AND RATIO OK TIIKIH ATOMIC WIOKJIITS. 65 



the palladium seemed likely to give a moi'e accurate value for the density than 

 could be obtained in any other way now possible. My [)alladium Avould absorb 

 about 3.8 grammes, and would give off as much as 3. 7 grammes at atmospheric 

 pressure, this quantity measuring over 40 litres. From the increase in net weight 

 alone could be hoped some increase in precision ; some from the decrease in gross 

 weight, for the palladium tube with its contents weighed eight hundred grammes, 

 while the larger globes weighed half as much more; some from the small surface of 

 glass exposed ; some from the disuse of stopcocks and their lubrication, exposed 

 as it is to so many accidents. But the principal gain hoped foi' was the fact that 

 mercurial vapoi- would have no effect on the toeiglit of the hydrogen used in the 

 detei'miuatiou ; and its effect on t\\e pressure and volume of the gas is negligible. 



Whether the improvement hoped for has actually been secui-ed is now to be 

 submitted to the judgment of those intei'ested. 



The use of palladium for the purpose of obtaining pure hydrogen was, so far 

 as I know, first suggested by Chii'ikott'. Its use for the purpose of accurately 

 weighing h^alrogeu first suggested itself to me in 1882, so that I discussed the 

 method with other chemists in 1883, and began preparations for the [)resent work. 

 The same method of weighing hydrogen suggested itself independently to Keiser, 

 to whom belongs the credit of first publishing results obtained by it ; (piestions of 

 priority are of slight consecpience, l)ut it seems that to me belongs the credit of 

 first inventing the method and beginning to work with it. 



13. HYDROGEN BY NEW JIETHOD. APPARATUS FOR MEASUREMENT OF VOLUME. 



My stock of palladium foil would absorb about 3.8 grammes of hydrogen, and 

 would give off about 3.7 grammes at atmospheric pressure. A volume sufficient to 

 contain this amount was made up of three globes. They were placed so as 

 to be used like one, while their individual capacities fell within the range of my 

 plant for determination. These three globes were the globes numbered 1, 6, and 7, 

 in the list of globes prepared for weighing gases by Regnault's method mentioned 

 on page 12. Of these, globe No. 6 had not been used before, for the reason 

 mentioned on page 54. 



These three globes were placed in three cylindei's, a, h, c, Fig. 23, surrounded 

 with finely crushed ice, and these again placed in a larger cylinder, r r, 1.2 metres 

 in diameter, and .9 metre high. This tank was surrounded with a non-conducting 

 layer. The globes were now connected to a common inlet tube whose branches 

 led, one to the syphon barometer, one to the self-acting Toepler [)um[), and one to 

 the place for admitting hydrogen. The lattei- tnlie was closed by a fusible metal 

 plug till the proper time. 



