a ah aaa 
Remarks upon Arsenic. 79 
_ Ath. We may collect the arsenate of silver thus formed, mix 
it with a little black flux, introduce it in the bulb by the extrem- 
ity a of the tube ab, (which extremity is to be subsequently 
closed by being heated,) and then heat the bulb, the arsenate ~ 
will be decomposed, and the arsenic will make its appearance in 
the form of a metallic ring in the capillary portion of the tube d, 
a ote oa : 
“ experimenting with Marsh’s apparatus, we should ef. course 
be sure.of the purity of the materials used in generating the hy- 
drogen gas, as well as of those used for carbonizing the animal 
matter.. We should submit them all to the same examination 
alone, as we did in company with the substance which was the 
object of our experiment, that is to say, we should evaporate to 
dryness the same quantity, or even more sulphuric and nitric acids 
and water than was used, and test it with the same quantity of 
zinc. . It must be understood. at the same time, that all the re- 
agents should be tested before as well as after the experiment. 
_.In my last letter, I mentioned that it was generally supposed 
afer the experiments. of M. Orfila and others, that the bones con- 
tained. sagan and it was also believed that the muscles did; 
there havin; been obtained taches resembling in some dente 
those. of. arsenic, -which, I gave then as my opinion, were no 
doubt caused by the sulahue.ae, phosphorus contained. in the 
muscles. 
MM. Deager ee Pianie bape been ocenpying themselves 
particularly with the investigation of the question of the exist- 
ence of arsenic normally, in the animal economy. In their ex- 
periments they found that by taking a small portion of a muscle, 
and carbonizing it imperfectly, they were able to obtain taches 
resembling in all respects those of arsenic, but which in reality 
Were not, for they ascertained that they were produced by the 
Sulphite and phosphite of ammovia and an animal volatile oil, 
formed during the imperfect carbonization ; and also by the aid 
of about one grain and a half of each of these salts and eighteen 
drops of spirits of turpentine, they formed these taches in con- 
siderable quantity ; they have stated that they resemble in all 
papecie. those of arsenic, but no one accords with them on that 
int. The committee of the Academy of Sciences. stated. what 
