DECEMBER 3, 1903] 
NATURE 
109 
which Sir David Gill was himself the first to direct attention. 
And he has completely photographed, on a moderate scale, 
the Southern Hemisphere. The plates were measured in 
Holland by Kapteyn, who has published the results recently 
in a valuable work, the ‘‘ Cape Photographic Durch- 
musterung,”’ for which Kapteyn received the Royal Astro- 
nomical Society’s Gold Medal in February, 1902. It may 
be recalled that on that occasion Kapteyn expressed very 
warmly his indebtedness to Sir David Gill. 
Sir David Gill had a large share in initiating the Inter- 
national Astrographic Chart; he has also been very active 
in superintending the Geodetic Survey in South Africa. 
Royat MEDAL. 
The other Royal Medal is conferred upon Dr. Horace 
T. Brown, F.R.S., for his work on the chemistry of carbo- 
hydrates, and on the assimilation of carbonic acid by green 
plants. 
His memoir (H. T. Brown and G. H. Morris, Journ. 
Chem. Soc., 1893) on the ‘‘ Chemistry and Physiology of 
Foliage Leaves”’ is of value as confirming the rougher work 
of Sachs on the amount of carbohydrate assimilated per leaf 
area per unit of time, but especially as being the first 
thorough investigation into the manufacture and transloca- 
tion of the various sugars in the green leaf. This paper 
also contributes to our knowledge of the action of diastase 
in the leaf; and in this connection may be mentioned the 
paper on the ‘‘ Germination of the Graminee”’ (H. T. 
Brown and G. H. Morris, Journ. Chem. Soc., 1890), which 
is a valuable contribution to the study of diastase and other 
enzymes. 
His Presidential Address to the Chemical Section of the 
British Association, 1899, gave an account of work of the 
highest interest to botanists, such as the relation between 
the amount of assimilation of carbon and the partial pressure 
of the carbonic acid in the atmosphere, and the rate of 
absorption of carbonic acid by a leaf, as compared with the 
absorption by a solution of caustic alkali. These and other 
points are developed in the memoir on “‘ Static Diffusion 
of Gases and Liquids in Plants’? (H. T. Brown and 
F. Escombe, Phil. Trans., 1900), which is one of the most 
important works on assimilation by plants that we possess. 
In this remarkable essay, Brown develops the principles 
determining the amount of diffusion from gases and solu- 
tions into absorbing surfaces, and shows that leaves con- 
form in the size and number of the stomata to absorbing 
surfaces of high efficiency. 
The earliest important chemical work of Horace Brown 
was on the influence of pressure on fermentation. He dis- 
covered that other gases besides carbonic acid were given 
off in the fermentation of malt worts and of grape sugar, 
and that the hydrogen evolved increased as the pressure 
was diminished. The formation of acetic acid during the 
fermentation out of contact with air was shown to be due 
to a direct transformation of the sugar into acetic acid. 
In conjunction with Heron and Morris, he made a series 
of valuable investigations into the nature of starch and its 
transformations. He showed that the action of malt extract 
upon soluble starch might be represented by the successive 
removals of maltose by hydration (hydrolysis), the 
successively formed residues being a series of dextrins. 
He was the first to apply Raoult’s freezing-point method 
to the systematic determination of the molecular weights of 
the carbohydrates, and his measurements showed that 
soluble starch was much more complicated than the dex- 
trins derived from it, the starch molecule possibly consist- 
ing of four complex amylin-groups arranged round a similar 
fifth group. But later work on dextrinic acid led to the 
view that the starch molecule is made up of the residues of | 
80 maltan groups and 4o dextran groups, linked in ring 
form through oxygen atoms, and that the maltan portion 
of the ring is attacked by successive stages of hydrolysis, 
forming dextrins and finally maltose. The molecular weight 
of starch cannot be less, according to these experiments, | 
than 32,400. 
The investigation of ‘* secondary fermentation ’’ produced 
by a small quantity of dried hops in beer led to his im- 
portant work on the chemistry and physiology of foliage | 
leaves, in which he gives reasons for supposing that cane- 
sugar is the first sugar to be synthesised by the assimil- | 
NO. 1779, VOL. 69| 
atory processes, and that this is the starting point of the 
metabolic changes in the leaf. 
The discovery of the solution of the cell-membranes of 
grass seeds by a cellulose-dissolving enzyme secreted in the 
epithelium led him to investigate the corresponding action 
on the cell-walls of starch granules in the processes of 
animal digestion. After exhaustive experiments, he con- 
cluded that the cell-walls were attacked by an enzyme pre- 
existent in the grain. 
Davy MEDaAt. 
The Davy Medal for the most important discovery in 
chemistry is awarded to M. Pierre Curie, and Madame Curie, 
Docteur és Sciences, for their researches on radium. 
The discovery of radium—whether it be regarded from the 
point of view of the extraordinary properties of that sub- 
stance, unique in their intensity if not in their kind, or of 
the undeviating aim and invincible patience with which the 
clue to its separation has been skilfully followed, or of the 
extended, even revolutionary, views of the constitution of 
matter and of the stores and transformations of energy in 
Nature which the study of its properties is opening up to 
us—may well be characterised as the most important dis- 
covery in chemistry of the present time. 
Hucues MEDAL, 
The Hughes Medal is awarded to Prof. Johann Wilhelm 
Hittorf for his experimental researches on the electric dis- 
charge in liquids and gases, extending over a period of 
more than half a century into the present year. 
The results of his work have been published in a series 
of papers, of which the first, on the electric conductivity of 
mercury, appeared in Poggendorff’s Annalen so long ago 
as 1851, and was followed, in the years 1853 to 1859, by 
others, giving an account of his masterly investigations of 
the migrations of the ions in electrolysis. In conjunction 
with Pliicker he took up the examination of the spectra 
emitted by gases under the influence of electric discharges 
from an induction coil, and communicated the results to the 
Royal Society in 1864; and in the ensuing twenty years 
he published, from time to time, a number of papers on 
electric conductivity in gases, which have greatly contributed 
to the advancement of our knowledge of that subject. In 
1898 and 1899 he published papers on the electromotive 
behaviour of chromium and on the passive state of metals, 
and in the three years of the present century further papers 
on the rates of motion of the ions. 
It is now the jubilee of the publication of his first paper 
on the last-named subject, a paper which marks an epoch 
in our knowledge of electrolysis. In that paper, and those 
which followed it in the next five years, by his careful 
measurements of the movements of the ions in a great 
variety of cases, he laid a solid foundation on which sub- 
sequent investigators have reared a large superstructure. 
The view of the constitution of electrolytes, and of chemical 
compounds in general, to which his research directly led, 
was so contrary to that in vogue amongst chemists at that 
time that it challenged opposition, but time has vindicated 
its accuracy and importance. His researches on electric 
conductivity in gases have been almost equally fruitful, for 
they have served as the starting point from which other 
observers have advanced, and have thus led up to modifi- 
cations of our ideas of the constitution of matter quite as 
profound as those suggested by the migrations of the 
ions. 
PROF. ROBERT HENRY THURSTON. 
BY the death of Prof. Robert Henry Thurston, which 
occurred with tragic suddenness on his birthday, 
October 26, the United States has lost its most dis- 
tinguished engineering professor, and a devoted 
educationist whom it will be difficult to replace. 
He was born at Providence, Rhode Island, in 1839, 
and was the son of Robert L. Thurston, the founder 
of the Providence Steam Co. His early training was 
of that twofold character which has been so much 
discussed during the last year or two, a collegiate 
education at the Brown University, where he gradu: 
