APRIL 14,.1904] 
NATURE 567 
wupters, X-ray tubes, apparatus for fluoroscopy and radio- 
raphy, primary and secondary batteries, high frequency 
apparatus, dynamos, and other instruments. Many useful 
‘details as to the various instruments are described; and the 
catalogue also contains about thirty pages of practical hints 
to beginners, which will prove of assistance to those who 
propose to work with Réntgen ray,* high frequency and 
-electromedical apparatus. 
A SECOND edition of Prof. Stanislas Meunier’s volume on 
““La Géologie expérimentale’? has been published by M. 
Félix Alcan, Paris. The work contains many ingenious and 
instructive experiments illustrating the phenomena of 
geology and physical geography, and most of them can be 
performed successfully with very simple appliances. The 
‘original edition was reviewed in Nature in August, 1899 
qvol. Ix. p. 388), and the new volume, though dealing 
essentially with the same subjects, is differently arranged, 
-and includes much new matter. 
Pror. W. Ostwatp’s ‘“ Grundlinien der anorganischen 
Chemie” (Leipzig: Engelmann; London: Williams and 
Norgate), which originally appeared in 1900, and was re- 
viewed in Nature of April 11, gor (vol. Ixiii. p. 557), has 
reached a second edition. The work provides students with 
a text-book in which chemistry is developed from the outset 
in accordance with modern theoretical knowledge. The 
book attracted immediate attention, not only on account of 
the author’s eminence as a teacher and investigator, but 
also because of its plan of treatment. The new and revised 
edition will certainly meet with the same success as the 
‘original work, of which the edition of four thousand copies 
was exhausted in about three years. 
A SECOND edition of ‘‘ Towers and Tanks for Water- 
works,’? by Mr. J. N. Hazlehurst, has been published by 
Messrs. Wiley and Sons (London: Chapman and Hall, 
Ltd.). The book deals with the design and construction 
of metal stand pipes and tanks for storing up water at a 
sufficient elevation to provide adequate pressure for its 
Proper distribution. A review of the original volume 
appeared in Nature of September 26, igor (vol. Ixiv. p. 
525). Another work just published by Messrs. Wiley is the 
eighth edition of ‘‘ The Theory and Practice of Modern 
Framed Structures,”’ by Messrs. J. B. Johnson, C. W. 
Bryan, and F. E. Turneaure. This comprehensive volume 
is. designed for use in technical schools and by engineers 
in professional practice. A large part of the original work 
has been re-written, and many changes have been made 
in other parts to bring them into close touch with modern 
Practice. The new designs and improvements in methods 
of description, the practical character of the text and illus- 
trations, and the use made of graphical representation, 
combine to make the volume one to which all students of 
engineering should have access. 
A DETERMINATION of the molecular weight of solid 
phosphoretted hydrogen, described by Messrs. Schenck and 
Buck. in a recent number of the Berichte, has shown that 
this compound has a more complex formula than that which 
has usually been assigned to it. The method employed 
consisted in determining the depression of the freezing point 
of a solution in yellow phosphorus, and the results obtained 
indicate that the molecular weight corresponds with the 
formula P,,H,, and not with the simple formula P,H,. 
M. GurtiaumeE sends a correction of the note on nickel- 
steel which appeared in our issue of March 24 (p. 496); 
the coefficient of expansion of y-iron is greater than that 
NO. 1798, VOL. 69| 
of a-iron, and all non-magnetic steels in which the iron 
is retained in the y form, such as Hadfield’s manganese 
steels, retain the large coefficient of expansion character- 
istic of this modification of iron. M. Guillaume adds that 
“the function of nickel in the alloys is essentially to unite 
into a single change the two transformations of pure iron, 
and thus, as M. Osmond has shown, to eliminate altogether 
the 8 variety; then, on account of the state of mutual dis- 
solution in which the two chief constituents of the alloy 
are found, to create an equilibrium varying with the 
temperature, such that the transformation of a into y iron 
and conversely takes place over a considerable interval in- 
stead of being concentrated at a single point as in pure 
iron.”’ 
A soMEwnat striking observation is recorded by Dorn 
in the Physikalische Zeitschrift. A tube of alkali-free Jena 
glass, containing 30 mg, of radium bromide, had been 
sealed up on December 3, 1902, in order that some experi- 
ments might be carried out on the supposed loss in weight 
of radium salts. Six months later, on May 27, 1903, it was 
desired to open the tube. This was done by means of a 
triangular file, but as soon as the metal touched the surface 
of the glass the tube was pierced by an electrical spark so 
bright as to be clearly visible in broad sunlight close to the 
window, whilst the sound was mistaken by an assistant in 
the room for the discharge of an induction coil. It is 
suggested that the retention in the tube of the positively 
charged a particles and the escape of the negatively charged 
8 particles must have set up a potential difference between 
the inside and the outside of the tube so great that it was 
ultimately able to pierce through 0-3 mm. of glass. 
THE electrochemical behaviour of radium is discussed by 
Mr. Alfred Coehn in a recent number of the Berichte. From 
the thermochemical data it would appear that the separation 
of the metal would be increasingly difficult in the series 
Ca, Sr, Ba, but when a mercury kathode is used the voltage 
required is greatly reduced owing to the energy liberated 
in the formation of an amalgam, and the order in which 
the metals separate is reversed. Thus it requires 02 volt 
more to separate strontium than barium, and 0 25 volt more 
to separate calcium than strontium; if the series were con- 
tinued radium should require 03 or o-4 volt less than 
barium, and metallic radium can actually be precipitated 
by barium amalgam. Owing to the very small proportion 
of radium in the crude bromide it is impossible to effect a 
sharp Separation of the metals except with an impracticably 
small current density, but a considerable concentration may 
be effected by this method. It is of interest to note that 
freshly prepared (unoxidised) radium amalgam, like the salts 
of the metal, only slowly attains its maximum activity, whilst 
the silver anode, which at first exhibits a very powerful 
induced activity, soon becomes altogether inactive. 
Tue additions to the Zoological Society’s Gardens during 
the past week include a Maccarthy’s Ichneumon (Herpfestes 
fulvescens) from Ceylon, presented by Mr. Arthur M. 
Dowson, R.N.; a Leadbeater’s Cockatoo (Cacatua lead- 
beateri) from Australia, presented by Mr. W. A. Ridley; 
a Cocteau’s Skink (Macroscincus cocteaui) from the Cape 
Verde Islands, presented by Mr. — Hastings; two Painted 
Frogs (Discoglossus pictus), European, presented by Dr. 
F. G. D. Drewitt; three Jays (Garrulus glandarius), 
British, purchased; an Eland (Orias canna), a Mouflon 
(Ovis musimon), eight American Timber Wolves (Cants 
occidentalis), a Muscat Gazelle (Gazella muscatensis), born 
in the Gardens; a Black Swan (Cygnus atratus), bred in 
the Gardens. 
