a blood red solution; and both of them give the same colour to the persalts of iron.

The red solutions, produced by both of these acids, lose their colour on the addition of acids, alkalies, protomuriate of tin, and the solar rays.

The disappearing of the red colour by the sun's rays is owing to the peroxide of iron being changed into protoxide; for ammonia throws down a reddish precipitate from the red solution; but a green precipitate (protohydrate of iron) from the liquid rendered colourless by the solar light.

When the liquids rendered colourless by the sun are placed in a dark place, but exposed to the air; or better, if they be placed in contact with nitrous acid in the state of vapour, the blood red colour appears again; because the iron is again converted into peroxide.

Writing with common ink becomes red, when plunged into sulphuretted chyazic acid, as it does when plunged into meconic acid.

But the analogy between these two acids does not go further. Solution of gold deprives the compound of sulphuretted chyazic acid and peroxide of iron of its red colour; but it produces no alteration in the solution of peroxide of iron in meconic acid.

Finally, meconic acid is solid, crystallizable, and capable of subliming, while sulphuretted chyazic acid is a liquid, and a violent poison.

Dr. Sommering made a set of experiments on dogs with sulphuretted chyazic acid, meconic acid, and morphia. We cannot enter into a detail of the numerous experiments which he made on this subject. As a paper on the subject will be published in Schweigger's Journal, we shall confine ourselves here to the following observations which contain the general results.

Outline of the Physiological Experiments.

Concentrated chyazic acid occasions sudden death, when administered in the quantity of half a gros. When the acid is much diluted with water, and given in repeated doses, it acts on the organs of respiration, produces convulsions, and death ensues more slowly.

A small quantity of this acid affects the respiration. The acid is voided in the urine, without producing permanently bad consequences.

A dog, upon which the diluted acid was made to act for 24 hours, and which died in consequence, was opened. The presence of the acid could be detected in the blood, and still more easily in the urine.

Sulphuretted chyazate of potash, administered in the same

doses, produces similar effects. This salt then, as well as the acid, acts in the same way as prussic acid.

Meconic acid, taken in a dose of from eight to ten grains, produces no sensible effect upon young and weak dogs: and the original opinion of M. Sertürner seems to be much better founded than the recent assertion that meconic acid is the most violent poison among vegetable substances.

Meconiate of soda, in a dose of 10 grains, produces no sensible effect.

Morphia, in a dose of 10 grains, or even four grains, is narcotic in an eminent degree. A dog fell asleep immediately, and slept 24 hours without interruption; but did not die.

Recapitulation of the Chemical Experiments.

It follows from the facts stated in this paper:

1. That we cannot obtain pure sulphuretted chyazate of potash, nor pure sulphuretted chyazic acid, when we calcine prussiate of potash and sulphur at a red heat.

2. That it is sufficient to fuse the mixture, if we do not wish to push the decomposition further than is necessary for the purity of the products.

3. That we may obtain pure sulphuretted chyazic acid by distilling sulphuretted chyazate of potash, mixed with dilute sulphuric acid, or still better with phosphoric acid.

4. That sulphuretted chyazic acid exposed to the sun, or placed in contact with the air, allows sulphur to precipitate without assuming a red colour.

5. That the acid, when exposed to a red heat, is decomposed into sulphur, prussic acid, and ammonia.

6. That nitric acid, or chlorine, does not precipitate sulphur from sulphuretted chyazic acid, but forms sulphuric acid, and sets prussic acid at liberty.

7. That iodine decomposes the acid, and produces hydriodic acid.

8. That sulphuretted chyazic acid has no other analogy with meconic acid than that of forming blood red liquids with peroxide of iron and the persalts of iron.

9. That sulphuretted chyazic acid is an excellent reagent for salts containing peroxide of iron; but only when there is no excess either of acid or alkali in the liquid.

10. That sulphuretted chyazic acid is not composed of the elements of prussic acid in other proportions united to sulphur; but appears to consist of a chemical combination of prussic acid and sulphur; and the sulphur is the cause of all the singular properties of this acid composed of three combustible bodies.

11. Finally, that the discovery of Porrett should make us attentive in manufactures of prussian blue to avoid a potash which contains sulphur, or even too great a quantity of sulphate; because it would occasion a considerable loss in the formation of the prussian blue.

ARTICLE IV.

Account of a newly discovered Metal, and the Analysis of a new Mineral. By Prof. Stromeyer. (In a Letter to Dr. Schweigger.)*

Gottingen, April 26, 1818.

THE last number of your excellent journal, which I received yesterday, and which, among other interesting discoveries and researches, gives an account of a new metal discovered by Berzelius, has suggested to me the propriety of sending you for the same publication an account of a new metal discovered by me during the course of the last winter.

As I was last harvest inspecting the apothecaries' shops in the principality of Hildesheim, in consequence of the general inspection of the apothecaries of the kingdom having been entrusted to me by our most gracious Regency, I observed in several of them, instead of the proper oxide of zinc, carbonate of zinc, which had been almost entirely procured from the chemical manufactory at Salzgitter. This carbonate of zinc had a dazzling white colour; but when heated to redness, it assumed a yellow colour, inclining to orange, though no sensible portion of iron or lead could be detected in it. When I afterwards visited Salzgitter, during the course of this journey, and went to the chemical manufactory from which the carbonate of zinc had been procured; and when I expressed my surprize that carbonate of zinc should be sold instead of oxide of zinc, Mr. Jost, who has the charge of the pharmaceutical department of this manufactory, informed me that the reason was, that their carbonate of zinc, when exposed to a red heat, always assumed a yellow colour, and was on that account supposed to contain iron, though the greatest care had been taken beforehand to free the zinc from iron, and though it was impossible to detect any iron in the oxide of zinc itself. This information induced me to examine this oxide of zinc more carefully, and I found, to my great surprize, that the colour which it assumed was owing to the presence of a peculiar metallic oxide, the existence of which had not hitherto been suspected. I succeeded by a peculiar process in freeing it from oxide of zinc, and in reducing it to the metallic state. I have found the same oxide in tutia, and in several other oxides of zinc; and it exists likewise, as might have been expected, in metallic zinc. But in all these bodies it exists only in a very minute proportion, which can scarcely exceed between and of the whole.

