May 27, 1915| 
NATURE 
393 

conditioned by exposure and lack of nutrient salts. 
Vegetative reproduction is caused by the high humidity 
maintained over the marsh in the intertidal periods. 
This prevents the attainment of a limiting concentra- 
tion in the cell-sap necessary as a stimulus to the 
formation of sexual reproductive organs. The cause of 
spirality is prebably unequal distribution of nutrient 
salts. The same factors were shown to be operative 
in causing the change in morphology of the floating 
Sargasso weed. Brown seaweeds may function on salt 
marshes either as pioneer vegetation, undergrowth, or 
covering vegetation after erosion, and in these capaci- 
ties often play an important part in the economy of 
the marsh.—H. N. Dixon: A collection of Borneo 
messes made by the Rev. C. H. Binstead. 
Geological Society, May 12.—Dr. A. Smith Wood- 
ward, president, in the chair.—G. Hickling and W. R. 
Doa; Parka decipiens, Fleming. The paper is a joint 
statement of originally independent investigations of 
this Old Red Sandstone organism. The views of 
Fleming, Hugh Miller, Mantell, Lyell, Powrie, Page, 
and others are quoted to illustrate the chequered career 
of this enigmatical fossil in geological literature. To 
Dawson and Penhallow, supported by Reid and Mac- 
Jair, belongs the credit of making the first serious 
attempt to obtain definite evidence as to its nature, 
and of establishing its vegetable character. The pre- 
sent account is based on the observation of great 
numbers of specimens in the field, and on the micro- 
.scopic study of impression-material, of thin sections, 
and of macerated material. _ The plant is most 
abundant in the Lower Old Red of the Kincardine- 
Forfar-Perth area, where it is by far the commonest 
fossil, especially in the shale-bands;. Parla is confined 
to the lower two-thirds of the Caledonian Series. It 
is recorded from a few other localities in central Scot- 
land, and also from the Upper Ludlow and Lower 
Old Red of the ‘‘Hereford”’ area. The organism is 
shown to be a complete cellular thalloid plant, agree- 
ing generally in its vegetative structure with certain 
alge, but differing from all known alge in the pro- 
duction of cuticularised spores. 
Institution of Mining and Metallurgy, May 20.—Sir 
T. K. Rose, president, in the chair.—J. J. Beringer : 
The physical condition of cassiterite in Cornish mill 
products. This paper was in course of preparation 
when the author contracted an illness which ended 
fatally, and as a consequence it lacks the valuable sum- 
mary of conclusions which the author would have com- 
piled as the result of his exhaustive series of experi- 
ments in a subject to which his last few years had 
been largely devoted. He had, in fact, made most 
detailed investigations into the mode of occurrence of 
the particles of cassiterite in the ores of Cornish lodes 
and in the mill products resulting from the reduction 
of those ores, with a view to reducing the losses on 
the dressing floors. The chief conditions governing 
his investigations were: the actual measurement of 
the sizes of the particles; the determination of the rate 
at which particles of various sizes settle in still water 
and against upward currents, with methods of separat- 
ing and collecting particles of a given size; the com- 
pilation of tables showing specific gravity and assay 
value of particles in relation to their size; a study of 
the action of particles of various sizes in their passage 
over various forms of concentrating machinery; and, 
finally, an investigation of some special mill-products, 
and a general study of the mineral cassiterite as found 
in some Cornish lodes. For reporting the mean diameter 
of particles as measured under the microscope the 
author used the micrometric unit of one-thousandth 
of a millimetre, and established a relationship between 
that form of measurement and a classification based 
on the rate of falling in still water and the different 
NO. 2378, VOL. 95] 

rates of upward current between which the particles 
in a mixture can be separated. The paper contains 
an attempt to give a definite size value to the much- 
discussed terms ‘“‘sand’’ and “slime,” with further 
subdivisions of the latter condition into “‘silt,”’ ‘* fine 
silt,” and ‘‘clay.”. A valuable section of the paper 
deals with the action of the material when passing 
over concentrating machinery, different types of which 
were experimented with in great detail. In an appen- 
dix are given valuable hints on the uses of the micro- 
scope in determining the size and nature of minerals, 
a subject which Mr. Beringer brought forward at a 
meeting of the institution shortly prior to the pre- 
paration of the material embodied in this paper.— 
H. F. Collins: Note on the concentration of gold in 
bottoms in the converter. With a view of utilising 
the gold contents of converter copper which is not 
rich enough to make electrolytic refining profitable, by 
means of a partial oxidation of the bath of white 
metal to “ pimple’? metal and ‘bottoms,’ and the 
separation of the latter before completing the oxida- 
tion, the author devised a simple method of treatment 
which has been in actual practice for about a twelve- 
month. In this method a small acid-lined converter is 
used, provided with a taphole opposite the tuyeres, 
which, during the process of blowing to precipitate, 
is closed by a plug of clay attached to an iron rod. 
When the metal is thoroughly molten, the bar is 
withdrawn and the copper allowed to run off into 
moulds until white metal appears in the stream, when 
the taphole is closed and the converter returned to 
position for the next similar operation. The success 
of the method depends primarily on running the 
charge hot, losing no time in skimming and not 
adding too much cold scrap after skimming, so that 
the reduced copper is well above the melting point of 
‘““pimple ”” metal.—Donald M. Levy and Harold Jones : 
The Morro Velho method of assay of gold-bearing 
cyanide solutions. The method here described is 
based on the precipitation of the gold by means of a 
zinc-lead couple from the boiling solution in the pre- 
sence of suitable quantities of silver and lead salts. 
By this means, sufficient silver is introduced to yield 
with the gold a suitable parting alloy. The presence 
of the lead salts causes the preduction of a lead-zinc 
couple which facilitates the complete liberation of the 
metallic gold from solution, and yields a bulky pre- 
cipitate of the lead and values which settles easily and 
thus ensures carrying down the precipitated gold.— 
F. A. Eastaugh: The effect of different methods of 
crushing on the ash of coke. The object of the ex- 
periments here described was to find the true ash 
contents of the coke, in order to discover whether the 
discrepancies occurring so frequently between the 
amount of ash found by sellers and buyers are due to 
different methods of preparing samples for test pur- 
poses. In the experiments, all made from one parcel 
of metallurgical coke, remarkable differences resulted 
from the employment of different methods of crushing 
the samples. 
Paris. 
Academy of Sciences, May 17.—M. Ed. Perrier in the 
chair.—G. Humbert: The positive binary quadratic 
forms.__D. Eginitis: Observations of the Mellish 
comet (1915a) made at the Observatory of Athens with 
the Doridis equatorial (40 cm.). Positions are given 
for, April 8, 10, 13, 14, 15, 21, and 22.—Ernest 
Esclangon: The quasi-periodic integrals of a linear 
differential equation.—Maurice d’Ocagne : Remarks on 
the subject of circular anamorphosis.—A. Buhl: New 
geometrical applications of the formula of Stokes.— 
Daniel Berthelot : Calculation of the Despretz-Trouton 
constant. By combining the equation of Van der 
Waals with the law of the rectilinear diameter of 
Mathias, the ratio of the internal latent heat of 
