f 44 Snow of Antimony. [Book VK 



quiring a perceptible degree of red heat before if be- 

 comes fluid. In the fame degree it emits yapours 

 copiouQy if frefn air is admitted, which always pro- 

 motes the volatility of metals. If thefe fumes are 

 condenfed, they form a white powder. In particular 

 circumftances they cryflailize. They are, indeed, a 

 perfect metallic calx, to which the names of argentine* 

 and fnow of antimony, have been applied. This fub- 

 ftance is fo highly charged with the oxygenous prin- 

 ciple, as to be ibluble in water, and 'to approach to the 

 nature of an acid. 



To calcine antimony by heat and air alone, let the 

 metal be powdered, then lay it on a broad mallow vef- 

 fel, and apply heat not fufficient to convert it into 

 fumes. This operation cannot be well performed, 

 tmlefs the antimony is in a ftate of minute divifion, fo 

 as to prefent a large furface to the ai/. The procefs 

 muft be conducted with caution at the beginning, on 

 account of the fufibility of this compound of fulphur 

 and antimony ; but in proportion as the fulphur is dif- 

 fipated, the remainder becomes more refractory, and 

 the fire may be raifed to fuch a degree as to make 

 the veffel in which the antimony is contained red hot. 

 The furface of the metal becomes at firft tarnifhed, 

 and foon afterwards it is changed into an earthy pow- 

 der of a dufky colour, which, by continuance of the 

 procefs, becomes white. Thefe calces have a different 

 degree of fufibility according to the degree of cal- 

 cination. When little calcined a ftrong heat converts 

 them into a glafs of an opake or black colour. When 

 further calcined more heat is required, and the glafs 

 is a deep yellow. When calcined to whitenefs, the 

 moft violent heat will not melt them without the addi- 

 tion of borax, and the mafs is then of a pale yellow* 

 Here we obfcrye the effect of the prefence of oxygen 



in 



