270 
PHARMACEUTICAL MEETING. 
first, as they will be perfect, for if the liquid is violently shaken to detach them 
from the sides they are generally more or less broken. 
To obtain stellate crystals, a piece of carbonate of ammonium, about 1| to 2 
drms. in weight, should be added to urine, and left to stand as before ; the de¬ 
posit generally consists of large stellate crystals, sometimes of sufficient size to 
enable their shape to be observed with the naked eye. The crystals should be 
washed with distilled water, to which a little liquor ammonia; has been added ; 
in this they will remain unchanged. 
Calcic oxalate may be obtained by dropping a single small crystal of 
oxalic acid into 8 or 10 oz. of urine, and leaving it at perfect rest for some 
hours. If the deposit is then examined under the microscope, it will be seen to 
consist in great measure of octahedral crystals of oxalate of calcium. A great 
deal of the deposit will be very small, but the larger crystals may be separated 
by shaking the liquid, allowing it to stand a few minutes, and pouring it off ; 
the larger crystals will be found at the bottom. The production of large 
crystals of the calcic oxalate is somewhat uncertain ; but when, as in this case, 
the necessary materials are so easily procured, one or two failures is of little 
moment. 
Before concluding this paper a few hints may be acceptable as to the methods 
of preparing some of the well-known slides of crystallizations. Perhaps the 
most popular of all these is salicin. The following method, although different 
from what has been generally presented, will be found to give a good result:— 
A saturated solution of salicin in cold water is poured on to a slide, and held 
over a flame until it is at the boiling-point; it is then poured off the slide, and 
there will be found remaining only a viscid film. This must be allowed to be¬ 
come quite cold, care being taken to keep it from moisture and currents of air. 
The under surface of the slide must then be held close to the flame of a lamp 
or gas-jet. The moment the salicin begins to crystallize, it must be removed 
some few inches from the flame, or else it will fuse. If after a few seconds it is 
only partially crystallized, the vacant spot should be again held close to the 
flame, taking care to remove it the moment crystallization commences. If this 
plan is closely adhered to, the u wheels ” of salicin will be produced. 
Oxalurate of ammonium, asparagine, and many other substances, crystallized 
in the same form, may be prepared by evaporating the solutions by the aid of 
heat. Some crystals—as citric and tartaric acids, sulphate of cadmium, and 
others very soluble in water—produce beautiful slides of crystallizations if they 
are evaporated by a very gentle heat, continued until the process is complete. 
I have endeavoured to describe these processes in simple language, and with 
much detail, in order that those who are inclined to adopt them may meet with 
the same success as myself ; but I would venture to remind my readers that 
many little things materially interfere with the perfection of the operations, 
such as the opening or shutting of a door, a movement or even a breath on the 
part of the operator, and, above all, the slightest film of dirt on the slide. 
The instances I have adopted are those of well-known bodies ; but all crystals 
may be obtained by one or other of the processes given ; the method of crystal¬ 
lization varying according to the solubility of the substance employed. 
It only remains for me to add, that for much advice and assistance in this 
matter I am indebted to Dr. Leonard Sedgwick. 
122, Fore Street, F.C. 
Dr. Attfield thought the paper they had just heard could hardly be dis¬ 
cussed before examining the specimens ; but he had had the pleasure of seeing 
them ; and, indeed, it was from having seen them when preparing his book, 
lately issued, that he had asked Mr. IV adding ton how he had obtained them in 
