200 
NATURE 
[APRIL 25, 1912 
the period of ionium could at once be found. For 
example, if the period were 100,000 years, there should 
be 12°5 grams of pure ionium per ton of uranium. 
Auer von Welsbach, in a masterly chemical separation 
of the rare-earth fraction from 30 tons of Joachims- 
thal pitchblende, separated a preparation, which he 
described as thorium oxide, containing ionium, the 
activity of which was measured by Meyer and von 
Schweidler. To obtain a maximum estimate for the 
period of ionium, I assumed that Welsbach’s prepara- 
tion was in reality pure ionium oxide (which it cer- 
tainly was not, as it gave the thorium emanation), 
and so I obtained the period of a million years as 
the upper possible limit. In proportion as the per- 
centage of ionium oxide present is less than 100 per 
cent., this period must be reduced.2 Thus we have 
fixed the period of ionium as between 10-° and 107° 
years, if ionium is the only intervening long-lived 
member. 
Quite recencly a method has been devised for cal- 
culating the period of ionium from the range of its 
a-particles, which is based upon an empirical mathe- 
matical relation holding between this range and 
the periods of the substances giving a-rays in the 
case of the other members of the series.* The most 
recent estimate by this method is about 200,000 years, 
which may be accepted provisionally as the most 
probable at the present time. If this is correct, there 
should be 25 grams of ionium per ton of uranium in 
minerals. A variety of evidence thus leads to the 
conclusion that to detect the growth of radium 
from uranium either still larger quantities of 
uranium or still longer time is necessary. 
Even after ten years, that is, at the end 
of 1916, if the period of ionium is as estimated, 
the uranium in No. III. preparation should only have 
produced 12x 10-'* grams of radium, which is rather 
less than half the amount that will then have been 
formed by the ionium initially present. Nos. I. and 
Il. preparations are very much less favourable. But 
it is interesting to consider No. IV. preparation, 
which, though only 26 years old, has more than 
seven times as much uranium as No. III. From the 
present slope of the curve it appears to have little 
more than one-half as much ionium, relatively to the 
uranium, as No. III., whereas the relative initial quan- 
tity of radium is about twice as great as in No. III. 
After eight years, that is in 1917, the quantity of | 
radium produced from the uranium should be about 
equal to that which will have by then been produced 
from the ionium present. A distinct upward slope 
should be detectable in the growth curve some time | 
before this. But this is the best, if the estimate of 
the period of ionium assumed is correct, that the 
present set of experiments can offer to the solution of 
the problem. With the experience already gained, 
especially in dealing with large quantities of uranium 
and in the methods of measurements of the minutest 
quantities of radium, there should be no difficulty in 
20 kilograms, of the requisite degree of purity as 
regards ionium and radium, to determine directly 
in a few years the period of ionium from the growth 
curve provided it is not greater than 200,000 years. 
A favourable opportunity is being awaited to initiate 
this large-scale experiment. It requires a small room 
to itself in a permanent institution uncontaminated 
with radium, and some guarantee that once installed | 
the preparations will remain undisturbed for a reason- 
able term of years, and that the measurements will 
be continued in a comparable manner should the 
period of life of the original investigator prove in- 
2 Soddy, Ze Radium toro, vii., 297- A AN 
3 Geiger2 Nuttall, Phil. Mag., rot, xxili., 613} 1912, Xxili., 439- 
2217, VOL. 89] 
ne 
sufficient. It is not enough to set aside a quantity 
of uranium for our successors to see if any radium 
has grown in it. It is essential that the exact form 
of the growth curve should be known before the 
problem in question can be fully answered. There 
may be more than one long-lived intermediate product 
between uranium and radium. NHowever, such. in- 
direct information as has been acquired as to the life 
period of ionium indicates that it alone is sufficient to 
account for the present results as regards the absence 
of growth of radium from uranium. 
THE CROCKER LAND EXPEDITION. 
eee ENCE was made in Nature of February 
22 (p. 560) to the expedition organised by the 
American Museum of Natural History and the 
American Geographical Society to reach and map 
Crocker Land, in the north polar seas north-west of 
Grant Land, and to make all the scientific studies 
en route and in other parts of the Arctic regions that 
circumstances may permit. 
The expedition will leave Sydney, N.S., by special 
steamer about July 20, 1912, and it is proposed to 
land on the south side of Bache Peninsula (Flagler 
Bay), lat. 70° 10’ N., and establish winter quarters. 
The ship will then be sent home. About the middle 
of September, sledging supplies to Cape Thomas 
Hubbard will be begun, and the work will be carried 
on throughout the winter during the moonlight 
periods. _ Cape Thomas Hubbard will be left with 
the return of dawn in February, 1913, and the expedi- 
tion will push across the ice to Crocker Land. Crocker 
Land will be left about May 1, and a return will be 
made to Cape Thomas Hubbard. Scientific work 
will be carried on in Grant Land and along the 
return route to winter quarters on Flagler Bay, where 
the expedition expects to arrive in July, 1913. In the 
spring and summer of 1914 there will be an expedi- 
tion from Whale Sound (Inglefield Gulf) directly east- 
ward to the summit of the ice-cap of Greenland, at 
| the widest part of that island. The return to New 
York will be in the autumn of 1914 by special ship. 
The leaders of the expedition -will be Mr. George 
Borup, assistant curator of geology in the American 
Museum of Natural History, and Mr, Donald B. 
MaeMillan, both of whom are well known by their 
worl done under Admiral Peary in his last polar 
expedition. 
It is estimated that not less than fifty thousand 
dollars (10,000l.) should be provided for the absolute 
needs of the expedition, in order to enable it to accom- 
plish the results that have been outlined above. On 
the proviso that sufficient funds are contributed from 
outside sources, the American Museum of Natural 
History has agreed to appropriate in the course of 
the expedition six thousand dollars in money, and 
has taken over its organisation and management. 
| The American Geographical Society has made an 
obtaining and dealing with sufficient uranium, say | 
appropriation of six thousand dollars toward the ex- 
pedition, and Yale University an appropriation of one 
thousand dollars, while other subscriptions have been 
promised. 
UNIVERSITY AND EDITCATIONAL 
INTELLIGENCE. 
Grascow.—The degree of Doctor of Science was 
conferred upon the following on April 22 :—Leonard 
Findlay: Thesis, ‘‘The Etioloey and Condition of 
the Blood in Spontaneous and Experimental Rickets, 
with additional papers.” David Robertson: Tliesis, 
“The Mathematical Design of Transformers; Elec- 
trical Meters on Variable Loads; and other original 
| : 
