( 418 ) 



exercise au iiifluejice on the \-elueity and are, therefore, catalyzers. 

 It was sliowii In Houdouakd that, whilst CO^ in contact with C is 

 practically totally converted at 1000° into ('O. Ihc aniounl of CO. 

 in the gaseous mixture in equilihriuni increases at lower teinpei-atures 

 in accordance with the sign of the heatetfect C(),4-C=-2C()— 4-2000 

 cal. until at 445° tiie CO is practically completely converted into 

 CO, and C. 



From this follows that below 445°, CO exists in a nietastuhh' 

 condition. 



iNVESTKrATlON. 



<r. Prrjtnrnfinn of tlw (-(thilijzcr (DkJ /)i-<'//iii/ii((r>/ (>.ijh'riinr)ffs. 



1. The following research was instituted with the ohjecl of 

 determining velocities of reaction in the melasjal)le region in [)i-esence 

 of a catalyzer. The apparatus em|)Ioyed hy ns was in the main the 

 same as that used by van 't Hoff iji his research on the velocity of 

 transformation of detonating gas into water. 'J'he reaction vessel, 

 however, was lilled with a catalyzer obtained in (he following manner. 



Pumice stone was brolven u|) into small lumps, drenched with a 

 solution of Ni(N03)2 t^'^^i^ dried, ignited and tinally reduced in a 

 cnrrent of hydrogen or carbon moiioxide. 



This reduction, it was obser\ed, takes place in two stages. The 

 greyish-black surface of NiO first turns yellow owing to the formation 

 of a suboxide (Ni.^ O?) ') and afterwards on complete reduction again 

 becomes dark-grey. When operating al a high temperature, reduction 

 with Hj or CO gives apparently, the same material. If, however, 

 the reduction takes place in a cui-rent of CO at 445"^ a layer of 

 carbon is deposited on the rediu-ed nickel. 



2. The experiments with nickel-pumice ol)tained by rcdiu'tion 

 with either H., or CO at a Iii(//i, temperature gave the following 

 result '). 



At 310^ (boiling point of diphenylamine) the activity of the catalyzer 

 did not appear constant. Successive fillings continually gave smaller 

 diminutions of i)ressure in the same length of time. -' 



1) Muller, Bell (.rhcinical News 20, 258). 



-) Coating the uiner wall of tlie reaction vessel with nickel did not appear to 

 alTect tlie result, prol)ably because tlie surface of llie glass wail was very small 

 as compared with llie surface of the catalyzer. 



