another substance, which formed white flocks, and did not communicate any colour to borax (therefore vestium).

I dissolved a portion of the impure regulus, first obtained from the ore in nitric acid, and without freeing it from the arsenic, I precipitated by potash. The precipitate was dissolved in sulphuric acid, sulphate of potash was added, and the liquid was brought to the degree of concentration requisite to yield crystals. The nickel crystals were at first, as was usually the case, very light green; but by repeated solutions and crystallizations, they became darker and darker, because more of the white oxide of vestium was separated every time it was crystallized. The white flocks obtained by all these processes I mixed with sulphate of potash, and again evaporated to separate the nickel still more completely. I then digested it with sulphate of potash, filtered, and reduced the oxide in a good wind furnace with common salt and charcoal. The regulus which I obtained had a very fine granular fracture, was very brittle, and its fracture showed a very white colour. By exposure to the air, it soon lost its lustre.

I dissolved a portion of this regulus in nitro-muriatic acid, and decomposed a portion of this green solution (for nickel has a very strong colouring power upon acids) by potash. I dissolved the white precipitate in sulphuric acid, added a portion of sulphate of potash, in order to separate the nickel by crystallization, and washed the salt formed in cold water. The white flocks, which rendered the solution muddy, were separated, and decomposed by carbonate of ammonia added in excess. By this means I obtained a fine white precipitate; and the ammonia was but slightly coloured. Thus I procured vestium merely in combination with arsenic (for that metal had not been separated).*

The iron is sometimes of very difficult separation, sometimes it is easily got rid of. This diversity seems to depend upon the different portions of iron contained in the ore under examination.

One portion of the vestium may be easily purified, by dissolving the carbonate in nitro-muriatic acid, evaporating to dryness, and washing the dry mass with water. The dry residue (submuriate of vestium) is tolerably pure, or at least may be made so by a second evaporation with muriatic acid. But a great deal of vestium remains in the solution along with iron, nickel, and cobalt. These experiments are not always equally successful. The solution may contain arsenic or not: when the arsenic is entirely removed, the oxide of vestium cannot be reduced to the metallic state.

I tried to decompose by carbonate of potash a solution of the impure regulus, after 1 had mixed it with sal ammoniac. The solution was at first blue from the nickel which it contained; but it soon changed into green. A white precipitate fell, which

→ Another time I precipitated the solution by acetate of lead, expecting in vain to separate the arsenic by that way and get the vestium pare,

resembled vestium. The green ammoniacal ley being neutralized with sulphuric acid and evaporated, let fall, besides nickel crystals, flocks of vestium. As these appeared after the solution had stood some days, I conceive it to be the vestium and not the oxide of iron which changes the blue colour of an ammoniacal solution of nickel into green; for the iron separates itself much

sooner.

6. Method of determining the Presence of Vestium in Ores. We can determine the presence of vestium in ores three different ways.

1. The ore fused into a regulus is to be dissolved in nitromuriatic acid, and the arsenic separated by the process above described. Decompose the solution freed from arsenic by caustic ammonia not in a state of too great concentration, and after filtering, add to the liquid carbonate of potash. If vestium be present, it separates altogether in the state of a white precipitate.

2. Or the ammoniacal solution may be decomposed by oxalate of potash, which throws down the vestium. If, on the other hand, carbonate of ammonia be poured into the solution, the vestium is not precipitated.

3. Or without freeing the muriatic solution from arsenic, we may pass a stream of sulphuretted hydrogen gas through it as long as a precipitate continues to fall. This precipitate being collected and heated is very easily reduced into the metallic state. Dissolve the regulus in nitric acid, and treat the solution in the way above described; or the metal may be thrown down by carbonate of potash, the precipitate be redissolved in sulphuric acid, decomposed by ammonia or potash, and evaporated. In short, we must proceed as in the preparation of vestium above described.

Appendix by the Editor.-It is evident from the preceding paper, that Dr. Vest has never obtained his new metal free from arsenic, nickel, and cobalt. Hence the experiments of Mr. Faraday and Dr. Wollaston (Royal Institution Journal, vi. 112) cannot be considered as sufficient to invalidate the existence of the substance called vestium by Dr. Vest. If his account of that substance be accurate, of which it will not be in our power to judge till the nickel ore of Schladming is examined by some other person, it is obviously different from every other metal with which we are at present acquainted.

ARTICLE IV.

On the Anthrazothion of Von Grotthuss, and on Sulphuretted Chyazic Acid. By R. PORRETT, Jun.

THE new name which M. Grotthuss has given to this acid, he informs us, was in consequence of his discovering that the name of sulphuretted prussic acid, which in Germany had been substituted as a synonyme for sulphuretted chyazic acid, was not applicable; as he had ascertained by his experiments that although it contained the same elements as prussic acid, yet they did not exist in it in the same proportions, and that neither prussic acid nor cyanogen as such exist in it. I trust, however, to be able to prove to chemists that this assertion is exceedingly erroneous; and that consequently no such reason exists for adopting the new term recommended by M. Grotthuss.

Besides new naming a substance already known, M. Grotthuss has given the name of anthrazothion to a principle which is not known, but which he conceives to exist in some sulphuretted chyazates, although he acknowledges that he has not been able to isolate it. It will be time enough to consider the propriety of this name when the principle itself has been obtained; in the mean time it will be useful to look a little into the arguments and suppositions on which its existence is defended.

