AND RATIO OF THEIR ATOMIC WKUillTS. 



07 



obvious that leak.-iye from the globes towards tlie air-i)uiii|) coulil take place only 

 as iiiei'fiiry was forctnl out fioiii tins closed s^iace tlii-ou<;Ii I lie keys of tlie stop- 

 cocks ; wliic'Ii would easily lie detected by inspeetiou. 



Tlie apparatus uiet ;dl reasonable expectations until a time when, as was 

 afterwards found, the key of the stopcock e formed an inci[i:ent crack, pi'odu<-ing 

 ca[>i'icious and intermittent leakage. 



14. 



-IIYDKOOKN I5V NEW METHOD. CAI'ACITV ( U' CONNE(V|'I N( 1 'rUHES. 



It is obvious that when a weighed (piantity of hydrogen was admitted to these 

 irlobes, the connectinir tuljes and one branch of the sviihon barometer had to be 

 filled ; so that the ca[)acity thus added to the globes had to be determined. 

 Part of these tubes was always at the temperature of the globes themselves, being 

 covered with melting ice, while pait was at the temperature of the room, or at the 

 temjiei'ature of the water with which the baiometer was suriounded. These two 

 parts had to be determined separately. 



The tul)e leading to the barometer being closed by fusion, c, Fig. 24, a three-way 

 stopcock, e, was fused to the tube for ad- 

 mitting hydrogen shown at d. <)ne bianch 

 of this was connected to an air-pumji, and 

 the other to a gas burette standing in sul- 

 phuric aciil. Water could not l)e used, for 

 condensation of its va])or on the cold ]iaits 

 of the connecting tubes would cause ei-ror. 

 First, the blank space between the key of 

 the stopcock and the fusible metal at <1 was 

 determined. This was done by exhausting 

 this s[)ace by turning the stopco(d< into 

 the [iroper position, dui'ing which time the 

 level of the acid outside and inside the 

 burette was made the same, and the level 

 I'ead off. Then the degree of exhaustion was noted, and the key of the stopcock 

 was turned so that the vacuous space was filled with air from the burette, the 

 volume and tem[tei'atui-e of which were also noted, after making the adjustment 

 of level again. The volume of the air thus drawn from the burette was obviously 

 e(pial to the volume of the exhausted space, after applying a correction for the 

 imperfection of the vacuum. 



AVhen a few concordant determinations of the blank space had been made, the 

 fusible metal was removed by fusion, and the same determination made of the vol- 



FlG. 24.- 



-Aj)jiaratiis for (letcrniinint; \ uhinic of 

 connecting tubes. 



