317 



Cast iron 

 Steel (soft) 

 Antimony (pure) 

 Platinum (commercial) 



0-00112 

 0-00103 

 0-00098 

 0-00068 



On comparing these coefficients with those found by previous ex- 

 perimenters, we find that they agree very closely in those cases where 

 commercial metals have been employed. But when we come to those 

 metals which we employed in a pure state, such as lead, tin, zinc, 

 silver, copper, bismuth, antimony, cadmium, and gold, we find a 

 marked difference, which we attribute to our experiments having 

 been made with pure metals ; and we are confirmed in this view by 

 several series of experiments made with impure or commercial 

 metals. 



We give in our paper several series of experiments which prove 

 that, as for conductibility of heat by bodies, their molecular condi- 

 tion exercises the greatest influence on their expansion. For ex- 

 ample, we have found that the same bar of steel gives, according to 

 its degree of tempering, the following ratios of expansion : 



The influence of the molecular state of bodies is also clearly illus- 

 trated in the class of compounds or carbonates of lime; 



Chalk 



Lithographic stone 

 Stalactite 

 Marble 



Rates of expansion 

 from to 100. 

 19'6 

 45-0 

 67-0 

 71-0 



