Alarch 15, 1873.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
727 
Spanish, flies ( Lytta vesicatoria , Fabr.). Bretonneau* * * § ** * iso¬ 
lated the same principle from the Chinese blistering 
flies about the year 1828. The process used for many 
years for the preparation of this principle was the one 
suggested by Robiquet, in which the aqueous extract of 
the powdered bug is exhausted by hot alcohol, the solu¬ 
tion evaporated to dryness, the residue treated with warm 
ether, the ethereal solution evaporated spontaneously, 
and some yellow matter removed by washing the crystals 
with cold alcohol. This process is based upon the observa¬ 
tion made by Robiquet and other investigators, that can- 
tharidin, when pure, is insoluble in cold and hot water, 
but taken up by this menstruum directly from cantha¬ 
rides in consequence of the presence therein of a yellow 
matter which renders this principle soluble in water. 
Ed. Rennardf has recently denied the correctness of this 
statement, he finding that cold water dissolves 0-02, and 
boiling water between 0-290 and 0-297 per cent, of pure 
cantharidin ; the same author also found that this prin¬ 
ciple volatilizes with the vapours of boiling water, alco¬ 
hol, and even chloroform. 
Thierry + used ether or alcohol of specific gravity 
85 for exhausting the cantharides, distilled the ether 
and the alcohol, removed the oil, and obtained the can¬ 
tharidin from the aqueous residue by crystallization and 
subsequent purification. 
In 1851 Professor Procter observing that chloroform 
is a good solvent for cantharidin, proved^ the practica¬ 
bility of obtaining it by this menstruum directly from 
different blistering bugs. This process was improved 
by Mortreuxjj in 1864, by treating the residue left after 
the evaporation of chloroform (or if ether had been used, 
after the evaporation of this solvent) with bisulphide of 
carbon to dissolve the fat, and recrystallizing from hot 
.alcohol. A. Fumouze** corroborates this statement, using 
for the recrystallization of the cantharidin, chloroform. 
Bluhm and Dragendorff+f state that a portion of the 
cantharidin is contained in cantharides in a combination 
in which it is not dissolved by alcohol, ether or chloro¬ 
form ; in order to obtain the whole amount of this prin¬ 
ciple, they recommend to mix the powdered cantharides 
with water and calcined magnesia, exsiccate the mixture, 
and treat the dry mass with dilute sulphuric acid in 
slight excess, when the cantharidin may be extracted by 
solvents ; or the acidulated mass is again exsiccated and 
then exhausted with ether or chloroform. Rennardf 
improves on this by saturating the mixture obtained 
-after exsiccation with magnesia, with chloroform, and 
then supersaturating with sulphuric acidthe chloro¬ 
form prevents the crystallization of the liberated can- 
rtharidin, which is for this reason dissolved by a much 
>smaller quantity of ether. 
The above contains nearly all the scientific literature 
• on the preparation of cantharidin, and all the processes 
which may lay claim to at least approximate accuracy 
in their results. In experimenting with the Chinese 
flies, various questions that presented themselves could 
mot be solved in time for the present meeting; among 
'them an inquir} 7- into the usefulness of petroleum-ben- 
jzine in the preparation of cantharidin, and also the es¬ 
timation of that portion of this principle, which accor¬ 
ding to Bluhm and Dragendorff is not taken up from 
*the blistering bugs by the usual solvents. 
In regard to the quantity of cantharidin obtainable, I 
/can find no earlier researches than those made by Wil¬ 
* ‘ Journal de Pharmacie et de Chimie,’ 1828, 67. 
f ‘ Das wirksame Princip des wassrigen Destillates der Can- 
-thariden.’ N. Jakrbuch fur Pharmacie, 1872, July 22. 
J ‘ Journal de Pharmacie et de Chimie,’ xxi. 41. 
§ ‘American Journal of Pharmacy,’ 1851, p. 124. 
|| ‘Journal de Pharmacie et de Chimie,’ 1864, p. 33. Will’s 
‘ Jahresbericht,’ 1864, p. 646. 
** Journ. de Pharm. et de Chim., 1867, 161. These dePhar- 
iinacie: De la cantharide officinale. 
