266 



Expansion of 

 water. 



Capacity for 

 heat. 



Mercury and 

 water. 



Cibabgein ca- 

 pacity. 



oi^ TiiE NitrfitE or keat. 



pnHicles. And I can conceive-, that the agency of attraction, 

 whether oi' aggregation or of composition, may in every case 

 be iiifluenced or regulated by the pavticiilar state of'apposi- 

 tion of particles. . 



It will readily be acknowledged', that m'udi difficulty and 

 uncertainty still exist in this qnestioii ; but I conceive, that 

 the difficulties areinconliparably greater in relation to the the- 

 ory of repulsive caloric, than in the view ofthe subject, which 

 has been given. If we could explain the cause of the ex- 

 pansion of water, cooled from 40° to 10°, we should probably 

 find little difficulty in understanding the similar arid pre- 

 cisely equal expansion, when the same water is raised in its 

 temperature from 40° to 70°. 



Capacity for Caloric. 



It ^^ould be extraordinary indeed, if all bodies were 

 equally susceptible of vibration ; no property of matter is 

 equally possessed by all the innumerable substances, which 

 nature presents to our attention ;' gravity, hardness, elas» 

 ticity, &c. are possessed in ari equal degree by no two bodies 

 with which we are acquainted: such is the diversity in 

 Nature's works ! Nor are all bodies equally susceptible of 

 change in the state of their vibration. This proposition is 

 sufficient to account ibr the variety in the capacity of dif- 

 ferent' bodies, and ofthe same body under different forms, 

 for heat. Mercury is more susceptible of vibration than 

 water; solids than fluids; fluids than gasses :ihe quanti- 

 ties, for CO ui pari son, being ascertained by weight*. 



Let mercury at 40° be mixed with an equal weight of 

 water at 80°; mercury is more susceptible of change in the 

 state of its vibration than water, and will consequently suf-» 

 fer more change ; its intensity of vibration will pass more 

 nearly to that of the water, than the intensity of vibration in 

 the latter will to that of the mercury : the resulting tempe- 

 raturie will therefore be above the mean ; i. e. more nearly 

 that ofthe water than the mean. If the experiment be re-» 

 versed, the effect will also be reversed. 



K* during the time of the change in the susceptibility of 

 any body for vibration (this change being to diminish its 



* In speaking formerly ofthe high susceptibility of air for change in 

 *jbraiion its quantity was considered by bulk, not by weight. 



susceptibility 



