Compounds of Phosphoric Acid with Aniline. 1 5 



were formed did not contain soda, and were similar in appeai- 

 ance to the salt first-described. Similar results were obtained 

 by neutralizing the acid phosphate of aniline with carbonate 

 of soda. The salt produced did likewise not contain soda, 

 the common phosphate appearing to be produced. 



II. Pyrophosphate of Aniline. 



There ai'e two pyrophosphates of aniline, acid and neutral, 

 which are always formed together when aniline is added in 

 excess to pyrophosphoric acid. The precipitate produced by 

 addition of aniline to pyrophosphoric acid is gelatinous, and 

 becomes quite hard when exposed to the air. 



Several combustions showed me that the compound ob- 

 tained in this way consists of a mixture of the neutral and the 

 acid pyrophosphate. I have not yet been able to obtain the 

 neutral salt in a state of purity, but I found that by keeping 

 the pyrophosphoric acid in great excess, the acid salt may be 

 procured. The best way of forming it is to add aniline to 

 rather concentrated pyrophosphoric acid (obtained by decom- 

 posing pyrophosphate of lead by hydrosulphuric acid), when 

 the acid salt is precipitated along with the neutral compound ; 

 the mixture is then to be heated until the whole is dissolved, 

 an excess of acid added, and the solution evaporated in the 

 water-bath ; upon cooling, the whole solidifies to a mass of 

 beautiful white needles, which are to be pressed in bibulous 

 paper, washed with aether, and finally dried in vacuo. This 

 salt appears as white silky needles, very similar to the com- 

 mon basic sulphate of quinine ; they are very acid, soluble 

 in water, and almost insoluble in alcohol and asther ; the cry- 

 stals and their aqueous solution, hke all other aniline salts, 

 become red when exposed to the air. 



Analysis. 

 When burnt with oxide of copper — 



I. 0-223 grm. of the substance gave 0'333 grm. of carbonic 

 acid and 0*117 grm. of water. 



II. 0'2C9 grm. of the substance gave 0*389 grm. of carbonic 

 acid and 0-132 grm. of water. 



III. 0'350 grm. of substance, neutralized by ammonia and 

 precipitated by nitrate of silver, gave 0*578 grm. of pyrophos- 

 phate of silver. 



These numbers correspond to the following pcr-cents. : — 

 I. II. III. 



Carbon . . . 39*00 39*43 

 Hydrogen . . 5*G8 5*45 



Phosphoric acid ... ... 38*85 



