106 
ORIGINAL AND EXTRACTED ARTICLES. 
ON THE SUBLIMATION OE THE ALKALOIDS. 
BY WILLIAM A. GUY, M.B., F.R.S., F.R.C.P., 
PROFESSOR OF FORENSIC MEDICINE, KING’S COLLEGE, LONDON, ETC. 
IY. 
Those who have experience of crystallization, whether on the large or the small 
scale, whether by deposit from solutions or by sublimation, well know that after 
taking every known precaution to deserve success, they are very far from being able 
to command it. Their failure may be complete,—that is to say, they may obtain 
no crystals at all; or it may be partial, crystalloids taking the place of crystals 
of defined form ; or, again, crystals which only occasionally make their appear¬ 
ance as exceptions to the rule, may wholly usurp the place of those which their 
experience had led them confidently to expect. Such has been my own ex¬ 
perience of sublimates of arsenious acid, of which I must, by this time, have 
procured and examined several hundreds, observing, in every instance, the one 
well-known precaution of receiving the sublimate on a heated surface. Many 
sublimates out of a series so obtained have proved complete failures, while others 
have been crowded with sparkling crystals visible by the naked eye: and, on 
examining these more successful specimens under the microscope, though the 
majority have been found to be rich in octahedra, a minority have been almost 
wholly made up of some unusual forms, such as triangular plates, or mottled 
and distorted crystalloids. After rejecting the failures, I find that I have kept 
as many as thirty-eight specimens; and out of these, twenty-six are characterized 
by the marked predominance of the octahedron well formed and unblemished, 
and four by the octahedron well formed but mottled; while of the remaining 
eight, six are mottled and distorted, and two consist of triangular plates to the 
almost entire exclusion of the octahedron. Of the occurrence among the octa¬ 
hedra of large thin plates of many forms, of four-sided prisms, and*of thick 
plates of every shape, I take no account, as such exceptions do not affect the 
value of the inference to be drawn from the prevailing form. 
These facts I adduce as a fitting preface to what I have now to say on the 
various forms assumed by the sublimates of the alkaloids, with the proviso that 
if arsenious acid is found to yield sublimates, of which some are wanting in all 
characteristic features, and others (the majority) display in the midst of the 
prevailing octahedra varieties more or less perplexing, as much, at least, may be 
expected in the case of the alkaloids. This, indeed, is obviously an understate¬ 
ment of the case; for the alkaloids undergo visible changes of form and colour 
when heated, from which changes arsenious acid is wholly free; and it is but 
reasonable to suppose that the vapour disengaged from those substances while 
these changes are going forward, should itself undergo changes of composition 
affecting the character of the sublimates. This natural expectation is fully 
justified by experiences of those alkaloids which, like strychnine and morphine, 
yield crystalline sublimates. If we take strychnine as the type of this class, 
and such I believe it to be, and conduct the process of sublimation with care 
and caution, applying at first a moderate heat, and increasing it by degrees, we 
ought to obtain a series of sublimates of distinct crystalline formation, both 
before and after the melting of the alkaloid; then a few colourless sublimates 
without crystals; and, last of all, a series of yellow or yellowish-brown subli¬ 
mates evidently discoloured with empyreumatic matter, and the effect of a sort 
of destructive distillation. If the process be narrowly watched we shall observe 
