490 Mr. De la Rue on Cochineal. 



mate of lead, gave -6064 grrn. carbonic acid and -0662 grm. 

 water. 



These numbers give the following per-centage quantities : — 



I. II. ■ III. 



Carbon ... 26-46 



Hydrogen . ... ... 1*18 



Potash . . 25-74 25-92 



corresponding with the formula 



Ci6H3N3 0,6+2KO, 



as may be seen by comparing the theoretical and experimental 

 numbers. 



363 100-00 



I was not successful in preparing a nitrococcusate of potash 

 with one equivalent of fixed base ; the method I adopted was 

 saturating a given weight of acid with carbonate of potash, 

 and then adding the same amount of acid to the bibasic pot- 

 ash salt ; on washing with tether the greater part of the ex- 

 cess of acid was removed, leaving the bibasic salt behind. 



Nitrococcusate of Ammonia. — This salt was prepared by 

 passing an excess of dry ammoniacal gas through an aetherial 

 solution of the acid dried in the atmosphere ; the solution be- 

 came turbid, and by standing for a short time deposited the 

 salt in clusters of needles adhering firmly to the sides of the 

 vessel ; these were removed, washed with jether, and dried on 

 bibulous paper. It is volatile, and sublimes on being heated, 

 most probably with decomposition, 



I. -6011 grm. of the salt dried in vacuo was dissolved in a 

 small quantity of boiling water and decomposed by strong 

 hydrochloric acid, which immediately separated the acid in 

 f rystals ; the mixture was dried in a water-bath, and the ni- 

 trococcusic acid removed by aether, a little bichloride of pla- 

 tinum and alcohol being added to the aetherial washings to 

 precipitate a trace of chloride of ammonium. The residue, 

 precipitated as ammonio- chloride of platinum, gave -8208 

 grm. of the double chloride. 



II. -6126 grm. dried in vacuo and burnt with oxide of cop- 

 per, the mixture being made in the combustion-tube, gave 

 .'6525 grm. carbonic acid and -2191 grm. water. 



