ATOMIC WEIGHTS 37 



1.24297 

 1.24303 

 1.24286 

 1.24271 

 1.24283 

 1.24260 

 1.24314 

 1.24294 



Mean, 1.24289, ± .00004 



The weight of hydrogen evolved from one gramme of aluminum was 

 found in Thomsen's gravimetric research to be 0.11190, ± .000015. Hence 

 the weight of one litre at 0°, 760 mm., and 10.6 meters above sea level 

 at Copenhagen is: 



.090032, ± .000012 



or at sea level in latitude 45°, 



.089947, ±: .000012 gramme 



The data for oxygen are given in somewhat different form, namely, 

 for the volume of one gramme of the gas at 0°, 760, and at Copenhagen. 

 The values are, in litres: 



.69902 



.69923 



.69912 



.69917 



.69903 



.69900 



.69901 



.69921 



.69901 



.69922 



Mean, .69910, ±: .00002 

 At sea level in latitude 45°, .69976, ± .00002 



Hence one litre weighs 1.43906, ±.00004 grammes. 

 Dividing this by the weight found for hydrogen, 0.089947, ±.000012 

 we have for the ratio H : 0, 



15.8878, ± .0022 



The determinations, by Jaquerod and Pintza,' of the weight of a litre 

 of oxygen, can hardly be utilized here. They give, as the mean of five 

 observations, the value 1.4292 grammes, but without the individual 

 figures, and with no corresponding data for hydrogen. The ratio now 

 under consideration, therefore, is not directly given by their work. 



^ Compt. Rend., 139, 129. 1904. Compare also Jaquerod and Scheuer, ibid., 140, 1384. 1905. 



