.-,8 DKN'SITIKS OF OXYGEN ANU HYI)KO(iKN 



1)V ac'tuallv iloterminiiiL'' tli(> amount of iiitrosjen iviiiaiiiiiii; in the tjas wli'uli was 



weighed 



This iiiii^lil have Keen <loiie by taking liyilrogen from the gh)l)f in which it 

 iiad been weighed, and analyzing in some suitable ai>i)aratus. C'ireumstanfes made 

 it convenient to adopt a slightly ditieivnt nn-iti-.d. Instead of filling one globe 

 with hydrogen which was to be first weigiied and then analyzed, two globes were 

 filled at the same time. They had been exhausted to the same degree. The cur- 

 rent of gas divided and went to the two globes in quantities proportional to their 

 capacities ; so that the two contained gas of identical quality. One globe was 

 afterwards detached and weighed. The other globe remained permanently con- 

 nected with the ai)paiatus for determining the impurities in the gas, an<l was 

 somewhat elaboi-ately guarde<l against possibility of leakage.* 



With this aj)paratus, the method of determining the amount of nitrogen in the 

 hydi-ogen was as follows: A vacuous tube containing copper oxide was heated 

 till no more gas was given oil'. Tliis tube was connected to the globe containing 

 the hydrogen reserved foi' analysis, and the copper oxide was heated. By noting 

 the change of pressure in the globe the amount of hydrogen withdrawn from it 

 was determined. Then the connection with the globe was closed, the copper oxide 

 was cooled, and the gas remaining was extracted with a Sprengel pnnq), and trans- 

 fei-red to the eudiometer. The structure of the puuq) made im[)ossible any 

 admixture of air with the gas tiansferred with it, for the mercury which 

 actuated it all passed thi'ongh a vacuum tiap which was kept exliausted by an 

 auxiliary [ninqi. 



AVhen in this way, let us say, <>ne litre of hydrogen had been withdrawn from 

 the part reserved for analysis, and had been reduced to, say, ten cubic centimetres, 

 it was measured in the eudiometer, mixed with oxygen and exploded, and so the 

 amount of hydrogen in the lesidue was determined. Since cui)ric oxide is at best 

 but a treacheious material, examination was also made for gas absorbable by alkali, 

 and when absorption occurred, the experiment had to be resumed with a better 

 sample of copper oxide. If the experiment showed no absorption, the gas not 

 hydi-ogen was considered as nitrogen. Since qualitative examination showed that 

 sulidiur and .aibon were not present, this supposition was prt)bal)ly justified. It 

 will be noted that it isaniattei- of indifference whether the oxygen used in the 

 ex[)losion contained nitrogen, l)ut it did not. 



In several experiments of this series, nitrogen was found in (he hydrogen. 

 Hut after a consideiable volume of hydrogen had been produced, the appaiatns 

 was practically free from nitrogen except after breakage. Soon after the use of 



* Aiiii-iictiii yoiirnal of Siifiue, 41, 220. 



