30 



DENSITIES OF OXYOEN AND HYDROfJEN 



repeated a few times. Riders were not used. Tbe globe remained on the lialaiiee 

 at lea-^^t twenty-four hours, and the observations were repeated at intervals. The 

 |);)sition of e(|uilil)rium of the unloaded balance and thn value of a scale divi>i<>n 

 were observed s^ultifientlv often. 



I 



I 



Fi<;. lo. — Halance, case, and metal box ; for accurate weighing of globe. 



Tile e.vliaustioii of the globes fur the pur[tose of determining the tare, hardly 

 needs mention. The weight of the gas remaining in the globe was always com- 

 puted fidiii the indications of the McLeod gauge. All weights were eori'eeteil fur 

 the weight of the air displaced by them. 



18. 



-VEKTI'ICATIOX OK TlIK WKKMITS KM ri.oVKO. 



The weights employed were, first, a brass kilogramme and its subdivisions to 

 one milligramme, and, secondly, a platinum gramme and its sulnlivisions to one 

 tentli of a milligramme. The relation of these to each other has been determined 

 on three occasions. The chief object of determining the relation between the small 



