78 MOLECULAR WEIGHT AND POLYMERISM 



dissolved bodies by animal charcoal *, of dyes by fibres 2 , 

 and so on are rather to be treated as surface phenomena. 



We will choose the simplest of such compounds for 

 detailed examination the so-called palladium hydride 3 . 

 What essentially concerns us in the research is the change 

 in the amount of hydrogen absorbed by palladium at 

 constant temperature, when the pressure, and therefore 

 the concentration, of the hydrogen is changed, as well as 

 the concentration of the solution of hydrogen in palladium 



Fig. 12. 



formed. The apparatus (Fig. 12) allows of bringing a 

 known weight of palladium in e at definite temperature 

 into contact with hydrogen whose pressure could be read 

 off the manometer, whilst the quantity absorbed could be 

 estimated from the original amount and the amount 



1 Schmidt, Zeitschr. f. Phys. Chem. 15. 56. 



2 Witt, Farbenzeitung, 1890-91, No. i ; Walker, Appleyard, Journ. Chem. 

 Soc. 69. 1334. 



3 Hoitsema, Zeitschr. f. Phys. Chem. 17. i. See also Shields, Proc. Roy. Soc. 

 Edinb. 1897-98, p. 169. 



