more complete destruction of the electro-chemical opposition in the bodies united together. Thus, for example, potassium separates the metal from oxide of copper with the appearance of fire, but from the oxide of iron only with an increase of temperature; because iron has a stronger affinity for oxygen than copper has, and therefore destroys the electro-chemical properties of oxygen more completely than copper (though potassium destroys them still more completely).

Potash free from water (obtained by the action of potassium on the peroxide of potassium) exposed to the action of oxymuriatic gas, absorbs it with an increase of temperature, which when the potash has been previously heated amounts to the appearance of fire. The same thing takes place with the hydrate of potash, though in a less degree. By this absorption oxygen gas is set at liberty. If this oxygen proceeds from the potash, the experiment would show that chlorine has a stronger affinity for potassium than oxygen has, and therefore that it destroys the electro-chemical properties of potassium more completely than oxygen does; and consequently that chlorine is a more electro-negative body than oxygen. But chlorine constitutes the basis of euchlorine and chloric acid, that is, the electro-positive ingredient; therefore chlorine is less electro-negative than oxygen; but it is self-evident that it cannot be at the same time both more and less negative than oxygen. Therefore the separation of the oxygen from the potash in these experiments is inconsistent with the electro-chemical doctrine. Hence it clearly follows that either the electro-chemical doctrine, or the new opinion respecting the nature of chlorine, must be false. On the other hand, according to the old doctrine, it is very conceivable that in the super-oxide of muriatic acid the acid allows the excess of its oxygen to escape, in order to combine with the salifiable basis, for which it has a greater affinity. As the quantity of oxygen in the new compound remains the same, the separation proceeds entirely from the affinity of the radical of the basis of the salt. Hence it follows that the explanation afforded by the old theory is perfectly satisfactory, and agrees with the other parts of the theory of chemistry.

4. Chlorine combines with Sulphur, and forms a Chloride of Sulphur.

The chloride of sulphur is the muriate of sulphur discovered by Thomson; and, according to the old doctrine, it must be a compound of muriatic acid and the oxide of sulphur. With respect to this compound, the new doctrine appears at first sight to have a great superiority over the old one, because it is not under the necessity of admitting the existence of one oxide of sulphur no where else to be found. Yet such a supposition is by no means improbable. We are acquainted with several bodies not capable of existing insulated in a particular degree of oxidation, and which are decomposed whenever we attempt to procure them in a separate state.

If this be the case with the oxide of sulphur, we need not be surprised that it can only be exhibited in a state of combination. When the muriate of sulphur is decomposed by water, all the oxygen of the sulphur combines with one-half of the sulphur, and forms sulphurous acid; while the other half of the sulphur appears to be reduced. According to the new doctrine, the water is decomposed, the hydrogen forming with chlorine muriatic acid, and the oxygen with a portion of the sulphur, sulphurous acid. The superiority of the new doctrine, therefore, consists in this, that it has no occasion to suppose the existence of a lower degree of oxidizement of sulphur (an opinion in other respects not improbable). But we shall soon destroy this apparent superiority, and turn the weapons of the new opinion against itself.

The substance discovered by Dr. Marcet and myself by the action of aqua regia on sulphuret of carbon is sufficiently known. According to the old doctrine, it must be considered as a combination of three acids free from water, namely, muriatic acid, sulphurous acid, and carbonic acid. The quantity of oxygen in the last two is equal to each other; and that in the muriatic acid as great as in both the others. According to the new doctrine, this body must consist of one proportion of phosgene (the name given to the body formed by the combination of carbonic oxide and chlorine) and one proportion of a compound of chlorine, sulphur, and oxygen. But the proportion of sulphur and oxygen in this compound is quite the same as in the oxide of sulphur admitted by the old doctrine in the muriate of sulphur (the sulphur is combined with half as much oxygen as in sulphurous acid). Hence it is obvious that the new doctrine must admit the existence of the same oxide in order to explain the nature of the compound in question. The new doctrine, therefore, in this point of view, has no superiority whatever over the old doctrine.

