3 =a 
ce Means of detecting Arsenic in the Animal Body, §c. 289 
“until the mass becomes perfectly dry ; water is now poured 
it, and heat applied for ten or fifteen minutes; the liquid is now 
filtered, and tested by the apparatus. » The bouts muscles, brain, 
&c., if examined, must undergo the same process. 
There 3 is yet another advantage, that has not been mentioned, 
_ connected with the carbonization of animal matter by nitric acid; 
it is, that if antimony be present, it becomes converted into anti- 
monious acid, which is insoluble in water. 
Mention bate been made only of the manner of separating 
arsenic from animal matter, by the aid of Marsh’s apparatus, 
and it may be well to give a brief account of one or two new 
methods adopted by Mr. Persoz to serve the same end, with this 
additional advantage, that it enables one to ascertain the exact 
{ present. 
th suspected materials, after having sufficient reason to sup- 
pose that they do not contain a poison of organic origin, or mer- 
Curial or antimonial preparations, are subjected to ue action of 
dilute nitric acid, in order to destroy those parts that tire decom- 
posed by this agent. Most of the organic substances having un- 
dergone this decomposition, the residue is diluted with water, and 
heated to the boiling point, and then left to cool; the fatty and 
tesinous substances rise to the surface, are taken off and washed, 
and the washings added to the original liquid, which is then 
evaporated to the consistency of syrup. The liquid now hasa 
dark brown tint, an evidence that it still contains a quantity of 
~ Organic matter. Nitric acid, therefore, is again added, and a new 
Oxidation takes place. We recommence to evaporate, and con- 
tinue to add nitric acid, until the liquid acquires a lively orange 
tint, when a careful evaporation is commenced, first over a naked 
fire, and then by the means of vapor. An approximate value be- 
ing made of the quantity of residue, twice and a half times its 
Volume of pure nitrate of potash is added, for the purpose of com- 
Pleting the oxidation. Water is next sina upon these materi- 
als, and heat applied and continued until the water is evaporated 
and the residue is dry; by this means an intimate mixture is 
brought about between the nitre and animal substances. In this 
Patt of the operation, care must be taken to extend the matter as 
much as possible over the surface of the capsule as soon as it be- 
gins to dry. The capsule is now heated almost to redness, when 
“ oo takes place, and propagates itself through all the 
