474 
emanation from a weighed amount, the proportion of 
radium present may be estimated. A comparison with the 
leak due to the emanation of a known weight of radium 
must of course be made. For this purpose it would be 
best to weigh out, say, a milligramme of radium bromide, 
dissolve it in a litre of water, and evaporate a small 
measured quantity of the solution in a suitable tube. In 
this way the effect due to a standard quantity could be 
determined. 
The method of experimenting was as follows :— 
The powdered mineral was placed in a hard glass com- 
bustion tube, drawn out and sealed at one end, connected 
to a mercury gas-holder at the other. The mineral was 
heated to redness, and the gaseous products collected in the 
gas-holder. When the evolution of gas had ceased, the 
point was broken off, and air drawn into the gas-holder up 
to a standard volume. 
For measuring the electrical effects an electroscope was 
used. This was exhausted, and the gas extracted from the 
mineral, together with the air, which had been used to 
make up its volume to a sufficient amount, was admitted. 
After a few hours, enough for the deposited activity to 
attain its full value, the rate of leak was read. The day 
and hour were noted, and the gas was pumped out into a 
test-tube and stored over mercury. After a sufficient time 
had elapsed it was again introduced into the apparatus by 
means of a syphon gas pipette! and the rate of leak again 
measured. In the meantime the apparatus had been avail- 
able for making measurements with other gases. 
In some cases the emanation was initially so strong that 
it could not be conveniently investigated. In such cases 
a portion of the gas was diluted with air for measuring 
the rate of decay at first. The concentrated material was 
kept until, by lapse of time, it had become weak enough 
to be conveniently used. Its activity was followed until 
it had become too small for measurement. 
With this preface the results for the various minerals 
tried may be given in the form of a table. The rates of 
leak are given in scale divisions per hour. When air alone 
filled the apparatus, the rate of leak was 2-25 sc. div. per 
hour. This was in each case subtracted. 
| Sy |e eg RS a“ |\Puo%a 
fn ee jFeies 
SE |LSOL] woo | SS cvs 
f EICESZ/C SE |U nous 
Mineral Locality 2e [oge| ore |s2es7 
zu jelar| eke (e5ee 
Se 1s9 on) tt) exe 
So” ass [a ia Soe 
= 
Samarskite .| N. Carolina, U.S.A..| 20 20,600 | 103,000 | 3°48 
Fergusonite ol|WNorway.t 00s) eine 7 4,280 61,000| 3°80 
Pitchblende .| Cornwall. . . .| 40 | x1,900 29,800 3°50 
Malacone « Hitteroe, Norway . 20 1,440 7,200 | 3°81 
Monazite . Norway a) Selman Wail SESE 2,060 4,000} 3°50 
a » .|N.Carolina. . . .| 82 37 45 3°81 
as Brazil . ee Of OeO 54 II 2 3°80 
Zircon . NeiCarolinals mene 60 24°6) 41 4°05 
| } 
All the minerals give radium 
varying quantity. 
These tests were not started quickly enough to give in- 
formation as to the presence of a very quickly decaying 
emanation. This was tested for independently. 
The mineral malacone is of peculiar interest, because it 
has been found to contain argon as well as helium (Ramsay 
and Travers, Roy. Soc. Proc., vol. Ixiv. p. 131). Helium 
is formed by the degeneration of radium, and it is reason- 
able to assume that the other kindred gases have had a 
similar origin. It was hoped, therefore, that malacone 
might contain some new radio-active element. It is still 
possible that it does so, but, if so, this substance gives no 
emanation distinct from that of radium. 
The meteorite of Augusta, co. Virginia, has also been 
found to contain argon and helium. But no emanation at 
all could be obtained from 20 grammes of it. 
The minerals ‘were all tested for. thorium emanation by 
drawing air over them in the cold; the only one in the 
above list that gives it is the Norwegian monazite, and 
emanation, though in very 
1 The methods of manipulation used in storing and transferring the 
a without loss were those described in Dr. ‘Lravers's book, ‘ The Study 
of Gases.” 
