on the CompoJUlon of James’s Powder. 347 
.fulphur ceafes, and a light grey powder is produced. The 
fame prefcription was given to Mr. Willis, above forty years 
ago, by Dr. John Eaton, of the College of Phyficians, 
with the material addition, however, of ordering the calcined 
mixture to be expofed to a great heat in a clofe veffel to render 
it white. Mr. Turner made this powder above thirty years 
ago by calcining together equal weights of burnt hart’s horn 
and antimony in an open veffel, till all the fulphur was driven 
off, and the mixture was of a light grey colour. He likewife 
was acquainted with the fad, that by a fufficient degree of fire 
in a clofe veffel this cineritious powder turned white *. Mr. 
Turner alfo prepared this powder with a pound and a half of 
hart’s horn lhavings and a pound of antimony, a.s well as with 
fmaller proportions of bone. Schroder prefcribes equal 
weights of antimony and calcined hart’s horn ; and Poterius 
and Michaelis, as quoted by Frederic Hoffman, merely 
order the calcination of thefe two fubftances together (aligning 
no proportion), in a reverberatory fire for feveral days. In the 
London Pharmacopoeia of 1788, this powder is called Pukis 
mtimonialh ; and it is dire&ed to be prepared by calcining toge- 
ther equal weights of hart’s horn lhavings and antimony. 
Powders made from various proportions of antimony and 
bone-alhes, after folution in nitrous acid, left a refiduum of 
antimonial calx much lefs or greater in quantity than James’s 
Powder did by the fame menftruum, except two of Mr. Tur- 
* It Is probable, that this powder was made far feveral years with merely the 
heat necelfary to carry off the fulphur and calcine the bone, in an open veiTeL 
over a charcoal fire in a common grate, and corifeqiiently it was of a light clay or 
•afii colour. In this manner, Mr. Bromfield told me, he prepared Schawan- 
berg’s Powder 46 or 47 years ago. Its property of turning white in a greater 
.degree of fire appears to have been a fubfequent difcovery. 
ner’s 