5. Chlorine combines with Phosphorus in two Proportions.

The compounds formed by the action of oxymuriatic acid on phosphorus are, according to the old doctrine, compounds of muriatic acid and phosphorous or phosphoric acids free from water. When water comes in contact with them, it decomposes them, and reduces them to the state in which they exist when united with water. But according to the new doctrine these compounds are peculiar acids free from water, in which the phosphorus constitutes the base, or the electro-positive; and chlorine, the electro-negative ingredient. These acids are capable of uniting only with one base, namely, ammoniacal gas. By all other bases they are decomposed, a phosphate and a chloride being formed. The old doctrine appears to me in this case to be both simpler and more correct; as it considers the ammoniacal salt as a double saft without water, and composed of two acids united to one base; and the compounds of these two acids with other bases, either as equally double salts, or as mix

tures of phosphates and muriates, formed according to circumstances, either with or without chemically combined water.

6. Chlorine does not combine with Charcoal, but it unites with its own Bulk of Carbonic Oxide Gas.

From the phenomena peculiar to muriatic acid flows the old doctrine that this acid cannot exist in a separate state, as is the case also with nitric acid, oxalic acid, tartaric acid, and several others. If we suppose that charcoal has a weaker affinity for oxygen than the basis of muriatic acid has, oxymuriatic acid gas may only be reduced to muriatic acid when an oxide is present with which the acid may combine. If carbonic oxide were not unlike other oxides (as is in general the case with suboxides), it would combine with muriatic acid, and form a muriate of carbonic oxide quite similar in appearance to the combination of one volume of chlorine with one volume of charcoal. According to the old doctrine, we can in some measure see why charcoal does not act upon chlorine, while the new doctrine affords no explanation of the reason why charcoal is the only element incapable of uniting with chlorine without the intervention of oxygen.

1

When chlorine combines with its own volume of carbonic oxide, it forms a strong gaseous acid, which has obtained the very improper and intolerable name of phosgene gas. This acid, according. to the new doctrine, is analogous to chloro-phosphoric acid, but distinguished from it by containing oxygen gas. It is the only example of an acid composed of one electro-positive body, charcoal, and two electro-negative bodies, chlorine and oxygen. This acid is capable of uniting only with a single basis, ammoniacal gas, and forming with it a salt. By all other salifiable bases it is decomposed, and there is formed a carbonate and a chloride. Phosgene, then, is a pretty strong acid, composed of one basis and two oxygens (sit venia verbis), which is capable of forming a salt only with one base; since with all other soluble bases it forms a very different compound of a carbonate and a chloride.

According to the old doctrine, oxymuriatic acid gas contains half its bulk of oxygen in excess. Therefore carbonic oxide gas finds in its own bulk of oxymuriatic acid gas a sufficient quantity of oxygen to convert it into carbonic acid. By the mutual action of the two gases, carbonic acid and muriatic acid gases are formed, which unite with each other, and form a double acid, in which both acids contain an equal proportion of oxygen. This acid unites both with bases free from and containing water. Some of these compounds are true triple salts, composed of one basis and two acids; others only a mixture of a muriate and carbonate. To the triple salts belong the ammoniacal salt, the lead salt, and perhaps many others, which may also be formed by a mixture of muriates and carbonates. For example, if moist carbonate of lead be introduced into a boiling hot and saturated solution of muriate of lead, the

two salts combine, and form an insoluble triple salt, composed of one basis and two acids. It appears to me that in this case also the old doctrine accords with our other chemical opinions.

(To be continued.)

ARTICLE VI.

On a New Compound of Phosphorus and Potash. By the Chevalier Sementini, Professor of Chemistry at Rome. *

THE Compound of potash and phosphorus remains still unknown. No mention is made of it in the modern books of chemistry; and Klaproth, in his Dictionary of Chemistry, says frankly that "the science has not yet pointed out a mode of combining that substance with phosphorus.

