206 



provided with four brand) tubes, which can all be shut off by cocks 

 secured by mercury. For the filling with a single gas the presence 

 of two of these branch tubes is suflicient, namely I and m, resp. 

 with the cocks D and E. Tube I leads, as appears from the tig., 

 to the mixing vessel, in which the normal volume at 1 atmosphere 

 can be determined. The tube m leads to the gas reservoir via the 

 puritication apparatus. This gas reservoir is in casu a cylinder of 

 hydrogen as said above. The rubber tube, which is connected with 

 the pressure regulator, is fastened on the other side with solution to 

 a horizontal glass tube r. This tube r has a vertical side tube s, 

 ± 1 111. long and ending at the bottom into a vessel with mercury. 

 Further r is connected by means of a rubber tube to a tube of infusible 

 glass q, wliieh is filled with platinum asbestos. The latter tube is 

 connected again by means of a rubber tube to an ordinary drying tube 

 p, with phosphorpentoxide, and the latter tube is again in connection by 

 means of rubber with the above mentioned tube ???. All the closures 

 of rubber to glass are secured with solution. 



In order to fill the measuring tube with pure hydrogen, the cocks 

 E, D, and F are opened after the already mentioned operations 

 (Comm. N". 6, p. 828'!. The position of three-way-cock A is such 

 that both sides of a are in communication with d. The three-way- 

 cock B shuts off the tube // at the top. Position I. 



The airjet or oil-pump is made to serve in the beginning, the 

 Gaede-pump completing the evacuation. When the air is sufticiently 

 rarefied, the cock E is closed, and the empty tubes m, j), q, and ?* 

 are filled with hydrogen from the cylinder. The mercury, which in 

 the tube s has risen to barometer height in the meantime, will 

 descend; the mercury difference in the tubes ƒ and </ still indicating 

 the barometric height. ^) Then the hardglass tube q is heated, till 

 the platinum asbestos begins to glow. The cock E is slowly opened. 

 And while the gas is flowing into the empty space k and further, 

 the hydrogen tube is again opened, so that the pressure in the tubes 

 m, p, </, and r always remains ± 1 atra. This is desirable because 

 in case of too great rai-efaction the glowing hardglass tube q indents, 

 and soon gives way. The gas that flows through in to the different 

 tubes, is almost pure, for the oxygen, for so far as it is present in 

 the electrolytic-factory hydrogen, is quite combined with hydrogen 

 to water through the catalytic action of glowing platinum asbestos, 



b On account of an eventually too high pressure the tubes m, p, q, and r 

 might burst now, if the open tube s with mercury safety valve had not been 

 added. 



