358 SULPHUR AND PHOSPHORUS, 



of chlorine are merely the phosphoric acid from the sublimate, 

 and the phosphorous acid from the liquor, and muriatic acid 

 gas ; so that the quantity of phosphorus being the same, it is 

 evident that phosphoric acid must contain twice as much oxy- 

 gen as phosphorous acid, which harmonizes with the results 

 And the facts of the decomposition of hydrophosphorous acid. For supposing 

 phosphoric water to be composed of two proportions of hydrogen, and 

 acid contains one of oxygen, and the number representing it 17} then 1/4 

 oxy'r>-en*ar"'^ P^*^^^ ^^ hydrophosphorous acid must consist of two propor- 

 phosphorous tions ; 34 parts of water, and four proportions of phosphorous 

 acid, containing 80 of phosphorus and 60 of oxygene • and 

 three proportions of phosphoric acid must be formed, con- 

 taining three proportions of phosphorus QO, and six propor- 

 tions of oxygen gO, making 150. 

 Water atid the It is scarcely possible to imagine more perfect demonstrations 



phosphor. of the laws of definite combination, than those furnished in the 



compounds 



shew com- mutual action of water and the phosphoric compounds. No 



pletely the products are formed except the new combinations : neither 



laws of defi. " f ' 



pite combina- oxygen, hydrogen, chlorine, nor phosphorus is disengaged, 



*'o"' and therefore the ratio in which any two of them combine 



being known, the ratios in which the rest combing, in thesQ 



cases, may be determined by calculation. 



Phosphoric I converted phosphorus into phosphoric acid, by burning it 



acid produced 5n a great excess of oxygen gas over mercury in a curved glas$ 



in oxyg. con- tube, and heated the product strongly. I found in several pro- 



tams 20 phos. cesses of this kind, that for every grain of phosphorus con- 



°^y°' sumed, four cubical inches and a half of oxygen gas were 



absorbed ; which gives phosphoric acid as composed of 20 of 



phosphorus to 306 of oxygen ; a result as near as can be 



expected to the results of the experiments on the sublimate and 



the hydrophosphorous acid. 



Unless the product of the combustion of phosphorus is 

 strongly heated in oxygen, the quantity of oxygen absorbed 

 is less, so that it is probable that phosphorous acid is formed, as 

 Xvell as phosphoric acid. 

 Common phosphorous acid is usually described, in chemical authors, 



phosphorous gg a fluid body, and as formed by the slow combustion of phos-» 

 ' * ^" ■ phorns in the air ; but the liquid so procured is, I find, a solu- 

 tion of a mixture of phosphorous and phosphoric acids. And 

 the vapour arising from phosphorus in the air at common tem- 

 peratures, 



