339 
NOTE ON THE DETECTION OE ARSENIC IN COPPER. 
By W. Odling, M.B., F.R.S. 
As even in the most satisfactory performance of Reinsch’s 
test for arsenic—the deservedly favorite test of English 
toxicologists—there is always some, although but an extremely 
small quantity, of the copper wire, foil, or gauze, dissolved, 
and as commercial copper is rarely quite free from arsenic, 
and sometimes contains a very notable proportion thereof, it 
is important that the copper to be used in medico-legal re¬ 
searches as a precipitant for arsenic should be specially 
tested as to its purity.* But as in the ordinary mode of 
experimenting by ReinsclFs process the amount of metal 
dissolved is scarcely appreciable, it is quite unnecessary to 
submit any considerable quantity of it to examination. If a 
solution of four or five grains of the copper does not yield any 
evidence of arsenic, it is quite pure enough for the purpose, 
even though a little arsenic should be recognised in the solu¬ 
tion of a larger quantity. 
As a means of detecting traces of arsenic in copper, the 
author believes that the following process is superior to any 
hitherto proposed in conjoint delicacy and rapidity of ope¬ 
ration : 
A few grains of the copper cut into fine pieces are placed 
in a small tube-retort, with an excess of hydrochloric acid, 
and so much ferric hydrate or chloride as contains a quantity 
of iron about double the weight of the copper to be acted 
upon. The mixture is then distilled to dryness, some care 
being taken at the last to prevent spurting. 
The whole of the copper is in this way quickly dissolved, 
and any arsenic originally contained in it carried over in the 
form of chloride of arsenic, which may be condensed in a 
little water with the excess of aqueous hydrochloric acid. 
The resulting distillate is then tested for the presence of 
arsenic, by treating it with sulphuretted hydrogen, or pre¬ 
ferably by boiling in it a fresh piece of clean copper foil or 
gauze. In some cases the residue left in the retort may be 
treated with a little fresh hydrochloric acid, again distilled to 
dryness, and the distillate collected and tested along with that 
first produced. 
Most oxygenants other than ferric chloride are objection- 
* Taylor, ‘Guy’s Hospital Reports,’ [3], vi, 201. Abel and Field, 
* Journal of Chemical Society,’ xiv, 291, 
