430 



as well. In our first experiments we had used the hydrogen out of 

 a KiPP apparatus and had conducted it through a tlask with alkaline 

 pyrogallol-solution; the quantities of hydrogen that had been calcu- 

 lated and measured did not diverge greatly. 



Afterwards we employed a hydrogen-bomb and obtained far too 

 great absorption-numbers (nos. 9, 10, 12, 14 and 15). At tirst not 

 being prepared for the presence of oxygen in the purified gas we 

 excluded as well as we could all other sources of the coming in 

 of oxygen in the apparatus by repeated washing, preliminary 

 treatment of the palladium, and the avoiding of rubber-junctions. 

 When however the surplus continued, the presence of oxygen 

 was thought probable and determined in the following way. 



1). By hydration of larger quantities of substance in the same 

 quantity of solvent and with the same amount of catalyser. 

 And indeed it was found that on applying: 



± 1 gram cinnamic acid-methylester the surplus ^ 55 cc.m. N'. 12. 



3 „ „ „ „ ,, = 46 ,. „ 14. 



8 „ „ „ „ ,. =115 „ . 16. 



In case of the presence of oxygen in the hydrogen the surplus 



used must be approximately proportional to the quantity of methylester 



reduced, if at least the amount of the oxygen in the H, is constant. 



Whereas we conducted the gas through an alkaline pyrogallol 



solution, this will surely not have been the case, but an increase 



of the surplus when applying more substance is indubitable. 



2). By some blank experitnents. 



For this we took 100 ccm. 80 7o alcohol and 3 ccm. palladiumsol 

 saturated with H,, they were put into the hydration-vessel, after it 

 had been filled with hydrogen in the usual manner. 



We actually observed an absorption of gas in four control- 

 experiments, it amounted to between 20 to 30 ccm. ; it is curious 

 that though far more gas was in the burette, the action came to 

 an end with this. 



The cause of it may be, that on account of diffusion all oxygen 

 had come from the burette into the hydration-vessel, or that the 

 catalyser is paralysed ; the former cause seems the moj'e probable. 

 Now the hydrogen was freed from oxygen by means of a tube 

 with red-hot copper shavings ; hereupon a decrease of only one 

 ccm. took place in 60'. 



But v)hen loe loere noio going to hydrate the cinnamic acid-methylester 

 loith this very purided hydrogen, which had also b e e7i carefully freed 

 from oxygen, the process was an extremely slow one. (N". 17). 

 Of course this might be due to an accidental paralysis of the 



