439 



■^ 



apparatus is reproduced in fig. 4. The water vapour enters tlirough 

 the tube R, which is ground off at the end, so that the water vapour 

 leaves the tube in a cylindrical jet. The gas mixture enters through the 

 ^ ^ I tube G, ending in a capillary concentric with R, the 

 f r end of which is in a plane with the endpiane of R. 



Opposite the tube /^ at a distance of 3 mm. there 

 is a tube D, the opening of which is formed by a 

 circular sharp edge of a diameter of 6 mm., and 

 manufactured from metal for the purpose. The outer 

 part of the cylindrical jet coming from R is as it 

 were peeled off by the sharp edge. With a suitable 

 choice of the current velocity tiiis outer part of the 

 vapour current practically contains only the com- 

 ponent of the mixture which diffuses more rapidly ; 

 this component is separated from the water vapour 

 by condensation, and collected in a vessel. By far the 

 greater part of the gas mixture admitted through G 

 lIJ passes on through the tube M with the inner part 



t'ig. 4. of the vapour current, is also freed of the water 

 vapour by condensation, and again admitted through G by means 

 of a circulation pump. 



If the apparatus is to work well it is chiefly necessary that the 

 velocity of the current is accurately regulated, and besides it is 

 practical to lead the condensed water va[)Our back ; else the water 

 in the heating vessel would diminish too rapidly. Fig. 5 represents 

 the whole apparatus. In the glass vessel IT, which is 50 cm. 

 long and has a diameter of 10 cm. the water is heated electrically 

 by means of a heating wire wound on a laj'er of asbestos. The 

 pressure of the water vapour in this space can be determined by 

 means of a thermometer T suspended in the vapour. This water- 

 vapour flows through a tube to a bulb B, and from there to the 

 tube R of the diffusion apparatus, while simultaneously the gas 

 mixture to be separated, enters the tube G through a very narrow 

 capillary tube. By the regulation of the pressure of the gas 

 mixture before it enters the capillary tube, an accurate control of 

 the velocity with which the mixture is admitted, is made possible. 

 The two parts, into which the gas current is split up by A 

 pass on through the tubes HM resp. and leach the condensation 

 vessels 6\ and 6',, which are provided with cooling jackets K^ and 

 A',. Here the water vapour is condensed, and the water runs back, 

 to W as is seen in the figure. The part separated by diffusion is 

 collected in 6\, and the rest of the gas mixtures in C,. Both 



