Phosphorus and Sulphur, fi?c. 421 



phosphorus is disenffaced, and therefore, ihe ralio in which 

 any two of them coaibine heing known, tlie ratios in which 

 the rest combine, in these cases, inay be d^;le^nlined hy cal- 

 culation. 



I convened phosphorus into phosphoric acid, by burning 

 it in a jjreat excess of oxvgen gas over mercury in a curved 

 glass tube, and heated the product strongly., I found ill 

 several processes of this l;ind, that for every grain of phos- 

 phorus consumed, four cubical inches and a hall of oxygen 

 gas were absorbed ; which gives phosphoric acid as com- 

 posed of 20 of phosphorus to 30"6 of oxygen ; a result as 

 near as can be expected to the results of the experiments 

 on the subhniate and tlie hvdrophosphorous acid. 



Unless the product of the coml)Ustion of phosphorus is 

 strongly heated in oxvgen, the quantity of oxygen absorbeu 

 is less, so tiial it is probable that phosphorous- acid is 

 formed, as well as phosphoric acid. 



l'h(5sphoroiis acid is usually described, in chemical authors* 

 as a fluid bodv, and as formed by the slow combustion of 

 phosphorus in the air; but the liquid so procured is, I find, 

 a solution of a mixture of phosphorous and phosphoric 

 acids. And the vapour arising from phosphorus in the air 

 at common temperatures, is a combination of phosphorous 

 acid and the aqueous vapour in the air, and is not, 1 find> 

 perceived in air artitici.'x!!y dried. 



In this case, the phosphorus becomes covered with a 

 white fihn, which appears to be pure phosphorous acid, 

 and it soon ceases to shine. 



A solid acid, volatile at a moderate degree of heat, may 

 be produced bv burning phosphorus in very rare air, and 

 this seems to he pho'-phorous acid free from water ; but 

 some phosphoric acid and spnie yellow oxide of phos- 

 phorus are always formed .it thf same time. 



The peculiar gas differs exceedingly from pho^phorettcd 

 hydroiicn formed bv the action of earths and alkahcs and 

 pii(>sphoi us u[)on water ; for this last gas is spoiitaneouslv 

 inflammable, and its specific gravity is seldom more than 

 half as great, and it does not afford more than l'5 its 

 volume ot hydrogen when decomp'>sed by ptjtassiutn ; ic 

 diflers in iis quahiies in difTerenl eases, and probably con- 

 bisis of (liffetent mixtures of hvdrogen wit!i a pecuhar gas, 

 consisting of two parts of hvdrogen and 20 of phosphorus j 

 or it mu-*i contain several proportions of hydrogen to ont 

 of phosphorus. 



1 venture to propose the name hyJrophosphoric gas for 



the new gas ; and according to the principles of iw)men* 



D d a claturcj 



