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A NEW SOLVENT FOR EXTRACTING CANTHARIDIN. 
The whole was laid on thick filtering paper to absorb the oil, the 
crystalline matter dissolved in a little chloroform and alcohol mix- 
ed, which by spontaneous evaporation yielded it in a much purer 
form, though not entirely colorless. The cantharidin appears to 
be associated with less fixed oil in the potato fly, than in the 
Spanish insect ; the oil has much less color and is more fluid. The 
cantharidin separates in sword shaped prisms, terminated obliquely. 
Mylahris cichorii. — Having in my possession a specimen of the 
Chinese blistering fly, Mylabris cichorii, the same trial was made 
with it. One hundred and twenty grains, in powder, was perco- 
lated with chloroform till exhausted. The solution possessed a 
deep brown color, without a tinge of green. A few drops evapo- 
rated yielded a crop of crystals admixed with a transparent brown 
oily matter. The crystals were larger than those yielded by either 
of the preceding flies under the same circumstances. The tinc- 
ture was then suffered to evaporate spontaneously, and yielded an 
oily crystalline residue, weighing 14 grains. The crystalline mat- 
ter was separated from the brown oil by absorption with filtering 
paper, and was purified in the same manner as in the preceding 
experiments. The crystals corresponded in shape with cantharidin 
from the two varieties of cantharis. 
In stating the weight of chloroform extract obtained from each 
of the three species of insects examined, no conclusive evidence 
can be drawn relative to their activity, as in the two first experi- 
ments the flies were not exhausted. Besides the amount of oil 
and coloring matter varies, and as the whole of the cantharidin in 
neither case was isolated from the extract, its absolute amount is 
undetermined. The fixed oil must be well pressed out from the 
crystals before purifying them by recrystallization. 
In order to feel assured that the substances obtained were really 
the blistering principles of the insects, a small quantity of each 
mixed with a little oil was applied to my arm, and left on for eight 
hours. Vesication had occurred before their removal in each in- 
stance, but more perfectly with the Spanish and Chinese flies than 
with the indigenous variety, owing, as was afterwards observed, to 
the crystals of cantharidin in the latter substance not being pro- 
perly comminuted and disseminated through the oil. On the appli- 
cation of cerate, however, they were all equally developed. 
