496 Mr. De la Rue on Cochineal. 



These per-centages, translated into the most simple expres- 

 sion, lead to the formula, Cgi Hu NOg as may be seen from 

 the following table : — 



Careful and repeated examinations for sulphur proved the 

 absence of this element as a component of the new white sub- 

 stance. I have been unable to produce a compound to con- 

 trol the proposed formula, though several methods were 

 adopted ; amongst others, I attempted to form a lead com- 

 pound by adding acetate of lead to an ammoniacal solution of 

 the substance; I obtained merely a bulky precipitate, con- 

 sisting of little else than oxide of lead. 



This substance is sparingly soluble in cold water, much 

 more so in boiUng water ; insoluble in alcohol and aether ; 

 soluble in hydrochloric acid, which appears to be driven off 

 by evaporation, leaving the substance in large crystals. In a 

 large quantity of nitric acid it dissolves with a slight evolu- 

 tion of gas ; the solution evaporated spontaneously furnishes 

 long crystals, which are in all probability a new acid ; if dis- 

 solved in a small quantity of nitric acid, the mixture becomes 

 spontaneously heated, violent action takes place, and the pro- 

 duct is lost ; frequently the substance becomes blackened into 

 charred masses. It is soluble in ammonia, from which it is 

 again recovered by the evaporation of the ammonia. It is 

 soluble in the fixed alkalies, and is precipitated from these 

 solutions by saturating with an acid. 



In a short paper, entitled "Valerianic Acid and a new 

 body from Casein," Baron Liebig* describes a new substance 

 obtained by fusing casein with hydrate of potash until an 

 evolution of hydrogen takes place along with ammonia. On 

 saturating with acetic acid the aqueous solution of the fused 

 mass an aggregate of fine needles was produced, which were 

 purified by repeated solution in carbonate of potash and re- 

 precipitation by acetic acid. A preliminary analysis led to 

 the formula Cjg Hg NO^, differing from the result I obtained 

 in the analysis of the white substance from cochineal by two 

 carbon, two hydrogen, and one oxygen. The properties of 

 the two bodies being however so analogous, it is extremely 

 probable that they are identical, a presumption I am sup- 

 • Liebig's Annalen, vol. Ivii. p. 127. 



