ON THE DETECTION OP ARSENIC. 
281 
and consequently within the reach of very few apothecaries 
in this country. 
Sensible of these deficiencies, and as an apothecary, feeling 
how likely some of us may, one day or other, be placed in a 
situation requiring an application of our chemical knowledge 
in presence of judicial authorities, it occurred to me that 
a manual or code, based upon established processes taken 
from the most authentic sources, would be of immense utility 
in guiding an operator in his researches. For this purpose I 
have collected the choicest matter in reference to this subject, 
contained in the works of Berzelius, Leibig, and Orfila, che- 
mists, whom the scientific world, look up to, as the highest au- 
thorities. I have also derived valuable assistance from the 
use of selections made by M. Lassaigne, and embodied in 
his very useful work entitled, " Dictionnaire des Reactives," 
illustrated by diagrams some of which I have transferred to 
this paper. 
Having concluded these incidental remarks I shall now pro- 
ceed with my labors in the order prescribed. 
The form in which arsenic is commonly adminstered as a 
poison is that of arsenious acid, or white arsenic, commonly 
called ratsbane. The sulphurets are sometimes used, being 
kept in the shops under their common names of Realgar and 
Orpiment; their employment, however, is rare, on account of 
the difficulty of disguising their color, and their being poi- 
sonous in a far less degree than white arsenic. Of this last it 
is our main object to speak. 
White arsenic, ranked at the present day among the acids, 
is met with in commerce, in white pieces, opaque at their 
surfaces, commonly presenting, in their interior, a semi-trans- 
parent and vitreous layer. Its specific gravity is 3.7. Ex- 
posed to the air it soon loses its primitive transparency and 
becomes of a milk white color, more friable and according to 
Guibourt, a little more soluble in water. Its taste is harsh, 
and slightly acrid, with a sweetish aftertaste. Heated in open 
vessels it wholly sublimes in small transparent tetrahedral 
crystals. Thrown upon burning coals, it volatilizes in white 
vol. vi. — no. iv. 36 
