OXYGEN. 27 



These weights with various corrections relative to temperatures and 

 pressures, and also for the compression of the exhausted globe, ulti- 

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

 1 : 15.882, HZ .0023. 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, ih .000029 



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

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



Leduc, working by Regnault's method, somewhat modified, and cor- 

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



H. O. 



.06947 1.10501 



.06949 1.10516 

 .06947 



Mean, .06948, =b .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 produced 

 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. J 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. 1889. Also Am. Chem. Journ., 11, 509. 



fCompt. Rend., 113, 186. 1891. 



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