•ft ‘ Pharmaceutische Zeitschrift fur Russland,’ 1865, 160. 
Loc. cit. 
liam R. Warner,* who employed Robiquet’s process 
mentioned above for determining its quantity, and ob¬ 
tained from Lytta vesicatoria 0*41, from Lytta vittata 0'40, 
and from Mylabris cichorii 0 43 per cent, of cantharidin. 
Mortreuxf gives the average percentage of cantharidin 
in good cantharides as 0'5 per cent., estimated by his 
process. According to Fumouze’s experiments, cantha¬ 
rides collected in 1866 in different parts of Europe, 
yielded 0 275, 0-435, 0-48, 0*48, and 0-50 per cent, of 
this principle, while three samples one year old yielded 
but 0-17, 0*215, 0*375 per cent., and the worm-dust 
separated from the next to the last sample 0"425 per 
cent., or double the quantity obtained from the can¬ 
tharides from which the dust had been sifted. 
Bluhm and Dragendorff found in commercial can¬ 
tharides only 0*264 per cent, of cantharidin isolated by 
their process mentioned above ; in Mylabris quatuorde- 
cim-pustulata. however, 0*486 per cent. Rennard sepa¬ 
rated from cantharides of unknown age, 0*38 and 0-431 
per cent.; from cantharides one year old, collected near 
Heidelberg, 0-489 per cent., and from a sample eight 
months old, collected near Pultawa, 0-57 per cent, of 
cantharidin. 
Fumouze’s estimation of the value of the hard and soft 
parts of cantharides deserve mention yet; he found in 
the former 0-118, in the latter 0-778 per cent., and in tho 
whole bugs 0-415 of cantharidin. 
It appears from these essaj’s that the amount of can¬ 
tharidin which should be contained in the cantharides, 
ought not to be less than two-fifths of one per cent., and 
might probably be placed at a somewhat higher figure. It 
also appears probable that the cantharides lose in strength 
by age; but it seems likely that in all cases cited above, 
the bugs were freed as much as possible from the worm- 
dust which Fumouze has shown to be rich in cantharidin, 
and since the mites destroy only the soft parts which 
contain a large amount of the active principle, its de¬ 
crease in the remaining portions of the bugs is easily 
accounted for. 
Regarding the comparative strength of the Chinese 
blistering bugs, which by O’Shaughnessy is placed at 
one-third, by Warner only at one-twentieth above the 
officinal cantharides, these discrepancies are easily ac¬ 
counted for, since the statement of the former doubtless 
refers to the recently collected Mylabris, while the ex¬ 
periments of the latter were made with commercial bugs 
of uncertain age, and probably separated from the worm- 
dust. I find, however, no notice of any analysis made 
by O'Shaughnessy, and it is possible that his statement is 
based upon the epispastic properties of the bugs in ques- 
tion. 
In estimating the amount of cantharidin in the com¬ 
mercial Chinese bugs, I determined for reasons stated 
before, not to separate the worm-dust. Fumouze’s pro¬ 
cess was used for this purpose in the following manner : 
600 grains of the powdered mylabris were introduced into 
a wide mouth glass-stoppered bottle, which was then 
filled with chloroform; after macerating for three days 
the liquid portion was poured off and filtered through 
a little cotton. The maceration with chloroform was 
repeated several times, until a drachm of the filtered 
portion left on evaporation merely a faint yellowish spot. 
Twelve ounces of chloroform were consumed in this 
operation. To avoid any loss of the active principle by 
transferring the chloroformic tincture into other vessels, 
the liquid was at once collected in a porcelain capsule, 
and the chloroform allowed to evaporate spontaneously. 
The residue, which was of a brown colour, was then 
treated with bisulphide of carbon, and the solution, in¬ 
cluding the undissolved cantharidin, transferred to a 
small ‘filter, which was subsequently well washed with 
bisulphide of carbon. After the odour of this liquid 
had disappeared from the funnel, chloroform was poured 
* ‘ American Journal of Pharmacy, 1856, p. 193. 
f Loc. cit. 
