360 LETTERS ON NATURAL MAGIC. 



LETTER XIII. 



.Spontaneous combustion In tlie absorption of air by poivdered 

 charcoal, and of hydrogen by spongy platinum Dobereiner's 

 lamp Spontaneous combustion in the bowels of the earth 

 Burning cliff's Burning soil Combustion without flame Spon- 

 taneous combustion of human beings Countess Zangari Grace 

 Pett Natural fire temples of the Guebres Spontaneous fires in 

 the Caspian Sea Springs of inflammable gas near Glasgow 

 Natural light-house of Maracaybo New elastic fluids in the 

 cavities of gems Chemical operation going on in their cavities 

 Explosions produced in them by heat Eemarltdble changes of 

 colour from chemical causes Effects of the nitrous oxide or 

 paradise gas when breathed Remarkable cates described 

 Conclusion. 



AMONG the wonderful phenomena which chemistry pre- 

 sents to us, there are few more remarkable than those of 

 spontaneous combustion, in which bodies, both animate 

 and inanimate, emit flames, and are sometimes entirely 

 consumed by internal fire. One of the commonest experi- 

 ments in chemistry is that of producing inflammation by 

 mixing two fluids perfectly cold. Becker, we believe, was 

 the first person who discovered that this singular effect 

 was produced by mixing oil of vitrol with oil of turpen- 

 tine. Borrichios showed that aquafortis produced the 

 same effect as oil of vitrol. Tournefort proved that spirit 

 of nitre and oil ^f sassafras took fire when mixed ; and 

 Homberg discovered that the same property was possessed 

 by many volatile oils when mixed with spirit of nitre. 



Every person is familiar with the phenomena of heat 

 and combustion produced by fermentation. Ricks of hay 



