ba 
May 21, 1885] 
NATURE 
71 
their distribution and intensity with those of the hydrogen rays, 
by M. A. Cornu.—On the electric conductibility of solid mer- 
cury and of pure metals at low temperatures, by MM. Cailletet 
and Bouty. From numerous experiments made with mercury, 
silver, tin, aluminium, magnesium, copper, iron, and platina, 
the authors conclude that the electric resistance of most pure 
metals decreases regularly when the temperature is lowered from 
o to —123, and that the coefficient of variation is apparently 
much the same for all. It seems probable that the resistance 
would become extremely slight at temperatures lower than 
—200°, although this point has not yet been practically tested. 
Note on the action of aluminium on the chloride of aluminium, 
by MM. C. Friedel and L. Roux.—An inquiry into the reason 
which renders mechanical exciters incapable of bringing into play 
the excito-motor regions of the brain proper, by M. Vulpian.— 
Remarks on MM. A. F. Marion and G. de Saporta’s ‘‘ Eyolu- 
tion of the Vegetable Kingdom,” by M. Duchartre.-—On a 
method of reconnoitring the enemy’s position at great distances 
with a description of the telemetrograph, an instrument invented 
for carrying out these operations (one illustration), by M. A. 
Laussédat.—On the cure of progressive myopy by the processes 
of iridectomy and sclerotomy, with remarks on the theory of this 
ophthalmic affection, by M. H. Dransart.—Note on the theory 
of the figure of the earth, by M. O. Callandreau.—Remarks on 
a new and accurate method of astronomic observation by means 
of a fixed lunette attached to the meridian, by M. Ch. von Zenger. 
By this simple process the angle of position and the distance of 
the double stars may be determined and measurements taken of 
the parallax of the sun or the stars. For simple observations a 
precision of o’’o2 may be relied upon which is considerably 
greater than that hitherto obtained by the use of the most accurate 
and powerful meridian lunettes.—Results of experiments under- 
taken at the national powder mills of Pont-du-Buis with 
the regulating apparatus of two turbines for the purpose 
of testing the conclusions deduced from M. Léaute’s memoir 
on oscillations at long intervals in machinery set in motion 
by hydiaulic agency, by M. A. Bérard.—On the polarisation 
of the metallic capillary tubes by the flow of fluids under 
high pressure, by M. Krouchkoll. When a conducting fluid 
is driven through a capillary metallic tube at a_ pressure 
of less than fifteen atmospheres, the tube and the fluid 
being placed in communication with the mercury of a capillary 
electrometer, no polarisation of the tube takes place. But if 
the pressure be raised, the author shows that the tube begins to 
become polarised, the polarisation increasing with the pressure. 
—Description of a new electric pile, at once simple and cheap, 
which has been named the “ self-accumulator”’ by the inventor, 
M. Jablochkoff. For this pile it is claimed that it emits no 
odour, that it utilises the local curréats which are so troublesome 
in ordinary piles, and especially that it supplies electric power 
at a very low price, for in it filings, cuttings, and other waste 
forms of metals may be employed.—On the tensions and critical 
points of some vapours, by MM. C. Vincent and J. Chappuis. 
The author's observations are here confined to hydrochloric 
acid and the chloride of methyl, the object being to show 
how the maxima tensions of a series of liquefied gases 
vary with the temperature, to determine the critical points 
of these products, and to compare the results obtained 
for the purpose of verifying the hypotheses advanced by 
MM. Nadejine and Pawlowsky. — Note on the oxy- 
chlorides of aluminium, by MM. P. Hautefeuille and A. 
Perrey.—On the apparent volatilisation of silicum at a tempera- 
ture of 440°, by MM. P. Hautefeuille and A. Perrey.—Note on 
a method of preparing arsenical acid, and on the existence of com- 
binations of arsenious and arsenical acids, by M. A. Joly.—On the 
limit of combination for the bicarbonates of magnesium and 
potassium, by M. R. Engel.—On a hydrochlorate of proto- 
chloride of chromium, by M. Berthelot.—A calorimetric study 
on the effects of the tempering and cold-hammering of cast 
steel, by M. Osmond.—Remarks on the mineralogical consti- 
tution of the Sierra Nevada of the Iberian Peninsula, by 
M. Guillemin-Tarayre.—On the liberation of carbonic acid and 
the absorption of oxygen by leaves kept in dark places, by MM. 
