ON THE SUBLIMATION OF THE ALKALOIDS. 
107 
that, so long as the vapour is colourless, it deposits itself as a mist in which by- 
degrees snow-white spots, often circular in shape, and often coalescing into 
larger spots, develope themselves, which spots are of crystalline formation. But 
if, when the mist appears, and before the spots show themselves, we withdraw 
the disk of glass, we obtain sublimates of the second order. Now, if we exa¬ 
mine these three orders of sublimates by the microscope, the first is found to 
have a distinct crystalline texture, the forms and varieties of which I shall de¬ 
scribe on a future occasion; the second, to consist of circular colourless drops 
packed close together, rarely coalescing, and maintaining their separate cha¬ 
racter for weeks and months together, or from the first forming a continuous 
w r aving pattern with well-preserved interspaces; the third, also, of drops or 
waving patterns, but tinged more or less deeply of the colour with which burning 
paper stains the fingers. This description is equally true of morphine, except 
that the crystalline form rarely shows itself before the alkaloid melts. 
I propose to call these three varieties of sublimate:—the crystalline , the 
watery or watered, and the smoked; and I shall devote to them seme time and 
attention, inasmuch as I have learnt by experience'that they may all be made to 
yield valuable indications. 
Helwig, though he recognizes the discoloration of the last-formed sublimates 
of strychnine and morphine, does not appear to have taken any notice of the 
watery variety. He seems to assume that the thicker stains of strychnine and 
morphine, in which, be it recollected, he does not recognize any crystalline 
formation, are the only ones worthy of attention ; and to these alone does he 
apply his reagents. The watery and the smoked varieties seem to have been 
disregarded or rejected.* But when we are dealing with substances which 
undergo in the heating such changes of form and colour, and when we call to 
mind that arsenious acid, which undergoes no such changes, does not always 
yield a crystalline sublimate, it is easy to understand how important it may be¬ 
come to turn to good account those sublimates of the alkaloids which do not 
assume a crystalline texture. And when we further recollect that many of the 
alkaloids yield no other sublimates than those which come under the description 
of watery , watered , or smoked , we must be still more anxious to try the effect of 
reagents upon these varieties, as giving a chance of discovering some certain 
means of diagnosis. 
To the smoked sublimates my attention was forcibly drawn very early in this 
investigation by the extraordinary size and brilliancy of the crystals instantly 
formed in a smoked sublimate of morphine treated with a solution of bichro¬ 
mate of potash,—a result, as I have already shown, due in part, if not wholly, 
to the action of the distilled water itself. The discovery of this very curious 
and striking reaction with the smoked sublimate of morphia has led me to select 
that alkaloid as an illustration of the sort of results which we may expect to 
obtain with the alkaloids and analogous active principles. The questions which 
must suggest themselves to the practical man equally with the philosophical 
inquirer are these :—1. What proportion of the sublimates of an alkaloid yield¬ 
ing crystalline forms may be expected to assume this character? 2. Do the re¬ 
agents which produce characteristic effects on the crystalline sublimates affect 
equally, or similarly, or in any other characteristic manner, those sublimates, 
whether watery or smoked, which are wholly destitute of crystalline forms? 
These two questions will be found fully answered in the following account of a 
series of experiments with morphine commenced at the end of June, and com¬ 
pleted, as far as was necessary for my present purpose, at the end of July. The 
description is from notes taken at the time. 
* See, as justifying this statement, the description given of the sublimation of morphine and 
strychnine at pp. 9 and 21. 
