The Theory of ii.xphfions, ^^ 



ttiat a cubic foot of frozen water contains more watery par-* 

 tides than a cubic foot of fluid water, fince^ in the former 

 cafe, the particles are undeniably more clofely approximated 

 and compreflcd than in the latter. Now, is it poffible that 

 frozen water, whofe particles have been condenfed, occupies 

 more fpace than water in the ftate of fluidity ? I have often 

 feen water freezing in open veflels, fuch as the copper veflels 

 of kitchens. Sec, and I have always remarked, towards the 

 middle of the veflel, a rifing, divided by chinks, which doubt- 

 lefs had been formed by the efcape of atmofpheric air during 

 the congelation of the water. It is this phenomenon which 

 has probably led to a wrong conclufion. Befides, the hog's 

 fat, which, like water, becomes folid by cold, or by the ab- 

 fence of caloric, is diminiflied in bulk by condcnfation ; and, 

 if the air which efcapes in this procefs produce no burfting, 

 it is becaxife the fat is always fet to cool in open veflels. 

 Upon what ground, then, could an exception be made to 

 the general law ? But I now come to explain the effeft pro- 

 duced by lightning when it ftrikes a tree, See. 



No perfon, fo far as I know, feems yet to have accounted 

 for the fliattering of trees by the ftroke of lightning. A mo- 

 ment's refle6lion, however, fuffices to difcover and explain 

 the caufe. As it is only by a careful analyfis of fafts that 

 we can deduce juft conclufions, I proceed to examine what 

 happens in the moment of the lightning ftriking a tree, and 

 it will be feen whether this ladder will enable us to reach to 

 the caufe of this phenomenon. 



Since the beautiful experiments of Lavoifier, of Fourcroy, 

 8cc. have demonftrated that caloric is the caufe of the re- 

 pulfive power of the atoms of bodies, there is no doubt that 

 the more the atoms of a body are removed from one another, 

 the greater is the capacity of fuch a body to contain caloric, 

 or the more caloric it contains. It is alfo inconteftably 

 proved, that the bodies which are conftantly in the ftate of 

 gas, in the common temperature of the atmofphere, contain 

 a great quantity of caloric, and in proportion to their fpecific 

 capacity for holding it. So likcwife the elc6lric fluid, or what 

 might, with more propriety, be called the cleAric gas, muft 

 contain a prodigious quantity of caloric, fince this element 

 . Vol. VII. L always 