P, P. Dehérain and L. Maguenne.—Note on a new gutta-percha 
plant, by M. E. Heckel. As a substitute for the Isonandra 
gatta, Hooker, which is threatening to disappear, the author 
_ proposes the Butyrospermum Parkit, Kotschy, which possesses 
similar properties, and which is widely diffused throughout 
is 
equatorial Africa, between Upper Senegal and the Nile basin. — 
A fresh contribution to the question of the origin of boric acid : 
analysis of the Montecatini waters between Florence and Pistoja, 
by M. Dieulafait.— On an arrangement enabling the observer to 
follow with the eye the phenomena presented by aquatic animals 
subjected to a pressure of 600 atmospheres, by M. P. Régnard. 
—On a new apparatus intended to detect infinitesimal quantities 
of blood wherever present in fluids or on solid substances, and 
named the ‘‘hema-spectroscope” by the inventor, M. M. de 
Thierry.—On pathological urines, by M. A. Villiers. —Note on a 
method for measuring the intensity of sensations, and especially 
those of colour, by M. Aug. Charpentier.—On the formation 
and development of the spores in Cladothrix dichotoma, 
by M. A. Billet.—A study of the Bacterium uree, by M. 
A. Billet.—Remarks on the cause of a new epidemic recently 
prevalent amongst the domestic ducks in the neighbourhood of 
Castres, Tarn, by M. A. Caraven-Cachin. This disease, which 
at one time raged with great violence, was ultimately traced to 
the leaves of the Adlantus grandulosa, Desf., or varnish of 
Japan, growing in the district and eaten by these birds. 
BERLIN 
Physiological Society, April 17.—Prof. Busch spoke on 
anomalies in human teeth, and illustrated his observations in 
part by preparations laid before the Society, in part by plaster 
casts. In the first place he treated of anomalies of situations 
he had observed in teeth—the horizontal position of a wisdom 
tooth, which, pressing against the third molar, produced inflam- 
mation in the latter ; the projection of teeth through the aveolar 
wall of the maxilla on the anterior or posterior side, an occurr- 
ence happening mostly in the case of permanent canine teeth 
which pushed their way through at a late period, when there 
was no place left for them in the jaw ; the exchange of situation 
between the canine tooth and the first bicuspid in the order of 
the teeth. Another kind of anomalies respected the number of 
the teeth, especially of the incisors. Instead of the normal 
number of four in each jaw, five were now and again ob- 
served, and in a few, very rare, cases, aS many as six. 
On the other hand, there were cases of only two in- 
cisors with a correspondingly large lacuna. ‘The failure of 
the wisdom tooth was not a rare occurrence. Anomalies of 
dental structure the speaker illustrated by pieces of ivory, which 
presented very remarkable deviations from the normal course of 
their fibres. In human teeth there had to be considered under 
this head enamel pearls, that is, smaller or larger round drops of 
enamel adhering to the roots, and having no connection with the 
crown. Anomalies of size were very rare. The breadth of the 
physiological variations amounted to about 3 to 5mm. Now 
and again, however, enlargements were observed as high as 
10 mm., and diminutions as low as too’9 cm. Inthe latter case 
crown and root had each transformed itself into the shape of a 
cone. Enlargements affected the root more frequently than the 
crown. Anomalies of the root were sometimes seen in curves 
shaped like an S$ or hook, but more frequently in the increase or 
diminution of the number of the roots. More than five out- 
spread roots, more or less perfect, had never been observed. 
Molars of the lower maxilla were not unfrequently found with 
three, and bicuspids with two separate roots. In incisors and 
canine teeth divisions of the tips of the roots were occasionally 
found with two pulps, or more or less deep segmentations. A 
diminution, as well as an increase in the number of the roots 
had also been observed; yet was the coalescence of separate 
roots of rarer occurrence than their increase by splitting. The 
frequency of the anomalies referred to was not great. Out of 
nearly 11,000 teeth examined, only about 100 anomalous 
specimens had been found. Still more seldom did swellings 
occur on the teeth. These were sometimes soft, and consist- 
ing of connective tissue ; sometimes completely calcified with- 
out containing one of the tooth tissues differentiated ; sometimes 
situated on the crown, sometimes on the root. These Odontoma, 
like the teeth themselves, were always to be found in particular 
grooves of the maxilla. No osseous coalescence of the teeth and 
maxilla had ever been observed. At the close the speaker pro- 
duced casts of gums which showed very considerable variations 
in their curves, ranging from an entirely flat up to a highly 
arched form.—Prof. Christiani communicated briefly the results 
of experiments carried out by Herr Gnezda on the poison of the 
cobra di capello (Waja trifudians). The poison was obtainedin 
India by causing the snakes to bite into snails or mussels 
wrapped in gutta-percha and filled with water. The watery 
solution thus obtained was reduced by evaporation. Of its 
physical and chemical qualities it was to be remarked that the 
