gg tlle GO oe a, 
Arsenic in the Bodies of Persons poisoned. 151 
purpose. A little charcoal is then let fall upon the arsenic, 
after it has been freed from all moisture by bringing it to a 
red-heat with the blow-pipe. The charcoal is then heated in 
the tube at the flame of a spirit-lamp, the point-of the tube 
being held out of the flame. When the charcoal is very red, 
“the point containing the arsenic is drawn into the flame. The 
arsenic is then instantly volatilized, and passing into vapour 
by the red charcoal, it is reduced, and reappears on the other 
side of the flame in a metallic state. The flame is then brought 
slowly towards the metallic sublimate, which is thus concen- 
trated into a smaller space in the small tube, and then pre- 
sents a small metallic ring shining like polished steel*. We 
have now only to verify, by its smell, that the metallic sublimate 
is arsenic. For this purpose, cut the small tube with a file a 
little above the sublimate, and, having heated the place where 
it lies, put the nose above it at a small distance, and the par- 
ticular odour of the metal will be immediately perceived. 
In the case where the solid arsenic cannot be found, we 
must collect as much as possible of the contents of the stomach 
and the intestines, or even cut the stomach in pieces, and mix 
it with its contents. The whole’is then to be digested with a 
solution of hydrate of potash. Hydrochloric acid is then added 
inexcess. The whole is filtered, and, if the liquid is too much 
diluted, it is concentrated by evaporation. A current of sul- 
phuretted hydrogen is then passed through it, which precipi- 
tates the arsenic in the form of the yellow sulphuret. If the 
quantity of arsenic is very small, the liquid will become yellow 
without giving a precipitate. It must then be evaporated, and 
in proportion as the hydrochloric acid becomes more concen- 
trated, the sulphuret of arsenic will begin to be deposited. It 
is then filtered. If the sulphuret remaining on the filter is in 
too small a quantity to be taken from the paper, add some 
drops of caustic-ammonia, which will dissolve it. Then put 
‘the liquid which passes the filter into a watch-glass, and eva- 
porate it. The ammonia will be volatilized, and will leave as 
a residue the sulphuret of arsenic. If it shall still be difficult 
to collect the sulphuret, we must put into the watch-glass a 
little pulverized nitrate of potash, and, with the finger, mix 
the sulphuret with the nitrate of potash, which detaches it 
from the glass. At the bottom of a smal] phial, or a piece of 
lass tube, shut at one end, melt a little nitrate of potash at 
the flame of a spirit-lamp, and introduce into it, when melted, 
a little of the mixture which contains the sulphuret of arsenic. 
It is oxidized with effervescence, but without fire, or detona- 
* Had the experiment been made in the wide part of the tube, the re- 
sult would scareely have been visible with a small quantity of arsenic. 
. tion, 
