427 



§ 2. Now the very rapid hydration of undecylenic acid-sodium, 

 with palladium-sol, during which process the contents of the reaction- 

 vessel were changed into a froth (p. 270), had revealed to us that 

 the method of investigating pursued up till now, did not sufficiently 

 guarantee the demand that we should keep the paralysis-layers 

 about the catalyser saturated with H,. 



Hence it was necessary : 



1 . to improve the hydration-vessel ; 



2. to take a quite definite catalyser, if possible the activity of the 

 same must be constant, and at any rate easy to control ; 



3. to work in a constant temperature. 



As regards the first requisite we selected the apparatus employed 

 by Mr. Cohen and one of us in our experiments on light, with which 

 the H, is spouted in small particles with great velocity through the 

 liquid '), the contact-surface of the gas with the colloidal catalyser 

 being thus very considerably enlarged. This is brought about by rotating 

 a hollow stirrer with great rapidity through the liquid ; in the gas- 

 space above the surface of the liquid is an opening. During the 

 rotation the gas is sucked through the stirrer and dashed into small 

 bubbles against a wave-breaker. This wave-breaker keeps the fluid- 

 level constant. 



A revolution-counter indicated thai the number of revolutions was 

 at least 2200 a minute. It is probable that we succeeded in keeping 

 the paralysis-layers saturated with hydrogen, as with a much slighter 

 velocity of rotation the same velocity of hydration was obtained in 

 otherwise similar conditions and when applying but moderate quan- 

 tities of the catalyser. 



As catalyser we used the palladiumsol prepared according to Skita 

 and Meyer *), which proved to be very active, so that we needed 

 but few milligrams of metal to obtain a velocity of hydration that 

 could be measured. The hydration-apparatus was placed in a 

 thermostat, in which was also an electric lamp, so that the vessel 

 could be observed without taking it out of the thermostat. We were 

 enabled to do so, because the hydration-apparatus had been fixed 

 in an iron frame-work that could be moved up and down with the 

 apparatus. 



The hydrogen was purified by conducting it through alkaline and 

 acid permanganate of potassium, through silver nitrate, through alka- 

 line pyrogallol solution and finally through concentrated sulphuric acid. 



1) Proc. KoD. Ak. Wet. 25 March 1916. 



2) B. 45, 3579 (1912); one c.c.m. contained one m.g. of palladium 



28* 



