|64 Pearson’s Experiments and Obfervations 
(g) Diaphoretic antimony left a refiduum which mixed with 
tartar formed metallic grains under the flame applied by means 
of the blow- pipe. 
(/6) Any of the above foluble antimonial calces by further 
calcination with air and fire become more difficultly foluble, 
or partly indiflbluble. 
The next experiments were made principally for the purpofe 
of knowing whether antimony calcined with vitriolic fele- 
nite, calcareous earth, and filiceous earth, would afford the 
fame fort of calx as. antimony calcined with bone-afhes. 
exp. x. 1500 grains of well burnt and dry plafter of Paris, 
mixed with as much pulverized antimony, were calcined toge- 
ther in the fame manner as the mixture for making Lile’s 
Powder, Exp. 3. In half an hour the fulphureous fumes 
difappeared ; after calcining half an hour longer in a heat 
that kept the bottom of the difli red hot, the mixture was 
of a reddifh brown or copper colour, and after cooling 
weighed 2520 grains. Suppofing, therefore, the whole defi- 
ciency of weight in this experiment to be from the fulphur 
carried off; and fuppofing the quantity of air combined with 
the metal to be the fame as in Exp. 2. the lofs of weight 
viz. 32 per cent . is more than would have been expected ; but 
as in experiments of this nature it is not perhaps poffible to 
Repeat them under precifely the fame circumftances, the dif- 
ference of 2 1 per cent, deficiency more than would have been 
calculated, may more reafonably be afcribed to the iublimation 
of antimony than to other caufes. By expofure to 70° of fire 
in a clofe crucible, this calcined mixture changed to a pale 
ftraw- coloured powder, and the fides of the veflel were glazed 
yellow. The change of colour was the fame in an open veflel 
in 6o° of fire. 
Though 
