( 672 ) 



and Bc and Bd 19 m. respectively, wliicli are wound in the sjiaee 

 between the unter wall Fa of the regenerator and the very thin 

 walled iinier cylinder 7/, divided into thi-ee parts by two wooden 

 rings. The inner diameter of the tubes is 7.5 mm., the walls are 1 mm. 

 thick. The two spirals can be joined otherwise than in the manner 

 sho\vn in the figure, but further description is uimecessary. A safety 

 cap A„ (c.f. the ethylene boiling vessel Comm, N". 14 § 5) is also 

 joined to the spiral, so that the bursting of the spii-als within the 

 boiling \essel is not ])0ssible. The figure shows cleai'ly how, without 

 a complicated construction, an intimate contact between the rising 

 vapour with the regenerator spiral is jn'odnced and also a constant 

 intermixture of the vapour partially warmed by contact with the 

 metal and of the still uidieated portions, convection currents which 

 extend to some distance being avoided. 



The interchange of heat between the vapour, which rises in the 

 regenerator, and the gas which is put into the spiral is furthered 

 without ajipreciable loss of i)ressure l)y friction, by laying a perforated 

 copper plate Bh,,,, through w Inch the spiral find its way, horizontally 

 above each lattice spiral i)\, (see detail right section and plan). This 

 plate is soldered to the spiral where it turns downwards. In the detail 

 figure to the right, section and view above a plate, the soldering 

 place can be seen to the right of i>\, at the vertical section of the 

 spiral. In this figure the |»ei'forations are only (h-awn over a small 

 portion of the plate foi- simplicity. The perforated plate is insulated 

 by wooden blocks Bb^^ from the adjacent lattice, against which these 

 blocks press. Further cotton and ])archment paper are wrapped round 

 the column of plates ajid thus the spiral with the plates is made to 

 a whole that just fits \n\o the regenerator space. In this way the 

 gas, finding the A\ay through the inner cylinder shut, can only 

 escape through tlie perfoi-ated plates. The inner cylinder is insulated 

 by paper from the })erforated plates, and is usually closed above by 

 Hu. Sh(»uld it have to sustain pressure owing to perhaps a sudden 

 violent development of \apour, or owing to the closure of a sieve 

 plate i)y the freezing of moisture the vapour can immediately escape 

 througli the safety valve Hi,^, the construction of which is shown 

 sufficiently in the drawing. 



The whole boiling vessel hangs on the solid neck (j„, along which 

 the vapour escapes, in the same manner as the ethylene boiling 

 vessel Ga rests with a collar (r, on a bracket (see PI. II). The main 

 outlet tube Ga gives off a brauch thi-ough a lai-ge but light cock 

 / — the construction of which is sufficiently showji on the drawing 



