Chap. .] Spontaneous Inflammation.. 149 



If one of the fub fiances contains a large quantity of 

 the bafis of pure air, and a- ftrong general attraction 

 e.y.ifts between the fubftances, a fimilar effect will enfua 

 Thus, if aqua fords, or ftrong nitrous acid, is poured 

 upon oil of turpentine, the attraction between the in- 

 flammable part of the oil and the pure air, which the 

 nitrous acid contains in abundance, will be fo violent, 

 that the whole will be inftantaneoufly converted into 

 flame. The fame effect is produced from a mixture 

 of black wad (an ore of manganefe, containing much 

 oxygen or pure air) with common linfeed oil. If a 

 quantity of nitrated copper allb, or rhe fak which is 

 formed by the folution of copper in the nitrous acid, 

 is moiftened, and inclofed in a piece of tin-foil, the fait 

 melts or deliquefces, nitrous fumes are emitted, and 

 the mafs fuddenly burfts into a flame. This effK. is 

 undoubtedly occafioned by the ftrong attraction of the 

 tin for the nitrous acid, by which the fire is extricated 

 in fb rapid a manner as to produce inflammation. 



The effects of fpontaneous inflammation are chiefly 

 feen in the mineral world ; and to this caufe is to be 

 attributed a variety of the mod formidable phenomena 

 of nature, fuch as volcanoes, earthquakes, .&c. 



M. Lavoifier defcribes an apparatus for afcertaining 

 the quantities pf heat extricated during the combuftion 

 of different fubftances. This contrivance refL on the 

 propofition, that when a body is burnt in the center 

 of a hollow fphere of ice, and fupplied with air at the 

 temperature of -32, the quantity of ice melted from 

 the infide of the fphere becomes a meafure of the re- 

 lative quantities of heat difengaged. With this appa- 

 ratus, phofphorns, charcoal, and hydrogen gas, gave 

 the following refults : 



One pound of phofphorus melted one hundred pounds 

 pf ice. 



L One 



