1916] REED—OXIDASE ACTION 59 
catalyzed by platinum black and which can be accurately and con- | 
veniently measured. 
About 80cc. of a solution containing o.0o5M NaOH and 
approximately o.3M formaldehyde was placed in an open beaker 
in a water bath maintained at a constant temperature of 30° C. 
The platinum crucible was freshly platinized and exposed to active 
oxygen (as previously described) for 5 minutes. It was then 
washed by rapidly dipping it into three changes of distilled water,” 
after which it was introduced into the solution of formaldehyde. 
The mixture was kept thoroughly stirred throughout the experi- 
ment, and at frequent intervals 2 cc. were removed and titrated 
with o.o5M HCl. This showed the amount of NaOH neutral- 
ized by the formic acid generated in the reaction. The results are 
expressed in the curve OA, fig. 1. 
The amount of formic acid formed in this reaction is very small 
when compared with the amount of formic aldehyde present at 
_the start. When equilibrium is reached, therefore, it must be the 
oxygen (presumably the oxygen that was combined with the 
platinum in the charging process), and not the aldehyde, that is 
used up. If this be true, by furnishing more oxygen combined 
with the platinum the reaction should proceed much farther. 
This condition was realized experimentally by recharging the 
platinum with oxygen. 
After the first reaction ee oxidized platinum and aldehyde 
had almost reached an equilibrium, the platinum electrode was 
removed from the solution and subjected to active oxygen as in 
the former case; it was then washed and returned to the same 
formaldehyde solution. Renewing, the supply of oxygen on the 
platinum in this manner caused the formation of more formic acid. 
The results plotted in the curve AB, fig. 1, indicate that the reaction 
proceeded at approximately the same rate as with the first charge 
of oxygen. Repeating the operation a third time gave the similar 
results plotted in the curve BC; he. 2. 
As a check experiment, the platinum after this amount of washing was placed 
in o.os5M NaOH without formaldehyde; titration showed no decrease in alkalinity, 
hence the washing was sufficient to remove the very dilute acid of the solution in 
Which it was oxidized. 
