i 
FEBRUARY 19, I1914| 
-NATURE 
699 
two ends of the spectrum, fourteen displayed a marked 
difference which is stated to be very great in some 
cases. In every case the star which is relatively faint 
at the violet end of the spectrum is the star of small 
proper motion. Mr. Adams points out that the 
evidence of this small amount of material is two 
slight to warrant any extended discussion on its appli- 
cation to the problem of the absorption of light in 
space. 
Wuo’s Wuo in AstroNomy.—The very excellent 
book, entitled ‘‘ Astronomical Observations and Astro- 
nomers,” and published under the auspices of the 
Royal Observatory of Belgium, which first appeared in 
- the year 1907, is well known to most of the readers 
of this column, and no doubt has been found a very 
useful book of reference. The work was from the 
pens of the astronomers at the Royal Observatory of 
Belgium, and the task of collecting and arranging 
the information was no light one. It is now proposed 
to bring the contents thoroughly up to date, and with 
this intention circulars have been widely distributed 
requesting that the printed forms be filled in. These 
forms ask for a. brief statement as to personnel, in- 
struments, researches, and publications of observa- 
tories, and it is hoped that everyone will do his best 
to make the volume as complete as possible, and so 
render more light the labours of M. P. Stroobant and 
his co-workers. 
WORK OF THE VIENNA RADIUM 
; INSTITUTE.1 
Cc the seventeen papers before us, from the Radium 
Institute at Vienna, five by Drs. von Hevesy and 
Paneth, both of whom are well known in this country, 
contain notable advances in our knowledge of the 
chemistry of the radio-active elements. The chemical 
identity of the several members of a group of isotopic 
elements has been further put to the proof and ex- 
tended to include the electro-chemical properties. An 
elegant application of this new phenomenon of isotopy 
has been made in analytical chemistry in the deter- 
mination of the solubility of such excessively insoluble 
compounds as lead chromate, sulphide, &c. The 
principle of the method is to add to the common 
element its radio-isotope in unweighable, but intensely 
radio-active, amount, and to estimate the distribution 
of the former after any chemical operation 
from the experimental distribution of: the latter 
by radio-active measurements. Thus radium 
D, derived from the decay of radium emana- 
tion, is added to lead before its precipitation by 
potassium chromate. Radium D being isotopic with 
lead, the ratio of the lead and radium D must remain 
unchanged by the precipitation. The quantity of lead 
in the filtrate is, of course, analytically undetectable, 
but the quantity of radium D is easily estimated. In 
this way the solubility of lead chromate in water at 
25° was found to be o-o1r2 mg. per litre, or twelve 
parts in a thousand million. 
Another important direction, in which these inves- 
tigators are extending, is in the application of col- 
loido-chemistry to the radio-elements. Often, as they 
and Godlewski in France have independently con- 
cluded, even these extremely attenuated solutions of 
the radio-elements behave as colloids rather than as 
electrolytes and their transport under the electric 
current is due to electrophoresis rather than to electro- 
lysis. Polonium is the centre of interest in many of 
these researches, for it is a new element, in the sense 
1 Mitteilungen aus dem Institut fiir Radium-forschung, xxxviii-li i. 
Ueber Neuerungen-und Erfahrungen an den Radium-messungen nach der 
Cee By V. F. Hess (Verh. D. Physikal. Ges., 1913, xv-, 
Tr. 20). \ 
NO. 2312, VOL. 92| 
that it is isotopic with no previously known one, and 
occupies a separate place in Mendeléeff’s table, so that 
its properties cannot, like those of the majority, be 
exactly determined by proxy. 
V. F. Hess describes a convenient method of deter- 
mining quantities of radium by the y-ray method, the 
quantity being read off by the constant deflection of an 
Elster-Geitel single quartz-thread electrometer, in 
conjunction with one of N. R. Campbell’s high resist- 
ances of xylol and alcohol. A long attempt to arrange 
a standard measuring instrument, calibrated once for 
all, which would give the quantity of radium without 
the necessity of employing a radium standard, might 
have been more successful if the author had been 
acquainted with A. S. Russell’s work on the measure- 
ment of y rays and the necessity, if disturbances from 
secondary rays are to be avoided, of using lead, not 
brass, for the walls of the electroscope. In the same 
field Flamm and Mache continue the account of their 
attempts to measure the radium emanation quantita- 
tively by the absolute value of the ionisation current 
in a guard-ring plate condenser. 
Hess has continued his determinations of the pene- 
trating radiation of the upper atmosphere by means 
of balloon ascents, and arrives at the startling con- 
clusion that above 2000 metres there is a rapid increase 
in the intensity of the penetrating rays. At these 
heights the penetrating rays from the earth itself 
would be absolutely negligible, whilst that from the 
radium emanation in the air, which has its origin in 
the earth and is of limited life, must be, at any rate, 
less than at the surface. The conclusion that a great 
part of the penetrating radiation cannot come from 
the known radio-active constituents of the earth and 
atmosphere is one that must evoke general interest, 
and calls for the further radio-active exploration of 
the upper atmosphere. 
Other papers deal with chemical decomposition pro- 
duced by radium rays and ultra-violet light (Kailan), 
the solubility of radium emanation and other gases in 
liquids (Stefan Meyer and Martin Kofler), the varia- 
tion in the ranges of the individual « particles through 
the probability variations in the number of molecules 
they encounter in their path (Freidmann), and the 
life periods of uranium and radium (Stefan Meyer). 
The latter research treats critically the known data 
from which these constants can be derived, and leads 
to the result that there is complete agreement among 
values obtained by independent methods. The most 
probable values for the periods of average life of 
radium and uranium respectively are 2500 and 
7-23. x10° years. Incidentally, it may be pointed out, 
this makes the perennial problem of the origin of 
actinium more of a mystery than ever, for there should 
be no such agreement among the methods, if, as is 
supposed, some 8 per cent. of the uranium atoms 
branched off into actinium at some point before 
radium is arrived at. But it may still be doubted 
whether some of the data chosen, particularly the 
equilibrium ratio between radium and uranium, are 
not at fault. Beas 
SMOKE AND SMOKE PREVENTION. 
us fin BIBILIOGRAPHY of Smoke and Smoke 
Prevention,” prepared by Mr. E. H. McClel- 
land, has been published by the University of 
Pittsburg, Pa. (Bulletin 2, 1913, pp. 164; price 
50 cents). The bibliography has been com- 
piled for the use of the Melton Institute of 
Industrial Research, consisting of a body of scientific 
experts, who are about to embark on an inquiry, the 
nature and extent of which is set forth in the first 
bulletin issued by the institute (‘‘ Outline of the Smoke 
Investigation’). It contains an apparently complete 
