866 
NATURE 
[JUNE 23, 1923 

Societies and Academies. 
Lonpon. 
Royal Society, Jume 14.—C. Chree: Magnetic 
phenomena in the region of the south magnetic 
pole. Magnetographs were in simultaneous operation 
from April to October 1912, at the base stations of 
the British and Australasian Antarctic expeditions 
on opposite sides of the south magnetic pole. A 
comparison is made of the regular diurnal inequalities 
and the amplitudes of the absolute daily ranges 
of the magnetic elements at the two stations. The 
data show the remarkable sensitiveness of the regular 
diurnal variations in high latitudes to the presence 
of magnetic disturbance. The results are also 
applied to the question of a suitable criterion for 
the daily activity of magnetic disturbance.—O. R. 
Howell: The catalytic decomposition of sodium 
hypochlorite by cobalt peroxide. The rate of de 
composition of sodium hypochlorite solution by 
cobalt peroxide is directly proportional to the amount 
ot peroxide present. It is accelerated by sodium 
salts and (in the case of sodium chloride) is directly 
proportional to the square root of the concentration 
of sodium ions present. The mechanism of the 
reaction probably consists in the linkage of hypo- 
chlorite ions to the positive oxygen, and sodium ions 
to the negative oxygen of the peroxide, with im- 
mediate decomposition of the quadrivalent oxygen 
compound. With a fixed amount of hypochlorite 
the rate is then proportional to the degree of ad- 
sorption of the sodium ions. The rate is retarded 
by alkali and the retardation is proportional to the 
adsorption of hydroxyl ions, The average tempera- 
ture coefficient of the reaction between 25° and 50° 
1s 2°37 and the Arrhenius activation coefficient E 
is 16,574. The catalyst is not affected by any of 
the common catalytic poisons.—N. M. Hosali: On 
seismic waves in a visco-elastic earth. Seismic 
waves are subject to damping and dispersion de- 
pendent on the period. For each type of wave— 
dilatational, distortional, or surface—there exists a 
minimum period below which a wave cannot be 
transmitted, and for any period above the minimum 
two distinct waves can be propagated, one heavily 
damped and slow travelling and one lightly damped 
and quick travelling. Observations indicate that if 
the material in the outer layers of the earth obey 
the theory here developed it should have a viscosity 
of order ro® or 10° C.G.S. units. This would have 
no appreciable effect on the velocity of propagation 
of earthquake waves.—J. W. Landon and H. Quinney : 
Experiments with the Hopkinson pressure bar. 
With a bar of uniform diameter the pressure wave 
produced by detonation of gun-cotton is considerably 
distorted as it is propagated, but the rate of distortion 
decreases as the wave travels along the bar. Pressure 
falls away rapidly as distance from the axis of the bar 
increases. To determine the maximum pressure 
produced in the detonation of gun-cotton the bars 
were submitted to special heat treatment in the 
hope that overstrain might be reduced. A sub- 
stantial improvement was observed except in so far 
as the life of the bars was increased. The highest 
maximum pressures recorded we1e 117 tons per 
square inch for a 1-ounce gun-cotton primer in 
contact with the end of the bar, and 82 tons per 
square inch with the primer ? inch away from the 
end. These results were obtained with a short bar 
of j-inch diameter. With concrete bars the pheno- 
mena exhibited are the same in general as with 
steel bars, except that the front of the wave appears 
to be entirely obliterated, and only the part in which 
NO. 2799, VOL. 111 | 


pressure is less than the crushing stress of the concrete 
is propagated along the bar.—S. F. Grace: Free 
motion of a sphere in a rotating liquid at right angles 
to the axis of rotation. The density of the sphere 
is equal to that of the liquid, and the motion. 
a small disturbance from one,of uniform rotation 
like a rigid body. The motion of the centre of the 
sphere is wholly in a plane perpendicular to the axis 
of rotation, and the disturbed motion of the liquid 
is symmetrical with respect to this plane. The 
path of the centre of the sphere is a spiral with a 
definite pole. The sphere winds round the pole in 
a direction opposite to that of the rotation of the 
liquid, the motion being such that the time of a 
complete turn tends to become constant and equal 
to one-half the time of a revolution of the undisturbed 
liquid. At points along the prolongation of the 
polar axis of the sphere the motion is parallel to 
the equatorial plane and is a maximum at the sphere. 
Parts of the solution are not applicable for large 
values of time.—B. F. J. Schonland: The passage 
of cathode rays through matter. The absorption 
of cathode rays of velocity 6 x 10%-1-2 x ro” cm./sec. 
in various metals has been studied with an arrange- 
ment designed to eliminate imterfereace from 
secondary rays and to measure both the fraction of 
the beam passed through and that actually absorbed 
in the foil. The latter fraction varies with thickness. 
and velocity in the same manner for all elements ; 
the nature of the variation of the former depends 
upon the absorbing material. The results are ex- 
plained by applying the theory of absorption due 
to Bohr, with which they are in quantitative agree- 
ment. : 
Association of Economic Biologists, April 27.— 
C. M. Wenyon: Recent observations on parasitic 
Protozoa in animals and plants. Certain parasitic 
Protozoa, such as the Coccidia, and some Hzmo- 
gregarines, which are inhabitants of the intestinal 
canal or wall of the intestine of vertebrates, and pass 
from host to host in the encysted form which escapes 
in the dejecta, have become so modified in the course 
of evolution, that they are no longer transmitted 
by means of cysts but are carried by bloodsucking ~ 
invertebrates. It is probable that the well-known 
parasites of malaria are modified Coccidia. Intestinal 
flagellates, such as Trichomonas, which are normally 
inhabitants of the lumen of the intestine, may occasion- 
ally enter the blood stream. Reichenow has shown 
that in the lizard the entry of the intestinal flagellate 
Eutrichomastix into the blood may lead to infection 
of the mites, which again give rise to an intestinal 
infection of lizards which devour them. Bene 
flagellates of insects like the flea or flies whic 
usually live only in the invertebrate, may establish 
themselves in the intestines of vertebrates which 
eat them. Thence they may invade the blood of 
the vertebrate and are undoubtedly ingested by 
blood-sucking insects. It is possible that the parasite 
of the disease “Kala azar’’ of man may be an 
insect flagellate which enters man by way ot the 
mouth, gains access to his intestine, and thence 
invades his tissues. Plants may be infected in like 
manner, for flagellates of the typically insect type 
have been found in various species of Euphorbia 
and other plants, and it has been shown by Franca 
that they are derived from bugs which feed upon 
the plants. M.S. G. Breeze: Some causes of sterili 
in Solanaceous plants due to Protozoa and Chytri- 
diaceous parasites. The plants investigated were 
varieties of potato and petunia, and the following 
points were noted : (1) An Ameceba, similar to Ama@ba 
gleba, attacks potato flowers virulently though without 
