ADULTERATION OF SULPHATE OF QUININE. 
267 
or losing its crystallized aspect ; lastly, it is far more soluble than 
sulphate of quinine in cold water and in alcohol. 
One of the distinctive properties of the three alkaloids in ques- 
tion, viz. , their behaviour with ether — places in our hands a ready 
means of detecting the mixture of cinchonine and quinidine, with 
quinine. Schweitzer (Lond. Med. Gazette, vol. xxi., p. 175) has 
already employed ether for the detection of cinchonine with com- 
plete success, and his process has, with justice, been subsequently 
quoted in most manuals, as it answers its purpose completely ; cin- 
chonine is known to be entirely insoluble in ether, whatever may 
be the quantity of the ether employed. The solubility of quini- 
dine in ether, as compared with that of quinine, is but slight: ten 
grains of pure sulphate of quinine dissolve in sixty drops of ether, 
and twenty drops of spirit of ammonia, while only one grain of 
sulphate of quinidine is soluble in the same quantity of the fluid; 
and in proportion, quinine containing quinidine will always be less 
soluble than pure sulphate of quinine. 
Guided by this fact I can recommend the following simple and 
very convenient process for the detection of quinidine and cincho- 
nine : — ■ 
Ten grains of the salt to be examined is to be put into a strong 
test tube, furnished with a tight-fitting cork; to this are to be added 
ten drops of diluted sulphuric acid (one acid and five water) with 
fifteen drops of water, and a gentle heat applied to accelerate the 
solution. This having been effected, and the solution entirely 
cooled, sixty drops of officinal sulphuric ether with twenty drops 
of spirits of ammonia, must be added, and the whole well shaken, 
while the top is closed by the thumb. The tube is then to be 
closely stopped and shaken gently from time to time, so that the 
bubbles of air may more readily enter the layer of ether. 
If the salt examined be free from cinchonine and quinidine, or 
contain the latter in no greater proportion than ten per cent., it will 
be completely dissolved ; while on the surface, where contact of 
the two layers of clear fluid takes place, the mechanical impurities 
only will be separated (in which respect the various sorts of com- 
mercial quinine differ.) After some time longer the layer of ether 
becomes hard and gelatinous, after which no further observation 
is possible. 
From the above statement respecting the solubility of quinidine 
23 
