92 PHILOSOPHICAL TKANSACTIONS. [aNNO 1791. 



Exppv. 3. '2000 grs. of antimony from the same parcel as that in the last ex- 

 periment, and an equal weight of hartshorn shavings taken from the same parcel 

 as those were in Exp. 1, were calcined together in the same manner that these 

 substances had been separately. During the first quarter of an hour, the mix- 

 ture smoked, was black, smelled strongly of sulphur, and felt soft. For 4- an 

 hour more, the smell of sulphur continued, the mixture turned brown, and the 

 bone was reduced to ashes. At the end of this time, not only the bottom of 

 the vessel might be kept red-hot without any signs of fusion ; but the smell of 

 sulphur, though weakly, continued for ^ half an hour more in a heat to keep a 

 great part of the mixture red-hot. At this time the sulphureous smell rather 

 suddenly disappeared, and could not be perceived, though a little of the mixture 

 was made quite red-hot for -J. of an hour further; during which no fume was 

 seen, or smell perceived. After cooling, a light grey or cineritious heavy powder 

 was left ; on examining which, argentine spicula were seen in the larger grains 

 of this calcined substance. It weighed 2200 grs. therefore the loss of weight 

 was 45 per cent. The Wedgwood pyrometer pieces indicated 8°. In other 

 similar experiments, the loss by calcination was from 37 to 41 percent.; there- 

 fore the mean proportion lost in these experiments must be stated at 41 percent* 



It appears that the calcination of antimony with bone-ashes is much more 

 speedy than when by itself, but the degree of fire was a little greater in the last 

 experiment than in that with antimony alone. Considering the nature of these 

 experiments, perhaps it may be more reasonable to impute the Si per cent, 

 oreater loss in this last experiment than the sum of the loss in Exper. 1 and 2, 

 to the greater insensible sublimation of the calx from more fire in one case than 

 in the other, than to refer it to the larger quantity of air combined with the 

 metal in the former of these last 2 experiments. 



Exper. 4. The above light clay, or ash-coloured powder, obtained in the last 

 experiment, by calcining together antimony and bone, being exposed to various 

 degrees of fire from 20° to l65° of Wedgwood's pyrometer, in close crucibles, 

 was not at all increased in weight, but generally lost about 5 per cent, when a 

 pretty large quantity, as a pound, was in the vessel. A part of this loss must be 

 referred to the adhesion or vitrification of the charge with the sides of the cru- 

 cible, and part to the deficiency of the bone itself, as above shown, by further 

 exposure to fire. I am sensible, that in experiments of this nature, all calcula- 

 tion must necessarily, to a certain degree, be vague ; yet it may be of some ap- 

 plication to observe that the proportion of antimonial calx, estimated to be con- 

 tained in Lile's powder, or pulvis antimonialis, and James's powder, from the 

 analysis of them, does not difl'er more considerably from the proportion of this 

 calx than may perhaps be reasonably ex[)ected on calculation, from these 4 last 

 experiments to exist in them : for 70^ parts of antimonial calx, to 54^ parts of 



