Iviii GENERAL SUMMARY OF SCIENTIFIC AND 



acid, and has discovered that the coefficient of solubility is a func- 

 tion not of the temperature at which it is determined, but of the 

 maximum temperature which the mixture may have attained pre- 

 viously, and of the time which they have been in contact. More- 

 over, the solubility is also variable, since decomposition takes place. 

 He concludes (1) that uric acid in solution has a variable solubility 

 coefficient, which is the higher the more dilute the solution ; (2) 

 that this increase in solubility is due first to the production of a 

 more soluble hydrate, and then to the dissociation of this hydrate 

 into urea and dialuric acid ; and (3) that this dissociation is facili- 

 tated by heat, especially in presence of potassium hydrate, 



Weber has determined anew with great accuracy the specific heat 

 of carbon, boron, and silicon by means of Bunsen's ice-calorimeter. 

 If the specific heat of these bodies be taken at a temperature where 

 they are constant, that of carbon is 0.467, silicon is 0.203, and boron 

 is 0.500, thus bringing the atomic heats under the law of Dulong and 

 Petit, as 5.6, 5.7, and 5.5 respectively. Three varieties of carbon 

 were employed, their specific heat being the same at the temperature 

 of 225. 



Schiiller and Wartha have proposed some modifications in the 

 ice-calorimeter of Bunsen, with a view of adapting it to more gener- 

 al use. The freshly fallen snow is replaced by ice, and the measure- 

 ments are made by weighing the mercury expelled. 



Naumann finds in the recent results of Kundt and Warburg upon 

 the specific heat of mercury vapor a complete confirmation of the 

 opinion which he, on purely theoretical grounds, expressed eight 

 years ago, that mercury and cadmium molecules are diatomic. 

 Moreover, he shows, in accordance with the dynamic theory of 

 gases, that the heat of the atomic motion is to the heat of the 

 molecular motion, and to the heat of expansion, as w : 3 : 2, in which 

 n is the number of atoms in the molecule. The specific heats of 

 gases, including that of mercury vapor, calculated on this hypothe- 

 sis, agree well with those experimentally determined by Regnault 

 and others. 



Marig Davy has called attention to the agricultural value of mete- 

 orological observations. He gives the results of experiments made 

 on growing wheat, in which the rate of transpiration was compared 

 with the temperature and the actinometric power, and also gives 

 statistics to show the connection between meteorology and crops. 

 He believes that at the close of May or early in June, at which time 

 the wheat is in flower, it is possible to deduce from purely meteoro- 

 logical data the value of the future crop. 



Gernez has published in full his paper on the evaporation of 

 superheated liquids. Having already shown that evaporation is 

 the only normal mode of vaporization of liquids, he now considers 

 the peculiarities of this mode of producing vapor. 



