* 
|4 MINERAIOGICAL 
§ 6 . 
Though in the courfe of thefe expe¬ 
riments no fign of filver or lead was 
difcovered, I made, in order to be quite 
certain, the following trial. 
Upon the calcined tin ore, § i. was 
poured nitrous acid, which a died with 
violence, emitting frequent red vapors. 
Being fufficiently digefted, water was ad¬ 
ded, and the reliduum, confifting of ful- 
phur, and calx of tin, feparated by the 
filtre. The clear blue folution was treat¬ 
ed with marine and vitriolic acid, and 
alfo with fome neutral falls containing 
thefe acids, without being in the lead al¬ 
tered, a proof that no filver or lead was 
mixed. 
§ 7 * 
