16 PROCEEDINGS OF THE AMERICAN ACADEMY. 



be known ; this information is given in the following table. For con- 

 venience the values of the conductivities, as printed on Page 50, 

 Volume xxxiv. of the Proceedings of the American Academy, are 

 appended. At least two specimens of each sort of marble except No. 15 

 were examined. 



To determine the variation of the specific heat with the temperature, 

 the following determinations were made by the " Method of Mixtures/'" 

 upon specimens of Carrara marble dried at temperatures somewhat above 

 100° c. 



These observations are well represented by assuming the following 

 expression for the specific heat of dry Carrara marble : — 



/S= 0.1844 + 0.000379 f 



The fifth column of the above table gives the values of the mean spe- 

 cific heat between the given temperatures computed by the formula 

 Q = 0.1848 (< — 25°) + .0001895 {t — 25°) '' where Q is the quantity 

 of heat in calories required to raise 1 gr. from 25° to the temfjerature t : 

 this expression corresponds to the equation above given for S. 



The 17th observation was marked for rejection, a piece of the sub- 

 stance having been dropped from the cup in which it was heated and 

 hastily picked up and dropped into the calorimeter. As it is difficult to 

 believe that this accident could cause so great a difference in the result 

 as appears, we have thought it best to retain the observation. 



Jefferson Physical Laboratory, Cambridge, 

 February, 1900. 



