ON THE ADULTERATION OF COCHINEAL. 63 
The purchaser now examines his cochineal by dyeing a 
sample of wool. The result obtained is compared with 
that of a cochineal whose tinctorial value is known to him; 
he operates at water bath heat for two hours. Having be- 
gun this investigation in the hope of giving an easier and 
quicker process than those which have been used up to the 
present time, I have endeavored to extract the coloring mat- 
ter of the cochineal by a single treatment. I obtained this 
result : that five decigrammes of cochineal, treated at water- 
bath heat for an hour, with 1000 grs. of spring water, and 
the addition of ten drops of a solution of alum, were almost 
entirely exhausted. The liquor when cold was perfectly 
transparent, and gave in the colorimeter the same results 
which I obtained by the first process. The apparatus 
which I used is composed of two flasks of about a quart 
capacity, suspended by their necks to a small plank, the 
two extremities of which rest on the edge of a cylindrical 
vase which serves as a water-bath for them. Before ap- 
plying heat, the weight of each flask containing the cochi- 
neal and the alum water in the indicated proportions should 
be separately taken. After an hour's boiling it is left to 
cool, each flask is again separately weighed, and to each 
of them is added the quantity of distilled water necessary 
to establish the primitive weight. 
Some time ago M. Boutigny sent me four specimens of 
cochineal which he had received from M. Pimont of Bol- 
beck: — 1, a cochineal from the Canaries; 2, a blackish- 
gray or zacatillee cochineal; 3, a black or zacatillee co- 
chineal; 4, and lastly, a small blackish-gray cochineal, 
known by the name of rosette cochineal. Till then I had 
employed as basis for my experiments cochineal from the 
Canaries obtained from a merchant in this town. 
The rosette cochineal gave me more coloring matter. 
The tinctorial value is to that of the gray cochineal as 105 
or 110 are to 100. 
In order to estimate a cochineal in the colorimeter, two 