NO. 1794, VOL. 69] 
NATURE 
[Marcu 17, 1904 
even this does not yield it very abundantly. A crystal of 
thorite, however, kindly lent me by Prof. Lewis, was found 
to give torrents of thorium emanation. Air drawn over it 
in the cold possesses strong discharging power. It was not 
permissible to heat the specimen, which might have injured 
it, so that the presence or absence of radium emanation im 
thorite could not be investigated. 
There can be no doubt that the other specimens of mona- 
zite contained thorium, for they were given me by the late 
Mr. W. Shapleigh, who was connected with the thorium 
industry, and used these varieties of monazite for preparing” 
thoria. They were, moreover, markedly radio-active, while 
the amount of radium emanation obtained from them was 
so small that their activity could not be mainly due to 
radium. They probably contain the thorium in what 
Rutherford and Soddy call the de-emanated condition, that 
is, the thorium emanation, though formed, is not able to: 
escape. 
It is a remarkable fact that these varieties of monazite, 
though they contain practically no radium, yield helium in 
fair quantity. There are several explanations possible- 
The radium originally present may have almost completely 
decayed into helium, and any other products which it may 
yield; or it may be that thorium, as well as radium, yields: 
helium by its decomposition; or, lastly, the helium may 
not, in this instance, have been generated by radio-active 
changes at all. 
It is interesting to know whether the minerals retain all 
the radium emanation which they generate when heat is 
not used to expel it. Two cases were examined. One 
hundred and fourteen grammes of powdered samarskite were 
kept for three weeks in a sealed glass tube. The air was 
pumped out and tested. It was found to contain about 
1/1s5oth part of the emanation, which could have been ex- 
iracted by heat. 
A similar experiment with malacone showed that about 
one-fiftieth of its emanation was able to escape in the cold. 
It appears, therefore, that these minerals retain nearly 
all their emanation. The same is probably true of the 
helium produced by the emanation. Samarskite which had 
been heated to redness was found to retain its emanatiom 
in the cold about as well as before. 
Part II. 
I happened to possess a small sample of a red deposit, 
coloured by iron, which is left by the water of the King’s 
Spring, at Bath. It occurred to me that it might be worth 
while to test this for radio-activity. The result was to 
show that the deposit was markedly active. On leaving it 
in the testing vessel (which was closed airtight) for a few 
days, the activity was found to increase to several times its. 
initial value. This shows that the deposit gives off an 
emanation freely, even without heat. 
Experiments were then made to test the rate of decay of 
this emanation. It proved to be identical with the rate of 
decay of the emanation of radium.’ The activity is wholly 
due to that element. 
This deposit was collected inside the King’s Well itself, 
where the hot water issues from the ground. Other deposits: 
are left in the tanks and pipes. ‘They are less active than 
that collected near the source. 
Deposits from another of the hot springs at Bath, that 
known as the Old Royal Spring, have also been tested. 
These were found to be active also. In this case there was. 
no opportunity of collecting the deposit at the well head 
itself, but it was found that the deposit left in the channel 
near the source was more active than that in the tanks. 
further from it. 
It was interesting to determine whether the water itself 
contained any radium in solution. There could be little 
doubt that there must be traces left in solution, after the 
deposit had settled out. But, since the Bath water contains 
1 In the first experiment made, I obtained a small residual leak when the 
radium emanation had decayed. This was attribuied to a new emanation, 
of greater durability. But I have failed to repeat the experiment, and am 
forced to conclude that the leak was due to a failure of the quartz insula— 
tion, owing to the presence of moisture. It is very difficult to understand 
how this can have happened, for the gas was passed through drying tubes. 
When the rate of leak was tested with air in the apparatus, it had always a 
perfectly definite and constant small value. 