I have obtained, for the first time, the phosphuret of potash by the following process :

1. I saturated very strong alcohol with potash. This solution had a deep amber colour; its consistence was, as it were, oily, and its taste very caustic.

2. I introduced into this liquid pieces of phosphorus, which appeared instantly covered over with bubbles of gas. The phosphorus diminished in quantity, dissolving as this gas, which was a protophosphuret of hydrogen, was disengaged. When the first pieces were entirely dissolved, I introduced new ones; and I proceeded in this manner till all disengagement of gas was at an end, and till the phosphorus ceased to dissolve in the liquid. This saturation required at least 15 days.

3. At the end of this first operation I found at the bottom of the vessel a powder of a dark red colour, and scales of a certain brilliancy, but covered with that powder.

4. I separated the sediment of the liquid by the usual method of filtration; and the liquid appeared to differ from the alcoholic solution of potash by its straw colour; by its consistence, which was no longer oily, but fluid, like water; and by its taste, which had become sweetish and sharp.

5. I dissolved the scales that remained on the filter in pure water. The solution was muddy; but, on being filtered, it became limpid, like water.

6. There remained upon the filter a red powder, similar in appearance to kermes mineral.

7. The sides of the vessel in which the solution of the phosphuret had been made remained stained with black.

Translated from the Bibliotheque Britannique, Sept. 1815, vol. lx. p. 24.

8. The liquid of paragraph 4, which was exposed to the air, be came, after some days, covered with a yellowish pellicle, of an oily appearance, which disappeared after some weeks. When this substance was separated from the liquid, it assumed the appearance of No. 5.

9. The two liquids (Nos. 4 and 5), being evaporated to the con→ sistence of a syrup, yielded confused, and not permanent, crystals. Evaporated to dryness, they gave the phosphuret of potash under the appearance of a white opake mass, which, when strongly heated, burnt with a yellow flame. The residue of this combustion was a grey mass, semi-liquid, and deliquescent, and in its inside partly yellowish, partly blackish.

10. The scales remaining on the filter are a true phosphuret of potash, and do not differ from the liquids 4 and 5, but by the difference of the solid and liquid state. They deliquesce when left exposed to the air; and, when heated till they become dry, they take fire, and burn with a white flame.

.11. The red matter of No. 6 becomes darker coloured when left exposed to the air, but it remains humid and coherent. When treated with perchlorate (hyper-oxymuriate) of potash, it gives phosphorous acid gas, carbonic acid gas, and carbonate of potash.

From an attentive examination of all these facts, it appears that they are the result of a play of affinities, in consequence of which the greater part of the phosphorus combines with the potash. The compound divides itself into two portions, one of which precipitates under the form of scales, and the other remains in solution. The solution of the phosphuret of potash (No. 4) contains, likewise, a certain quantity of alcohol of phosphorus; and the yellowish pellicle with which the liquid becomes covered, when left exposed to the air, is owing to this, that the alcohol, on evaporating, leaves the phosphorus in a state of extreme division, which enables it gradually to disappear when left in contact of air.

Besides the principal compound, the phosphuret of potash formed in this process, others are likewise produced. The alcohol is decomposed, its hydrogen is developed in the state of gas, and dissolves at the same time a portion of the phosphorus. The carbon of the alcohol combines with the phosphorus and potash, which produces the reddish-brown matter of No. 6, which is a triple compound of phosphorus, potash, and charcoal, as appears from the products when it is treated with perchlorate of potash, No. 11.

The two solutions, Nos. 4 and 5, when burnt as described in No. 9, contain likewise a portion of oxide of phosphorus, from which proceeds the yellowish and blackish colours which alternate in the residue of this combustion.

I proceed to the action of the acids on the solutions of the phosphuret of potash of Nos. 4 and 5.

Hitherto the action of three acids only, the sulphuric, muriatic, and nitric, has been tried. They only produce an imperfect decomposition of the phosphuret of potash, Sulphuric acid deprives the VOL. VII. No IV.

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