JANUARY 3, 1907] 
NATURE 239 
Colin. A table is given showing the results of the mag- 
netic observations at twenty stations, to which is appended 
a discussion of the perturbations.—The evolution of the 
Tertiary mammals: the importance of migrations. The 
Miocene epoch: Charles Depéret.—The perpetual secre- 
tary announced the death of Jean Abraham Chrétien 
Oudemans, correspondant of the academy for the section 
of geography and navigation, and of Jacques Augustin 
Normand, correspondant for the same section.—The nature 
of the atmospheres of Mercury and Venus: P. Salet. 
Details are given of the method of observation by which 
it has been found that the light from Mercury is not 
sensibly polarised. It was shown by Landerer in 1892 that 
the light from Venus is similarly not polarised. The 
author concludes that it would be premature to draw con- 
clusions as to the nature of the atmosphere of Mercury 
from this result.—A formula applicable to the times of 
direct rotation of the planets and the sun: Emile Belot. 
The formula proposed is 
i 
where T is expressed in hours, a is the distance from the 
centre of the system, D the diameter of the planet in 
diameters of the earth, and d the density with respect to 
water. The times are calculated from this formula in ten 
cases, and the causes of the two large deviations observed, 
the sun and moon, discussed.—A method in the calculus 
of variations: M. Hadamard.—Partial differential equa- 
tions of the second order with two independent variables 
admitting a group of odd order of transformations of con- 
tact: J. Clairin.—The extinction of friction: L. Lecornu. 
The motion is considered of a system of homogeneous 
spheres having their centres fixed, and which exercise 
given mutual pressures at their points of contact. It is 
shown that this system, once set in motion and left to 
itself, has the peculiar property that the work of friction, 
with respect to the unit of time, tends constantly to 
diminish. This theorem still holds when, for one or more 
of the points of contact, the sliding is replaced by a 
rolling.—The unsymmetrical modification of some absorp- 
tion bands of a crystal under the action of a magnetic 
field: Jean Becquerel.—The variation of ferromagnetism 
with temperature: Pierre Weiss. A theory of ferro- 
magnetism is given based on a simple hypothesis concern- 
ing the mutual actions of the molecules. Experiments 
have been carried out on magnetite, which previous experi- 
ments had shown to be sensibly saturated in a field of 
500 Gauss, and of which the temperature corresponding to 
the disappearance of magnetism, 587° C., is easily 
accessible. The curve drawn from the theory is given, 
and on the same diagram ten experimental points are 
shown. The correspondence is very close at one tempera- 
ture only, that of solid carbonic acid, there being a sensible 
deviation from the curve.—The negative charge at a dis- 
tance of a metallic plate illuminated in an electric field: 
Mme. Baudeuf.—The cryoscopy of colloidal solutions of 
ferric chloride: G. Malfitano and L. Michel. The 
authors have shown the possibility in previous papers of 
using a collodion filter to separate the fine particles from 
the liquid in which they are suspended, and in the present 
paper apply this method to determine the lowering of the 
freezing point of the latter, considered apart from the 
small particles. In this way they find that the cryoscopic 
effect of the suspended particles is so small as to be beyond 
experimental measurement. In this case, at any rate, the 
magnitude of the suspended particles cannot be determined 
by cryoscopic methods.—The absolute atomic weight of 
dysprosium: Gustave D. Hinrichs. A discussion of the 
experimental results of G. Urbain. The atomic weight of 
dysprosium is assumed to be 162-5 exactly; the experi- 
mental figures and those based on this assumption are 
compared, and the deviations noted.—A colloidal compound 
of thorium with uranium: Béla Szilard. The compound 
described is obtained by heating precipitated thorium 
hydrate with solutions of uranium salts.—The action of 
alkaline silicates on soluble metallic salts: Robert 
Dollfus. A description of the phenomena observed when a 
crystal of ferrous sulphate is thrown into a solution of 
sodium or potassium silicate. The experiment has some 
NO. 1940, VOL. 75 | 
analogies with the culture of the artificial cell described by 
Traupe and by Stéphane Leduc.—The definite compounds 
formed by chromium and boron: Binet du Jassonneix. 
