416 

NATURE 
[JUNE 10, 1915 

The absorption coefficients are proportional to the 
amounts of electronic radiation liberated, and, there- 
fore, the absorptions of two elements, when equal 
numbers of atoms are present, will be proportional to 
the fourth powers of their atomic weights. The cor- 
puscular radiation liberated in the vapour of an 
element if it could be obtained as a monatomic vapour 
at 76 cm. can be expressed as 105 x 10° x (atomic 
weight)*, taking the corpuscular radiation in air as 
unity. The absorption coefficient of such a vapour 
would, therefore, be this number of times the co- 
efficient of absorption of air for the same type of 
X-radiation. The absorption of any element is pro- 
portional to the number of atoms present, and having 
calculated the absorption in a hypothetical vapour of 
this type, the absorption in the same element in any 
condition can be calculated by a simple density law. 
This is done for several elements (metals), and also, 
assuming an additive law, it has been calculated for 
some compounds. The agreement between the cal- 
culated values and the values obtained by different 
observers by direct experiment is close over a con- 
siderable range of radiations and absorbers.—Prof. 
O. W. Richardson ; Two experiments illustrating novel 
properties of the electron curreats from hot metals. 
The first demonstrates the cooling of a tungsten fila- 
ment when an electron current is allowed to flow from 
its surface. This effect is analogous to the cooling 
due to latent heat when a liquid evaporates. An ex- 
perimental lamp containing a fine filament of double 
tungsten is placed in one arm of a balanced Wheat- 
stone bridge actuated by the current which heats the 
wire. When the electron current is allowed to flow, 
by completing a side circuit from an electrode inside 
the lamp to a point in the adjacent arm of the bridge, 
the galvanometer is deflected in a direction which 
corresponds to a reduction of the resistance (and tem- 
perature) of the hot filament. The second, in which 
a similar experimental lamp is used, demonstrates 
the flow of electron currents from a hot filament to a 
surrounding cylinder against various opposing P.D.’s 
up to about 1 volt. On account of the large currents 
from tungsten this effect can easily be shown on a 
galvanometer. The data can be used to find the 
velocities of the emitted electrons.—Prof. Ernest 
Wilson: Experiments on high permeability in iron. 
1. When iron is subjected to a strong magnetic force 
it has the effect of reducing the permeability and 
increasing the hysteresis loss for given values of the 
magnetic induction. The effect can be largely re- 
moved by careful demagnetisation. It was thought 
that the earth’s magnetic force might also have a 
polarising influence upon exposed iron, and an effort 
has been made to remove it by placing the specimen 
in a magnetic shield, and carefully demagnetising it. 
The permeability corresponding to small values of the 
magnetic induction is thereby considerably increased, 
and the hysteresis loss diminished. After a long 
period of rest in the shield the permeability has 
diminished, and on taking the specimen out of the 
shield it maintains its high value. 2. As regards 
higher forces, the specimen in this case is not shielded, 
but is subjected to a magnetising force during the 
time that it is allowed to cool through the tempera- 
ture of recalescence. Either with an alternating or 
steady magnetic force a maximum value of the per- 
meability of more than 10,000 is obtained. The 
material has been tested in the form of laminated 
squares or rings. With straight strips 8 cm. long, 
I'5 cm. wide, and 0’053 cm. thick, built into the form 
of test pieces, the effect, though produced, could not 
be maintained, and the specimen with ordinary 
handling was reduced to the normal state.—T. R. 
Merton: An experiment showing the difference in 
NO. 2380, VOL. 95] 

width of the spectrum lines of neon and hydrogen. 
By ‘‘crossing’’ a Fabry and Perot étalon with a 
single prism spectroscope it is possible to discriminate 
between lines arising from different elements by the 
“visibility of the fringes.’ In the experiment a 
vacuum tube containing neon and _ hydrogen. is 
examined in this way. The neon lines, being narrow, 
show sharp interference fringes, but for the hydrogen 
lines, which are broader, the limiting order at which 
interference can be seen is too low for fringes to be 
visible. 
CAMBRIDGE. 
Philosophical Society, May 10.—-Prof. Newall, presi- 
dent, in the chair.—W. H. Mills: 1. The ketodilactone 
of benzophenone-2 : 4: 2’: 4’-tetracarboxylic acid. 2. 
The synthesis of 1 : 5-dibromo-3-isopropylpentane.—Dr. 
H. B. Fantham and Dr. Annie Porter: Further experi- 
mental researches on insect flagellates introduced into 
vertebrates. Herpetomoniasis can be induced in various 
warm- and cold-blooded vertebrates when the latter 
are inoculated or fed with herpetomonads occurring in 
the digestive tracts of various insects. The infection 
produced and the protozoal parasites found in the 
vertebrates resemble those of human and canine leish- 
maniases. An infection can also be induced in certain 
vertebrates when they are fed or inoculated with 
Crithidia gerridis, and both flagellate and non-flagel- 
late stages occur therein, but no transition to a 
trypanosome was found. The following Flagellata 
have proved pathogenic to warm-blooded mammals 
when the latter have been fed, or inoculated sub- 
cutaneously or intraperitoneally with them: Herpeto- 
monas jaculum, H. stratiomyiae, H. pediculi, and 
Crithidia gerridis. The hosts used were mice of 
various ages. That H. ctenocephali can infect dogs 
has already been shown by the authors. Herpeto- 
monas jaculum and Crithidia gerridis have also been 
successfully fed or inoculated into cold-blooded hosts, 
namely, fishes (Gasterosteus aculeatus), frogs, toads, 
lizards (Lacerta vivipara), and grass snakes (Tropi- 
donotus natrix). The authors believe that leish- 
maniases are arthropod-borne herpetomoniases, and 
that these maladies have been evolved from flagellates 
of invertebrates (especially herpetomonads of insects) 
which have been able to adapt themselves to life in 
vertebrates.—Sir G. Greenhill: Note on Dr. Searle’s 
experiment on the harmonic motion of a rigid body.— 
W. A. D. Rudge: The electrification given to the air 
by a steam jet. 
DUBLIN. 
Royal Dublin Society, May 18.—Prof. Wm. Brown 
in the chair.—Prof. G. T. Morgan and G. E. Scharff: 
Certain preliminary experiments in the utilisation of 
peat tar. Specimens of peat tar obtained from the 
hydraulic scrubbers of a producer plant burning peat 
were distilled fractionally and subjected to a pre- 
liminary chemical examination. The distillates con- 
sisted in the main of neutral (non-acidic) oils, con- 
taining a notable proportion of unsaturated com- 
pounds. The presence of these unsaturated sub- 
stances was manifested by the following properties : 
absorption of bromine or of atmospheric oxygen, 
decolorisation of permanganate and interaction with 
chromic or nitric acid. The fraction boiling at about 
300° deposited, on cooling, crystals of wax melting 
at 35-42°; this material, when. thoroughly drained 
from oil, was almost colourless. On washing the 
crude oils distilled from peat tar with dilute mineral 
acid a small proportion of ammonia was removed, 
together with pyridine and other organic bases. Ex- 
traction of the crude oils with aqueous alkali hydr- 
oxides and subsequent treatment of the alkaline 
liquor with dilute mineral acid led to the separation 
