exxiv Proceedings of the Asiatic Society of Bengal. [N.S., XV, 
the limits of his own laboratory. The outstanding feature of 
these transformations is their entire independence on any con- 
ditions which it has been within human power to impose, and 
it must be admitted that this indifference to all the charms in 
the repertoire of the modern chemist and physicist can hardly 
be considered a favourable omen for their attempts to carry 
out a process similar to one over which they cannot exercise 
the smallest control. 
Nevertheless such attempts have been made, and if no 
definite conclusions are apparent, the reason lies rather in the 
difficulty of interpreting the meaning of the experiments, than 
in any doubt regarding the results. 
I propose to pass over the earliest work, done by Cameron 
and Ramsay in 1907, on the production of lithium from copper 
ca by the action of radium emanation, not because their 
sults have been proved to be of no significance, but because 
soins of error which they did not suspect were afterwards 
discovered, and because no positive results have been obtained 
when those sources of error were absent. The neat at 
he 
ages of helium, the detection of which was the object of 
e experiment, was doubtful, but a gaseous substance which 
condensed in liquid air to a snow-white solid was observed. It 
appeared to be carbon dioxide, but was not further examined. 
c.c. of carbon dioxide. After 168 more days 1-08 c.c. of 
carbon dioxide was found. At this pre ‘ control experiment 
was set up, consisting of a solution of 3 0 grams of mercuric 
nitrate contained in a similar flask ite pike a in exactly the 
same way. From the 14th August, 1907, to the 30th March, 
1908, 1:209 c.c. of carbon dioxide was obtained from the 
thorium nitrate solution, and 0-015 c¢.c. from the mercuric 
nitrate. On the 9th February, 1909, a further quantity of 
carbon dioxide, amounting to 0°622 c.c. was recovered. Thus 
the same solution of thorium nitrate had given off cies 
4 c.c. of carbon dioxide, in a little less than three years, and 
showed no signs of stopping. 
Among the various possible explanations of the origin of 
the carbon dioxide, which I will refer to presently, is the one 
which postulates a degradation of the element thorium, under 
