116 
NATURE 
[APRIL 4, 1912 
tion being exactly balanced by a special form of 
Bronson’s ‘‘air resistance.” The special feature 
of the arrangement is that the radium standard is 
mounted on an optical bench at a distance from 
a lead ionisation chamber, and the distance is 
varied until exact balance is obtained. The 
strengths of different preparations are propor- 
tional to the square of the distances, correction 
being made for air absorption of the y-rays. Each 
method naturally has its own advantages and 
range of applicability. 
- After comparisons by both methods, the grati- 
‘fying result was arrived at that the Paris and 
Austrian standards agreed perfectly with one 
another within the limits of error of the measure- 
ments. Naturally, to obtain the highest possible 
accuracy with the methods, a much more ex- 
tended series of measurements than was ‘possible 
in the short time available would have been neces- 
sary. But it was clear that the error of measure- 
ment was certainly not greater than 1 part in 
300, and was probably much less. For example, 
for two single comparisons, the 31°17 mg. Vienna 
standard came out as 31°24 mg. and the ro’rr mg. 
as 10°13 mg. in terms of the Paris standard. 
The standards being entirely independent, this 
result reflects the greatest credit on the care and 
accuracy bestowed by Mme. Curie and the other 
investigators responsible for their preparation and 
for the methods of measurement. In future it will 
be possible to evaluate the quantity of radium in 
a preparation, in the absence of other radioactive 
substances giving y-rays, by simple y-ray com- 
parison with these standards without any chemical 
operations and without opening the tube in which 
it is sealed, with an accuracy of at least 3 or 4 
parts in 1000. 
The committee also had the advantage of having 
a standard, sent by Sir William Ramsay, and pre- 
pared from material employed in the just-published 
atomic weight determinations by him in conjunc- 
tion with Whytlaw Gray (Proc. Roy. Soc., 1912, 
86 A, 270). The quantity of radium was much 
smaller than in the others, and corresponded to 
less than 4 mg. of radium chloride. In addition, 
it was not comparable, either in the manner of 
its preparation or of its mounting, with the others, 
the tube in which it was contained being of 
quartz, relatively thick in the wall. For these 
reasons no definite comparison was possible of 
the same degree of accuracy as for the others. 
The committee accepted Mme. Curie’s standard 
as the International Radium Standard, and will 
ask for its preservation in the Bureau International 
des Poids et Mesures in Paris. They have ar- 
ranged for the 31°17 mg. Austrian standard to be 
similarly preserved in Vienna as a_ reserve 
standard. These standards are hereafter only to 
be used for purposes of comparison by the com- 
mittee, and are not to be taken away from the 
cities mentioned or to be used for experiment. 
Arrangements have been made for the preparation 
of secondary standards, of between 10 and 4o 
milligrams of radium chloride, to be provided to 
the Governments of the various countries desiring 
NO. 2214, VOL. 89] 
them for their official testing institutions. These 
secondary standards will be compared indepen- 
dently at Paris and Vienna with the international 
and reserve standards, and will be supplied with 
a certificate showing the result of the comparisons. 
Further particulars may be obtained from the 
secretary of the committee, Prof. Stefan Meyer, 
Institut fiir Radiumforschung, Waisenhausgasse 3, 
Wien IX, Austria. 
In the course of a few months it will be possible 
for each country to possess a radium standard 
which has been compared directly with the inter- 
national standard, which will enable measurements 
to be made in future with complete confidence, 
and will be invaluable both for scientific and 
commercial comparisons. 
The necessity of refunding to Mme. Curie a 
quantity of radium equivalent to that contained 
in the international standard has been a source 
of anxiety to the committee, who have no funds 
at their disposal. It is therefore most satisfac- 
tory to be able to announce that as soon as the 
need was made known, the sum necessary was 
generously donated in this country by Dr. and 
Mrs. G. T. Beilby as a personal tribute to 
Mme. Curie and her work. 
NOTES. 
Tue Terra Nova, the vessel of the British Antarctic 
expedition, arrived at Akaroa, New Zealand, on April 
1, and brought the news that on January 3 Captain 
Scott and five other members of the expedition were 
within 150 miles of the south pole, and that he intends 
to remain another year in the Antarctic. A detailed 
account of the work accomplished by the expedition 
has been obtained by the Central News, Ltd., agency, 
and appeared in the daily papers on Tuesday and 
Wednesday. Captain Scott left the base at McMurdo 
Sound on November 2, 1911, for the poleward 
journey, and had arrived at latitude 87° 32’ S. on 
January 3. Nearly three weeks before this date 
Captain Amundsen had reached the south pole. 
Though Captain Scott has thus been forestalled as 
regards the first arrival at lat. 90° S., the scientific 
results of the British expedition promise to make up 
for any disappointment which may be felt from the 
point of view of national sentiment. Specimens of 
coal of economic value, and well-preserved fossils, have 
been found near Granite Harbour by the western 
geological party. Marine biological work has been 
carried on continuously, and every phase of seal, 
penguin, and skua-gull life has been photographed 
with the kinematograph. By means of small balloons 
the direction of atmospheric currents has been studied 
up to a height of six miles, and the temperatures 
have been recorded up to a height of five miles. 
Valuable magnetic, electrical, tidal, pendulum, and 
other observations relating to terrestrial physics have 
been made, and much has been done also in the fields 
of ice work and physiography. A summary of scien- 
tific work accomplished was published yesterday, and 
we hope to refer to its details next week. Meanwhile, 
we offer to Captain Scott and the other members of 
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