1818.] of Phosphorus and Oxygen. 135 



generally employed : they were formed by passing the vapour of 

 phosphorus over the heated earth in a narrow tube, and were found 

 to be saturated compounds. When this phosphuret is projected 

 into water, phosphuretted hydrogen gas is disengaged, and after 

 some time a powder subsides to the bottom of the vessel, which is 

 completely insoluble in water and is of a yellow or brown colour. 

 Nitric and muriatic acids dissolve very nearly the whole of it ; 

 and it may be precipitated by ammonia, when it is said to exhibit 

 all the properties of a phosphate of the earth employed in the for- 

 mation of the phosphuret. The water which has been employed 

 in the above experiment contains a considerable quantity of 

 barytes, and it is combined with the new acid in question, 

 which may be obtained in a separate state, by adding sulphuric 

 acid, so as to form the sulphate of barytes, which is precipitated 

 from the fluid. The water may be removed by distillation, and 

 a strong acid is left, which does not precipitate any metallic 

 solution, and possesses a density approaching to that of concen- 

 trated sulphuric acid. To this, which M. Dulong regards as a 

 new acid, he gives the name of hypophosphorous, and styles its 

 salts hypophosphites. Iodine, in the solid state, put. in contact 

 with this acid, is rapidly dissolved, and the hydriodic acid is 

 produced ; it likewise converts chlorine to the state of hydro- 

 chloric (muriatic) acid. The hypophosphites are all very soluble, 

 even those of barytes and strontian ; they have the property of 

 precipitating gold and silver from their solutions in the metallic 

 state. When heated in glass tubes, we obtain phosphuretted 

 hydrogen gas, phosphorus, and a phosphate coloured by a little 

 of the red oxide of phosphorus. The neutral hypophosphites 

 slowly absorb oxygen, and become acid. 



A long, and as it appears very complicated, process was 

 employed to ascertain the composition of the hypophosphorous 

 acid. Four jars were filled with equal quantities of water, in 

 two of which was dissolved a certain quantity of the hypophos- 

 phite of soda ; a stream of chlorine was then passed through 

 them, until there was no longer any absorption. The pure water 

 in the two vessels served as a standard for measuring the excess 

 of chlorine that was retained in the solutions of the hypophos- 

 phite. " By means of nitrous vapour, procured from the nitrate 

 of potash, the chlorine was brought to the state of hydrochloric 

 acid ; and, by the solution of silver, the proportions of chlorine 

 were ascertained, which had been absorbed by the pure water 

 and the saline solutions respectively. The excess ot the latter 

 above the former was what had served to convert the hypophos- 

 phite into a phosphate ; and by the relation which chlorine boms 

 to oxygen, the quantity of this latter might be calculated which 

 is necessary to complete the saturation of the hypophosphorous 

 acid. The quantity of phosphoric acid was determined by adding 

 a .salt, either of barytes or of lime. By forming estimates 

 of the successive steps of this process, we arrive at the conclu- 



