abstracts: physics 627 



While great precision in absolute magnitudes is generally of minor im- 

 portance in such cases, the only way to gain insight into the question 

 of the variation of the temperature differences with the shape and di- 

 mensions of the blocks and the method of heating is actually to work 

 out numerical cases. 



Equations have been derived for the temperature distribution in 

 solids of several typical shapes, the solids being heated or cooled ac- 

 cording to one of two methods, viz., the surface of the body (i) is con- 

 tinuously heated (or cooled) at a uniform rate; or (2) experiences a 

 sudden change to a higher or lower constant temperature. With these 

 equations a number of calculations have been made and the results of 

 the computations are presented in tabular form and, in certain cases, 

 are also shown graphically. By the use of these tables and graphs it 

 is a comparatively simple matter to determine the temperatures within 

 solids of a large variety of shapes when, as is commonly the case, they 

 are heated or cooled according to one of the methods mentioned above. 



The equations given are in convenient form for calculation and for 

 showing a number of interesting qualitative relations between the tem- 

 perature gradients in various solids, and they will probably prove useful 

 in connection with the determination of specific heat and thermal con- 

 ductivity by dynamic methods. 



While the main interest at the time was in the application to glass 

 manufacture, the equations are perfectly general, as are also the qualita- 

 tive deductions made. B. D. W. 



PHYSICS. — Silicate specific heats. Second series. Walter P. White. 

 Amer. Journ. Sci. 47; 1-43. Jan., 1919. 



Specific heats of various forms of silica and silicates were determined 

 for upper temperatures from 100° to 1400°. The method was by drop- 

 ing from furnaces into calorimeters. Two new methods are described 

 for determining true or atomic heats from interval heats. On the whole, 

 the general temperature variation of the specific heats is one depending 

 mainly on the value of v, the atomic vibration period, for oxygen in 

 combination. Several forms of silica, whose expansion is very small, 

 and which therefore practically give values of specific heat at constant 

 volume, Cv, show that Cv for high temperatures appears to exceed 

 the theoretical value 5.96. Glasses show, in the main, a specific heat 

 only slightly above the corresponding crystal forms, but with a tendency 

 to increase at some rather high temperature. In several sets of poly- 

 morphic forms with sluggish inversions there were differences of about 



