VOL. LXXXI.] PHILOSOPHICAL TRANSACTIONS. QS 



bone-ashes, is as about 56.4 parts of this calx to 43.6 parts of calcined bone; 

 and, on analysis, James's powder afforded -jVo- of antimonial calx, and -^^ of 

 phosphorated lime, or nearly so, allowing for the waste. 



Exper. 5. This experiment shows the degree of fire necessary to render the 

 antimony calcined with bone of a white colour ; and that this whiteness does 

 not depend on the air, but on the fire, (a) 1500 grs. of the calcined mixture 

 of antimony and bone, Exp. 3, were kept red-hot in a close vessel for -i an 

 hour. On cooling, the powder changed from a cineritious or clay colour, to a 

 whitish colour with a shade of yellow. The sides of the crucible were not 

 o-lazed. The pyrometer in the middle of the powder had contracted to 40°. 

 This powder was much inferior in whiteness to James's powder, being much 

 yellower. 



(b) Another parcel of the same powder, Exp. 3, was exposed in the same 

 manner, but to a greater degree of fire, in which the crucible was almost white 

 hot for 4- an hour. After cooling, the powder was found changed to a loosely 

 cohering, snow-white, heavy mass, and the sides of the crucible were covered 

 with a yellow glaze. This mass, which was easily detached from the vessel, was 

 found covered with a yellow vitreous coat over the whole surface of it that had 

 been in contact with the crucible. In the white solid, on breaking it, many 

 argentine spicula were seen. The pyrometer used in all these experiments in- 

 dicated 71°. 



(c) 1500 grs. of the same parcel, Exper. 3, were exposed in an open crucible 

 to the fire of a melting furnace ; no fumes arose till the crucible began to be 

 almost white hot. After inverting another crucible, with a small hole in its 

 bottom, the fumes continued to ascend at times through the aperture for J- of 

 an hour. The crucible was then taken out of the fire, and on cooling a whitish 

 powder was found, but no glazing, and the pyrometer indicated 28°. On again 

 exposing this crucible with one inverted over it in the melting furnace, but to a 

 greater degree of fire, still more fumes arose ; but on cooling the charge was 

 still in the state of a powder, though whiter than before ; and the inside of the 

 inverted crucible was covered with silvery particles, and the hole of it was sur- 

 rounded with argentine spicula, in a stellated form. The pyrometer indicated 

 39°. On reducing a little of this powder to a greater degree of fineness, it was 

 as white as James's powder, with a yellowish cast like it, but inferior in white- 

 ness to a specimen of pulvis antimonialis. This crucible, containing its charge, 

 with a cover closely luted on it, was put again into the fire, which was raised 

 much higher than before ; and, after being exposed in it 20 minutes, the powder 

 in the crucible became a loosely cohering solid, as white as snow, with a vitreous 

 yellow coat, as before observed ; the inside of the crucible was glazed and co- 

 vered with spicula. The pyrometer-piece in the middle of the powder was alsa 



