OXYGEN. 27 



These weights with various corrections rehxtive to temperatures and 

 pressures, and also for the compression of the exhausted glol^e, ulti- 

 mately become for H, .158531 ; and for 0, 2.51777. Hence the ratio 

 1 : 15.882, ± .0028. For details relative to corrections the original 

 memoir should be consulted. 



In his paper " On a new method of determining gas densities,''' * Cooke 

 gives three measurements for hydrogen, referred to air as unity. They 

 are : 



.06957 



.06951 



.06966 



Mean, .06958, dz .000029 



Combining this with Regnault's densit}' for oxygen, as corrected by 

 Crafts, 1.10562, ± .000008, we get the ratio H : 6 : : 1 : 15.890, ± .0067. 



Leduc, working b}^ Regnault's method, somewhat modified, and cor- 

 recting for shrinkage of exhausted globes, gives the following densities : f 



H. O. 



.06947 1.10501 



.06940 1.10516 

 .06947 



Mean, .06948, zfc .00006745 



The two oxygen measurements are the extremes of three, the mean 

 being 1.10506, ± .0000337. Hence the ratio 1 : 15.905, ± .0154. 



The first two hydrogen determinations were made with gas ])roduced 

 by the electrolysis of caustic potash, while the third sample was derived 

 from zinc and sulphuric acid. The oxygen was electrolytic. Both gases 

 were passed over red-hot platinum sponge, and dried by phosphorus 

 pentoxide. 



Much more elaborate determinations of the two gaseous densities are 

 those made by Morley. X For oxygen he gives three series of data ; two 

 with oxygen from potassium chlorate, and one with gas partly from the 

 same source and partly electrolytic. In the first series, temperature and 

 pressure were measured with a mercurial thermometer and a mano- 

 barometer. In the second series they were not determined for each 

 experiment, but were fixed by comparison with a standard volume of 

 hydrogen by means of a differential manometer. In the third series the 

 gas was kept at the temperature of melting ice, and. the mano-barometer 



* Proc. Amer. Acad., 24, 202. 1S89. Also Am. Chem. Journ., 11, 509. 



tCompt. Rend., 113, 186. 1891. 



X Paper already cited, under the gravimetric portion of this chapter. 



