Chemical Science. 231 
is formed will re-act upon the undecomposed sulphate; and if 
the proportions be so arranged, thatthe sulphuret and sulphate 
are to each other as 29 to 20, the product of the operation 
ought to be pure lead. This is the case when sulphate of lead 
is heated with 0.06, its weight of charcoal. 
Secondly, Sulphate of lead may be converted into oxide, by 
heating it to whiteness with 0.03, its weight of charcoal. The 
oxide which I thus obtained was compact, vitreous, transparent, 
and of a fine resin-yellow colour. We see, then, that by the 
aid of charcoal only, we may convert sulphate of lead into sub- 
sulphuret, into pure lead, and into pure oxide. We may also 
decompose sulphate of lead by metallic lead; for this purpose 
the proportion of metal should be 0.68 that of the sulphate. 
With these proportions I obtained a very pure oxide. One may 
also conyert sulphate into oxide of lead, by heating it with sub- 
sulphuret in the proportion of 7,3 parts of the latter to 10 of the 
sulphate. 
Thirdly, Sulphurous acid may be obtained from sulphate of 
lead: but as this acid could only be used for the production of 
sulphuric acid, and, therefore, only as a substitute for sul- 
phur, it is useless to enter into the details of this decomposi- 
tion. 
Fourthly, In the lead furnaces, sulphate of lead and galena 
may be conveniently reduced together. 79 parts of galena, and 
100 of the sulphate, treated as usual in the reverberatory fur- 
nace, afford about 137 parts of metallic lead. 
Fifthly, Sulphate of lead may be decomposed by silica. 11 
grains of sulphate of lead were mixed with 16 of finely-powdered 
rock crystal ; this mixture was ignited for an hour in a small 
Hessian crucible; the loss of weight sustained in this operation 
amounted to 3.3 grains, which is little more than the weight of 
the sulphuric acid contained in the sulphate. A white, spongy, 
and translucent enamel was thus obtained. 4 parts of quartz, 
and 12 of sulphate, and 4 of quartz and 6 of sulphate, afforded 
compact and transparent yellow glasses, and the sulphate was in 
all cases decomposed. 
Sixthly, Sulphate of lead may be used for glazing pottery, 
and it may be substituted for minium in the manufacture of 
glass and pastes. 
Lastly, Sulphate of lead may be decomposed by carbonate 
of ammonia or carbonate of potassa, for the production of 
white lead. The former operation can only be economically prac- 
tised by manufacturers of sal ammoniac, and it is doubtful whe- 
ther the latter would afford aceruse equally fit for the painter’s 
use with that obtained by other and cheaper methods. (An- 
nales de Chimie et Physique, 'T. xx. p. 275. 
7. Green Fire.—In a former number of this Journal we 
