ABSTRACTS 



Authors of scientific papers are requested to see that abstracts, preferably 

 prepared and signed by themselves, are forwarded promptly to the editors. 

 The abstracts should conform in length and ijeneral style to those appearing in 

 this issue. 



PHYSICS.- — Reflecting power of stellite and lacquered silver. W. W. 

 CoBLENTz and H. Kahler. Bur. Standards Sci. Paper 342. Pp. 3. 

 1919. 



It is shown that the reflectivity of stelhte varies somewhat in the 

 visible spectrum, depending upon the homogeneity and no doubt upon 

 the exact composition of the alio}". 



Data are given on the reflecting power of lacquered silver mirrors, 

 before and after exposure to ultra-violet light. It is shown that owing 

 to photochemical action in the lacquer, the silver is turned brown in 

 color, thus reducing its reflecting power. W. W. C. 



CHEMISTRY.- — -Bibliography of scientific literature regarding helium. 

 Bur. Standards Circular 81. Pp. 21. 1919. 

 The year 191 8 marks the beginning of a new era in the history and 

 use of helium. Before that time only a few liters of the gas had been 

 collected and the cost per liter was enormous. During the war the 

 development of great fractionating plants capable of separating from 

 natural gas a sufficient quantity of helium to supply a fleet of airships 

 has aroused the keen interest not only of engineers and scientists, but 

 also of the general public, in the unique properties of this gas. This 

 circular contains a bibliography of the scientific literature relating to 

 helium prepared for use during the war and now published. Related 

 papers are grouped together in their chronological order, making the 

 bibliography, in efi"ect, a brief outline histor}^ of the subject. 



E. R. W. 



ENTOMOLOGY. — The ants of Cocos Island. William Morton 



Wheeler. Proc. Calif. Acad. Sci. [4] 2: Pt. 2, 299-308. June, 



1919. 



In this, the second publication dealing with the ants of Cocos Island, 



the author records seven forms of ants from the island. Two of these 



are considered realty endemic and characteristic. "It is evident that 



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