596 SCIENTIFIC RECORD FOR 188S. 



differing from each other by 20 per cent. (J. Phys., December, 1883 

 II, II, 562.) 



In Kopp's specific heat method, the solid is introduced into a tube, 

 together with a liquid of known specific heat, and this tube is heated 

 to a known temperature in a bath of mercury, and then immersed to a 

 fixed level in the calorimeter. Pagliani has modified this method by 

 using for heating the tube, in place of the mercury bath, the vapor of 

 any suitable liquid. The results, obtained with various solid organic 

 salts, agree well with those calculated from their solutions. (J. Phys., 

 December, 1883, II, n, 565.) 



Liebig has studied in the laboratory of the Johns Hopkins University 

 the variation in the specific heat of water, using the same method as 

 that which Eowlaud employed in his research on the mechanical equiv- 

 alent of heat and the same apparatus. The result which he has ob- 

 tained agree entirely with the statement of Eowlaud that the specific 

 heat of water decreases regularly from 0°, but differ as to the point of 

 minimum, that of Rowland being about 30°, while that of Liebig being 

 near 23°. No obvious explanation of the discrepancy appears. (Am. 

 J. Sei., July, 1883, III, xxvi, 57.) 



Vieille has investigated the specific heat of certain gases at elevated 

 temperatures. Assuming the constancy of the coefficient of expansion 

 at constant volume and the correctness of Marriotte's law for high tem- 

 peratures, he finds that the mean specific heat at constant volume of the 

 gases CO, N, H, and O, does not vary at most by more than two thirds 

 its value between 0° and 4400°. (C. B., April, May, 1883, xcvi, 1218, 

 1358.), 



Strecker has continued his determination of specific heats by Kundt's 

 acoustic method. Eepresenting the energy of the translatory move- 

 ment of the molecules by ~k and the total energy by H, the author finds 

 that the ratio of h to H divides the diatomic gases into two groups, in 

 the first of which this ratio has the value 0.6, and in the second from 

 0.44 to 0.50. In the first group are the gases O, N, H, C0 2 , N 2 2 , HC1, 

 HBr, HI. In the seconded, Br, I, IOl, IBr, 01(1). ( Wied. Ann., xvn, 

 85; J. Phys., January, 1883, II, II, 46.) 



Berthelot and Ogier have determined the specific heat of nitrogen 

 tetroxide at various temperatures. Calling the molecular weight 46, 

 corresponding to the formula NO* (0=8), the molecular specific heat is 

 found to decrease rapidly as the temperature rises, being 74.7 calories 

 from 27° to 67°, 51.3 from 27° to 150°, and 29.8 from 27° to 280°. 

 These authors have also determined, by the same method, the specific 

 heat of the vapor of acetic acid, and have found it to diminish as 

 the temperature rises, like nitrogen tetroxide. The molecular specific 

 heat (the molecular weight being 60) is 90.1 calories at 129°, 76.2 at 

 160°, 57 at 200°, 38.2 at 240°, and 28.5 at 280°. Berthelot and Ogier 

 have also determined the heat of vaporation of bromine, and find it to 



