Chemistry and Physics. 543 



influenced to the same degree. The second group sensibly van- 

 ishes while the regions near the heads of the third and fourth 

 groups remain visible on the photographic negatives. In like 

 manner, only the strongest lines of the metallic impurities of the 

 electrodes persist. For example, onty D for sodium, and g, H 

 and K for calcium. The most striking peculiarity of the spec- 

 trum at a few millimeters pressure consisted in the occurrence of 

 bands which are usually ascribed to compounds of carbon with 

 hydrogen. Although these bands have been often observed in 

 the spectra of flames and of certain high frequency discharges, it 

 is the first time that they have been found in the carbon arc. At 

 pressures of a few millimeters the lines a, /?, and y of the first 

 spectrum of hydrogen also came out with greater intensity than 

 the lines of any other element. At higher pressures, between 

 l cm and 2 cms , the hydrocarbon bands could still be observed, but 

 the hydrogen lines had sensibly disappeared. The presence of 

 the hydrogen lines supports the current view that the bands are 

 due to compounds of carbon with hydrogen. La Rosa tried in 

 vain to repress the hydrogen lines by removing all traces of 

 water vapor from the air surrounding the arc, by heating the car- 

 bons during the air washing, etc. He concludes that the hydro- 

 gen is necessary for the production of the bands, and that this 

 element gets into the electrodes in hydrocarbons during the pro- 

 cess of manufacture. The preceding phenomena are very sen- 

 sitive to changes in the pressure of the gases in which the arc 

 burns. In other words, the arc at 2 cms differs spectroscopically 

 from the arc at l cm , and the latter in turn is unlike the arc at 

 5 mms p ressure< o n the contrary, the amperage and voltage seem 

 to experience no corresponding variations and are certainly not at 

 all sensitive criteria for the nature of the arc. Finally, the inves- 

 tigator showed experimentally that the above mentioned spectral 

 changes are not due to alterations in the composition of the sur- 

 roundings of the arc. — Ann. d. Phys., No. 3, March 1913, p. 542. 



h. s. u. 

 8. The Fitness of the Environment y by Lawrence J. Hen- 

 derson. Pp. xv, 31 7. New York, 1913 (The Macmillan Co.). — 

 This text is an inquiry into the biological significance of the prop- 

 erties of matter. The old belief that natural selection is, on the 

 whole, quite adequate to account for biological fitness is shown to 

 be incomplete and fallacious. Emphasis is laid on the reciprocal 

 character of Darwinian fitness. The subject is approached from 

 the point of view of physical chemistry and the ultimate problem 

 is concisely stated as follows : " In what degree are the physical, 

 chemical, and general meteorological characteristics of water and 

 carbon dioxide and of the compounds of carbon, hydrogen, and 

 oxygen favorable to a mechanism which must be physically, chemi- 

 cally, and physiologically complex, which must be itself well- 

 regulated in a well-regulated environment, and which must carry 

 on an active exchange of matter and energy with that environ- 

 ment?" This problem is solved so completely as to show not 



