obtain pure soluble sulphur, it is necessary only to digest any kind of sulphur in sulphide of carbon, to filter the solution through cotton, and then to evaporate in a distilling apparatus. But the disagreeable odour and inflammability of sulphide of carbon render its employment both unpleasant and dangerous. Moreover, the sulphur thus obtained has to be freed from all trace of sulphide of carbon by repeated washings in ordinary

alcohol.

It is easier and more convenient to obtain perfectly pure soluble sulphur, by boiling for several hours in a water bath, any kind of sulphur with a solution of sulphite of soda, insufficient to dissolve it entirely. Thus, 100 grammes of flower of sulphur, kept boiling for four or five hours in a solution containing 16 grammes of

sulphite of soda to 100 grammes of water, would yield about 70 grammes of perfectly pure soluble sulphur. This result proves, in the first place, that sulphur insoluble in sulphide of carbon dissolves more rapidly than soluble sulphur in sulphite of soda. Thus, by submitting separately two samples of sulphur, of 50 grammes each, one soluble, the other insoluble, to the action of a solution of 50 grammes of sulphite of soda in 500 grammes of water, and weighing the residue after one, two, three, and four hours' boiling, I obtained the following results:

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The difference in the rapidity of absorption of these two sulphurs led me to inquire whether sulphite of soda acting on a mixture of the two sulphurs would not dissolve all the insoluble sulphur before affecting the soluble.

To determine this question, I took three portions, A B, and C, of the same flour of sulphur, each portion weighing 50 grammes. I treated them separately in a boiling-water bath with a solution of 10 grammes of sulphite of soda to 100 grammes of water. After an hour's boiling, I removed the sample A, which was reduced to 42 grammes; two hours' boiling reduced B to 39 grammes; and after three hours, C was reduced to 37°30 grammes. By the aid of sulphide of carbon, I found their composition was,

the

Specimen. Soluble sulphur Insoluble sulphur

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composition in centièmes, By noticing that the flour of sulphur employed gave

Soluble sulphur. Insoluble sulphur

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80.88

. 19'12

100.00

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it will be understood how sulphite of soda, by a sufficiently prolonged action on the flour of sulphur, can separate from it the soluble sulphur in a state of perfect purity.

The tendency of insoluble sulphur to dissolve itself more rapidly than soluble sulphur, is not the only cause of this separation. In fact, I have ascertained that by treating insoluble sulphur with a quantity of sulphite of soda, insufficient to dissolve it completely, that this insoluble sulphur is transformed by a few hours' boiling into soluble sulphur.

Finally, the aqueous liquid of the sulphite of soda exercises a double action on the flour of sulphur. In the first place, it dissolves insoluble more rapidly than soluble sulphur; secondly, it transforms insoluble into soluble sulphur. For these two reasons, sulphite of soda is an excellent agent for obtaining pure sulphur soluble in sulphide of carbon.-Journal de Pharmacie et de Chemie.

In a former number of the Journal de Pharmacie et de Chemie,

vol. xxiv. p. 343, M. Favre showed that insoluble sulphur, extracted from flower of sulphur, is more rapidly attacked by hypochlorous acid

than soluble sulphur.

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