proceedings: chemical society 263 



Aside from monthly mean temperatures the average temperatures 

 by periods of ten days (decades) are also desirable, and also the mean 

 temperatures for periods when the ground is covered with snow and 

 periods when the ground is bare; similarly, the mean temperature for 

 each period during which certain winds prevail. 



Summation of temperatures as suggested by Bussengo and de Can- 

 doUe do not indicate the actual requirements of plants for heat, since 

 they overlook the existence of an optimum temperature for the develop- 

 ment of each plant. 



Groups of days with a given temperature are considered preferable, 

 and the following classification is suggested : 



/ . Freezing days, with a daily average of 32° or less. These are 

 further subdivided into: (a) freezing days without thawing; (b) freezing 

 days with thawing. 



3. Cold days, with an average daily temperature ranging from 32° 

 to 40°F. This group should be further divided into: (a) days with 

 frost; (b) days without frost. 



3. Cool days, with an average daily temperature from 40.1° to 50°F. 

 This group should be divided into: (a) days with frost; (b) days without 

 frost. 



The paper discussed also the temperature of the soil, humidity of the 

 air, precipitation, snow cover, soil moisture, sunshine, and barometric 

 pressure. 



P. L. RicKER, Corresponding Secretary. 



THE CHEMICAL SOCIETY 



The 237th meeting was held at the Cosmos Club on Thursday, 

 April 9, 1914. The following papers were read: 



F. P. Dewey, of the Bureau of the Mint: The pyrometer in the assay 

 muffle. This paper is an emphatic protest against the practice of 

 stating specific temperatures for conducting assay work in the rnuffle. 

 The pyrometer is an excellent guide to temperature conditions in the 

 muffle^ but the success of the work depends upon the temperature of 

 the oxidizing lead button. This is entirely different from the pyrom- 

 eter reading and is vitally influenced by conditions which have little 

 or no effect on the pyrometer. (Author's abstract.) 



Discussion: Walker inquired whether an optical pyrometer had ever 

 been used; Dr. Dewej^ replied that the surface exposed is too small for 

 any accurate measurement. A. N. Finn inquired about American 

 pyrometers. 



H. S. Washington, of the Geophysical Laboratory: The distribution 

 of the chemical elements in the earth's crust. About 8500 rock analyses' 

 have been recently tabulated by the author. The distribution of chem- 

 ical elements as revealed by these analyses may be considered from two 

 viewpoints: (1) Their distribution in general over the earth's surface; 

 (2) their distribution with respect to each other. The earth's surface 

 is in a general way divisible into "petrographic provinces" distinguished 



