RESEARCH FOR ARSENIC AND ANTIMONY. 
231 
described at p. 541. If the hydrogen compounds of sulphur 
and arsenic pass over together, the application of a red heat 
leads to the production of an orange-yellow sulphide of arsenic 
at the end of the metallic deposit, Sulphur alone can never 
be mistaken for metallic arsenic. Its yellow colour, its property 
of readily melting, and the absence of an}’- solid product as a 
result of the action of nitric acid—are characters which will 
prevent any mistake on this ground. 
Novelty of the process ,—The reader will have perceived from 
the foregoing remarks that the process here recommended has 
no pretensions to novelty. It consists simply in the associa- 
tiob or arrangement of the well-known chemical properties 
of arsenic so as to render them more easily demonstrable 
than they have hitherto been. The processes of Marsh and 
Reinsch have been introduced in a form less objectionable than 
that in which they were left by their discoverers. 
The chloride of arsenic has been long known as a volatile 
compound. JBerzelius, and chemical writers subsequently to 
him describe its properties, and refer chiefly to one method of 
preparing it; namely, by distilling at a high temperature a 
mixture of arsenious acid and corrosive sublimate. In 1841 
Dupasquier found that arsenious acid was very soluble in hy¬ 
drochloric acid, and he considered the solution to contain 
chloride of arsenic. When submitted to distillation, he found 
the distilled product to be arseniferous. 1 Dr. Pereira states 
that on repeating the experiment he found the quantity of 
arsenic which distilled over was very small, and that the resi¬ 
dual liquor in the retort deposited octahedral crystals of arse¬ 
nious acid. 
In employing Reinsclv’s process in various analyses for 
arsenic in the dead body, during the years 1846-7, I found 
that there was a loss of arsenic ; and the following passage in 
reference to this subject occurs in the first edition of my work 
c On Poisons The boiling of the tissues in muriatic acid 
for the extraction of arsenic should take place in a close vessel , 
such as an alembic ora capacious retort with a receiver attached 
to it. There is, beyond all doubt, a loss of arsenic when this 
precaution is not adopted. In May, 1847, the following expe¬ 
riment was performed in order to determine this point. Four 
grains of arsenious acid were dissolved in five ounces of distilled 
water, to which five drachms of concentrated muriatic acid had 
been previously added. The vessel was so large as to prevent 
the possibility of any liquid being carried over mechanically . 
1 Quoted by Pereira from ‘Journal de Pbarmacie/ tome xxvii, p. 717, 
1811. Pereira, ‘ Elements of Materia Medica, 5 &c., by Tavlor and llees, 
1854, p. 720. 
