of Phosphoric Acid. 829 



lierto described, as to justify establishing for its reception a 

 'X genus, winch may be called Limiiophis* The specie^ 

 ,y properly be named Limnophis crassus, in reference to tlie 

 )t)able proportions of the extinct serpent thus indicated, 

 e specnnen was discovered by Mr. A. H. Ewing, a membei- of 

 ' \ ale party, in the Eocene fresh-water deposits, near Marsh's 

 rk, about fifteen miles from Fort Bridger, in Wyoming. 



'ale College. New Haven, March 20th, 1871. 



Art. XLIX. — Contributions to Chemistry from, the Laboratory of 

 >he Lawrence Scientific School No. U.~On the Estimation of 

 rhosphoric Acid; by Charles E. Munroe. 



§ 1. Though the methods commonly in use for the quantita- 

 tive determination of phosphoric acid are capable in most cases 

 f givmg accurate results, yet it will, I think, hardly be claimed 

 tor them, that they render new methods m -^ - - - 



therefore undertaken the following investigation in the hope 

 ot adding something of value to our analvtical resources. 



M_T attention was first called to the employment of ferric 

 enlonde with the addition of suflficient mercuric oxide to neu- 

 tralize the excess of acid. Free mercuric oxide was first added 

 uirectly, but, as_ a complete separation could not be effected 

 m this manner, it was found more advantageous to produce the 

 oxide in the solution itself. This was accomplished by first 

 adding mercuric chloride and then potassic or sodic hydrate. 

 As sodic hydratef can be obtained in commerce absolutely pure 

 J|if^ was employed. The precipitate, consisting of ferric phos- 

 pliate and ferric and mercuric oxides was then evaporated to 

 dryness in the manner recommended by Chatard,:}: filtered and 

 ^vashed on the Bunsen pump.§ Unhappily the phosphoric 

 acid redissolved after evaporation to dryness and the process 

 was therefore abandoned Bunsen's delicate test with magne- 

 sium wire was used throughout the work, sometimes in connec- 

 tion with ammonic molybdate, for the detection of phosphoric 



3 ofglass tubing one n 



