Sir H. Davy and Gay Lussac have investigated several compounds of phosphorus, particularly with muriatic and oxymuriatic acids, and with the new metals potassium and sodium, which I shall have to notice in their proper places. Other authors have written on phosphurets besides those I have mentioned, but they do not require to be particularly distinguished in this enumeration. We shall therefore proceed to describe the phosphurets more particularly. 1. _Phosphuret of hydrogen._ From recent experiments which I have made on phosphuretted hydrogen gas, I find the account already given (VOL. 1. page 456) is deficient, and in several respects inaccurate; I shall therefore substitute the following, as more perfect and correct. Phosphuretted hydrogen may be obtained nearly pure, by the methods recommended by Dr. Thomson. Phosphuret of lime that has been carefully secluded from the atmosphere, may be put into a small phial filled with water, acidulated by muriatic acid; into this a cork with a bent tube must be immediately put under water, so that the phial and tube are both full of water; gas soon begins to appear, which rising to the top of the phial, expels a corresponding portion of water, and in due time the gas itself comes over and may be received as usual: if the phial in which the gas is generated be warmed to 140 or 150°, the gas is given out more readily. A half ounce phial with 20 grains of phosphuret in small lumps, will produce 3 or 4 cubic inches of gas. If the phosphuret of lime has been previously exposed for a few hours to the atmosphere, the gas is more abundant, but consists chiefly of hydrogen, mixed with a little phosphuretted hydrogen.