388 Eliot and Storer on Arsenic as 
a be easily recognized by its characteristic odor. The mirror —— 
m at once, and gradually increased during the hour, which was t 
deuscion of the experiment. 
Having at hand a quantity of ro" ore from which this zinc is extracted, 
we extended our search for arsenic to the red oxyd of zinc, which is the 
source of this spelter. Several pene of the red oxyd, finely powdered, 
were moistened with 30 drops of pure nitric acid, and treated with a 
asured quantity of pure chlorhydric — prepared from common salt 
poe sulphuric acid free from arsenic. solution, with the very slight 
residue, was then gently evaporated to a sn bulk, with a small meas- 
ured quantity of Sanengncian's i na ba vai The imperfect eros 
ib] 
in the narrow part o f the reduction-tube. s de osit was asia 
any cursory examination, and bore no sa ga with the v ba deci 
istic reactions for arsenic. To obtain satisfactory results, the solution of 
driven off before the liquid is introduced into the bate 
If any further _— of the presence of arsenic the New —— 
spelter and its ore were needed, it might be found in se following op 
iment with a zine ‘which we ourselves : reducing the ate 
Jersey white oxyd of zine with charcoal, in a refractory retort suc / as par 
furnished by the dealers in chemical apparatus at Paris: 20 gra sr ed 
this zine, tested in Otto’s apparatus with purified sulphuric seid, vy 
in five minutes a distinct deposit of arsenie, and in half an hour 4 arg? 
mirror. oo 
To ascertain whether the Pennsylvanian and Vieille Montagne ie al 
were always free from arsenic, we procured and tested another we 
the zine manufactured at the Pennsylvanian and Lehigh zine wor age 
a second sample of Vieille Mantagne spelter. The Pennsylvanian nn 
was, as before, remarkably free from lead, leaving no residue W po 
; salvad in dilute sulphuric aeid; but on testing 200 geese ‘t 
’s apparatus with purified acid, it gave in half an houra ve epost 
in the reduction tube, which in an hour increased to a distinet 
coating. A similar result we obtained in testing the ‘ind sam 