The properties by which this new metal is distinguished are the following: it has a light white colour, inclining a little to grey, and in this respect comes nearest to platinum. It has a great deal of brilliancy, and admits of a fine polish. Its texture

* Translated from Schweigger's Journal, xxi, 297. (Published May 28, 1818.)

is very compact, and its fracture hackly. Its specific gravity is pretty considerable, amounting to 8.750 after the metal has been fused. It is very ductile, and may be hammered out into thin plates, both cold and hot, without the risk of cracking. Its cohesion appears to be pretty considerable, and to surpass that of tin. It belongs to the more fusible metals; for it melts before it is red hot; and an iron wire, heated to redness by a spirit lamp, readily melts it. It is likewise very volatile, rising up in the state of vapour, at a temperature not much surpassing that at which mercury boils. This vapour has no peculiar smell, and congeals, like mercury, in drops, which exhibit distinct traces of crystallization.

This metal undergoes no alteration when exposed to the air; but, when heated, it burns very readily, and is converted into a yellow coloured oxide, the greater part of which sublimes in the state of a yellowish coloured smoke, and covers any body held over it with a yellow coating. If the experiment be made before the blow-pipe upon charcoal, the charcoal is in like manner covered with a brownish yellow-coloured coat. It gives out no perceptible smell when it burns. It dissolves in nitric acid with the evolution of nitrous gas. Sulphuric acid and muriatic acid act upon it likewise, and hydrogen gas is given out; but its solution in these acids is a very slow process, The solutions are quite colourless, and are not precipitated by water. This metal appears to combine with oxygen in only one proportion. The oxide has a greenish yellow colour; but by exposure to a strong red heat, it acquires a tint of yellow; and if the heat be very long continued, it becomes nearly brown. As the orange and brown oxides dissolve in acids, as well as the greenish yellow, without the evolution of any gas, and form the very same kind of solutions, there is reason to believe that the alteration in the colour of the oxide is merely owing to the state of its aggregation, and not to any difference in the proportion of oxygen which it contains. This oxide withstands the strongest heat; and when raised to a white heat in a covered platinum crucible, by means of Marcet's lamp, it did not undergo fusion. When heated with charcoal, or any substance containing carbon, it is easily reduced to the metallic state; and the reduction takes place when the heat just begins to get red. To borax, it communicates no colour. It does not dissolve in the fixed alkalies; but a portion of it is taken up by ammonia. Towards the acids, it acts precisely as a salifiable base. The salts which it forms have almost all a white colour. Those with sulphuric acid, nitric acid, muriatic acid, and acetic acid, crystallize readily, and are very soluble. Those with phosphoric acid, carbonic acid, and oxalic acid, are insoluble. From the solutions of the first mentioned salts, it is thrown down white by the fixed alkalies, probably in the state of an hydrate, and the

precipitate is not redissolved by adding an excess of alkali. By ammonia, on the contrary, it is indeed at first precipitated white; but when an excess of the ammonia is added, it is again taken up. By carbonate of ammonia, it is thrown down in the state of a carbonate; but when an additional quantity of the precipitant is added, the greatest part of this carbonate is again redissolved. When this solution is exposed to the open air, the carbonate very speedily precipitates again. We may, therefore, employ carbonate of ammonia with advantage to separate this metal from zinc and copper, when it is mixed with them.

Prussiate of potash throws down this metal from its solutions in acids white; sulphuretted hydrogen, and the hydrosulphurets, throw it down yellow. This last precipitate, which, when dried, has an orange yellow colour, resembles sulphur auratum, and like it is a hydrosulphuret. From its colour and appearance, it might, by a careless observer, be mistaken for orpiment; but it is readily distinguished by its more pulverulent form, by its appearance before the blow-pipe, and by its easy solubility in acids, with the evolution of sulphuretted hydrogen gas. To judge from some trials, this compound of sulphuretted hydrogen and the new metallic oxide is well adapted for painting, both with water and with oil. It forms a very good yellow, which is durable; and in point of beauty is not inferior to chrome yellow. This metal is precipitated by zinc from its acid solutions, reduced, and in the dendritic state. But copper, lead, silver, and gold, are precipitated by it in the metallic state.

The compounds which this metal forms with sulphur, phosphorus, iodine, and the other metals, I have not hitherto been able to investigate with accuracy; though it seems to unite readily with several of these bodies; for example, when heated with platinum, it easily melts, and combines with that metal, and it forms with mercury a solid crystallizable amalgam. Hitherto I have not been able to make it unite with copper.

These are the particulars which I have hitherto been able to ascertain respecting this metal. They are so peculiar that I entertain no doubt about it being a new metal quite different from every other. As I found it first in the oxide of zinc, I have taken occasion from that circumstance to give it the name of Cadmium.

In consequence of the very small quantity in which cadmium exists in the oxide of zinc, and the metallic zinc examined by me, it has not hitherto been in my power to undertake experiments to determine the composition of its compounds, the shape of the crystals of its salts, and the action of its oxide and salts on organized bodies, &c. Indeed the whole of the metal which I had for my experiments did not exceed three grammes. I am happy, therefore, to be able to inform you, that within these few days, through Mr. Hermann, of Schönebeck, and Dr. Rodolff,

5