The ingots obtained by reducing chromium oxide by boron 
in the electric furnace contain two compounds, Cr,B, and 
CrB, both of which dissolve in a medium containing less 
boron, and which can only be isolated in a state of purity 
from nearly homogeneous ingots, the composition of which 
nearly corresponds to the substance required.—The 
anhydrous protoxides of the alkaline metals: E. Rengade. 
By applying to rubidium, potassium, and sodium the 
method previously used to obtain the oxide of casium, 
Cs,O, the lower oxides of these metals, possessing the 
general formula R,O, have been obtained in a pure state. 
—Some sulphates of tetravalent vanadium: Gustave Gain. 
—The use of special steels for rivets: G. Charpy. A 
systematic study of the thermal and mechanical properties 
of various alloys of steel has led to the use of a chrome 
nickel steel for rivets, the strength of which is 2-5 times 
that of the metal usually employed for this purpose, and 
this without the need of any special precautions in prac- 
tical use.—Some methods of estimating nitriles and 
carbamines; H. Guillemard.—A new method for estim- 
ating free sulphur: E. Berger. The sulphur is dissolved 
by fuming nitric acid to which a little potassium bromide 
has been added. This reagent acts in the cold, and in a 
few minutes.—The molecular weight of elaterine: A. Berg. 
The author has repeated his determinations of the mole- 
cular weight of elaterine, with the result of confirming his 
earlier views. The formula would appear to be C,,H,,O,. 
—Contribution to the study of the hydroxamic acids: R. 
Marquis. Benzhydroxamic acid, treated with thionyl 
chloride, gives phenyl isocyanate by a kind of Beckmann 
transformation. Salicylhydroxamic acid behaves differently, 
oxycarbanil being quantitatively formed.—A new method 
of formation of organic compounds of phosphorus: J. 
Berthaud. White phosphorus, heated with an alcohol in 
a sealed tube at 250° C., after some hours completely dis- 
appears. Among the products of the reaction are phos- 
phines, hydrogen phosphide, some phosphinic acids, and 
tetralkylphosphonium hydrate, the latter being the chief 
product.—The experimental reproduction of lithospherical 
folding: M. Hirtz. The effects of the gradual contraction 
of a planet are imitated by a layer of paraffin enclosed 
between two distended rubber spheres, the internal one 
being slowly deflated, and the contact of the external sphere 
with the paraffin being maintained by external pressure. 
The surfaces thus produced are compared with the surface 
of the moon.—The origin of helicoidal windings in crystal- 
lised bodies: Fred. Waltlerant.—Corrosion figures: P. 
Gaubert. A study of the corrosion figures produced on 
phthalic acid crystals by mixtures of alcohol and water.— 
A new mineral species, nepouite, a hydrated silicate of 
nickel and manganese: E. Glasser. The mineral was 
found in New Caledonia. The analyses lead to the com- 
position 2SiO,,3(Ni,Mg)O,2H,O. The name of nepouite is 
proposed from the place Nepoui, the locality where it was 
first observed.—The experimental reproduction of the 
mycetoma with black seeds: E. Pinot.—The nature of the 
latent life in seeds and on the true characters of life: Paul 
Becquerel.—Luminous radiations and the richness of 
wheat in nitrogen: J. Dumont. The radiations at the 
blue end of the spectrum are those possessing the greatest 
effect in causing the migration of nitrogenous materials, 
especially gluten, in seeds.—The influence of the valency 
of metals on the toxic power of their salts: Henri 
Micheels.—The genesis of proteid materials by a patho- 
genic microorganism at the expense of definite chemical 
substances: J. Galimard and L. Lacomme.—A new 
species of the genus Icticyon (Speothos) coming from the 
equator: E. L. Trouessart.—The influence of the geo- 
graphical situation on the development of height in man: 
Eugene Pittard. A study in the Canton Valais, Switzer- 
land, of the effects of soil, altitude, and aspect upon the 
human height.—Researches on nutrition balance of nitrogen 
and common salt: M. Letulle and Mlle. M. Pompilian. 
—An apparatus for administering chloroform. The Roth- 
Droeger apparatus: M. Guglielminetti. The regular dis- 
tribution of chloroform in the tissues when using an air- 
chloroform mixture of known proportions is based on the 
assumption that the breathing is regular. The apparatus 
