393 
Tin, 
suit of the hammering. It appears that this metal con- 
curs to produce the crystallization of the tin, and the sin- 
gularity exhibited by the solution of its oxyd in nitric 
acid. At first, nothing is manifested but a slight effer- 
vescence, which soon subsides ; but four or five minutes 
after, the mixtures become very hot, and a stronger effer- 
vescence takes place, accompanied with a great deal of 
nitrous gas, which is disengaged with an explosion, and 
there remains in the glass a magma of a pale red colour. 
The white oxyd of tin, mixed also with nitric acid at 
32°, exhibits neither effervescence nor disengagement of 
nitrous gas. 
I fused this reddish calx of tin with three parts of black 
flux and a little charcoal powder, and extracted from it 
18 pounds of tin per quintal. This metal was brittle, a 
property arising from the lead, which contributes also to 
attenuate the colour of the tin. If the lead is found there 
in larger quantity, it is because there are four-fifths oi tin 
absorbed by the alkaline flux. 
To determine the quantity of lead contained in the tin 
extracted from the amalgam of mirrors, I decomposed a 
hundred parts of it by four hundred parts of nitric acid 
at 32 °. A great deal of nitrous gas was disengaged, and 
there remained at the bottom of the matrass a white maer- 
O 
ma. I washed it with distilled water, and evaporated the 
ley, which produced a twenty-fifth of nitrous ammoniacal 
salt mixed with nitrate of lead, which predominates, and 
forms nearly two-thirds of the saline residuum ; a propor- 
tion which would indicate that the tin employed for sil- 
vering mirrors contains three pounds of lead per quintal. 
I now return to the mercury extracted by distillation 
from this amalgam. It volatilizes a portion of tin, which 
remains there so intimately combined that it cannot be 
separated by a second distillation of the mercury. I was 
able to disengage from it the tin by shaking the mere my 
