Vol. 6, 1920 
PHYSICS: L. B. LOEB 
107 
his work). Their counting chamber was a Rutherford and Geiger's spher- 
ical chamber with gas at reduced pressure. They obtained 2.92 X 10^^ 
7-rays from radium B and C per second per gram of radium. The material 
of their counting chamber was copper. In view of my results with cham- 
bers of different materials I decided to continue my experiments on this 
point especially as my results indicated that Lawson and Hess's value is 
probably low. My results at present indicate a value of 7 X 10^^ 7- 
rays from radium B and C per second per gram of radium. 
1 Geiger, H., Verh. D. Phys. Ges., 15, 1913 (534). 
2 Kovarik, A. F., and McKeehan, L. W., Physik. Z., 15, 1914 (434). 
3 Kovarik, A. F., and McKeehan, L. W., Physic. Rev., N. S., 6, 1915 (426). 
^ Kovarik, A. F., and McKeehan, L. W., Ibid., 8, 1916 (574). 
^ Kovarik, A. F., and McKeehan, L. W., Ibid., 13, 1919 (272). 
6 Hess, V. F., and Lawson, R. W., Sitzb. Akad. Wien, 125, 1916 (585). 
ON THE NATURE OF THE HEAT PRODUCTION IN A SYSTEM 
OF PLATINUM BLACK, ALCOHOL, AND AIR 
By L. B. Lokb 
National Research Fellow, Ryerson Physical Laboratory, University 
OF Chicago 
Communicated by R. A. Millikan, January 16, 1920 
When a small quantity of platinum black is introduced into an atmos- 
phere of air saturated with ethyl or methyl alcohol vapor a violent reaction 
takes place on the surface of the platinum causing it to become incandescent . 
The nature of this reaction has been explained in two ways. It is 
held by some that owing to the vast surface and poor heat conductivity 
of platinum black the adsorption of the alcohol vapor liberates sufficient 
heat to raise the temperature of the platinum considerably. This rise in 
temperature is supposed to accelerate the rate of oxidation of the alcohol 
vapor in the neighborhood of the platinum thus further raising its tem- 
perature until the substance becomes incandescent.* 
On the other hand it is held by others that the heat produced at the 
surface of the platinum black is due primarily to the oxidation of the al- 
cohol at the surface of the platinum. The adsorption of the alcohol is 
in this case considered as contributing relatively little heat. The surface 
of the platinum is, however, supposed to exert a "catalytic" action on the 
alcohol vapor and oxygen increasing the speed of reaction to many times 
that in air at ordinary temperatures. 
The writer's attention was called to the two explanations by Prof. 
Millikan and it occurred to the writer that a decision between the two ex- 
planations might easily be obtained experimentally. If a thermocouple 
* This explanation is ascribed to Wilhelm Ostwald by Prof. P. Sabatier, in a course 
of lectures given students of the A. E. F., at Toulouse, France, in 1918. 
