81 



a strip of cork, made two openings in the ice for the observation 

 of the beginning and end points. The test-lube stood vertical!}- in 

 ice, in whicli also two tubes left room for (lie observations. After 

 one determination the test-tube was lifted out of the ice, turned 

 upside down and put back in its place again after the upper bulb 

 was filled. 



Finally a determination was made in a bath of boiling methyl 

 chloride. 



At the suggestion of Prof. Kamerlingh Onnes a vessel of germaii 

 silver was constructed for this, in which the viscosimeter was sus- 

 pended in methyl chloride in snch a manner that it could be turned 

 round while inside and that the position of the liquid in the upper 

 bulb could be observed. In the construction connections with sub- 

 stances like sealing wax which come into contact with the cold 

 liquids have to be avoided. By this means we avoid contamination 

 of the liquid and cracking or giving way of the connections which 

 the cold might cause. All connections are therefore made in the lid 

 of the vessel. The three projections are represented in fig. 1, 2 and 

 3 at Vs of the actual size. The details in tig. 4 — 6 are actual size. 

 The vessel consists of a neck H of circular section, a wide part, of 

 elliptical section, E, and the bottom, whicli consists of a seinicircu- 

 larly bent strip R, the diameter of which is equal to the large axis 

 of the ellipse and two curved sideplates P^ and P.^ which complete 

 the vessel. The vessel is provided with a number of strengthening 

 rings V (necessary for working at low internal pressure) and stands 

 in a box filled with cotton wool. 



The viscosimeter hangs in the lower part of the vessel in a frame, 

 BG, which is attached to a german silver tube TS, which projects 

 above the vessel through an opening. This opening is made air-tiglit 

 by a stuffing box PB (fig. 4). The tube has a bend by which the 

 opening in the lid comes just ontside the middle, which is necessary 

 in view of the available space. This tube can be moved up and 

 down in the stnffing box. 



The viscosimeter can be turned round an axle. (tig. 5). The two 

 tubes of the viscosimeter wound round with silk are clamped between 

 two blocks B^ and B^ by two screws S^ and S^. B^ is soldered to 

 the axle. The axle is provided with a pulley K^, which is worked 

 by means of an endless spiral spring -S' V (fig. 1 and 2) by a second 

 pulley K^ in an air-tight box above the lid of the vessel ; the axle 

 projects outside through a stuffing box (see fig. 6). This pullej'^ is 

 raised up out of the way of the oilier parts on two tubes B^ and 

 Jl.^ soldered on to the cover, and through which the spiral spi-ing runs. 



G 



Proceedings Royal Acad. Amsterdam. Vol. XVI. 



