80 Mr Potter on the Specific Heats of Metals, %c. 



I have made several trials with wrought iron, which would 

 indicate that there is a slight difference between its capacity 

 and that of steel ; but I am not yet prepared to speak posi- 

 tively on the amount of difference. 



Reviewing the above table, I think we may conclude that 



the capacities in the first column of the following one are very 



near the truth for common temperatures. In the other columns 



I have wiven Mr Daltons numbers, and those of MM. Dulong 



and Petit for the same metals. 



._ , ~ ■„ , , Specific heats 



Specific heats Specific heats a F ccouli to 



from the fore- *™> r £*B ,0 MM. Dulong 



going table. Mr Dalton. an(] Fetit ° 



Iron, .110 .13 0.1100 



Zinc, -098 -10 0.0927 



Copper, .096 .11 0.0949 



Silver, .063 -08 0.0557 



Tin, .056 .054? .07 0.0514 



Gold, .046 .05 0.0298 



Bismuth, .039 04 0.0288 



Lead, -032 .04 .032 0.0293 



Here we see the great incorrectness of MM. Dulong and 

 Petit's numbers for gold and bismuth, and how little room 

 they had for pronouncing so decidedly on the labours of others. 

 And if the relative weights of the atoms of the metals had 

 been at the time sufficiently nearly ascertained, we see that 

 there is no proportion of error in Mr Dalton's numbers, as they 

 assert, which would have prevented him recognizing in them 

 the law respecting the capacity for heat of the ultimate particles 

 of gaseous bodies, which he has advanced in his new system 

 of chemical philosophy. This law, which he appears to have 

 noticed in several of the gases, he unfortunately expected to 

 hold without modification in all, whether simple or compound- 



