Liquefaction of Gases. 207 



It was desirable to obtain some numerical data as regards the 

 absorbing power for the several bands. For this purpose we 

 made use of the spectrophotometer of Grlan. The liquid 

 oxygen was contained in the innermost tuba, provided with 

 a flat bottom, of the apparatus shown in the annexe 1 figure 

 (fig. 4, taken from the Bulletin International, October 1891). 



Fi<r. 4. 



m. 



Fie-. 5. 



-EO- 





c t 



The thickness of the liquid could be varied to a known degree 

 by screwing up and down the tube ef, closed at both ends by 

 plane glass plates, and provided with a millimetre division. 



