TIN IN THE PROTOSULPH ATE OF TRON. 
67 
came soft and deformed. No sublimation took place, the 
sides of the tube remaining clear. 
2. Another portion was placed by itself in another tube, 
and heated; a yellow sublimate appeared, and a black, half 
melted mass could be seen at the bottom of the tube. The 
tube having been cut, the sublimate was detached; this, when 
burnt, gave a strong odor of sulphurous acid ; treated by am- 
monia, it yielded nothing to it; it was sulphur. 
3. The black, half fused mass of the preceding experiment 
was pulverized, mixed with subcarbonate of soda, and heated 
by charcoal to the complete absorption of the alkali. On 
examining the spot produced by this trial, white metallic 
globules could be perceived. This spot separated, ground, 
and washed in an agate mortar, left metallic spangles of a 
bright silver white, which were perceived to be tin. 
These experiments prove how indispensably necessary it 
is in medico-legal inquiries, always to obtain the poison in a 
pure state, and then by verifying its properties, to acquire a 
firm conviction. In fact, had I been content with the effect 
produced by the ammoniacal sulphate of copper, and the pro- 
perties of the sulphuret, the conclusion would have been, that 
the matters vomited contained arsenic. Although the color of 
the sulphurets of tin and arsenic, and their solubility in am- 
monia, are not exactly the same, they, nevertheless, are so 
analogous, that, in experimenting with small quantities, it is 
difficult to detect their differences. 
Ca use of the presence of Tin. 
It was presumable that the tin was derived from the vessels 
used in the preparation of the food, but the information ob- 
tained from the patient went to show that this could not be 
the case. Some of the hydrate of the peroxide of iron yet 
remaining, it was desired that a specimen should be procured 
of the same sulphate of iron which had been used in its pre- 
paration. This salt was labelled, "Pure Sulphate of Iron;" it 
came from one of the best manufacturers of chemicals in 
Paris. 
