ON THE PROCESS FOR PREPARING JAMES’S POWDER. 143 
exposed to any degree of fire in close vessels, without previous exposure to fire 
and air.” 
Pearson concludes from all his experiments that James’s powder consists of 
phosphate of lime and a peculiar calx of antimony, different from all others, 
composing a triple compound in the proportion of about 57 parts of calx of 
autimony and 43 of phosphate of lime, or a double compound of the same 
elements. 
I he admitted medical efficacy and the high price of James’s powder induced 
the various colleges of physicians to introduce into their pharmacopoeias a pro- 
cess for imitating it. They took for their guide the investigations of Pearson, 
and dictated formulae which apparently did not much differ from the prescription 
of that accomplished physician. This preparation, called Pulvis Antimonialis, 
proved an utter failure, having neither the composition nor the medical effects 
of the powder of James. In the manipulation of the manufacturers, the chief 
object seemed to be the production of a powder as white as snow,—the very 
quality which it ought not to possess if intended to resemble the powder of 
James, which at that time was always slightly yellow, or cream-coloured, or 
even stone-coloured, as w r e learn from Pearson. 
I made a number of trials of the process of the three British Pharmacopoeias 
(1816), but could not obtain the powder wdiite like the Pulvis Antimonialis of 
the druggists, or like the James’s powder then in use. The roasted materials 
introduced into a skittle-pot, with another inverted, both luted together, were 
maintained at a white heat in an air-furnace for two hours. When cold, the 
included matter was found converted into a dense, close-grained, buff-coloured 
mass, as hard as limestone and very heavy. Being again heated to whiteness, 
it became a deep olive-brown mass, harder than before. 
I repeated the process on new materials, heating them similarly in a different 
air-furnace, and obtained an olive-brown semivitrified mass with dark streaks, 
harder than the former mass, a small portion of a white enamel appearing on 
the side of the skittle-pot. 
It was plain, therefore, that the heat was too high, and that the use of the 
air-furnace, originally directed by Pearson, and adopted in all the pharmaco¬ 
poeias, was an error. I therefore repeated the process, and placed the skittle-pot 
containing the powder in a common fire-grate, heaping coal round and over it. 
In due time the skittle-pot became red-hot, and in this state it was kept for an 
hour and a half or two hours. When cold, it w^as found to be a snow-white 
powder, covered by a congeries of crystals a quarter of an inch thick. Thus one 
important fact was ascertained. 
On repeating this method several times, and using an iron ladle in a common 
coal fire, the resulting powder, instead of being uniformly white, proved in 
some instances to be buff-coloured ; but occasionally the snow r -w'hite powder 
was obtained. As the failure was not due to the final heating, it must have 
originated while the materials w r ere in the iron ladle. Various experiments 
convinced me that the heating in the ladle is the most important part of the 
whole process; and at length it became evident that when the heat, accompanied 
by continued stirring or raking, was maintained until the powder changed from 
dark brown to a light yellowish-grey, the final heating in a skittle-pot bright¬ 
ened it, or the greater part of it, to a perfect white. The light yellowish-grey 
colour here mentioned will be best understood by comparing it to the dust of a 
Bath brick, often used for cleaning dinner knives, but a little paler. 
But to heat the pow'der while in the ladle fully to this colour, but not beyond 
it, v T as the difficulty. 
During these experiments I perceived that when the quantities of the two 
ingredients w r ere as large as ten ounces of each, the resulting pow'der when 
taken from the skittle-pot never proved white, but generally dark grey, inter- 
