VOL. LXXXI.] PHILOSOPHICAL TRANSACTIONS. SQ 



Mr. Turner also prepared this powder with 1 4- lb, of hartshorn shavings and 1 lb. 

 of antimony, as well as with smaller proportions of bone. Schroder prescribes 

 equal weights of antimony and calcined hartshorn ; and Poterius and Michaelis. 

 as quoted by Frederic Hoffman, merely order the calcination of these 2 sub- 

 stances together (assigning no proportion,) in a reverberatory fire for several 

 days. In the London Pharmacopoeia of 1788, this powder is called pul vis anti- 

 monialis ; and it is directed to be prepared by calcining together equal weights of 

 hartshorn shavings and antimony. 



Powders made from various proportions of antimony and bone-ashes, after 

 solution in nitrous acid, left a residuum of antimonial calx much less or greater 

 in quantity than James's powder did by the same menstruum, except 2 of Mr. 

 Turner's proportions, viz. 2 parts of antimony and 1 of calcined bone, and equal 

 weights of bone shavings and antimony. The quantity of this calx was however 

 greater in the powder, from the former of these last 2 proportions, than the 

 latter of them ; which latter corresponded sometimes exactly, and always nearly, 

 with the weight of the calx from a given weight of James's powder. This calx 

 afforded also the same proportion of Algaroth powder as the calx in James's 

 powder ; and the insoluble part of the calx afforded metallic grains like those 

 from the insoluble part of the calx in that powder. 



I found then (says Dr. P.) an exact correspondence between what I consider 

 to be the essential and peculiar properties of James's powder, and the properties 

 of a powder made by uniting or mixing together the ingredients of James's 

 powder found by analysis. But, to show the identity or difference of the qua- 

 lities of these 2 substances, I made comparative observations on them, and re- 

 peated the above analytic experiments on James's powder with the preparation 

 made by calcining together equal weights of bone shavings and antimony, in an 

 open vessel, to carry off the sulphur, and then in close vessels applying such a 

 degree of fire as to render them white, that is, on the same preparation as the 

 pulvis antimonialis of the London Pharmacopoeia. 



First, I compared, more particularly, the sensible qualities of several different 

 specimens of James's powder with various parcels of the pulvis antimonialis 

 made by different chemists. All of these would be called white powders, but 

 not 2 of them were so in the same degree. Most of the papers of the pulvis 

 antimonialis were whiter than those of James's powder ; but others were of a 

 very light stone colour, and some had a shade of yellow, so as to resemble very 

 exactly James's povv'der ; but all the parcels of James's powder had either a 

 shade of yellow or of stone colour, and none were perfectly white, or so white 

 as some specimens of the pulvis antimonialis. Some of the parcels of James's 

 powder and of the pulvis antimonialis tasted brassy ; and other specimens of both 

 powders had no taste. All of these powders were gritty. Most of the parcels 



VOL. XVII. N 



