Messrs. Crace-Calvert and Lowe on, the Expansion of Metals. 231 



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 



