312 ScientijiG Intelligence. 



Vapor Pressures. 





Liquid Oxygen. 





Liquid Hydrogen. 





Pressure 



Temp, on 



Temp, on 



Temp, on 



Temp, on 



in mm. 



hydrogen scale. 



helium scale 



. hydrogen scale. 



helium scale. 



800 



90-60 



90° 70 



20°-4l 



20°-60 



760 



90-10 



90-20 



20-22 



20-41 



700 



89-33 



89-43 



19-93 



20-12 



600 



87-91 



88-01 



19-41 



19-61 



500 



86-29 



86-39 



18-82 



19-03 



400 



84-39 



84-49 



18-15 



18-35 



300 



82-09 



82-19 



17-36 



17-57 



200 



79-07 



79-17 



16-37 



16-57 



100 



. -. 







14-93 



15-13 



50 















14-11 



The authors add, in conclusion : 



'' Though the pressure coefficients of hydrogen and helium 

 between 0° and 100° C. show no appreciable difference, measure- 

 ments of low temperatures on the scales of the two thermometers 

 are not identical. It is probable that at the normal temperature 

 both gases may be considered as so nearly perfect that the differ- 

 ence between the gas scale and the absolute scale is insignificant. 

 As the critical point of helium lies much lower than that of 

 hydrogen, measurements of low temperatures on the helium scale 

 should approach more closely to absolute temperatures than mea- 

 surements on the hydrogen scale. It is pointed out that helium 

 should replace liydrogen as the normal thermometric substance. 



The melting point of hydrogen was found to be 14°* 10 on the 

 helium scale. 



The pure helium used in the thermometric measurements was 

 obtained by passing purified cleveite gas through a coil cooled 

 to 15° in liquid hydrogen boiling iti vacuo. An unsuccessful 

 attempt was made to liquefy this gas, which could not be con- 

 densed at 13° under a pressure of 60 atmospheres. 



The vapor pressures of solid neon were measured at tempera- 

 tures corresponding to 20°-4 (12-8"^"^) and 15°-65 (2-4°^"^). It was 

 shown that the vapor pressure did not change as the solid evapo- 

 rated, proving that neon is a homogeneous substance." 



II. Geology and Mineralogy. 



1. Martinique. — The July issue of the National Geographic 

 Magazine is called the " Martinique number," and is devoted to 

 descriptions and discussions of the volcanic eruption of Mt. Pelee 

 which began in May last, together with some references to the 

 contemporaneous eruption of La Soufriere on the island of St. 

 Vincent. The number is of double the usual size and is a valua- 

 ble contribution to the study of the recent eruptions in the 

 Lesser Antilles, containing as it does the reports of Robert T. 

 Hill, of the United States Geological Survey, and Israel C. 

 Russell, of the University of Michigan, two of the representa- 



