44 
NATURE 
[SEPTEMBER 14, 1916: 
rocks.—-M.- Friedmann; The vortices in’ a ‘liquid’ at 
variable temperature.—L, Hartmann; The determina- 
tion of the mechanical equivalent of heat by~ the 
method of Hirn. It is shown that‘ the «hypothesis 
which forms the basis of the determination of Hirn 
is not confirmed by experiment.—C, Camichel; The 
amplitude of the odd- harmonies in the strokes of a 
hydraulic ram.—G. A. Le Roy; A reagent for free 
chlorine in drinking water. The amount of free 
chlorine in drinking water which has been purified by 
means of hypochlorites is at present controlled by the 
well-known iodide of starch reaction, The new re- 
agent suggested, which has a higher sensibility than 
the iodide of starch, is the chlorohydrate of hexa- 
methylparaminotriphenylmethane. The violet colour is 
formed immediately, and its intensity is proportional 
to the amount of free chlorine present. Water con- 
taining only three hundred millionths of chlorine gives 
a visible reaction with the new reagent; about three 
times this quantitv is necessary to show the iodide of 
starch reaction. Details for the preparation and use 
of the reagent are given. 
Care Town. 
Royal Society of South Africa, July 19.—Dr. L. 
Péringuey, president, in the chair.—E. J. Goddard ; 
Pelodrilus africanus, a new Haplotaxid from South 
Africa. The species here described constitutes the first 
representative of the family Haplotaxidz recorded from 
South Africa. Of the two genera included within this 
family, one—Haplotaxis—is represented by fresh-water 
species in Europe, North America, and New Zealand, 
while the remaining genus—Pelodrilus—is represented 
in New Zealand by a species inhabiting damp earth. 
The African species is to be included in the latter 
genus. The specimens were obtained in mud on 
Sneeuw Kop, near Wellington, Cape Province, at an 
elevation of 5000 ft. above sea-level. ‘The length varies 
from 20 to 40 mm.—Paul A. van der Bijl: Note on 
Polysaccum crassipes, a common fungus in Eucaly ptus 
plantations around Pretoria. Polysaccum crassipes is 
so common in Eucalyptus plantations around Pretoria 
that it appeared interesting to determine in what rela- 
tion it stood to the Eucalypti. The investigation was 
begun at the Botanical Laboratories, Pretoria, and 
afterwards concluded at the Natal Herbarium, Durban. 
The morphology of the fungus is briefly dealt with 
and followed by suggestions which indicate that the 
relation between the fungus and host is one of sym- 
biosis. 
CaLcuTTa, 
Asiatic Society of Bengal, August 2.—Dr. N. Annandale : 
Zoological results of a tour in the Far East. I., The 
Mollusca of Lake Biwa, Japan. Lake Biwa, as might 
be expected from its geographical position and from 
what is known of the fauna of Japan genérally, seems 
to be, so far as the Mollusca are concerned, the meet- 
ing- ple ice of two lines of migration, one coming from 
the north, the other from the south. 
BOOKS RECEIVED. 
Index of Genera and Species referred to, and an 
Index to the Plates, in the Ibis (seventh, eighth, and 
ninth series), 1895-1912. Pp. 513. (London: British 
Ornithologists’ Union; W. Wesley and _ Son.) 
tl. 12s. 6d. 
Cradles or Coffins? By J. Marchant. Pop. 96. 
(London: C, A. Pearson, Ltd.) 1s. net: 
First Course in General Science. By Prof.. D. 
Barber and others. Pp. vii+607. (New York: H. 
Holt and. Co.) 
Cleator and Cleator Moor, 
NO. 2446, VoL. 98] 
Past and Present. By 
Rev.' Cesar'.€aine: | Pp. xviii +475- (Kendal: Ty 
Wilson.) 21s. net: ./* 
Earliest’ Man. ‘By F, W. H, Migeod. Pp.- xii+ 132, 
(London :' Kegan Paul and Co., Ltd.) 3s: 6d. net. ~ 
The Principles of Electrical Engineering and their- 
“pete By. Prof. G. Kapp. : Vol. i., Principles.” 
Pp. xii+356. “(London: E. Arnold.) 15S. net. teas 
The Bleiee of Non-Euclidéan Plane Geometry: ‘and 
Trigonometry. By Prof. H. S. Carslaw. Pp. ‘=e 
(London: Longmans and Co.) 5s. net. 
Royal Society of Arts. Cantor Lectures on Optical 
Glass. By Dr. -W. Rosenhain. (London: Royal’ 
Society of Arts.) Is. 
Raphael Meldola: Reminiscences of his Worth and 
Work. Edited by J. Marchant. Pp. xv +225. (Lon- 
don: Williams and Norgate.) 5s. net. 
Tree Wounds and Diseases: their Prevention and 
Treatment, with a special chapter on Fruit Trees. 
A. D. Webster. Pp. xx+209. (London : Williams and 
Norgate.) 7s. 6d. net. 
Mathematical Papers for Admission into the Royal 
Military Academy and the Royal Military College. 
February-June, 1916. By R. M. Milne. Pp. 30. 
(London: Macmillan and Co., Ltd.) 1s. net. 
Manual of Russian Commercial Correspondence. By 
; 
i 
4 
M. Sieff. Pp. xx+232. (London: Kegan Paul- and — 
Go.; Ltd.) 35.' 6d. nets 
| Sia a 4 
CONTENTS. PAGE 
A System of Physical Chemistry. By Prof. F. G._ 
Donnan, F.R.S. > 25 
The Flora of All Africa. “By Dr. W. Botting Hemsley, 
Hons .; sate Be oe 
Christianity in Partibus ae % ee 
por Bookshelf... -: a): | 
Letters to the Editor:— 
The Group Vermidea.—Dr. Sidney F. Harmer, , 
F.R.S. + aes 
The Refractometry of Lenses, ty Cc. “Martin . «ete aa 
An Oil Drive for Equatorial Telescopes. (Z//ustrated.) 4 
—Scrfiven Bolton. ieee... . . 
On the ‘‘Wolf-note” of the Violin and ’Cello.— — 
A. M. Tyndall; G. W. White ....... 29 
Birds in Studio and on the Hillside. (Jilustrated.) . 30 
Scientific Method in Brewing Practice ...... 31 
The British Association at Newcastle. . . 33 
Section B. — Chemistry ee Address (Abridged) 
by Prof. G. G. Henderson, D.Sc., LL.D., — 
F.R.S., President of the Section . - ete 
Notes. . Soo Se! 
Our Astronomical Column :— } 
Measurement of Close Solar Lines .... . » an. ae 
Spectra and Absolute Magnitudes of Stars... .. 41 
Observations of Minor Planetsin France .. . 41 
The Maritzburg ee eg of the South African Asso- 
ciation, ByC. F + a 
Economic History of the United States . - oe 
University and Educational Intelligence . ove ae 
Societies and Academies ......,.. - opeenee 
Books Received.\; ==. «>: eee; . 44 
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