302 
Substance Concentration ba 
Cane sugar 0:2 N 0:09 
a 31> 10-2 N 0°17 
4 6-1 10-3 N 0:47 
is 94% 10-4 N 063 
- 3°17 X 10-5 N 0°89 
Lactose 0:15 N 0:084 
a 31 10-2 N 0:15 
a 94 10-4 N 0:55 
ù 31 105N 0:85 
Glucose 01 _N 0 22 
sd 110-3 N 0°75 
5 2 10-3] N 0-83 
| 
It will be evident from the above results that cane sugar, lactose, 
and glucose are very strong retarders. Cane sugar and lactose have 
almost similar effects, though lactose is slightly stronger in its effect. 
it appears probable that sugars as a class will act as negative 
catalysts. It has been found that the sparingly soluble volatile sub- 
stances like camphor and menthol have marked negative effect while 
naphthalene, anthracene etc. have no catalytic effect. 
The effect of several organic acids and their salts were also 
investigated. (See Table next page). 
It is very peculiar that the weak acids like acetic, propionic, 
cacodylic ete. have comparatively small retarding effects. Their sodium 
salts also.exert practically the same effect. On the other hand comp- 
aratively strong acids like oxalic, salicylic, benzoic ete. exert much 
greater retarding effect, and their salts too exert the same effect as 
the acids. Moreover it is found that the sodium salts of stronger 
inorganic acid have no marked effect. 
We have found that hydroquinone has a very great negative 
effect on this reaction. For the same concentration, it exerts the 
greatest negative catalytic effect amongst the negative catalysts in- 
vestigated up till now. We tried to determine the temperature co- 
elficient of this heterogeneous reaction and see whether this becomes 
greater in presence of the powerful negative catalyst hydroquinone. 
Unlike most other heterogeneous reactions, we found that the temp- 
