ON TllL iLlU.l.MATlON OF THE Ai.HALCJ 1)S. 
71 
of the alkaloids as a test and diagnostic,* and more recently (in 1865t) he pub¬ 
lished a work, in large 8vo, of which the greater part is devoted to the tests for 
the jjoisonous alkaloids—morphia, strychnia, brucia, veratria, atropia, aconi¬ 
tine, solanine, digitaline, conia, and nicotia. In the case of the fixed alkaloids, 
the results of sublimation and the reactions of the sublimates are minutely de¬ 
scribed. The work contains carefully prepared tables of the reactions, and is 
enriched by no less than sixty-four micro-photographs, of which thirty-eight 
represent the crystalline forms of the alkaloids and their salts with various re¬ 
agents, and fourteen are devoted to sublimates and their reactions. 
Dr. Ilelwig states that the idea of submitting the alkaloids to sublimation first 
suggested itself to him as a natural extension of a method so successful in de¬ 
tecting and identifying minute quantities of arsenious acid and corrosive subli¬ 
mate ; and he lays claim to originality, inasmuch as he docs not find the subli¬ 
mation of the alkaloids described in any handbook of chemistry or forensic me¬ 
dicine, even the most recent. This claim to originality is, I believe, fully 
justified, though probably every manufacturing chemist must have recognized 
the fact that some at least of the alkaloids are sublimed by heat, and experi¬ 
menters on the small scale must have observed that the alkaloids, as a class, 
after melting, and before depositing carbon, give out a more or less dense vapour 
or smoke, which, if allowed to settle on a cool surface, might possibly present, 
under the microscope, characteristic appearances. 
This new application of the test of sublimation suggested itself to Dr. Helwig 
after becoming acquainted with the simple methods of obtaining sublimates of 
arsenic and mercury on fiat surfaces, with a view to microscopic and chemical 
examination, which I proposed in the year 1858.His own method of proce¬ 
dure with the alkaloids is as follows:—In a piece of platinum-foil of moderate 
thickness, a small cup-like hollow is formed ; in this a minute qua,ntity of the 
alkaloid is placed, and over it a microscopic slide {Ohjeettreiger). This sim.ple 
apparatus being placed on a suitable support, the flame of a spirit-lamp is cau¬ 
tiously applied until the alkaloid melts, from which point of time the sublimate 
bemns to form on the glass slide. 
o . 
Now, this mode of procedure is obviously open to objection. The successive 
changes that take place in the alkaloid—the discoloration, the liquefaction, the 
deposit of carbon, either on the spot (as happens with some alkaloids) or over a 
wide surface traversed by the liquid (as is the case with others)—cannot be dis¬ 
tinctly seen, and some diagnostic marks of the alkaloids as a class, and among 
themselves, are thus lost. Nor, again, can the formation of the sublimate itself 
be seen and watched, as it should be if we would obtain satisfactory results. 
There is also some risk in this sudden mode of applying heat, of causing the 
glass, which should receive the sublimate, to break. 
The method of procedure to which I should give the preference is the follow¬ 
ing:—Provide small crucible covers or slabs, or fragments of white porcelain, a 
few microscopic cell-glasses, with a thickness of about one-eighth of an inch, 
and a diameter of circle of about two-thirds of an inch, and disks of windo'w- 
onr account of Ciyptopia in the Pharmaceutical Journal of April, to he a mixed muriate’ cl 
Ciyptopia and Thebaia. 
* Presenius’s ‘ Vierteljahrschrift fiir analytische Chemie,’ ISGi, i. 
f ‘ Das Mikroskop in der Toxikologie. Beitrage zur mikroskopischen und mikrochomisclun 
Diagnostik der wichtigsten Metall- und PflanzeTigifte, fiir Gcrichtsarzte, gerichthche Chemikf v 
• und Pharmaceuten, mit eincm Atlas photographirter mikroskcpischer Pi aparate. Yen Dr. A. 
Helwig, pract. Arzte und Grossherzoglich-Hes.sischcm Kreiswundarzte in Mainz. 18C6. 
X “On the Production and Identilication of Crystals of Arsenious Acid and Crusts of Me¬ 
tallic Arsenic” (Beale’s ‘Archives of Medicine,’ no. iii., 1858); also “On the Micvcsccpic 
Cliaracters of the Crystals of Arsenions Acid ” (‘Jonrnal of the Microsccpic Society, ISUl,’ 
and ‘ Principles of Forensic Medicine,’ 2nd edit., 1861, p. 372). 
