154 
BRITISH PHARMACEUTICAL CONFERENCE. 
not had an opportunity of comparing sulphate of quinine by any other English 
maker, or a sample prepared as Br. Ph., with the foreign ones. 
Mr. Stoddart’s sulphocyanide test answers well when either very minute or 
very large quantities of quinidine or cinchonine are present in quinine. I have 
failed, however, to obtain decided results with a quinine known to contain five 
per cent, of impurities. There is one point to be noticed, that the purer the 
quinine is, the more decided and distinct the sulphocyanide of quinine crystals 
are deposited, and that the presence of quinidine or cinchonine affects more or 
less the shape of the crystals. 
The sulphocyanide of potassium failed to give any decisive results with the 
samples of foreign quinines, and although a very large number of experiments 
were made, I could only infer the presence of quinidine and cinchonine by the 
less distinctive character of the sulphocyanide crystals. Sulphocyanide of po¬ 
tassium gives crystalline precipitates with quinidine and cinchonine, and also 
precipitates the quinine from the compound tincture as perfectly as from an 
aqueous solution. 
The next precipitant tried, and from which I anticipated better results, was 
lodo-hydrargyride of Potassium solution, prepared as recommended by Mr. 
Tuck at the Bath meeting, for detecting methylic alcohol. This solution gave a 
crystalline precipitate with cinchonine sulphate, and yellow amorphous pre¬ 
cipitates with quinine and quinidine. The cinchonine crystals were small hairy 
tufts, somewhat resembling the crystals of tartrate of cinchonine. 
A solution of 240 grains of neutral tartrate of potash in 1 ounce of distilled 
water, was found to give crystalline precipitates with quinine, quinidine, and 
cinchonine. The tartrate of quinine is precipitated in tufts of needle-shaped 
crystals, the quinidine in prisms, and the cinchonine in minute tufts. 
I have not yet been able to decide whether the tartrate of potash will detect 
the presence of either of the alkaloids occurring as impurities in sulphate of 
quinine, but have found separate crystallization take place in a mixture of qui¬ 
nidine and cinchonine. At our next meeting I trust being able to detail fur¬ 
ther experiments with these and other of the alkaloids. 
The photographs sent to illustrate this paper were all taken with artificial 
light, as follows:—One of the eye-pieces of the binocular microscope was fitted 
into a hole through the front of an ordinary wood camera. The prism was then 
pushed out so as to admit light up one tube only. The light from a paraffine 
lamp was by means of a 2\ inch condensing lens, thrown through the ob¬ 
ject and tube of the microscope on to the focusing screen of the camera. By 
this means I was enabled to photograph any crystalline object with an exposure 
of ten minutes. The ordinary wet collodion process was used, and I have never 
had the least trouble in keeping the plates moist for that or even a longer 
time. I mention these matters in case any member should feel inclined to 
adopt photography as a means of copying microscopic objects. The great desi¬ 
deratum is an objective of good penetrating power. 
Note .—The photograph of the micrometer will show the value of actual in¬ 
stead of apparent measurement of magnifying power, in microscopic investi¬ 
gations. All the photographs were taken with a £ inch objective , said to mag¬ 
nify 245 diameters. 
The author of this paper is a chemist’s assistant at Newcastle-upon-Tyne. 
~ Mr. Stoddart could not agree that the sulphocyanide test failed to detect quinidine 
at the point supposed by the author of the paper: on the contrary, it would detect so 
little as 1 per cent, of quinidine. However, it was needful to make the sulphocyanide 
solution by the direct solution of sulphur, according to the instructions which he (Mr. S.) 
bad already published ; the use of ordinary crystals of sulphocyanide was not a sub¬ 
stitute for this. Mr. Stoddart spoke strongly in favour of using common and cheap 
