ON THE DETECTION OF ARSENIC. 
295 
hydrogen forms, and as it disengages, soon drives out all the 
atmospheric air. Allow the gas to escape for some time, to 
remove all chance of an explosion, then heat the tuhe to red- 
ness, by placing burning charcoal in the grate. You now in- 
troduce the decoction, previously treated as above directed. 
The froth that may arise, in the course of the operation, can 
never become troublesome. Should this, however, occur, you 
can make it descend by pouring a small quantity of alcohol 
into the straight tube. 
However little the liquid under examination may contain 
arsenic, it soon manifests itself at a short distance from the 
heated portion of the tube, in the slender part, where a small 
shining circle of metallic arsenic goes on increasing during 
the operation. When you perceive that the metallic zone does 
not grow any bigger, then arrest the operation, which may be 
maintained one or two hours, taking care that all the zinc em- 
ployed should be as much as possible dissolved. When the 
tube is cold, you may separate it from the rest of the apparatus, 
and assure yourself of the volatibility of the metal obtained, 
and test some of its properties without altering its metallic as- 
pect. Lastly, close the two extremities of the tube by means 
of a lamp, and preserve it for the purpose of conviction in a 
court of justice. 
In a new memoir read before the Royal Academy of Medi- 
cine, January, 1839, Mr. Orfila has shown, by a series of ex- 
periments repeated in cases of poisoning by arsenic, that this 
acid, introduced into the stomach or applied upon the cellular 
tissue of living dogs, is absorbed, and mixes with the blood, 
and is carried into all the organs of the economy. 
That it is to this absorption of the poison, that death, which 
follows, must be attributed. 
And that it is possible, with the aid of certain chemical pro- 
cesses, to separate metallic arsenic from the portion of arse- 
nious acid absorbed, even when no traces of this acid have 
been discovered in the matters proceeding from the stomach 
and intestines of the person poisoned. 
Mr. Orfila establishes, that arsenic may be detected in ex- 
