CANTHARIDES. 
505 
§ 662 .] 
contents of the stomach, intestines, and faeces (as well as in the blood 
and urine) of animals poisoned by the substance. A urine, containing 
cantharidin is alkaline and albuminous. Cantharidin, although readily 
decomposed by chemical agents, is so permanent in the body that it has 
been detected in the corpse of a cat eighty-four days after death. 
In any forensic case, the defence will not improbably be set up that 
some animal ( e.g . a fowl poisoned by cantharides) has been eaten and has 
caused the toxic symptoms, for cantharides is an interesting example of 
a substance which, as before stated, for certain animals (such as rabbits, 
dogs, cats, and ducks) is a strong poison, whilst in others (e.g. hedge¬ 
hogs, fowls, turkeys, and frogs), although absorbed and excreted, it 
appears, save in large doses, to be inert. Experiment has shown that a 
cat may be readily poisoned by a fowl saturated with cantharides ; and 
in Algeria the military surgeons meet with cystitis among the soldiers, 
caused by eating frogs in the months of May and June, the frogs living 
in these months almost exclusively on a species of Cantharis. 
Dragendorff recommends the following process :—The finely-pulped 
substance is boiled in a porcelain dish with potash lye (1 part of potash 
and 12 to 18 of water) until the fluid is of a uniform consistence. The 
fluid, after cooling, is (if necessary) diluted with an equal bulk of water, 
for it must not be too thick ; then shaken with chloroform in order to 
remove impurities ; and after separation of the chloroform, strongly 
acidified with sulphuric acid, and mixed with about four times its volume 
of alcohol of 90 to 95 per cent. The mixture is kept for some time at a 
boiling temperature, filtered hot, and the alcohol distilled from the fil¬ 
trate. The watery fluid is now again treated with chloroform, as above 
described. The chloroform extract is washed with water, the residue 
taken up on some hot almond oil, and its blistering properties investi¬ 
gated. The mass, heated with potash in the above way, can also be 
submitted to dialysis, the diffusate supersaturated with sulphuric acid, 
and shaken up with chloroform. 
In order to test further for cantharidin, it can be dissolved in the 
least possible potash or soda lye. The solution, on evaporation in the 
water-bath, leaves crystals of a salt not easily soluble in alcohol, and 
the watery solution of which gives with chloride of calcium and baryta 
a white precipitate ; with sulphate of copper and sulphate of protoxide 
of nickel, a green ; with cobaltous sulphate, a red ; with sugar of lead, 
mercury chloride, and argentic nitrate, a white crystalline precipitate. 
With palladium chloride there occurs a yellow, hair-like, crystalline 
precipitate ; later, crystals, which are isomorphous with the nickel and 
copper salts. 
If the tincture of cantharides has been used in considerable quantity, 
the urine may be examined ; in such a case there will collect on the 
surface drops of a green oil, which may be extracted by petroleum ether ; 
