394 
NATURE 
[JUNE II, 1914 
plates or prisms. The general behaviour of the sub- 
stance indicates that it is to be regarded as an 
‘atomic’? compound, in the ordinary sense of the 
term, rather than as a compound containing hydrogen 
dioxide of crystallisation.—Prof. H. E. Armstrong and 
E. E. Walker: Studies of the processes operative in 
solutions. XXIX.—The disturbance of the equi- 
librium in solutions by ‘strong’ and by “weak ”’ 
interfering agents. The effect of a large number of 
substances on the optical rotatory power of an aqueous 
solution of fructose has been measured and the views 
put forward in No. XXVI. of these studies with 
regard to the action of interfering agents have been 
confirmed and elaborated. ‘‘Strong”’ solutes, such as 
the sugars and metallic salts, increase the negative 
rotatory power of fructose, whereas ‘‘ weak ’’ solutes, 
such as the alcohols, ketones, and ethers, decrease it. 
The observed effect of the added substance (‘‘the 
interfering agent’’) is regarded as the algebraic sum 
of two opposing factors :—(1) A diluent effect causing 
dissociation of hydrates and other complexes in solu- 
tion; (2) an influence, opposite in effect to the first, 
depending on the reciprocal chemical attractive powers 
of the molecules of solvent and interfering agents 
promoting association. A simple mathematical ex- 
pression involving these two factors has been developed 
by means of which (2) has been evaluated. This value 
is denoted by A. Thus calculated, A is found to be 
very nearly proportional to the number of atoms of 
oxygen in the molecule.—Prof. H. E, Armstrong and 
E. H. Rodd: Morphological studies of benzene deriva- 
tives. VII.—The correlation of the forms of crystals 
with their molecular structure and orientation in a 
magnetic field in the case of hydrated sulphonates of 
dyad metals.—Dr. E. E. Fournier d’Albe: A_ type- 
reading optophone. A description is given of a new 
construction of the ‘‘optophone,’’ an instrument 
capable of translating light action into sound, and 
so making light recognisable by means of the ear. 
The new instrument is intended to enable totally blind 
persons to recognise and ‘‘read”’ ordinary letterpress 
by means of the ear. It consists essentially of a 
rapidly rotating disc perforated like a siren disc with 
several concentric circles of holes. A Nernst lamp is 
placed behind the disc with its filament stretched 
radially across the circles. The light, shining through 
the holes, gives regularly recurring flashes which, 
when of suitable frequency, can be detected by means 
of selenium and a telephone. An image of this line 
of intermittently luminous dots is thrown upon the 
type to be read, and the light diffusely reflected from 
the type is received on a selenium bridge. As each 
dot has a characteristic note, the sound heard in the 
telephone will vary with every variation in the reflect- 
ing power of the surface under examination. As the 
letterpress is moved on in the direction of the line of 
type, the sound changes rapidly with every 
change in the shape of the letters, and with 
some) practice’ the: latter can’ be. “read aby 
ear. Type 5 mm. high can be thus read by means 
of an ordinary high-resistance telephone receiver. The 
effect becomes rapidly fainter as the type diminishes in 
size, but ordinary newspaper type is readable with the 
help of a highly sensitive Brown telephone relay.— 
L. H. Walter: An application of electrolytically- 
produced luminosity, forming a step towards a form 
of telectroscopy. The author has investigated the con- 
ditions under which it should be possible to make 
practical use of the luminosity of anodes of alloyed 
aluminium forming part of a “valve” cell arrange- 
ment. The alloy known as ‘‘duralumin”’ is found to 
give the best results, and with sodium tungstate 
solution as_ electrolyte, corrosion is practically 
eliminated when this alloy is used as the anode. The 
arrangement permits of the construction of an appa- 
NO: 2325, 0VOl. nog 
ratus having a multiple anode, comprising a vast 
number of equal units in quite a small compass, each 
such unit being capable of being rendered luminous 
in any order or sequence desired and at a speed of 
some hundreds of times per second. Such an appa- 
ratus is capable of being employed as a receiver in 
phototelegraphy for the reproduction of pictures, etc., 
especially where these are received as electrical im- 
pulses.—P. G. Nutting : The axial chromatic aberratioa 
of the human eye.—L. V. King: The convection of 
heat from small cylinders in a stream of fluid, and the 
determination of the convection constants of small 
platinum wires, with applications to hot-wire 
anemometry. 
Geological Society, May 27.—Dr. A. Smith Wood- 
ward, president, in the chair—L. F. Spath: The 
development of Tragophylloceras loscombi, Sow. 
During his investigation of the Charmouth Lias, Mr. 
W. D. Lang collected fossil material with reference 
to its exact stratigraphical horizon. In the material 
Tragophylloceras loscombi, Sow., is represented by 
hundreds of specimens (chiefly young), and a study is 
given of the ontogeny of this ammonite. A number 
of specimens were dissected back to the protoconch, 
and their development traced in detail. Tables of 
measurements are given, and the other species of the 
genus are reviewed. The evolution of the suture-line 
was worked out in detail, and an important point 
brought out was the demonstration of a_ simple 
Psiloceras-like suture-line persisting to a late and post- 
constricted stage. The development of the suture-line 
in Psiloceras and Rhacophyllites is given for com- 
parison.—Prof. P. Marshall: The sequence of lavas at 
the North Head, Otago Harbour, Dunedin (New 
Zealand). The North Head forms a precipitous cliff 
ranging from 300 to 530 ft. in height; it presents a 
clear section of a succession of lava-flows, including 
trachyte, trachytoid nhonolites, kaiwekites, trachy- 
dolerites, and basalts. It appears that all the lavas 
were erupted from the same vent. Each sheet is 
covered by a bed of scoria, the coarseness of which 
proves that the centre of volcanic activity was not far 
distant. The lowest lava is a trachyte composed 
entirely of anorthoclase-felspar, and is succeeded by a 
phonolite in which sanidine is the conspicuous mineral. 
This is followed by a series of ten basalts of moderately 
basic character. The next flow is a kaiwekite, a lava 
of entirely different type, in which a hornblende allied 
to barkevikite forms the largest crystals. The basalts 
are succeeded by a phonolite which contains a few 
phenocrysts of anorthoclase. It is pointed out that in 
the lowest trachyte lime and magnesia are practically 
absent, but that the phonolite, although still deficient 
in these constituents, shows a distinct advance. The 
basalts as a whole are low in magnesia and above 
the average ia alkalies. In the kaiwekite the alkalies 
advance, and there is an increase in silica and decrease 
in lime and magnesia. The higher basalts are some- 
what richer in alumina and poorer in lime than those 
which occur lower in the section. The majority of 
the rocks fall into well-known and readily recognised 
groups. The porphyritic rocks of intermediate com- 
position may have formed from an _ undifferentiated 
magma. The chemical composition of the inter- 
mediate lavas, as well as their mineral composition, 
would suggest that the original magma was that of 
essexite. It is important to note that in the Island 
of Tahiti, where there is a similar assemblage of 
alkaline and basic lavas, the reservoir has been laid 
bare by denudation and contains essexite as the 
dominant rock. 
Paris. 
Academy of Sciences, June 2.—M. P. Appell in the 
chair.—L. E. Bertin: The instability in steamers re- 
sulting from a collision. A statement of the advan- 
