918 



SCIENCE. 



[N. S. Vol. XXI. Xo. 546. 



suits of successive strains distributed through 

 a long period, the older having occurred when 

 the rock lay below the zone of fracture. 



Geo. Otis Smith, 



Secretary. 



THE CHEMICAL SOCIETY OF WASHINGTON. 



The 159th regular meeting was held Thurs- 

 day evening, May 11, 1905, in the assembly 

 hall of the Cosmos Club. 



The first paper, entitled ' Chemical Glass- 

 ware,' was presented by Mr. Percy H. Walker. 

 Analyses and tests of durability and solubility 

 of a number of beakers and flasks were given, 

 and samples of the various glasses shown. 

 The most suitable for chemical use were zinc 

 boro silicates, and may be distinguished by 

 permanent trade marks. Much of the lime 

 alkali silicate glass sold in this country is of 

 very poor quality. 



The second paper, entitled ' A Colorimeter 

 for General Use,' was presented by Dr. Oswald 

 Schreiner. The speaker called attention to 

 the increasing use of colorimetric methods 

 for purely analytical and commercial purposes 

 for both organic and inorganic compounds, 

 and also for carrying on scientific studies in 

 physical, physiological, sanitary and agricul- 

 tural chemistry. A colorimeter of improved 

 form was then exhibited and described. The 

 parts coming in contact with the liquids are 

 entirely of glass, mounted in a camera of 

 wood. This instrument has the great ad- 

 vantage of speed and accuracy combined with 

 great versatility of application to colorimetric 

 solutions, together with simplicity in con- 

 struction. 



The third paper, entitled ' The Occurrence 

 of Extractives in Apple Skin,' was presented 

 by Mr. H. C. Gore. The quantities were 

 given in which apple wax and apple vitin 

 occur in the epidermis of the apple, both on 

 ripe apples and on apples examined at in- 

 tervals during growth. The method of an- 

 alysis of apple skins for apple wax and apple 

 vitin, stated briefly, consisted of extracting 

 the marc of the skin with petroleum ether, 

 followed by chloroform, the petroleum ether 

 extracting the wax and the chloroform re- 



moving the vitin. The extracted wax was 

 green or yellow colored, and melted at 59°- 

 60°. The crude vitin was a white powder 

 tinged with green or yellow and melted at 

 240°-250° C. The two varieties of summer 

 apples examined were poorer in these extract- 

 ives than the five varieties of wint-er apples. 

 The extractives were found to increase stead- 

 ily during the gi'owing season. In case of 

 ripe winter apples the wax amounts to about 

 30 mgms. per apple, the vitin to about 60 

 mgms. The probable importance of such 

 studies in connection with the disease resist- 

 ance of fruits was discussed. 



Mr. F. P. Dewey exliibited a specimen of 

 sodium ferrocyanide. A. Seidell, 



Secretary. 



THE NEW YORK ACADEMY OF SCIENCES. 

 SECTION OF ASTRONOMY, PHYSICS AND CHEMISTRY. 



The regular monthly meeting of the section 

 was on April 17 at the American Museum of 

 Natural History, with Dr. W. S. Day in the 

 chair in the absence of Dr. Ernest von Nar- 

 droff. The program consisted of the follow- 

 ing papers: 



Purposes and Plans of the Solar Eclipse Expe- 

 dition of August, 1905: S. A. Mitchell. 

 Dr. Mitchell gave an outline of the plans of 

 the various expeditions to be made to observe 

 the total solar eclipse which takes place next 

 August and which will be visible in Labrador 

 and Spain. He also spoke of the different 

 problems that the members of the expeditions 

 will endeavor to solve. The U. S. Naval Ob- 

 servatory expedition which Dr. Mitchell will 

 accompany will go to Spain on the U. S. 

 cruiser Minneapolis early in the summer. The 

 paper was illustrated by lantern slides. 



Variation of the Duration of Afterglow with 

 Change of Electrical Intensity and Fre- 

 quency of Oscillation of the Electrodeless 

 Discharge: C. C. Trowbridge. 

 A long-continued study of the duration of 

 afterglow has shown that smooth curves can be 

 readily obtained showing the variation of the 

 duration of the afterglow with change of pres- 

 sure of the gas. It has been found that the 

 maximum of duration of these curves, when 



