Mr. De la Rue o« Cochineal. 48J 



An analysis of the carminic {h) acid by chromate of lead 

 gave from — 



VIII. '3167 grm. '6203 grm. carbonic acid and •1402 

 water. 



The following table exhibits the per-centage results de- 

 duced from the foregoing analyses : the specimens were all 

 dried over sulphuric acid in vacuo, with the exception of ana- 

 lysis VII., in which the carminic acid was dried at 100° C. 



By the analysis of a copper salt of carminic acid hereafter 

 to be mentioned, it became probable that carminic acid might 

 still retain, when only dried in vacuo, a portion of the solvents 

 employed ; a presumption which was supported by the ana- 

 lysis VII., in which the substance analysed had been dried 

 at 100*^ C, and which gave a smaller per-centage of hydrogen. 

 A portion of carminic acid {i), being first dried in vacuo, and 

 then heated to a temperature of 121° C, was found to yield 

 a small quantity of acetic acid, and was not altered in its 

 properties, which were not in fact changed even at a tempe- 

 rature of 136° C. 



In the following analyses the carminic acid, previously dried 

 in vacuo * and then at a temperature of 120° C, gave, on 

 burning with chromate of lead, the following results : — 



IX. '3347 grm. {h) gave '6648 grm. carbonic acid and 

 •1381 grm. water. 



X. '3583 grm. (i) gave '7108 grm. carbonic acid and •1504 

 grm. water. 



These analyses give the following per-centage quantities : — 



IX. X. 



Carbon . . . 54*17 54-10 



Hydrogen . . 4-58 4*66 



The analysis IX. being of the same preparation as had 

 served for analysis VI II., it is fair to presume that all the 

 other specimens of carminic acid would have given the same 

 per-centage quantities as the specimen (A) if dried at 120° C, 

 as this particular specimen, dried in vacuo, yielded numbers 

 in close accordance with the mean of the other analyses. 



These numbers converted into the most simple expression 

 lead to the following formula, Cj4 H^ Og ; but an analysis of 

 a copper salt renders it probable that this formula has to be 



* The carminic acid fuses if exposed to a temperature of 120° C, with- 

 out having been previously dried. 



2X2 



