82 PROCEEDINGS OF SOCIETIES. 
meconine, and meconic acid are believed to be inert, whilst nar- 
cotine possesses properties widely different from those for which 
opium is usually employed. Of the bulkier constituents, the 
resin appears to be worse than useless, whereas the bitter extrac- 
tive, though opinions differ with regard to its precise properties, 
seems at any rate to increase the narcotic power of the more 
active constituents. A typical preparation of opium should, 
therefore, at least contain the whole of the morphine and codeine, 
with meconic or some other acid to keep them in solution, and 
the bitter extractive. Codeine itself, and the salts of both codeine 
and morphine, are readily soluble in either water or alcohol, the 
remaining principles are fully dissolved by alcohol, but scarcely 
soluble in water; hence, in the preparations alluded to, water 
rather than alcohol is used as the solvent. 
The process we adopt in examining the constituents of a fluid 
preparation of this sort under the microscope is a very simple 
one. 
Having, as a preliminary step, taken the specific gravity, and 
ascertained the percentage of carefully dried extract contained in 
it, we evaporate a small quantity, usually from four to six drachms, 
on a sand-bath in a watch-glass, to about the consistence of treacle. 
It is then poured upon a slip of glass and covered with a piece of 
thin glass, and after standing a few days, it is sealed in with gold- 
size. Crystallization sometimes commences before the prepara- 
tion is removed from the watch-glass, sometimes immediately 
after transferring to the glass slip, but in many cases for 
several days. The time taken is dependent upon one of two in- 
fluences, viz., the quality of the opium, and the exact degree of 
inspissation. 
In determining the value of a preparation from the appearance 
of this extractive under the microscope, we do not rely entirely 
upon the amount of crystallization, it is requisite to go one step 
further to obtain the full value of our labour, and by investi- 
gating the form and physical characters of morphine and its com- 
pounds, of codeine, narcotine, meconic acid, &c., place ourselves 
in position to see the significance of the appearance the slide 
presents, and to identify any crystalline principles which may 
be present. Nevertheless, even in the absence of very accu- 
rate knowledge, any one who will make a few experiments for 
the sake of practice, will soon be able, by observing the presence 
or absence, the abundance or scarcity, of certain forms of crystals 
easily seen in typical specimens, to pronounce with little hesita- 
tion on the quality or genuineness of samples of any of the or- 
dinary preparations of opium. 
Before proceeding to speak of the opiates which have come 
under our examination, it may seem necessary to say a few words 
on the forms assumed by the various opium principles and the 
physical characters their crystals present. 
In the first place— 
Morphine.—The pure alkaloid crystallizes in right-rhombie 
