Bertrand for the peroxidases). Thus with infinitesimal amounts of 
colloidal ferrocyanide of iron he claims to have been able to reproduce 
all of the reactions of the peroxidases. Thus it is filterable without 
loss of activity, its activity is weakened after one minute’s boiling, 
and traces of mineral acids reduce its activity. It is also sensitive to 
an excess of hydrogen peroxide, as has been observed by Bach and 
Chodat ( 27 ) for the plant peroxidases. Other compounds of iron and 
cyanogen exhibit similar properties, although less active than the 
ferrocyanide. In another communication, entitled “ Artificial Per- 
oxy diastases,” Wolff ( 457 ) points out that ferrous ferrocyanide acts 
in all respects like a natural enzyme. On the other hand, Wolff and 
Stoecklin ( 46 °) have found that while colloidal ferrous ferrocyanide 
acts like a peroxidase toward phenols, it fails to accelerate the 
oxidation of hydriodic acid by hydrogen peroxide. They conclude, 
therefore, that the catalytic action of vegetable peroxidases, such 
as extract of malt, on this reaction, is due to a special enzyme which 
may be eliminated by careful purification of the peroxidases. Con- 
tinuing these investigations, Wolff ( 458 ) has shown that a feebly 
alkaline solution of ferrous ferrocyanide acts as an oxidase toward 
%j 
hydroquinone. He also points out that the alkalinity of the liquid 
plays a principal role in such oxidation phenomena. Thus the 
manganous salts employed by Bertrand ( 56, 57 > 58 ) in his studies of the 
effect of manganous salts on the oxidation of hydroquinon, were 
always found to be alkaline toward alizarin Sulfate, helianthin, and 
even in certain instances to turmerol. It was also shown by Wolff 
I that the activity of neutral manganous salts, such as the sulfate is 
considerably increased by the addition of traces of pyridin, which 
does not precipitate manganese from its solutions. 
Euler . and Bolin ( 168 ) have also studied the oxidation of hydro- 
quinone in alkaline solution under the influence of manganese salts. 
The relationship of the manganous salt and alkali is compared to 
that of the enzyme and co-enzyme. These authors have also shown 
that laccase has no action on h} r droquinone in the absence of man- 
ganous salts, thereby confirming the work of Bertrand ( 57, 58 ). They 
showed further that laccase is not of the enzyme type, since solutions 
of it could be boiled for three minutes without destroying their 
activity. It was also found that salts of the hydroxy-acids, such as 
Rochelle salts, sodium citrate, calcium glucinate, and sodium mucate, 
accelerate the oxidation of hydroquinone in a marked manner when 
manganese salts are present, and these authors have suggested that 
laccase owes its activity to the presence of such salts. 
According to Stoecklin ( 413 ), iron tannate can act as a peroxidase, 
causing the oxidation of guaiacol and tyrosin and the conversion of 
alcohol into aldehyde by hydrogen peroxide. 
11670— Bull. 59—10 9 
