_ pulverulent when exposed to the air. Met with in both. 
ARS—ARS 
these forms, in the shops ; often sold in powder, a state in 
which it is adulterated with chalk, &c. 
The semi-vitreous lumps of arsenic break with a con- 
choidal fracture, and, reduced to powder, resemble loaf 
sugar. ; 
Quvatirres. “Acrid and corrosive taste, but not ina degree _ 
corresponding to its virulence ; after taste, swectish. In 
_yapour, inodorous, though said to give out the smell of 
garlic ; the alliaceous smell is now known to be confined 
to metallic arsenic in vapour. When arsenious acid seems 
to yield this odour, it is an evidence of its decomposition. 
This occurs when heated and projected upon ignited 
charcoal, or heated in contact with metallic bodies which 
readily unite with oxygene, as antimony and tin. It is 
stated by Orfila and other chemists, that when projected 
on heated copper, the alliaceous odour is evolved. Paris 
has proved that this only takes place when the copper is 
heated to a state of ignition, and that if a few grains of — 
the oxyde be heated by a spirit-lamp gr blow-pipe, upon 
a cold plate of copper, no alliaceous t is perceptible; 
the whole of the acid being dissipated before the copper 
can be sufficiently heated to de-oxydize it. Heated ona 
plate of zinc, the smell is not evolved until the metal is 
in fusion. If gold, silver, or platinum, be used with the 
same process, no smell is given off at any temperature. 
Paris remarks, that the flame of the spirit-lamp itself’ is 
capable of decomposing the oxyd, in consequence of the 
operation of its hydrogen—a fact which is very likely to 
betray the chemist into the belief, that the oxyd does real- 
ly give off the odour in question. It has been su . 
that the arsenical vapours which yield this odour, are not 
s0 pernicious as those. which are inodorous—a fact, which 
has been assumed by Paris, to account for the circumstance 
mentioned by Dr. Percival, that workmen who solder 
silver-filligree with an arsenical alloy, are never affected 
by the fumes. Dr, Percival mentions, that the men thus 
employed enjoy as good health, and live as long, as otheT 
artists. He mentions having seen a man at the ** Soho, at 
Birmingham, of more than fifty years of age, who had 
soldered silver filligree for thirty-five years, and had regu. 
larly, during that period, passed from eight to ten hours 
daily in his occupation; yet he was fat, strong, active, 
cheerful, and of a complexion by no means sickly. Neithet 
he nor his brother artists used any means to counteract the 
effect of their trade.” Dr. Rotherham, in his comr 
‘upon this fact to Dr. Percival, seems to think, without 
accounting in any way for the escape of the workmen, that 
‘the fumes of this very volatile and caustic mineral may 
