98 
RESEARCH FOR ARSENIC AND ANTIMONY. 
monite of potash. The alkaline liquid is poured off, or, if 
necessary, filtered,—acidulated with hydrochloric acid, and a 
current of washed sulphuretted hydrogen gas is then passed 
into it. An orange- or reddish-coloured sulphide of antimony 
is precipitated. This may be collected on a filter and washed 
with strong ammonia, in which it is insoluble. As sulphide 
of arsenic is quite soluble in ammonia, the insolubility of 
the precipitate in this menstruum is a proof of its antimoniai 
character. Any sulphide of arsenic contained in the preci¬ 
pitate would of course be removed by ammonia at this stage 
of the process. If, as it frequently happens, the solution of 
potash contains lead, sulphuretted hydrogen should be passed 
at once into the alkaline solution, and the liquid filtered. 
Sulphide of lead is thus separated, and sulphide of antimony 
may now be obtained from the alkaline filtrate by acidulating 
it w T ith hydrochloric acid. 
In the late cases of antimoniai poisoning at Liverpool, Dr. 
Miller, Dr. Edwards, and myself, carried the demonstration 
a stage further. The sulphide of antimony, collected on the 
filter, was boiled in strong and pure hydrochloric acid, and 
after the odour of sulphuretted hydrogen had disappeared, 
the acid liquid w 7 as introduced with pure zinc into a small 
Marsh’s tube, constructed for the purpose, and the dried 
gas submitted to a red heat in a capillary glass tube. A 
well-marked metallic deposit, having the characters of 
antimony, was thus obtained. A certain quantity of pre¬ 
cipitated sulphide is required for obtaining this additional 
corroboration. 
If a sufficient quantity of oxide can be procured as a sub¬ 
limate by heating one or more pieces of copper coated with 
antimony, this oxide may be dissolved in a small quantity of 
a strong solution of pure tartaric acid; and this solution, on 
being treated with a current of washed sulphuretted hydrogen 
gas, gives a precipitate of orange-red sulphide of antimony. 
This method was successfully adopted by Dr. Edwards in 
some of his numerous analyses in the Liverpool cases of anti¬ 
moniai poisoning (I860). 
In his c Reports ? for October, 1856, Dr. Odling published 
a method of testing the antimoniai deposit on copper by 
boiling the metal with a weak solution of permanganate of 
potash and potash. The antimony is here oxidized at the 
expense of the oxygen of the permanganate ; by Mr. Watson’s 
method it is simply oxidized by exposure to air. Of the two, 
the latter is less open to objection. 
A method which I had previously adopted consisted in 
deflagrating the copper with the antimoniai deposit in a 
