112 Mr. C. T. Blanshard on the Bole of Atomic Heat 



both melting-point and atomic heat in inverted order. The 

 same order is found to hold in their latent heats of fusion. 

 Thus Person found that tin requires 14*25 cals., whilst, 

 according to Rudberg, lead requires only 5* 8. There are no 

 data for comparing antimony and bismuth. In the zinc 

 group we find that the latent heat of fusion varies directly 

 as the melting-point. 



The irregularities in group III. a as to melting-point can- 

 not be explained in the above manner. The elements th;tt 

 follow Al, viz. Ga, In, and Tl, behave, as regards atomic heat 

 and melting-point, like the non-metallic groups. 



The inverse ratio between melting-point and atomic heat 

 in the intermediate groups is well illustrated by carbon and 

 boron. The former, which has never been melted, has the 

 lowest atomic heat of all solid or liquid elements ; whilst the 

 latter, which is very infusible, has the next lowest. 



If the above laws are true, they should enable melting- 

 points not yet ascertained, as of thorium, molybdenum, &c, 

 to be predicted with tolerable accuracy. Thus, Th should 

 melt at about 700°, Mo at about 2000°. " Buchholz found this 

 latter to be imperfectly fusible at a white heat. Again, the 

 melting-points and specific heats of new elements should be 

 capable of being predicted with much greater accuracy than 

 has been possible hitherto. Thus Brauner's Bohemium (see 

 'Nature' for October 11, 1894) has had the specific heat of 

 0'03 predicted for it from Dulong and Petit's constant, but 

 no melting-point. By referring to group VI., where it will 

 occur after tellurium, Bo = 2 13, it is easy to see that this 

 element will have a melting-point of about 650° and specific 



heat of about — — r =0*0286. 



Volume-Heat. 



The following is a carefully calculated table of volume- 

 heats, a further factor for comparing the elements, of value 

 for their classification, introduced by Dr. Wm. Preyer, Das 

 genetische System der cliemischen Elemente (Berlin, 1893). 



Volume-heat is the atomic heat -5- the atomic volume, and 



W 

 therefore =CW-5-yr = CD ; where C is the specific heat, 



W the atomic weight, and D the specific gravity of the 

 element. 



The specific gravities are taken at 0°, and the specific heats 

 at a constant temperature also, as near 15° as possible. The 

 natural groups are those of Lothar Meyer, as modified by 



