( G33 ) 



be admitted at the required pressure into the condensation spiral CS 

 from the cyhnder RN tlirough a final drying tube D^ containing phos- 

 phoric anhydride, as well as directly from the compressor. The spiral is 

 placed in a vacuumglass B with a protecting c^dinder A. Liquid oxygen 

 is admitted into B through (h'.Iiq from the oxygen circulation of f ho 

 cryogenic laboratory, viz. from the condensation spiral which is cooled 

 in the ethythene boiling flask (Comm. 14, Dec. '94). The oxygen escapes 

 llu-ough (h'.rrq), a wide safety tube >S being connected in the ordinary 

 way, and is compressed into the spiral by a BiiOTHKRHOOD-compressor 

 which is lubricated with glycerine and arranged as described iji 

 Comm. 51. It may I)e remarked that, with a view to the possibility 

 of an explosion of a glycerine mist mixed with oxygen, the pressure 

 in this operation is Jiot raised above 80 atmospheres. (Comp. the 

 explosion described in the Zeitsch. f. Kohlensiiure Industrie 1903). 



The nitrogen condenser itself has been drawn in detail on plate 

 VII. In so far as the parts cori'espond — either with plate V for 

 the cover, or Avith plate I of Comm. 51 for the regulation cock 

 described there — the same lettei's have been used, but as some of 

 the parts differ a little the letters have an additional accent. As in 

 the case of the small cryostat plate V, the cover is coated internally 

 with nickel-paper, while the upper turns of CS are i)rotecled again 

 by a ring of paste board and nickel-paper. The condensation spiral 

 consists in the condenser proper C'S'^ and the regenerator CS\ ; here 

 the same pi-inciple has been applied which has been followed in the 

 cryogenic laboratory from the first (Comp. Comm. 14 Dec. '94) ; the 

 vapour of the oxygen is forced by the cylinder B'\ which is closed 

 at the bottom with the stopper B'\„ to pass along the regenerator spiral. 

 As in the ethylene boilingflask (see comm. 14 Dec. '94) the level 

 of the liquid oxygen in the glass tube W is indicated b}- a cork 

 float (b\ with a steel capillary dr.^ to which a thin reed d^ is 

 fastened; the steel capillary passes through a glass tube B\^. 



Liquid nitrogen flows out through the fine regulatingcock h h^ of 

 the same kind as that through which the liquid gas is admitted into 

 the cryostat. For the description of this cock compare Comm. 51 

 and 54. 



It may be added that Gaz' shows the connection ^^'ith the auxiliary 

 apparatus described in Comm. 54 for operations where i/^C is used, 

 which connection make it possible for the gas to stream back to the 

 gasholder Gaz. 



V. Arrnnfiement of a Burckhardt-Weiss vacuumpomi) to he Ksed 

 imth a circulation for low temperature. The well-known excellent 



