A56 TRANSACTIONS OF SECTION A, 
of the component lines obtained by Michelson by the analysis of the visibility 
curves for the interference fringes observed in his interferometer. 
9. Lhe Production and Origin of Radium. 
By Professor E. Rutnerrorp, J. 2.8. 
The results of experiments were described on the growth of radium observed 
in solutions of actinium. By suitable chemical treatment a solution of actinium 
was obtained which showed only a minute fraction of the growth of radium nor- 
mally observed. No evidence was observed that the active deposit of actinium 
changed directly into radium. It was shown that the results were most simply 
explained by supposing that there exists in actinium a new substance of slow rate 
of change which is transformed into radium. This substance differs in chemical 
properties from actinium, and can be separated from it by suitable chemical 
methods. It was pointed out that this new substance may prove to be the inter- 
mediate product of slow change between uranium and radium. There was no 
direct evidence that actinium itself was the true parent of radium. 
Further experiments are in progress to endeavour to isolate this new sub- 
stance in order to examine its chemical and radioactive properties. 
10. The Effect of High Temperature on the Activity of the Products of 
Radium. Sy Professor E. Rutuerrorp, /.R.S., and J. E. Peravet, 
FR.S. 
Bronson has shown that the activity of the products of radium is not appre- 
ciably altered by exposure to a temperature of 1600°C. On the other hand, 
Makower, working with the active deposit of radium, found that there was a small 
decrease of its activity, measured by the 8 and y rays, when exposed for some time 
to a temperature of about 1100° C. The experiments of Schuster and of Eve have 
shown that the highest obtainable pressures have no influence on the activity of 
radium, 
In the present experiments the emanation from about four milligrams of 
radium bromide was momentarily exposed to the influence of the very high tem- 
perature produced by the explosion of cordite in a closed steel bomb. The bomb 
used in these experiments was constructed by Mr. Petavel, and had been used by 
him in previous experiments on the pressures developed during explosions. The 
bomb was a complete sphere of mild steel, about 4 inches internal diameter and 
about 2 inches thick. About forty-six grains of cordite were placed in the 
bomb, and after exhaustion the emanation was introduced. About four hours 
later the emanation is in equilibrium with its products, and the activity due to 
the y rays, which passed through the bomb, was observed by means of an electro- 
scope placed outside the bomb. The cordite was fired electrically, and obser- 
vations were made of any change of activity. By running the electroscope during 
the explosion, it was found that no sudden burst of activity occurred, showing 
conclusively that the normal rate of disintegration of the product, radium C, was 
not much altered by this process. Three experiments were made with equal 
weights of cordite, but of different diameter, in order to vary the suddenness of the 
explosion. In every case the activity measured by the y rays was found to have 
decreased about 9 per cent. after the explosion. The activity gradually rose again, 
reaching nearly the equilibrium value after three hours. A special experiment 
showed that the rate of change of the emanation itself was not altered by the 
explosion, 
The maximum pressure of the gases during the explosion was about 1200 
atmospheres, and the maximum temperature certainly not lower than 2500° C. 
The change of activity produced by the explosion may be due either to a sudden 
alteration of the distribution of the active deposit or to a change in the amount 
or period of the products, radium B and radium C, Since the active deposit of 
