The results of Davy and the French chemists appear to be discordant; but I apprehend they may be reconciled. It appears probable from both, that the phosphuret of potassium must be a compound of one atom of each, or 35 potassium and 9⅓ phosphorus; that is, 100 potassium and 27 phosphorus nearly. Now in Davy’s method of treating the compound with acid, it is most probable that the atom of potassium takes one of oxygen to form potash, and the atom of phosphorus takes one of hydrogen to form one of phosphuretted hydrogen; but 3 volumes of pure phosphuretted hydrogen contain 4 volumes of hydrogen, (see page 178); and Davy obtained nearly ¾ of the volume of gas which the potassium alone would have produced, which therefore accounts for the fact as stated by him. On the other hand, the French chemists by treating the phosphuret with hot water, probably determined the resolution in this way: the potassium resolved the water into oxygen and hydrogen the last of which was liberated in a free state, and of course produced the usual volume; the phosphorus also resolved the water into oxygen and hydrogen, one half of it taking the oxygen to form phosphorous acid, and the other half taking the hydrogen to form phosphuretted hydrogen, which of course would produce phosphuretted hydrogen amounting to ⅜ of the volume of free hydrogen or 38 per cent. nearly, which would make up the volume of gas to 138, or nearly 140, as observed by them. It is not unlikely that 2 or 3 per cent. of hydrogen might be added by the further decomposition of water by the phosphorous acid, in order to make it into phosphoric acid. 19. _Phosphuret of sodium._ No particular experiments having been detailed of this compound, we must infer it is similar to the last mentioned, and consists of one atom of sodium, 21, and one atom of phosphorus, 9⅓; that is, 100 sodium and 44 phosphorus nearly. 20. _Phosphuret of bismuth._ If we may judge from M. Pelletier’s experiments, bismuth has but a weak affinity for phosphorus. By projecting portions of phosphorus amongst melted bismuth, he succeeded in uniting some of it to the metal; he estimates the quantity at 4 per cent.; whereas by theory it ought to be 15 per cent. supposing them to unite atom to atom. I do not find that the salts or oxide of bismuth are materially affected by phosphuretted hydrogen water. 21. _Phosphuret of antimony._ Phosphorus may be combined with antimony, according to Pelletier, by the same means as with the other metals. The phosphuret has a white, metallic appearance and lamellar fracture. The ratio of the elements was not determined. By theory supposing one atom to unite with one, it would be 40 to 9⅓, or 100 antimony to 23 phosphorus nearly. Phosphuretted hydrogen water seems to have no effect on the salts or oxide of antimony. 22. _Phosphuret of arsenic._