i6o Mr. Velaval on the Cauje of the 



equably> and regularly, to reflcd the incident 

 rays; as their rcfiedlive power is proportionate to 

 their fpecific denficy, which is very great; and 

 as they are difpofcd indifcriminately to rcfl-ed all 

 the differently refrangible rays. 



Mercury, filver, lead, and tin, are pellucid and 

 colourlefs, whendiflblved in their proper menftrua. 

 In the fokitions of other metals, fome colouring 

 particles are mixed with the colourlefs particles. 

 The opacity, and the vivid luftre of the entire 

 metals, which confift of thofe pellucid particles, 

 united with phlogifton, arife from the powerful 

 retleftion of the furfaccs, which intercede the me- 

 tals and the air. 



Mctah do not owe their fhining appearance to 

 their metallic particles, but to their phlogifton. 

 For, calcination, which difengages the inflamma- 

 ble principle from metals, deprives them alfo of 

 their luftre. 



The refleftive power, of the inflammable princi- 

 ple, is fo great, that it imparts, to various pellucid 

 colourlefs fubftances, a fhining appearance, per- 

 fedly refembling the luftre, and hue, of metals. 



Plumbago, which has a metallic appearance, 

 and luftre, confifts of two fubftances, which, when 

 feparate, are not only pellucid, and colourlefs, but 

 abfolutely invifible. For its fole conftituent parts 

 are phlogifton, and fixed air. * 



* D. Scheele, in Aa Stockh. 1778. 



Many 



