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Mr, PoRRETT on the nature of the Salts 
Analysis of sulphuretted Chyazate of Protoxide of Copper. 
A. Twenty grains of sulphuretted chyazate of protoxide of 
copper were heated to 413° for half an hour, without experi- 
encing the least diminution of weight ; consequently this salt 
does not contain any water. 
B. Ten grains of crystallized sulphate of copper were dis- 
solved in water, together with fifteen grains of green sulphate 
of iron, and were decomposed by sulphuretted chyazate of 
magnesia ; the product was sulphuretted chyazate of protoxide 
of copper: after washing and drying at 212°, it weighed 4.58 
grains. Now as the whole of the copper contained in the ten 
grains of sulphate entered into the composition of the 4.58 
grains of sulphuretted chyazate in the state of protoxide, and 
as the quantity in those ten grains is according to Proust 2.56 
grains, which reckoned as protoxide is equal to 2.88 grains, 
it follows that 4.58 grains of the sulphuretted chyazate contain 
2.88 grains of protoxide of copper, or 62.85 per cent. 
C. Five grains of sulphuretted chyazate of protoxide of 
copper were decomposed by nitric acid, and the resulting 
nitrate of copper converted into a muriate, from which the 
copper was thrown down in the metallic state by iron ; it 
weighed 2.82 grains, which reckoned as protoxide is equal to 
3.172 grains, or to 63.44 per cent. 
As this salt does not contain any water (A), its only con- 
stituents are sulphuretted chyazic acid and protoxide of copper, 
which exist in it in the following proportions. 
