' 



ON THE.MATERIA.Ury OF CALORIC. ^Ofc 



fince if it could exifi, at the fame lime, in the fame olfle^, with 



.pther Bodies, their volume would never he enlarged by the ad- 

 dition of heat. Oi' iorin or. figure,- as only a .mode of exten- 

 sion, it i&unnepej&ry to prove that caloric is pqflefled ; and in- 

 deed there is perhaps only one general quality of master that 

 will not be allowed .it, viz. attraction. That ca!o;ic is. in- It has not been 

 fluenced by the attra&ion ofgravitation ? or by cohefive atlrac- . ofwei she. 1 * 1 ** 

 lion, has never yet been proved. Yet the various experi- 

 ments of Bu (Ion, Whitehurft, Fordycc, Fictet, &c, cannot be 

 alledged as proofs, that it is actual!) devoid of this property ; 

 /Ince they only deci< ill quantities, which can be 



artificially collected, are not to be valance Hgainlt the 



grotter kinds of matter. One kind of. attraction, that w 

 has lately been termed chemical al k, after a 



lull lurvey of phenomena, be j epicated of cai.or-ic — and 



if its pqffieffior v be rendered probable, we ; 



thence derive a powerru! a-ument in favour of its mate- 

 riality. 



That chemical affinity has a confiderable fiiare in producing I* appears to 

 the phenomena of f^gf, tf$gt jpfcfyg i'ro.n the following ^la" 

 confiderations : 



1. All the characters-, diftinguifliing caloric yvhen feparate, becaufeits pro- ... 

 ceafe to be apparent, when it has contributed to a change °t combination" "* 

 form in other bodies; and .the properties of the fubflanees fo 



changed are alio materially altered. Now this is the only 

 unequivocal mark of chemical union that we am apply in any 

 inftance; and chemical union implies the exi.ilence and ef- 

 ficiency of chemical affinity. 



2. The relation of caloric to different fubilances, appears and it fhews 



to obferve that peculiar law, which, in other milances, j s elective affinity} 

 termed elective affinity. If a compound of two or more prin- 

 ciples,, a metallic oxide for inflance, be expofed in a high tem- 

 perature, the caloric forms a. perfect union with the one, but 

 not with the other. In certain inftances, caloric is evolved 

 when two fubftances, attracting each other more powerfully, 

 than they attract caloric, produce, on admixture, an elevation 

 of temperature. In other iniiances, caloric is abforbed when 

 it is attracted by the new compound more ftrongly than by the 

 feparate components. Such facts warrant the deduction, that - 

 caloric is fubject to the laws of chemical affinity. But the pre- 

 cife order of its affinities remain* to be decided by future expe- 

 riments, 



3. Caloric 