In examining the suppositions which M. Grotthuss makes in order to admit the existence of anthrazothion, it appears that having concluded the sulphuretted chyazate of protoxide of copper to be a compound of anthrazothion with metallic copper, he explains its formation when sulphuretted chyazate of potash is poured into a mixed solution of a salt of peroxide of copper with a disoxidizing body, by supposing that the disoxygenating substance combines with th of the oxygen of the peroxide, and that the remaining ths combine with and separate the hydrogen from the sulphuretted chyazic acid, converting it to anthrazothion, which unites to the reduced copper; he further supposes that the water formed from the oxygen of the copper with the hydrogen of the acid enters into the new compound, which he consequently terms an anthrazothionhydrate.

A very simple experiment will suffice to show the fallacy of these suppositions. Let the sulphuretted chyazate of protoxide of copper be decomposed by a solution of potash, sulphuretted chyazate of potash will then be formed, and protoxide of copper will remain; now if the decomposed salt had been a compound of anthrazothion and copper, the water present must have furnished hydrogen to the anthrazothion, and oxygen to the copper; but as, according to M. Grotthuss, anthrazothion combines with three atoms of hydrogen, it must detach an equal number of atoms of oxygen from the water; two of these atoms of oxygen

would combine with the metal and convert it to peroxide, and the other atom must escape as gas; but as in the process no peroxide is formed, nor any oxygen gas liberated, it is very clear that the compound cannot be such as M. Grotthuss conceives it to be.

M. Grotthuss asserts that this compound " contains a notable quantity of water, though Porrett affirms the contrary:" this quantity he afterwards states at 4th of its weight. I did certainly affirm the contrary; and having since repeated my former experiments, I now reaffirm it; however, I by no means intend to assert that no water can be formed when it is heated so highly as to be decomposed; for as, according to my experiments, its acid contains an atom of hydrogen, and its oxide an atom of oxygen, it follows that an atom of water should in that case be produced which did not pre-exist as water in it: the weight of this water, however, would not exceed th of the sulphuretted chyazate, and would only amount to about half the quantity which M. Grotthuss procured. I can only account for the remaining half on the supposition that he had not sufficiently freed by lixiviation the sulphuretted chyazate which he employed from adherent salts which would surrender their water of crystallization when heated.

The arguments used by Von Grotthuss to induce a belief that the copper exists in this compound in the metallic state are the following:

1. That by the action of heat upon it, a peculiar gaseous body separates with a particular smell, which M. Grotthuss, both from the analogy of cyanogen and because it is absorbed by ammonia, and then strikes a blood-red colour with solutions of iron, considers as anthrazothion.

2. That after the action of heat there remains a sulphuret which contains the copper in the metallic state.

3. That it is nearly insoluble in muriatic acid, whilst, on the contrary, the alkaline sulphuretted chyazates are very soluble therein.

4. That during the combination of sulphuretted chyazic acid with easily reducible oxides, the former must undoubtedly reduce the latter, because its carbon, sulphur, and hydrogen, are each capable of reducing such oxides.

5. That at the instant when it is forming in a mixture of acetate of copper and alcohol, a brown colour is perceptible, which disappears when it is completely formed.

The insufficiency of these arguments for the purpose for which they are advanced will appear from the following obser

vations:

1. What M. Grotthuss conceives to be a peculiar gaseous body, and which he considers as anthrazothion, I have found to be only a mixture of gas and vapours, principally consisting of a compound of sulphur with cyanogen, resembling that formed

1

when cyanogen and sulphuretted hydrogen are mixed together; it also contains azote and sulphuret of carbon, the latter readily distinguishable by its peculiar smell, and sometimes a minute quantity of sulphuretted chyazic acid comes over with it unaltered. From 10 gr. of sulphuretted chyazate of copper, I obtained about two cubic inches of this mixture of gas and vapour over mercury; but this diminished considerably in bulk as the vapour condensed, the surface of the mercury at the same time becoming tarnished; and there remained after the action of an alkaline solution only about half a cubic inch of azote. The same quantity of sulphuretted chyazate, when previously mixed with half its weight of copper (in that state of minute division in which it is precipitated from its solutions by iron) gave, on the application of heat, about three cubic inches of permanent gas, which was cyanogen.

2. The sulphuret left behind containing the metal in the metallic state, is nothing more than what should occur considering that the oxygen in the protoxide is only in the proportion necessary to form water with the hydrogen of the acid; it therefore follows, as I said before, that when the compound is decomposed by heat, water must be formed, and the metal reduced; but it does not follow that the metal was in this state before that decomposition takes place.

3. The little solubility of sulphuretted chyazate of copper in muriatic acid will, I apprehend, be thought a very inadequate proof that it contains the copper in the state of metal, when it is considered that oxalate of copper has also very little solubility in this menstruum, and yet it contains the copper in the state of peroxide; and that, on the other hand, cyanuret of mercury, which contains the metal in the metallic state, is very soluble therein.

4. With respect to the argument that the carbon, hydrogen, &c. of the sulphuretted chyazic acid must undoubtedly reduce the easily reducible oxides, I conceive it will be sufficient answer to state that, if there were any truth in this remark, the acetates of silver, mercury, and copper, with a variety of similar salts, could have no existence.

5. With regard to the brown copper colour which a mixture of acetate of copper with alcohol momentarily assumes when sulphuretted chyazate of potash is added to it, I can assert that the mixture becomes indeed brown, but presents no metallic appearance; the colour is exactly similar to that of protomuriate of copper when it contains a little permuriate; it, therefore, merely indicates the presence of protoxide in the solution, but not that of metallic copper.

Having thus shown that no grounds exist for considering sulphuretted chyazate of copper as an anthrazothionhydrate, I shall now show its real composition.

In an experiment detailed in my paper, on the nature of the