398 Dr. Hofmann 07i the Metamorphoses of Indigo. 



monia and precipitated by chloride of" calcium, gave, after 

 heating to redness, 0'153 grm. of carbonate of lime, whicli 

 corresponds to 32' 18 per cent, of anhydrous oxalic acid. 



Theory. Found. 



2 equiv. of Oxalic acid = 900-00 31*77 32*18 

 1 ... Base . . =1594*69 56*30 



3 ... Water . = 337*50 _21"93 



2832*19 100*00 

 The above salt corresponds in its constitution to the bin- 

 oxalate of ammonia and to Zinin's binoxalate of naphtalidan. 

 As a neutral oxalate of aniline is known, I thought I might 

 obtain the neutral salt of the chlorinated base by mixing its 

 watery solution with oxalic acid in such a way as to leave the 

 former in great excess. From this mixture, on cooling, sepa- 

 rated needle-form crystals, which were washed and recrystal- 

 lized. The combustion with chromate of lead gave from 

 0*4'215 grm., dried at the temperature of the air, O^GBQS grm. 

 of carbonic acid and 0*1490 grm. of water, corresponding 

 in the 100 parts to 



Carbon 42*69 



Hydrogen .... 3*92 

 hence proving that even under the conditions above-mentioned 

 an acid salt had been formed. 



An acid oxalate of aniline has not as yet been analysed. 

 1 endeavoured to form such a salt by saturating aniline with 

 a large excess of oxalic acid. The precipitate formed was 

 washed and frequently recrystallized from water. The needles 

 obtained in this way possessed great similarity to the acid 

 salt of the chlorinated base; they were, however, neutral oxa- 

 late of aniline, as was proved by the combustion. 0'3660 grm. 

 of the salt gave 0*8 IBS grm. of carbonic acid and 0*2088 grm. 

 of water. In 1 00 parts, 



Carbon 61*01 



Hydrogen .... 6*33 

 The formula is Cg O3, C12 H7 N + HO, which gives 



Carbon 60*79 



Hydrogen . . . .5*79 

 Nitrate of chloraniline is obtained by simply heating the 

 base in dilute nitric acid. On cooling, the fluid becomes filled 

 with tabular crystals, which generally possess a reddish tint. 

 The salt is tolerably soluble in both alcohol and water. By 

 heat it fuses into a dark mass, which forms with alcohol a 

 beautiful rich blue solution, from which the nitrate, partly un- 

 changed, again separates. 1 could not sublime this compound. 



