825 



At the top of the glass vessel there is a cock a, which, opened, 

 gives access to the glass tubing he, which leads to the steel high 

 pressure cock C. This cock has been specially constructed for the 

 quantitative transferrence of gases, as was described in these Pro- 

 ceedings already before. ') 



With this cock we reach the second " pi-essure stage". It 

 consists chiefly of a large cast-iron vessel J) of more than 2 /. 

 capacity, which can be closed at the top v/ith a heavy iron piece 

 E with bayonet joint and leather packing. This piece E is bored 

 through and a heavy glass tube F, of more than barometer height, 

 has been cemented in it. On its bottom this tube F is attached to 

 a glass jar G, of about 1 /. capacity ; at its top it passes with a 

 sealing-wax joint into a steel capillary, which gives a connection 

 with the high-pressare-cock H, which can shut off the third "pressure 

 stage". 



The said cock C is fastened to the bottom of the iron vessel D, 

 the vertical opening is in connection with a thin glass tube F' , of 

 a length of at least 80 cm. When the piece E with the glass jar G 

 is placed into the iron vessel, the tube F' gets inside F, as is shown 

 in the figure. Through an aperture i' the vessel D is further in 

 connection with a steel tube ƒ, which connects D with the high 

 pressure-three-way-cock P, where the third pressure stage begins again. 

 The tube ƒ is again connected with D by means of a steel-to-steel 

 closure, as was already described in this series of communications^). 

 On the steel tube ƒ, the end-piece of which is ground conical, a 

 double steel cone g is screwed, w^hich is in its turn pressed against 

 D by means of a flange plate h, with bolts, fastened in the iron 

 vessel D' and nuts. (Cf. fig. 7). The closure of F \n Z) is 

 elucidated by fig. la and lb. A steel ring E^ is pressed into a 

 leather ring E^, which is F-shaped in section by means of a plate 

 E^ fastened with screws on E (see the figure). The leather ring 

 extends through the pressure, presses therefore against E and D, 

 and effects in this way the closure. E is held in its place by a 

 piece D^ with bayonet joint. When the projecting sectors D., are 

 rotated so that they get before the opening D^ of the rim D^ (see 

 fig. lb), the piece D^ can be taken out, and with it the piece E 

 and G. 



The highest pressure stage consists in the lirst place of the obser- 

 vation vessel proper L, a heavy steel tube of ± 1 m. length and 



1) These Proc. XI, p. 915. 



«) These Proc. XV, p. 1024 and fig. 2. 



53* 



