( 669 ) 



oxygen — on llie etliylene circulation, so that this might he made a type 

 of a low toinpcratiire circulation with a small quantity of working 

 gas. The removal of the pi-inci|»al deticiencies of Pktkt's tirsj cycle 

 in place of which my niethylchloride cycle is used, was llnis, as 

 far as possible, defei-red until an ethylene condensation was recpiired 

 quicker llian the one then necessary. 



One inqtortant iinproxement in the cascade method could uol he 

 dispensed with even dien in the niethylchloride circulation, if I wished lo 

 work with success, ll was (he inlroduction of a i-egencrator with the 

 niethylchloride refrigerator. Regenerators had been ali-eady, as 1 found 

 later, used or patented by Siemens and Solvay for freezing-machines. 

 Still it ap[)ears that tliey were tirst used \)\ me for the systematic 

 |)roduction of liquetied gases, and that the combination of regenerators 

 with the cascade method, in addition to my other auxiliary a[»paratus, 

 tirst made this method practical. 



The regenerator, where the \aponr rising from the niethylchloride 

 cools the ethylene which [)rocee(ls to the condenser immersed in 

 methylchloride, has been very curtly mentioned inComni.N"14{Dec.'94). 

 It is shown on PI. IV of Conim. N" 51, Sept. '99 and on PI. II of 

 the present communication, where further under © the same letters 

 will be found as employed in Comm. N" 51. In the following the 

 details are always indicated by suftixes to the (lothic lettei-s which 

 are used as distinctive for the various kinds of apparatus. 2^ƒ,Ms the well 

 known Pictkt refrigerator (tirst designed for sulphur dioxide), ^e 

 the regenerator. The liquid nietli3dchl()ride tlows into the condenser 

 through 2)^ (/ cf. Comm. N" 51), and is pumped away through ^a'. 

 The spiral within the regenerator contains N^O in the case repre- 

 sented in the plate (represented by doubly marked lines). 



This refrigerator and regenei*ator is now almost exclusixely used 

 for the production of liquid N.,( ) (cf. Comm. N" 51 Sept. '99). A 

 refrigerator and regenerator with a much larger working surface and 

 a better construction is combined with the condenser and its pump 

 for use with liquid ethylene. These were constructed with great care 

 by the mechanist of the cryogenic laboratory Mr. C. J. Klim. Their 

 description has now become necessary, since the increased rapidity 

 ^vith which this (piantity of eth^dene can be circulated by their 

 means has rendered many recent iiieasurements possible. 



The ethylene boiling vesseP) of § 5 Comm. N" 14 Dec. '94 served 

 as a model for the new arrangement. In that model the regenerator 

 and refrigerator haxe l)eeii combined to a single piece of apparatus. 



1) Represeoted in the account by Matthias, l-lev. Gen, deb' Sciences 30 April 

 1893, p. 385, 



