SELECTED ARTICLES. 
ART. XIV.— ON THE PRESENCE OF TIN IN THE PROTO- 
SULPHATE OF IRON, AND THE INCONVENIENCES 
THEREFROM IN EXAM1NANATIONS FOR ARSENIC. By 
M. Sarzeau, of Rennes. 
The presence of a small quantity of tin in the protosul- 
phate of iron is a fact, in a chemical point of view, of but 
small importance, but the circumstances accompanying its 
discovery, appears to me to give it some consequence in legal 
medicine. I publish this note for the purpose of removing 
one of the causes of doubt and difficulty which are so trouble- 
some injudicial investigations. 
Towards the end of June, my assistance was required 
in a case of poisoning by arsenic; the patient had been treated 
by the hydrate of the peroxide of iron. Among the substances 
for examination, were the matters vomited. These were not 
abundant, and contained bread, curdled milk, &c. Having 
been rubbed up in a glass mortar to obtain a very fine pulp, 
they were diluted with distilled water, and submitted to the 
action of a stream of chlorine until deprived of color, and per- 
fectly saturated. In this state the liquid was left for some 
hours in a closed flask; shaking it occasionally, and then 
filtered. The filtered liquid was boiled to drive off the excess 
of chlorine; it was acid. Tested with ammoniacal sulphate 
of copper, it gave a precipitate which, even after frequent 
washings, retained a color sensibly green. Treated by a 
stream of sulphuretted hydrogen, it soon became yellow, 
and deposited a fine yellow precipitate. This precipitate was 
soluble in ammonia, from which it could be precipitated by 
acids. As all these reactions tended to prove the presence 
of arsenic, the sulphuret was dried at the temperature of boil- 
ing water, and submitted to the following trials: 
1. A part was triturated in an agate mortar, with recently 
prepared quicklime; this mixture was introduced into a tube 
closed at one end, and heated; at first with care, afterwards 
the temperature was gradually increased until the tube be- 
