New method of obtaining Cantharidine. 141 
Cantharidine may be produced by three methods which 
are very analogous, differing only in the price of the men- 
struums used. These are alcohol, etherial alcohol at 40° and 
alcohol at 34°. 
Whatever may be the vehicle employed, the product is 
identical in quality and quantity. When cantharides are 
treated with ether, but little green oil is obtained, and it is 
easy to separate the cantharidine from this oil. With ethe- 
rial alcohol, there is more green oil, and finally, with alcohol 
the proportion is still greater. The difficult part of this pro- 
cess is to separate the cantharidine from the green oil. 
The etherial tincture of cantharides is of a slight greenish 
yellow, although the green oil is very soluble in ether. The 
etherial alcoholic tincture is much higher coloured, and that 
prepared with alcohol is almost black. 
To obtain cantharidine the cantharides are to be macerated 
in one of these menstruums for some days, and the mixture 
then placed in an apparatus for filtering by displacement. 
When the solution has drained off, another portion is to be 
added till ij passes almost colourless. The quantity retained 
by the powder is obtained by chasing it off by means of wa- 
ter. The tinctures are to be mixed together, and distilled, to 
obtain the ether or alcohol employed. 
This being done, the retort is suffered to cool, when the 
cantharidine will crystallize in scales, if the solution is con- 
centrated; and in beautiful four-sided prisms, if it is weak. 
This cantharidine, not being perfectly white, it is again to 
be subjected to the action of boiling alcohol, with the addi- 
tion of animal charcoal. Instead of subjecting the filter 
made use of, to pressure, if cold alcohol be poured on it, this 
will dissolve all the green oil which contaminates the can- 
tharidine. 
Pure cantharidine has no smell. When heated in a glass 
tube, it melts at 210° C. and is sublimated in white fumes 
which condense at the upper part of the tube, in brilliant, 
acicular crystals. A black matter remains at the bottom of 
the tube which is insoluble in water, alcohol or ether. 
Concentrated sulphuric acid does not dissolve cantharidine, 
