( 163 ) 



The whole construction can stand exhaustion, which is necessary 

 to fill theapparatus with pure h J drogen. After the case Z7, of which the 

 parts Z7i and U^ are connected together by beams, and the case V 

 are mounted separately, the vacuum glass E is placed in position 

 and the case V is connected with the case U. The entire lique- 

 factor is suspended from the ceiling by means of some rods and is 

 particularly supported by the stout outlet tube F^ for air and the 

 outlet tube ^5 for hydrogen. 



Plate II represents the circulation schematically: the pieces of appa- 

 ratus in their true proportions, the connections only schematically. 

 The liquefactor is designated by the letters Si q. The compressed hydro- 

 gen is admitted through Kc, the hydrogen blown off is let out 

 through Khd or Khc. 



i. Before the apparatus is set w^orking it is filled with pure 

 hydrogen (the cock M being open) by means of exhaustion and 

 admission of pure hydrogen along Kc. In the drying tubes 2)^ and 

 '^b the pure hydrogen is freed from any traces of moisture which 

 it might have absorbed. 



§ 3. The compressors and the gasometers. 



a. The hydrogen is put under high pressure by means of two 

 compressors in each of which the compression is brought about in 

 two steps. 



While other physicists use compressors with water injection running 

 at great speed of the same kind as I have formerly arranged foi' 

 operations with pure gas (comp. Comm. N". 14 of Dec. 'G-l, § 10, 

 and N". 51, Sept. '99, § 3), I have used for the hydrogen circulation 

 slowiy running compressors (see PI. II Q) at 110 and -p at 80 revo- 

 lutions per minute) which are lubricated with oil. To enable 

 constant working with hydrogen the highest degree of purity of 

 the gas is required. For if air is mixed with the gas it is deposited in 

 the regenerator spiral and when some quantity of it is collected there 

 it will freeze and melt alternately through the unavoidable variations 

 of temperature in different parts of the spiral, so that even small quanti- 

 ties, taking into consideration that the melted air Hows downward, 

 necessarily must cause blocking. And such small quantities of air may 

 easily come in through the large quantity of injection water which is 

 necessary- for the above mentioned compressors with water injection 

 or may penetrate into the pieces of apparatus ' 1 ich are required 

 wiien the same injection water is repeatedly used. Lastly the chance 

 of losing gas is much smaller with the last mentioned compressors 



