494 ' Mr. De la Rue on Cochineal. 



acids to exist in the form of hyponitric acid, the formula of 

 nitrococcusic acid will be represented by 



C,«/!lu To., 2HO. 



'16 





This acid would consequently derive from a non-nitrogenous 

 acid, having the composition expressed by the formula • 



Ci6H6 04,2HO. 



When I first began this investigation I imagined that a 

 similar relation might exist between nitrococcusic acid and 

 carminic acid ; the analysis of these acids, however, as well 

 as the simultaneous production of a large quantity of oxalic 

 acid in its oxidation, showed that this view was erroneous, 

 and that nitrococcusic acid was derived from carminic acid in 

 a more complex manner. Some attempts were made to pro- 

 duce the non-nitrogenous acid, the coccusic acid, but unsuc- 

 cessfully. 



The experiments of MM. Cahours and Laurent on the 

 oxidation of the oils of anise and of tarragon [Oleum dracun- 

 culi) have made us acquainted with anisic acid, the composi- 

 tion of which is Cjg Hg Og. ■ The formula agrees with the 

 composition of the hypothetical hydrated coccusic acid. 



Anisic acid, however, as well as nitranisic acid, being mono- 

 basic, it was not probable that the further introduction of the 

 elements of hyponitric acid Avould convert it into a bibasic 

 one ; nevertheless it was my intention to have studied the 

 further action of nitric acid on the acids mentioned, in order 

 to obtain if possible trinitroanisic acid, and to compare this 

 substance with the acid obtained from carminic acid, when an 

 account of some new experiments of M. Cahours came under 

 my notice, of the action of a mixture of concentrated sulphuric 

 and nitric acids on anisic acid, by which he has succeeded in 

 preparing trinitroanisic acid. The experiments of M. Ca- 

 hours have not yet been published in detail, and from his 

 short account it was not possible to decide on the identity or 

 non-identity of nitrococcusic and trinitroanisic acids. A small 

 specimen of anisic acid at my disposal was treated in the 

 manner described by him ; after acting for some time water 

 threw down an acid, from the insolubility of which I conclude 

 that these acids are only isomeric. 



Investigation of the Mother-liquor from wJiick the Carminic 

 Acid had been separated. 



On evaporating the mother-liquors of carminic acid and 

 separating the lead held in solution by means of hydrosul- 



