466 



proper management the peroxide was drained to the last drop, 

 dried on the capsule, collected with great care on glazed hot 

 paper, and thence transferred to a bulbed tube of Bohemian 

 glass, M'ithout the smallest loss. The bulbed tube had been 

 previously heated, and counterpoised in the scale-pan of the 

 balance. The bulb was then gradually heated until the per- 

 oxide was red-hot ; the weight of the peroxide of tin was 

 16'678 grains, equivalent, according to the estimate of Berze- 

 lius, to 13-112 grains of metallic tin. This mode of deter- 

 mining the quantity of peroxide of tin I found much better 

 than filtering and burning the filter. 



" In order to discover the quantity of lead, pure sulphate 

 of soda, in quantity known to be more than suflScient, was 

 added to the solution of nitrate of copper. No precipitate 

 ensued. The whole was introduced into a retort, a receiver 

 was attached, and the acidulous water was distilled ofi". The 

 process required the greatest vigilance, for the least increase 

 of heat towards the end caused the liquid to sputter and shoot 

 out particles in all directions, a circumstance which had im- 

 posed on me the necessity of abandoning a former analysis of 

 this celt. At length the nitrate of copper showed a tendency 

 to solidify, the heat was then raised until nitrous gas began to 

 appear. The heat being withdrawn, some distilled water was 

 added, which dissolved the nitrate of copper, but left a small 

 quantity of sulphate of lead. This, being washed with fre- 

 quent small portions of distilled water, was separated in the 

 same manner as the peroxide of tin had been, and heated to 

 an obscure red. Before it had cooled entirely it was ascer- 

 tained to weigh 1*75 grain, which, according to the estimate 

 of Berzelius, indicated 1'142 grain of metallic lead. 



" The next step was to ascertain the quantity of copper. 

 The washings of the sulphate of lead were added to the solution 

 of nitrate of copper ; the whole was distilled in a retort, with 

 the same precautions as before, until the nitrate showed a 



