es ‘ Means of detecting Arsenic in the Animal Body, §c. 285 
es - : * ; Fy es 
_ phuret of antimony is formed. Another process will be stated 
for arriving at the same end, when mention is made of a method 
_by which I propose to separate arsenic from organic substances. 
The importance of studying this double tache will be evident to 
every reflecting mind, for it may not unfrequently happen that the 
physician called upon to administer to a person supposed to be 
boring. under the effects of arsenic, may usé.-tattar emetic to dis- 
embarrass the stomach of the supposed poison; death taking 
place, an examination is made of the liquid found in the stomach 
and intestines, of urine, &c., by means of Marsh’s apparatus, and 
atache is obtained which is not easily volatilized, and which has 
the appearance of antimony. What then is to be done? Why, 
-We are to proceed in our experiments as just stated, and the two 
metals, if both be present, are to be separated. 
The tache from sulphur has all the characteristics of that sub- 
stance; color yellow, volatile, with a suffocating smell, &c. 
There is not the least probability of confounding it with any 
thing else. © . 
The tache from phosphorus possesses three different shades, 
brilliant white, brilliant yellow, and rust color. When the quan- 
tity of phosphorus is very small, either the first, or only the first 
and’second are seen. It is volatile, reddens- litmus r, and 
is insoluble in cold nitric acid, so that there cannot be the least 
occasion for mistaking between this and arsenic. 
_ ‘The next substance that prodtices a tache when introduced into 
the apparatus in question, is iron, but it ought not to be classed 
With the others, for Iam firmly convinced that it is not due to 
any iron that may be dissolved by the hydrogen; in other words 
. that there is no ferruginous hydrogen. My reason for so be- 
lieving is based upon the following facts :—If we desire to obtain 
this tache, a considerable quantity of iron, or some salt of iron, 
must be used, and the gas made to generate rapidly. Now observe 
What must take place. The action of the liquid being violent, a 
Spray is formed, which consists of the dilute acid and whatever 
salts it May hold in solution, in this case iron as one; this spray 
Passes along with the hydrogen through the jet; the hydrogen 
being now ignited, a porcelain surface is placed in contact with 
the flame, which, becoming heated, enables it to evaporate 
the water from the salt of iron, which deposits itself, and after- 
Phi becomes decomposed by a continuation of the heat, the 
Vol. xx, No. 2.—Jan.—March, 1841. 37 
