300 CARNEGIE INSTITUTION OF WASHINGTON. 



4. Surface Tension. 



Dr. Emmett K. Carver continued the work on surface tension and 

 brought it to a stage at which further pubhcation is desirable. 



It has been shown that the finite contact angle, the one weak point in 

 the capillary-rise method, does not exist with the liquids studied if the 

 glass be properly cleaned and if evaporation of the liquids be prevented. 



The correction for the capillary rise in the wide tube calculated by 

 Rayleigh and Laplace has been experimentally verified. 



An experimental curve for the capillary rise in tubes that are not wide 

 enough to come under the mathematical equations has been obtained. 

 This experimental curve fits smoothly between the theoretical curve 

 for wide tubes and the theoretical curve for narrow tubes. 



It has been shown that the method of calibrating tubes by weighing 

 a mercury thread is not appreciably affected by a film of air between 

 the mercury and the glass. The difference between capillary rise in 

 air and in vacuo has been determined. 



The surface tensions of water, benzene, toluene, ether, chloroform, 

 carbon tetrachloride, and dimethylaniline have been measured. The 

 surface tensions of the substances measured by Mr. L. B. Coombs in 

 apparatus V have been calculated, using our experimental correction for 

 the rise in the wide tube. 



5. Melting-Point of Benzene. 



This investigation, in the hands of Dr. Carver, continued an earUer 

 research previously carried out with the help of Dr. J. W. Shipley. 

 The object was the study of the effect of dissolved air on the melting- 

 point of benzene. Without the correction for the effect of atmospheric 

 pressure on the melting-point (0.029°), the difference in melting-point 

 due to air was found to be —0.003°; with this correction the difference 



is -0.032°. 



6. Standard of Temperature. 



Dr. Victor Yngve, with the help of Professor Harvey N. Davis, 

 of the Department of Physics, using the latter's very carefully prepared 

 platinum resistance thermometers, compared the standard Baudin 

 mercury thermometers employed for several years in the Wolcott 

 Gibbs Memorial Laboratory with the platinum standard. They 

 found e\ddence of a deviation from the probable thermodynamic basis 

 similar in direction (although somewhat less in extent) to that found by 

 Dr. T. Thorvaldson and mentioned in the Year Books 13 and 14. This 

 study is to be continued, and when the temperature scale from 16° 

 to 20° is finally established to within 0.001° in every part, a large quan- 

 tity of thermochemical work can be computed and published. 



Several of these investigations, as well as those mentioned in previous 

 reports, have appeared in print during the current year, and are men- 

 tioned in the bibliography (pp. 36-46). 



