*/6 Examination of the received Doclrines 



a priori, determine the properties of the compound from a 

 previous knowledge of thole of the ingredients. Every fuhftance 

 has, for one of its properties, a capacity for heat. If two 

 be united chemically, the capacity of the compound for heat 

 may not be that of the funi of the capacities of the ingre- 

 dients for the fame fubllance. Indeed it feldom or never 

 turns out fo. If bv any procefs then we change the capa- 

 city of two or more bodies ; or, by uniting them, produce a 

 third, whofe capacity for heat is greater than the fum of 

 that of the ingredients, this new compound mult demand 

 from the common flock of heat difiufed through the atmo- 

 fyhcre and other neighbouring fubftances (A) an additional 

 portion. Is there any thing in all this to lead us to the. no- 

 tion that the paffage of heat from the atmofphere, or other 

 contiguous bodies, into the new compound, is the operation 

 of any other than the general law by which heat tends to an 

 equilibrium among all the bodies in a fyflem (B), and dif- 

 fuses iifelf among them in proportion to their capacities for 

 heat (E) ? Is not the operation of thefe laws fuffie'ent to 

 explain the phenomena without the aid of any others? 



But, bolides, is it not a general fact, in all cafes whefe a 

 rapacity far a greater quantity of heat is produced in a com- 

 pound than the fum of the capacities of the ingredient?, 

 that the fum of the volume of the compound is greater than 

 that of the ingredients ? And is it not equally true, that, 

 when ingredients, before in union, are found, on being fe- 

 parated, to have acquired capacities for heat, whofe fum 

 is greater tfiafl was that of the body in which the ingredient*, 

 were united, the fum of the volume of the ingredients 

 is greater than the volume of the compound was * ? Can it 

 he correct to fay that it neither affects our fenfes, nor is cog- 

 niiable bv any external fign ! when we can fee with our 

 eves its effect in the iucreafe it has made in the volume of 



'■' At the rVo merit of writing T do not 1 ecol left a fingle exception. 



In cafes where crylialiifation is concerned there may be fome apparent 



. s in t'.ic cafe of water and ice ; but thefe will not affeft my argu- 



)r is enough for me that (be effe£l holds generally in the cafes 



ich :he do&tine of latcnr heat is applied — an rffetl perfectly con- 



*.-..- . ,.'. [a the general iav, ^D), and alio cgnifalk by mirftnfss. 



th« 



