( 675 ) 



The flask is packed in Ihe same way as the ethylene boiling vessel 

 (Comm. N" 14) first with nickel paper and then with several layers 

 of wool, the number of layers increasing at the colder parts, as can 

 be seen from the drawing PL I. They are contained between varnished 

 and nickelled paper as is seen in Ch, Ci, Ck, C, Fh, Fi, Fi„ while 

 horizontal strips of felt, dotted in the drawing, prevent convection 

 currents. These various layers form airtight compartments, which 

 are connected together by means of small tubes C,n C„, while the 

 whole airtight space is connected with the atmosphere through a 

 drying tube FL The outer surface is painted white. 



§ 2. The methylchloride cycle. A short description of this is 

 desirable. The liquid methylchloride is preserved in the tubulated 

 condensor C^>, which is cooled by running water. Its pressure is 

 measured by the manometer and its level can be seen in the level 

 glass @^,, with blow-off cocks as used with water boilers (to make 

 a reading the connecting tube for liquid meth^ichloride ©^^j must be 

 cooled with ice as shown diagrammatically on PI. II (for further par- 

 ticulars the quoted description of Mathias p. 383 N" 2)). A large 

 cock QVi protected by a fdter (shown I.e. as N° 9) makes it possible 

 to shut the condenser off immediately by a small movement, even when 

 a strong stream of methylchloride is sent through the condenser. This 

 cock is followed by a regulating cock ©^.^ to which the tubes for 

 liquid methylchloride are connected. The latter run to : 



"I'^f. the refrigerator D, which is used to obtain liquid nitrous oxide, 

 either in the manner given in Comm. N" 51 Sept. '99, or by drawing 

 it off into a vacuum vessel II from wliicli the nitrous oxide can 

 be siphoned over into other vacuum vessels and thus be brought to 

 apparatus arranged in other rooms. 



As far as the nitrous oxide circulation according to Comm. N" 51 

 is concerned the mercury and auxiliary compressors (Comm. N" 54) 

 can be used as ï in place of the Brothekhood of Comm. W. 51. 



The various pieces of apparatus, for which the nitrous oxide in 51 

 is used, are generally connected to the tube App and the sack 2Ö 

 from which the gas can be repumped into 25. Plate II shows the 

 use of a small 2 K.G. cylinder 35 of the kind usually used in this 

 laboratory for this purpose. 



2"'^. other apparatus formerly described e.g. one of the cryostats 

 (Comms. N" 51 and 83), 



3"^ the boiling vessel for the preparation of liquid ethylene ^ 

 PI. II as described in § 1, either directly or through the regenerator 

 S' where the methylchloride is cooled by cold vapour coming from 

 another vessel and passing from In to Ex, 



45 



Proceedings Royal Acad. Amsterdam. Vol. VI, 



