L. G. M. BAAS BECKING AND H. C. HAMPTON 
265 
III. 
We shall start now with the description of our own experiments. 
We used a rather large reaction vessel connected with a manometer by a 
ground joint. The vessel was closed by a ground stopper. Joint and 
stopper were fastened on the bottle with 
strong rubber bands. On the ground 
stopper was sealed a small vessel with two 
holes. The small vessel contained the 
peroxide, while the larger held the enzym. 
The idea was borrowed from Haldane's 
well known apparatus for blood-gas deter- 
mination. By turning the vessel in a 
plane perpendicular to the paper, the 
peroxide flowed from the smaller vessel 
into the larger one. In this plane the 
vessel could also be shaken. If the fluid 
contained catalase, oxygen would be lib- 
erated. This would increase the pressure 
in the vessel and the mercury column in 
the manometer would rise. 
The autographic writer was simple to 
make. We had at least four methods 
from which to make our choice: (i) 
Transfer of the movement by levers ; (2) 
transfer of the movement by air (Marey, 
Buisson); (3) direct record of mercury 
level by sensitive paper; (4) direct trans- 
fer. 
The second method would not be 
the most efhcient in our case, for, like 
the first method, it would record the 
results either enlarged or reduced. In 
the case of the third method we could 
not use coordinate paper. Therefore, 
we transcribed the pressure by means 
of a wooden float which carried a thin 
glass rod on which a glass pen was sealed at right angles to the rod. This 
we kept in position by a glass slide-bar and a weighted hair. This simple 
arrangement made it possible to register differences of mm. in the mercury 
level. The friction had an effect of ru mm. We therefore always calculated 
the records in millimeters. The efficient speed for the rotating drum was 
in our case one revolution in eight minutes for a diameter of 10 cm. The 
pen went over the distance of i mm. in —3- seconds. The speed should be 
slower in the case of purer enzyms in which the action is feeble. The 
Fig. I. Self-recording manometer 
with modified Haldane apparatus. 
