( 673 ) 



— to tlie wide feeding tube of the Burchhardt — Weiss \acuuin 

 ])iimp (^l PI. II), arranged as described in Conini. N". 83. 



A second narrower branch witli ordinary cock X runs to one of the 

 combined pnnips of tlie Société Crénèvoise, mentioned in domm. N". 14. 



On commencing- to work with tlie metiiylchloride circidation ^ 

 is used alone, aftei-\vards 51 and ^ in series. Naturally when no 

 more liquid ethylene is required than was foi'merly used (Comin. 

 No. 14 Dec. '94) the pump 33 can be used alone and ^j (PI. II) 

 remains closed. 



A third branch Gf goes to the safety cap K, the construction of 

 which is sufliciently shown in the diagram, and as soon as the 

 pressure reaches above the atmospheric the vaponr is conveyed into 

 large rul)ber sacks S? of 500 liters capacity each which are tlieni- 

 selves connected with a safety tube Spi,. 



If a sudden violent development of vaponr occurs or the outlet 

 becomes closed unexpectedly, the vaponr can escape through the 

 safetycap Af PI. I. The arrangement of this can be seen from tlie 

 detailed drawing near A/. Tlie caoutchouc sheet AIi,^ covei-ed on its 

 lower surface by a tin plate nearly up to the sides, and tixed to 

 the rim A fa (on which a rim is turned to prevent lateral motion), 

 rests on the perforated {date Afe and is thus protected from the etfect 

 of exhaustijig the vessel. It is also not blowm out l)y pressure as it is 

 pressed by the cap J/^. As soon as the pressure rises above that at 

 which the spring is set (0,15 Ats above the atmospheric) the catch on 

 which the spring presses tlies open, the cap is driven upwards and 

 the caoutchouc bursts. 



The soldered connection between the main outlet tube and the 

 regenerator is not exposed to strain since above and below^ the latter, 

 stout wooden rings Fd Fe are laid and strengthened with iron bands 

 Ffj^ Ffj.y The upper is fastened to the cover by three rings 7^^, the 

 loAver is drawn against the upper l)y steel wii-es F/\^^ at constant 

 tension temperature, changes l)eing allowed for by springs 7^y',,. The 

 tension is adjusted to the mean of the w eight of the whole apparatus 

 and that of the regenerator. The lower ring F^j^ Just mentioned is 

 fixed sideways by bands Sa and >S'^; (see chief figure and detailed figure 

 to left), it carries further anoflier iron band >S, onto which various 

 cocks are fixed (see also PI. II, €"). 



The cock JV to admit methylchloride is also fixed on an extension 

 Sc of this ring. The most advantageous cock Avould be one constructed 

 in the manner of that on the ethylene boiling vessel (see Mathius 

 description 1. c. p. 385). It is however sufficient that it siiould Iiave 

 the construction of that at 5D (PI. II. of this and PI. IV of Comm. 



