720 
ON THE SUBLIMATJON OF THE ALKALOIDS. 
glass about the size of a shilling. Place the porcelain slab on the ring of a 
retort-holder or other convenient support, then the glass cell, and upon the 
porcelain, in the centre of the cell, a minute portion of the alkaloid or other 
v/hite powder, or crystal reduced to powder. Then pass the clean glass disk 
through the flame of the spirit-lamp till the moisture is driven oflf, and adjust 
it with the forceps over the glass ring, Now apply the flame of the spirit-lamp 
to the porcelain, underneath the powder or crystal, and continue the heat till 
the powder undergoes its characteristic change and gives off vapour. 'Watch 
the deposit of this vapour on the glass disk, and remove the spirit-lamp either 
directly or after a short interval, as experience may determine. 
These are mj’- reasons for recommending this mode of procedure in preference 
to that advocated by Dr, Helwig :—By employing a flat white slab of porcelain, 
the heat of the lamp is applied gradually, and every change of consistence, 
colour, and position which the powder undergoes is easily observed. The ring 
of glass, as compared with a ring of metal, has the advantage of conducting the 
heat from the surface of the porcelain to the glass disk so slowly as to guard 
effectually against the danger of breaking, and if the pow'der after melting 
changes its place, the glass ring, wuth the disk upon it, is easily shifted. The 
disk of window-glass is very convenient both for the experiment itself and for 
the subsequent application of liquid tests. It will also bear a moderate heat, if 
required. The disks, however, are not essential; their chief recommendation 
IS the facility they afford of multiplying experiments. The common glass 
slide, or a slip of w’indow-glass (as being less liable to scratch, and bearing heat 
better than plate-glass) may be substituted when only a few experiments are in¬ 
tended to be made.* An oblong slab of wmod, somewhat larger than the micro¬ 
scopic slide, with a circular aperture and ledge to support the glass disk, enable 
us to examine the sublimate under the microscope, and a similar piece of thick 
cardboard, with a hole punched in the centre of it, serves for the mounting of 
the preparation.f 
By this mode of procedure I have obtained sublimates of veratria andsolanine, 
which correspond closely with the descriptions and photographs given by Helwig ; 
but, in the case of strychnia and morphia, I have got very distinct and extremely 
beautiful crystalline sublimates (not exceptional, but as the rule) where he 
has failed and though I am not yet prepared to assert positively that the 
strychnia and morphia sublimates can always be distinguished by their crystal¬ 
line forms alone, I am able to correct the statements contained in the following 
passages:— 
“It (the sublimate of morphia) consists of perfectly homogeneous spots of 
round, very sharply defined granules, closely packed together, which, when 
magnified a hundred and sixty times, are transparent, but among which no trace 
of a ciystalline formation can be discovered (p. 9) and “ Examined microsco¬ 
pically, a sublimate of strychnia is not to be distinguished from a sublimate of 
morphia; precisely the same spots of round transparent granules, without 
trace of crystalline formation (p. 21).” 
My object, in the present communication, is to draw attention to a new me¬ 
thod of procedure, which, even if it should fail to realize the sanguine expecta¬ 
tions of Dr. Elelwig, will certainly deserve and receive the attention of the 
As the disks of glass can only bo conveniently cut b 3 ’ a revolving diamond, which few gla¬ 
ziers iiossess, it mav’’ be well to mention that thej' maj' be procured of Mr. Eade, 130, High 
Holborn, at a cost of two shillings the gross. 
f yVhen dealing with larger quantities (such as a grain or more) of the alkaloids, the short 
specimen tube maj" be substituted for the porcelain and microscopic cell-glass. But the re¬ 
sults are far from satisfactory; and it would certainly be better to sublime successive small por¬ 
tions of a hundredth of a grain or less, from the porcelain. 
X I have also obtained veiy fine crystalline subhmates from the new alkaloid Cryptopia. 
