Inquiry into the Laws of Affinity, 



107 



Elaftlcity a£ts by producing efFefts oppofite to thofe of cohcfion, and which confift either 

 in withdrawing feme fubftances from the aftion of others in a liquid, or in dlminifhing 

 the proportion which exifts within the fphere of activity i but when all the fubftances 

 are in the elaftic ftate, their a£lion is fubje£led to the fame conditions. , 



If tables were formed which would reprefent to difpofition, to infolubility, or volatility, 

 in the different combinations, they would fervc to explain a great number of combinations 

 which take their origin from the mixture of different fubftances, and from the influence of 

 heat. 



9. Caloric afts upon bodies like the other folv§nts, when it Is not in a ftatc of radiant 

 faloric, becaufe in this cafe it is not in combination. 



It is neceflTary that it fliould exceed the greateft part of the force of cohefion, in order to 

 render a body . liquid, and other affinities may concur with it to produce this effedi, in 

 the fame manner as itfelf concurs with the a£lion of other folvents. 



It is not diftributed among bodies in proportion to their ponderable quantity, or their 

 bulk, when it produces the degrees of temperature indicated by rhe thermometer, in the 

 fame manner as an acid does not take up an equal quantity of the different alkalis, to attaia 

 the fame degree of faturation, and the tables of fpecific caloric are fimilar to thofe of 

 fpecific acidity or alkalinity, which might be conftru£ted : the former determine the 

 capacity of caloric, the latter would determine the capacity of faturation *. 



One difference, however, would exift between thefe tables is, that thofe of acidity or 

 alkalinity would reprefent the whole faturation to a certain aflumed point, becaufe pure 

 acids and alkalis might be employed: but the fpecific calorics could only be determined 

 from an unknown point of faturation to another point, becaufe the bodies fubmltted to ex- 

 periment are already combined with a quantity of caloric. The refults which may be 

 obtained between two degrees of the fcale of the thermometer, have no known connexion 

 with the total quantities. To attempt to form a conclufion of one from the other, is the 

 fame as to pretend to determine the comparative folubility of the muriate of foda and the 

 nitrate of pot-afh in water, by experiments made only at or towards the point of ebullition 

 or of congelation. In the former cafe we {hould fay that three parts of water would be 

 required for the folution of one part of muriate of foda, and only half a part would be 

 neccflary to diflblve one part of the nitrate of pot-afli ; in the latter that much lefs water 

 would be required to diflblve the muriate of foda than to diflblve the nitrate of pot-afh f. 



* Several chemifts have bufied themfelves in determining the coDftltuent parts of chemical combinations •. 

 no perfon has carried this point to fuch an extent, and with fo much fuccefs, as the celebrated Kirwan j 

 though the methods he employed are fubjefl to fome difcufiion. 



The fame chemift has eftabliftied that the affinities are proportionate to the quantities producing the 

 faturation ; but he confidered them as forces independant of the proportions and other conditions which 

 modify them. 



+ This confideration alone, that fpecific caloric has no known relation to the quantity of caloric com- 

 bined in a body, fliews that the experiments by.which Rumford has lately pretended to prove that caloric is 

 not a conftituent partcf bodies, cannot lead to fuch a conclufion. 



V % On 



