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IX. The Theory of Explojions. Comjnumcated tn a Tjetferfrom 

 Mr. Blanch ET to Dr. Mitch ill, ProJ'cffhr of Che^ 

 milhy, Natural Hifcrv, and Agriculture, in Cohimhia 

 College, in the State of Ne-zu-York. 



, -I HE caufe of cxplofions, in general, wliicli, at firft view, 

 appears to be finiple and eafy to compreheiul, is, neverthe- 

 It:fs, befet with nvany difficulties ; and it is with much re- 

 hiftancc that I have ventured to difcufs this fubjeol. 



In order to avoid a tirefome recital, I fliall decHne to ftate 

 the opinions of philofojihers upon this fuhjecl. My deiig-ii 

 is to explain the immediate caufe of cL-rtaiii phenonienaj 

 which feem hitherto to have eluded their refearch. Tlie 

 phenomena, which feem to be exceptions from general prin- 

 ciples, becaufe they are prefenled under an irregular and pe- 

 culiar form, are included in tlie following queftions : — What 

 is the immediate caufe of the burfting of veflels containing 

 water in the ftate of congelation ? In what manner does 

 lightning rend and fliiver a tree into fo many pieces ? Whence 

 arife volcanic explofions and earthquakes ? Thefe inquiries 

 form the fubjedl of mv letter. 



As to the immediate caufe of the burfling of vclTels filled 

 with congealing water, the celebrated Dr. Black, according 

 to the obfervation of Dr. Dickfon, (fee Medical Repofitory, 

 Vol. III. p. ■J,c^.) fcems, in fome degree, to have underftood 

 it, when he fuppofes, " that in the moment of the conver- 

 fion of water into ice, the latent heat of the water, then fet 

 at liberty, enters into the air which is contiguous to its fur- 

 face, or combined with the water, and dilates it with fuch 

 force that it produces a fepiration of the ice into an irregular 

 .form, and a burfting of the containing and refifting vcfiels." 

 But this explanation, however ingenious, is not entirely fa- 

 tisfaftory. Befides the caloric extricated from freezing wa- 

 ter, which mav dilate the air combined with it, there is an- 

 other agent which efcaped Dr. Black's attention; that is, 

 the fudden detachment of atmofpheric air which is found 

 Jod<j(;d in the interftices of the particles of the water. 

 • From ihc American Medical Repofitory, Vol. III. No- 3. 



The 



