462 
PHARMACEUTICAL MEETING. 
of sulphate of quinine, and added ammonia to it, unless the precipitate were 
used in large excess, and various precautions taken, the precipitate invariably 
contained sulphuric acid, a certain proportion of which could not be removed 
by any amount of washing. If the requisite precautions were taken, viz. to 
have a solution tolerably dilute, the amount of ammonia tolerably large, and 
the solution kept quite cool, then you had a very bulky precipitate, which had 
to be collected on a filter and washed. It must be washed quickly, before it 
aggregated aud contracted, because if it did that before it was washed, there 
was invariably a portion of the mother liquor included within it in a vesicular 
state. It was also necessary to use a considerable quantity of water in order 
to get the hydrate of quinine free from sulphate of ammonia, and this water 
necessarily dissolved a portion of the hydrate of quinine, and that portion was 
lost in the estimate. The precipitate was to be dried and weighed, but only 
that which was insoluble could be so treated; that dissolved in the liquid was 
lost. That which had to be dried was a hydrate of quinine, or a compound of 
quinine with three atoms of water. Dry hydrate of quinine was a definite 
chemical compound, and it could be dried by putting it into a steam or hot-air 
bath at 212° F. At that temperature you could not drive off the whole of the 
water of hydration, but only a portion, and that portion seemed a variable 
one; so that if the precipitate were dried at that temperature and weighed, 
the result constantly varied in weight. It might be weighed several successive 
times, and each time there would be a loss, and this process might be continued 
for a great length of time. It was necessary to heat hydrate of quinine to 250°, 
in order to drive off the whole water of hydration, and at that temperature it 
was possible to obtain an anhydrous quinia in a definite condition. He had 
brought a note of one or two experiments which he had made in this way.^ In 
the first place he took 10 grains of common sulphate of quinine, a definite 
composition (which would contain theoretically 743 grains of anhydrous 
quinia), and treated it by making a solution in sulphuric acid, using all the 
precautions he had stated, but the total quantity of mother liquor was 5 oz. 10 
grs. The precipitate being dried at a temperature of 212°, weighed at the end 
of the first hour 6'9 grs., at the end of the second hour 67 grs., and at the end 
of the third hour 6-54. There was thus a constant loss going on, and it would 
be seen that the least weight was nearly 1 gr. below the theoretical quantity of 
anhydrous quinia, which should have been obtained ; and yet it was not really 
anhydrous at that temperature. By the other method, that given in the Phar¬ 
macopoeia, the formation of basic sulphates was avoided, and also the difficulty 
of having any of the quinine left in the mother liquor. In fact, you got the 
whole of the quinine which could be extracted together, and it only remained 
to dry it, and get it of a definite weight, and the drying was attended with no 
greater difficulty than in the case of precipitated quinine ; as far as his obser¬ 
vation went rather less. He found that with a constant temperature of 212°, 
he got first 8’26 grs., then at the end of an hour 876 grs., and at the end of 
the third hour it was reduced to 8 grs., at which point it remained tolerably 
constant, so that it then contained -57 gr. of water of hydration. If, however, 
it were exposed to a temperature of 250°, there was very little difficulty in 
getting in two hours a constant weight approaching, as nearly as possible, the 
theoretical yield. At the end of the first hour it was 7'6 grs., at the end of the 
second hour it was 7'5 grs., and at that weight it remained constant. On the 
whole, therefore, he believed the present process was more easy and certain than 
that recommended by Dr. Redwood. > . 
Mr. Bland said he should like to raise one point as to the question of their 
responsibility in following out literally the Pharmacopoeia. He perfectly agreed 
with Dr. Redwood that a heavy responsibility lay upon them, but at the same 
time it was shared, he believed, by the prescribing surgeon, although they did 
