482 
Substance 
Concentration 
Ki catalyst 
Ki blank 
Cane sugar 
0-2 N 
009 
J» 
31 X tO-2 N 
0-17 
M 
6-7 X 10-3 N 
0-47 
9-4 X 10-“ N 
0'63 
» 
3-1 X 10-3 N 
0-89 
Lactose 
0-15 N 
0-084 
>J 
31 X 10-2 N 
0-15 
» 
9-4 X 10-“ N 
0-55 
3-1 X 10-3 N 
0-85 
Glucose 
0-1 N 
0 22 
M 
1 X 10-3 N 
0-75 
M 
2 X 10-“ N 
0-83 
It vvill be evident tVoiu tlie above results tbal cane sugar, lactose, 
and glucose aie vecy strong retarders. Cane sngar and lactose have 
alinost siniilar effects, thongh lactose is slightlj strongei' in its effect. 
It a|)pears pcobable thal sngars as a class will act as negative 
catalysts. It bas been found that the sparingly soluble volatile snb- 
stances like catnphor and nieiithol have rnarked 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 |)ecnliai‘ that the weak acids like acetic, pi'opionic, 
cacodylic etc. have coinparatively small retarding effects. Their sodium 
■salts also exert practically the saine effect. On the other hand comp- 
aratively strong acids like oxalic, salicylic, benzoic etc. exert mach 
grealei' letarding effect, and theii- salts too exei't the same effect as 
the acids. Moreover it is found that the sodium salts of stronger 
inorganic acid have no rnarked effect. 
We have found that hydroquinone has a very great negative 
effect on this reaction. Kor the isanie concentration, it exerts the 
greatest negative catalytic effect amongst the negative catalysts in- 
vestigated up till now. We tried to deterinine the temperature co- 
ëfficiënt of this hetei’ogeneous reaction and see whether this becomes 
greater in piesence of the powerful negative catalyst hydroquinone. 
Oiilike most other helerogeneons reactions, we found that the temp- 
