Febhuary ]6, 1906.] 



SCIENCE. 



271 



be connected by a line of steamers plying be- 

 tween Hawaii and Salina Cruz. 



Frederick Knab. 

 Washington, D. C. 



the temperatures of the beginning of evapora- 

 tion and boiling in a vacuum (Differences I.) 

 and between boiling in a vacuum and boiling 

 at atmospheric pressure (Differences II.). 



SPECIAL ARTICLES. 

 THE PRIMEVAL ATMOSPHERE. 



The geological import of certain chemical 

 work' carried out at the University of Heidel- 

 berg by Professor Krafft and his students 

 seems to have been overlooked. 



Krafft has determined for a number of 

 metals the lowest temperatures at which they 

 evaporate in a nearly perfect vacuum. He 

 estimates the vacuum obtained as having a 

 pressure of less than one millionth of an at- 

 mosphere. In order to avoid all action of 

 gravity the evaporation temperatures were 

 determined in a tube (1 to 1.5 cm. diameter) 

 placed horizontally. 



He has also determined the boiling points 

 in vacuum of the metals, i. e., the temperature 

 it is necessary to reach to force a steady ' satu- 

 rated ' stream of vapor upwards from the 

 liquid against the force of gravity. 



In boiling under ordinary pressure it is 

 necessary to force the stream of vapor up- 

 wards against gravity plus the atmospheric 

 pressure. 



Krafft finds that it requires the same num- 

 ber of degrees rise, within the limit of error 

 of the experiment, to pass from the tempera- 

 ture at which evaporation in a vacuum begins 

 to the temperature at which boiling in a 

 vacuum occurs as to pass from the latter tem- 

 perature to the temperature at which boiling 

 at atmospheric pressure (760 mm.) occurs. 



In other words, that the same rise of tem- 

 pei"ature is required to overcome the force of 

 gravity at the earth's surface as to overcome 

 the atmospheric pressure and from this the 

 conclusion is drawn that gravity and atmos- 

 pheric pressure are equivalent. 



Krafft's experimental data are given in the 

 following table, also the differences between 



'Ben d. chem. Ges., XXXVI. (1903), pp. 1,090 

 and 4,344; XXXVIII. (1905), pp. 242, 254 and 

 262. A brief review of the work is given by Pro- 

 fessor Renouf, 4to. Chem. Jour., XXXIII. (1905), 

 p. 506. 



It will be noted that, whether a metal of low 

 boiling point or one of high boiling point is 

 taken, the two differences are for any given 

 element very nearly the same. The lack of 

 exact agreement is probably largely due to the 

 experimental difficulty of measuring some of 

 the temperatures. \ 



The writer wishes to direct attention to the 

 bearing of the above on the question of the 

 character of the primeval atmosphere and on 

 the theories of world formation. 



The atmosphere is held about the earth by 

 the action of gravity and from the above we 

 are forced to the conclusion that the mass of 

 the atmosphere is as gi-eat as gravity is able 

 to control. Perhaps this will be made clearer 

 by the crude comparison of the interaction of 

 the earth and the atmosphere to that of a 

 rotating bar magnet and its iron filings. 



The magnet is capable of exerting a certain 

 attractive force. When the filings are present 

 in full amount, i. e., when the magnet can 

 hold no more filings, the attractive f9rce of 

 the magnet for the filings is exactly equal to 

 the attraction of the filings for the magnet. 

 If a less amount of filings were present the 

 attractive force of the magnet would be greater 

 than the attractive force exerted by the filings. 

 If a larger amount of filings were placed in 

 contact with the magnet a certain amount, 

 the ' full amount ' mentioned above, would be 

 held and the rest would be thrown off, i. e., 

 the attractive force exerted by the iron filings 



