428 



Before use the palladiumsol had been saturated with hydrogen, 

 the gas was also condiicled for some time through the hydration- 

 vessel, while the spray-stirrer liad been brought into action, and the 

 substance to be reduced was already in the vessel. 



By means of a three-way tap the hydration-vessel was connected 

 \vith a graduated Lunge-burette, which the //, tilled. By means 

 of a simple lever-apparatus gas-volumes could always be read during 

 a constant mercury-level. The accompanying figures show the complete 

 installation in elevation and in plan. By way of elucidation it may 

 be remarked that in the drawing we find between the purification- 

 flasks of the hydrogen and the dryingtlasks a copper tube with 

 iron mantle, filled with copper-shavings. This tube is heated in 

 a chamotte-oven and serves to free the hydrogen from oxygen. 

 The ends of this metal tube are provided with refrigeration-jackets. 

 (See below). 



The first experiments were made w^th cinnamic acid in aqueous 

 solution at high temperature and without thermostat; afterwards in 

 96 7o alcohol at the usual temperature. Herein the catalyser frequently 

 proved to flock out, so that we finally worked in 80 % alcohol, 

 always about 25°. Besides cinnamic acid, we also examined other 

 substances. 



With the readings of the hydrogen that had been absorbed we 

 noticed the barometer and the temperature in the neighbourhood of 

 the gas-burette; as a rule we took 3 m.g. palladiumsol against 

 0.5 to 1.5 gr. of the hydrated substances. 



We subjoin a tabulated summary of a series of experiments. 



The summary gives two series of experiments; in the first series 



of 15 the /ƒ, had not been conducted along a red-hot copper-spiral. 



Though the character of the results obtained is in accordance 



with what was found before, yet it appears even in a superficial 



investigation that great irregularities occurred. 



The velocities of hydration diverged in a rather considerable 

 degree under comparable conditions; this is especially striking in 

 the reduction of the cinnamic acid-aethylesters where the initial- 

 velocity of absorption was found to be within the limits 5.5 and 

 80 cm. per 10' (N». 8—11). 



The cinnamic acid-methylester too revealed strange leaps, the 

 commencing velocity being between 10 and 40 ccm. per 10'. 



Then we were struck with another phenomenon, viz. that not 

 unfrequently the number of absorbed ccm. //^ surpassed the number 

 calculated to a considerable extent ; we had observed this before 

 and this fact has been repeatedly observed by other investigators 



