318 
ON VESICATING APPLICATIONS. 
He also remarks, that although Cantharidin in its isolated 
state is insoluble in water, and in cold alcohol, yet it is taken 
up by both these liquids, when associated with other constitu- 
ents of Cantharides, as the green concrete oil, or the yellow 
matter. 
The latter portion of Robiquet's paper is devoted to an 
account of his investigations, with the view of determining 
the character of the free acid which is always found in infu» 
sions of Cantharides. It is worthy of particular observation, 
that he discovered in recently collected Cantharides a con- 
siderable portion of uric acid, but was unable to obtain the 
same result from those which had been kept some time. On 
the other hand, the latter were strongly impregnated with 
acetic acid. Referring to the fact of his not being able to dis- 
cover uric acid in old Cantharides, he states, "and if I had not 
obtained it frequently from the fresh Cantharides, I should 
regard the result as doubtful." He also remarks, " it is cu- 
rious to observe that these insects, which exercise so marked 
an action upon the urinary organs, present, in their composi- 
tion, several points of analogy with urine." 
Thierry's process for procuring Cantharidin is, to macerate 
the bruised fly in ether for several days ; to obtain the whole 
of the etherial essence by displacement ; to distil off the ether, 
and to treat the residue with boiling alcohol, and animal 
charcoal. The Cantharidin is thus obtained pure, in crystals. 
1000 parts of Cantharides yield four parts of pure Can- 
tharidin. 
It may also be obtained by treating the flies with alcohol 
instead of ether. 
Cantharidin possesses neither acid nor alkaline properties, 
According to Gmelin, it may be considered a solid volatile 
oil. It is fusible at a moderate heat, forming a yellow oil, 
which by a stronger heat is dissipated in white vapors, and 
again condenses into acicular crystals. In Dr. Pereira's ac- 
count of Cantharidin, it is stated to be soluble in concentrated 
boiling sulphuric acid, forming a brown solution. It is also 
