AA, an ordinary phial with a large mouth having a capacity of 
from ten to sixteen ounces, in which the gas is generated ; B, a 
tube little less than half inch in diameter traverses the cork and 
reaches nearly to the bottom of the phial ; it is for the purpose of 
introducing the liquid to be examined and the sulphuric acid. ©, 
another tube of a much small diameter, and bent at an obtuse 
angle; this serves to conduct the gas into a tube D, about ten 
‘inches long and an inch in diameter, filled with cotton or asbes- 
tus. E is a glass tube, (it is to be preferred if it be of refracting 
glass ;) its internal diameter should not be more than from one 
twelfth to one tenth of an inch, and its extremity should be 
drawn out to a capillary opening: F' is a bent sheet of tin per- 
forated with two holes, and which serves to support that part of 
the tube heated by the alcoholic lamp G. 
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ui ff (Hi, : 
sncuinpitviaie g alae emiegensinineaied fitch son samen of. the 
phial should be left empty. The zinc and liquor to be tested are 
first introduced. The tube Eis then heated by the lamp, after 
which we introduce slowly the sulphuric acid through the tube 
B. The gas being generated, it first traverses the tube D, where 
it deposits most of its moisture, as well as that portion of the 
liquor which passes out of the phial along with the gas. The 
gas arriving at the point of the tube E that is heated, is decom- 
posed, and the arsenic deposits itself a little further up the tube, 
in the form of a metallic ring. The gas that passes out of the 
extremity is inflamed, and. any arsenic that may still remain 
combined with it, is received on a porcelain surface. 
- This is the method of operating, that seemed to the committee 
most likely to give delicate and accurate results. They seem to 
think that fused chloride of calcium is not to be preferred to the 
Cotton or the asbestus; but from many experiments that I have 
