IIO 
NATURE 
[DrceMBER 3, 1896 
A VALUABLE memoir by Prof. Augusto Righi, entitled «* Sulla 
propagazione dell’ elettricita nei gas attraversati dai raggi di 
Rontgen,” has just been published by Signori Gamberini é Par- 
meggiani, Bologna. Practically all the experimental work 
which has advanced the knowledge of Réntgen rays is brought 
together and coordinated in the memoir, full references to the 
original papers being given in each case. 
THE Cambridge University Press is about to issue a ‘* Manual 
and Dictionary of the Phanerogams and Ferns,” by Mr. J. C. 
Willis, Director of the Royal Botanic Gardens, Ceylon. The 
work is in two volumes, printed on thin paper, the second of 
which can be placed in the pocket as a handbook for ready 
reference in a botanic garden or museum. The first volume 
serves as an introduction to the second or dictionary part, and 
deals with the vegetable morphology, variation, and the prin- 
ciples of classification in a decidedly original manner. It con- 
siders plants largely from a biological standpoint, and attempts 
to indicate the effects of the environment on the organisms. 
THE Annales of the French Meteorological Office for 1894 
have recently been published. They consist of three large 
quarto volumes : (1) Memoirs, containing a discussion of tracks 
of thunderstorms, magnetic observations at various places, with 
a summary of the principal disturbances, and a comparison of | 
the curves with those furnished by the registration of earth- 
currents, showing the relation which exists between these 
phenomena; a discussion of the observations made on the 
Eiffel Tower, &c. (2) Observations made at French stations 
and in their colonies. (3) Rainfall values: the number of these 
stations is 2039, which exceeds those given in any previous 
year. 
CHEMICAL papers abound in the volume of Proceedings (vol. 
Xxill. mew series, 1895-96) just issued by the American 
Academy of Arts and Sciences. We select for special mention 
the following subjects of contributions to the volume :—The 
composition of the Ohio and Canadian sulphur petroleums, by 
Charles F, Mabery ; the chemical potential of the metals, by 
Wilder D. Bancroft. Among the conclusions are: (1) The 
potential difference between a metal and an electrolyte is not a 
function of the concentration of the salt solution, nor of the 
nature of the positive ion, except in certain special cases. (2) | 
It is a function of the electrode, of the negative ion, and of the 
solvent ; a revision of the atomic weight of zinc, by T. W. 
Richards and E. F. Rogers; (with o = 16 the atomic weight 
found is 65°404; with 0 = 15°96, the value is 65°240; and 
for 0 = 15°88, it is 64’912); thermo-electric interpolation 
formule, by Silas W. Holman; melting points of aluminium 
(660°), silver (970°), gold (1072°), copper (1095°), 
(1760°), by S. W. Holman, R. R. Lawrence, and L. Barr. 
The melting point of gold was assumed by the observers, and 
upon it the other values more or less depend. There are also 
papers on the thermal conductivity of mild steel, the outline of 
Cape Cod, and the embryology of the star-fish. 
ALL chemists will welcome the appearance of a new instal- 
ment (part 2 of vol. ii.) of the ‘‘ Lehrbuch du Organischen 
Chemie,” by V. Meyer and P. Jacobson, which has just been 
issued. The new part deals with the aromatic phenols, quinones, 
aldelydes, ketones, and carboxylic acids, With the next part, 
the second volume, which deals with the chemistry of carbon 
rings, will be completed. 
Mr. Crookes has been experimenting witha solution of 
ucium nitrate, and a larger quantity of precipitated oxalate, 
both supped by M. P. Barriere, the patentee of the alleged 
new element, lucium. In the Chemztcal News he describes his 
experiments, and states that the results have convinced him that 
the claim of lucium to form one of the chemical elements is not 
justified. Chemical examination confirms the results obtained 
0. 1414, VOL. 55 | 
and platinum | 
by spectrum observations, that lucium is nothing but impure 
yttrium. 
In the current number of the Zeétschrift fiir Physikalische 
Chemie, H. Euler gives the results of a series of measurements 
of the electrolytic dissociation of some organic acids at different 
temperatures. On warming a solution of benzoic acid the 
ionisation—?.e. the fraction existing in the form of ions— 
increases until 35° C. is reached, after which it decreases, 
showing that the heat evolved by the change of the undis- 
| sociated molecule into the ionic condition is negative at tem- 
peratures lower than 35°, and positive at higher temperatures. 
m-Oxybenzoic acid also has a maximum ionisation between 
25° and 30°. In general the ionisation either increases or 
decreases continuously as the temperature is raised. These 
results are of interest in view of the belief, which is not un- 
frequently met with, that the ionisation necessarily increases 
with rise of temperature. 
THE additions to the Zoological Society’s Gardens during the 
past week include a Leopard (4edis pardus, 2) from Ceylon, 
presented by Surgeon-Major N. Manders ; two Tigers (Fedés 
tzgris, 8 6) from India, presented by Captain Alex. W. Thorny- 
croft, Royal Scots Fusiliers ; a Malabar Squirrel (Sczarus maxe- 
meus) from India, presented by Mr. G. W. Vidal; a Ring- 
tailed Coati (Vasea v2fa),a —— Courlau (4vamus, sp. inc.), a 
King Vulture (GyAagws papa), three Violaceous Night Herons 
(Nycticorax violaceus) from South America, an Impeyan Monaul 
(Lophophorus tmpeyanus) from the Himalaya Mountains, pur- 
chased. 
OUR ASTRONOMICAL COLUMN. 
EPHEMERIS FOR COMET PERRINE.—The following positions. 
for Perrine’s comet have been computed by Otto Knopf, and are 
given in Edinburgh Czrcular, No. 51 :— 
Ephemeris for Berlin Midnight. 
R.A. Decl. Brightness, 
1896. h ms. ae 
Dec. 4 19 52 8 +4 42°7 0°99 
5 19 51 49 4 14°7 
6 19 51 3 BN47.2 1'00 
7 19 51 14 3 20°2 
cS) 19 50 59 2 536 
9 19 50 44 2 27°5 
10 19 50 31 2 18 I‘O1 
II 19 50 19 I 36'5 
12 19 50 7 1 Bea) 
i) 19 49 57 0 47° 
14 19 49 47 +O 23'0 104 
The Beieniness ee this comet on November 2 has been takem 
as unity. 
““THE ASTROPHYSICAL JOURNAL. ’—Among the articles of 
this journal for the present month may be noted Mr. W. Je 
Humphrey's further study of the effect of wave-lengths of 
lines in the are spectra of certain elements. In this investiga- 
tion he has examined the lines of several other elements, 
the best out of one hundred and seventy-five negatives having 
been employed. The new facts thus gleaned haye necessitated — 
a modification of his previous statement concerning the connec- 
tion between the atomic weights and the shift of the lines. 
Prof. J. Feényi communicates a statement with two diagrams. 
of the positions of the prominences on the solar limb at the 
time of the recent eclipse on August 8 Mr. Alexander 
Roberts, commenting on the growing importance of the value 
of the light ratio, adds some notes on a method of determining 
this quantity. Mr. Wadsworth, in continuation of the series of 
articles that has been given on “‘ The Modern Spectroscope,” 
describes an ingenious fluid prism without solid walls, and its 
use in an objective spectroscope. The general idea of the 
arrangement may be summarised quite briefly. A Littrow 
spectroscope has its axis of rotation arranged horizontally. 
The collimating beam from the slit falls on a free horizontal 
surface of a liquid contained in a glass or metal cell, and is 
there refracted. A mirror, also movable about the same axis, 
is immersed in the liquid at such an angle that it receives 
