4 
on 
NALTOKE 
[| NOVEMBER 15, 1906 
patent rights. It is not our province to enter into 
the details of this controversy; we need only say that 
Mr. Schulz claims that he has succeeded better than 
any other inventor in solving the difficult problem of 
designing a practical and not too complicated turbine 
in which the steam consumption per horse-power hour 
is economical, not only at full power, but also when 
the engine is working at low loads, and he also 
claims that he has simplified the arrangements neces- 
sary on board ship, where go-astern machines must 
be provided as well as the go-ahead turbines. 
author gives a clear description of the mechanical 
details by which the inventor has secured the results 
he claims. This bool should be carefully studied by 
all those interested in the history of the development 
of the steam turbine. IDs els 18%, 
BOOK Sree He 
Ueber chitindse Fortbewegungs-Apparate einiger 
(insbesondere fussloser) Insektenlarven. By Dr. 
Wilhelm Leisewitz. Pp. iv+143; with 46. illustra- 
OUR 
tions in the text. (Munich: C. Reinhardt, 1906.) 
Price 4 marks. 
Tue author commenced his observations with the 
terminal appendage in the larva of Xiphydria drome- 
darius. This larva, which is almost apterous, lives 
in galleries in rotten wood, and the appendage is 
used firstly as a prop and partly to compress the 
loose substance behind it to give it a firm support as 
it gradually progresses by gnawing away the wood 
in front. He then extended his researches to the 
hairs, bristles, &c., of other internal-feeding larve, 
especially those which are apterous or subapterous, 
and in this small volume we have the results of his 
careful investigations. 
The chitinous appendages used for locomotion by 
such larva consist chiefly of (1) undifferentiated hairs, 
(2) spines, (3) warts, and (4) bristles. Where the 
larvee live in hard substances, like wood or bark, the 
appendages consist of short, stiff hairs or spines and 
warts, but when the larve live in soft substances, 
like’ rotten wood or mould, they are provided with 
long, slender hairs or bristles of varying form. 
The greater portion of the essay is devoted to larve 
of Coleoptera, though a few others belonging to the 
orders Neuroptera, Lepidoptera, Diptera, and 
Hymenoptera are also noticed. 
Apart from the physiological interest of the inquiry, 
it is also of some importance to the systematist, for 
the author claims to have discovered trustworthy 
characters in the chitinous appendages, which will 
allow many species of Coleoptera, hitherto supposed 
to be indeterminable in the larval state, to be easily 
recognised. W. FEF. Kirsy. 
Map of the British Isles. Constructed by W. and 
A. K. Johnston. Size 72 inches x 63 inches. 
Mounted on cloth with rollers and varnished. 
(London: W. and A. K. Johnston, 1906.) Price 
21S. 
Tue teaching of geography has received much atten- 
tion in recent years, and the increased importance 
given to the subjects in schools has led to the pro- 
duction of several new series of excellent wall maps. 
The present map is a new addition to one of these 
series. It is boldly printed, and coloured in a manner 
to make it easily visible in all parts of a large class- 
room. The scale is 1: 633,600, or ten miles to an 
NO. 1933, VOL. 75 | 
The | 
inch. The populations of the different towns are 
indicated by means of symbols, but it is to be feared 
that these will be of little use to anybody but the 
teacher. The map will require to be supplemented 
by an orographical one if the physical geography of 
our country is to be studied satisfactorily. 
LETTER TO THE EDITOR. 
[Lhe Editor does not hold himself responsible for opinions 
expressed by his correspondents. Neither can he undertake 
to return, or to correspond with the writers of, rejected 
manuscripts intended for this or any other part of NATURE. 
No notice is taken of anonymous communicitions.] 
The Production of Radium from Actinium, 
THE experimental evidence on the growth of radium from 
uranium has in the past been somewhat conflicting. Both 
Mr. Soddy and Mr. Whetham have stated that they observed 
an inerease with the time in the amount of radium in 
solutions of certain uranium salts which were under ex- 
amination. The writer, however, was able to show that, 
starting with a solution of uranium nitrate carefully 
purified by repeated crystallisation, the amount of radium 
formed in an interval of eighteen months was less than 
one two-thousandth of the amount which was to be ex- 
pected from the disintegration theory. 
I think that this discrepancy is readily explained by the 
results of an experiment which I have just made on the 
growth of radium from actinium. A kilogram of carnotite 
ore containing about 20 per cent. of uranium was decom- 
posed with an excess of dilute hydrochloric acid, and the 
solution thus obtained was treated with hydrogen sulphide, 
the precipitated sulphides being subsequently removed by 
filtration. To the solution was then added a fraction of 
a gram of thorium nitrate, followed by a solution of 
ral grams of oxalic acid. After standing for several 
days, the slight precipitate which formed was completely 
removed and converted into a soluble nitrate. The nitrate 
in dilute solution was again treated with an excess of 
oxalic acid, and this second precipitate was converted into 
a soluble chloride. I have found from a_ considerable 
number of experiments that practically all the actinium 
contained in a uranium mineral can be separated in this 
manner. 
The solution of the chlorides containing the actinium was 
sealed up in a glass bulb, and about two months later, on 
April 25 last, the gases and emanation were boiled out and 
collected. After standing for some minutes the gas was 
introduced into an electroscope. The activity of the eman- 
ation corresponded to a content of 5-7x10~-° gram of 
radium in the actinium solution. The bulb was again 
sealed, and was allowed to remain undisturbed until to-day, 
when the radium emanation present was again removed 
and tested. The amount of radium emanation now found 
corresponds to 14:2X10-* gram of radium, indicating that 
there has been formed in the solution during this interval 
of 193 days a quantity of radium equal to 8.5x10-° gram. 
This is equivalent to the production of about 1-6x10-* 
gram of radium in one year, and since the amount of 
radium in equilibrium with 200 grams of uranium is 
7-6xX10-° gram, the value of A(year)—? for radium can be 
calculated, and is given as 2-2x10-*. ‘The indicated half- 
value period would be about 3100 years. This number can 
only be regarded as approximate at present, since the 
original content of uranium in the material used, and the 
completeness of the separation of the actinium, are both 
uncertain. I think, however, that another step has been 
made towards the solution of the somewhat complex 
problem of the genesis of radium, and, since the amount 
of actinium in a mineral is apparently always proportional 
sev 
to the amounts of uranium and radium present, that 
actinium will prove to be the looked-for intermediate 
product. Bertram B. BoLtwoop. 
Sloane Laboratory of Yale College, New Haven, 
Conn., November 5- 
