328 Scientific Intelligence. 



the heal capacity per gram-atom of nil the solid elements, 

 excluding those of very low atomic weight, is the same and equal 

 to 6-4 calories per degree. The value varies considerably with 

 differenl elements and also at differenl temperatures. A few 

 years ago attention was called by G. N. Lewis to the fact that 

 if the specific heat at constant volume is considered, I he devi- 

 ations from the average are considerably smaller and also thai 

 the new value, 5-9 calories per degree, is identical with that cal- 

 culated on the basis of equipartition. The specific heats at con- 

 stant volume are derived from the usual ones at constant pressure 

 by taking into consideration the expansion by heat and the 

 compressibility of the elements. 



The specific heats under consideration were determined at 

 temperatures between 65 and 300° absolute, and the results show, 

 in accordance with other recent work, that the atomic heats even 

 at constant volume are by no means uniform. In the case of 

 each metal a series of determinations of the atomic heats was 

 made at different temperatures, but only those at the extreme 

 temperatures need be given here : 



Metal 



Sodium 

 Potassium 

 Magnesium 

 Calcium 



At the higher temperatures, which are at about ordinary 

 room-temperature, the atomic heats of all the metals except mag- 

 nesium are very high, while that of the latter is very near the 

 ideal value, although it is very low at the lower temperature. It 

 appears that no modification of the atomic heat law has as yet 

 been found wmieh makes it other than an approximation even 

 at ordinary temperatures. — Jour. Amer. Chern. Soc, 40, 489. 



H. l. w. 



3. Reagents and Reactions; by Edgardo Tognoli. Trans- 

 lated from the Italian by C. Ainsworth Mitchell. 12mo, pp. 

 228. Philadelphia, 1918 (P. Blakiston's Son & Co.).— This is 

 a useful little book from the standpoint of the analytical chemist. 

 Its principal part is devoted to clear descriptions of such chem- 

 ical tests as are frequently referred to, especially in foreign 

 literature, only by the authors' names. These names are 

 arranged alphabetically in the book, but a collective index is 



Absolute 

 temperature 



Constant 

 pressure 



Constant 

 volume 



( 64-6° 

 (293-5° 



4-52 

 6-79 



4-47 

 6-29 



j 68-6° 

 1286-7° 

 \ 74-9° 

 {288-5° 



5-76 

 710 

 2-90 

 611 



5-69 

 6-52 

 2-87 

 5-91 



( 67-6° 

 (293-5° 



3-93 

 6-75 



3-91 



6-48 



