J38 On the Combinations [Feb. 



phosphorus, placed in other circumstances, would absorb the 

 same quantity of oxygen, or whether in fact there were not 

 other phosphoric acids. The action of chlorine was employed 

 for this purpose ; and the result was that, according to the esti- 

 mate founded upon this process, 100 parts of phosphorus require 

 123 parts of oxygen, to be converted into phosphoric acid, so that 

 we are justified in concluding that the acid produced by the 

 medium of chlorine, is exactly similar to that produced by nitric 

 acid. 



ft has already been observed that Sir H. Davy gives a differ- 

 ent statement respecting the constituents of phosphoric acid : 

 he conceives that 100 parts of phosphorus require 150 of oxygen, 

 and that the phosphoric requires twice as much oxygen as the 

 phosphorous acid. As his calculation depends upon the idea 

 which he entertains concerning the constitution of the chloruret 

 of phosphorus at the maximum, or the perchloride of phosphorus, 

 it appeared necessaiy to examine this substance. For this pur- 

 pose a vessel was filled with chlorine, the weight of which was 

 ascertained ; into the same vessel, after removing the chlorine, 

 a minute quantity of phosphorus was introduced, and it was 

 again filled with chlorine, by which means the phosphorus was 

 immediately converted into the perchloride ; and by ascertaining 

 the addition of weight acquired by the vessel, it was calculated 

 that 100 parts of phosphorus were united with 549*1 of chlorine ; 

 Sir H. Davy's estimate makes the latter number 666. As.it had 

 been before found that the chloruret at the minimum, or the pro- 

 tochloride, was composed of 100 parts of phosphorus to 347*7 

 parts of chlorine, and as 347*7 is to 549*1 very nearly in the 

 ratio of 3 to 5, we may conclude that the oxygen of the phos- 

 phorous acid, is to that of the phosphoric in the same ratio, 

 instead of that of 1 to 2. Phosphoric acid must then be com- 

 posed of phosphorus 44*48 parts, and oxygen 55*52 parts ; oi 

 phosphorus 100 parts, and oxygen 124*8 parts. 



A remarkable phenomenon is mentioned as taking place from 

 the decomposition of the chloruret of phosphorus by water. If 

 a piece of this substance is projected upon water, the violent 

 heat which is evolved reduces the greatest part of the chloruret 

 into vapour. If, on the contrary, the chloruret in powder is 

 thrown upon water, not much heat is excited ; but an oleaginous 

 fluid is formed, which soon begins to act upon the water, a great 

 increase of temperature ensues, and the oily body disappears. 

 This oily matter was collected in a separate state, and submitted 

 to a number of experiments, which showed it to be different 

 from either of the chlorurets ; but it is conceived to be rather a 

 union of several bodies, than a specific compound. What 

 appears the most probable, is, that it is a hydrate of the chloruret 

 of phosphorus, holding in solution a large quantity of this same 

 chloruret. 

 When phosphorus is burned in oxygen, or in atmospherical 



