332 
NAT ORE 
[May 28, 1914 
Ross in regard to his discoveries in connection with 
deadly tropical diseases. Science was everything to 
industry, and man found that money profits could be 
made by taking advantage of the advances of science. 
He was an optimist about industry, but he could not 
be an optimist when he looked round and saw mem- 
bers of his profession who had laboured for nothing, 
scarcely even the thanks of the public, certainly with- 
out those rewards for which those engaged in industry 
rightly and properly looked. He referred also to the 
fact that the headmasters of the public schools gener- 
ally were clergymen, and deprecated the lack of pro- 
vision made in those schools for scientific instruction. 
Sir William Byrne (Home Office), in proposing the 
toast of ‘The British Science Guild,’’ said that he 
agreed with the statement in the annual report of the 
guild, that Government Departments used the services 
of scientific men without remuneration. The charge 
was irrefutable. Virtue might be its own reward, 
but science rarely was. He sympathised with them, 
and promised that so far as he was concerned he 
would do his best to alter this state of things. 
FLUIDS WITH VISIBLE MOLECULES. 
ROF. JEAN PERRIN (of the University of Paris) 
in his recent course of lectures at King’s College, 
London, dealt with aggregates of suspended particles 
regarded as fluids consisting of visible microscopic 
molecules. The Brownian movement of such particles 
appears to be due to molecular agitation, suggesting 
that particles in suspension function as enormous 
molecules. If this is so, the laws of gases extended 
by Van’t Hoff to solutions apply also to dilute emul- 
sions consisting of uniform grains, and from a know- 
ledge of the osmotic pressure of this “ gas of visible 
molecules,”” one can calculate, using Avogadro’s law, 
the ratio of the masses of the grains to those of the 
molecule of any gas, an indefinite vertical column of 
emulsion in equilibrium having the properties of a 
miniature atmosphere. 
Suitable emulsions are prepared by isolating uniform 
particles of precipitated resin by fractional centri- 
fugalisation. Such emulsions obey the laws of gases 
and give the correct value for Avogadro’s number N, 
whatever the size of the particles. 
Since dilute emulsions obey the laws of gases con- 
centrated emulsions should behave analogously to 
compressed fluids, and the equation (P+a/V?) 
(V—b)=RT, be applicable, where V represents the 
volume of the emulsion, b is four times the volume of 
the grains present, and a a constant which in Van der 
Waals’s equation corresponds to cohesion. | Experi- 
ment, while verifying the prediction, shows the in- 
teresting peculiarity that in the case of emulsions 
the cohesion constant is negative, the grains repelling 
one another appreciably. This result allows the ex- 
perimental determination of the thickness of the 
double layer of electrification by contact, and throws 
light on the properties of colloidal solutions. 
The Brownian activity of a grain is defined as 
E?2/t, where E? is the mean square of the displacement 
in the time t. An emulsion should diffuse as a solu- 
tion of visible molecules with a speed proportional to 
the speed of the molecules which compose it. It can 
be shown that the speed of diffusion D is 1/6 E?/t, and 
since in the steady state as many molecules pass 
upward through any level by diffusion as pass down- 
ward through the level by gravitation, Einstein’s 
equation holds, viz. :— 
Payee oP 
t N wars 
NO, 2326, VOL..03)| 
where r¢ is the radius of the grains and z the viscosity 
of the intergranular fluid. Thus both by measuring 
the rate of diffusion and by measuring the displace- 
ment Avogadro’s constant has been determined. 
Emulsions were prepared of such a nature that those 
grains touching one side of the retaining vessel be- 
came attached and the emulsion progressively weaker 
by diffusion, the variation with time in the number of 
grains captured giving a measure of the rate of 
diffusion. 
By selecting relatively large spherules it was found 
possible to measure their rate of rotation, and thus 
verify Einstein’s formula for the Brownian movement 
‘of rotation. 
These theories also apply to grains suspended in a 
gas except that Stokes’s law is no longer applicable, 
but by applying an eleciric field to the charged par- 
ticles LTownsend’s equation for the diffusion of ions 
relates the charge on the granule with Avogadro’s 
number and the activity of its Brownian movement. 
SRE Uv _6RT DD 
Ne : 
H 1 SI 
The values of N, the number of molecules in a cubic 
centimetre of a gas under standard conditions, de- 
duced by these various methods, exhibit a remarkable 
concordance. Prof. Perrin concluded his lectures with 
a critical comparison of the results of his measure- 
ments of N with the values which have been deduced 
from determinations of the charge of an electron, 
from counting alpha particles, and from the theory of 
radiation. : 
\ CONTRIBUTIONS TO VERTEBRATE 
PALHONTOLOGY. 
a HE skull of a remarkable new generic type of 
horned dinosaur (Styracosaurus albertensis), from 
the Cretaceous of the Red Deer River, Alberta, is 
described and figured by Mr. L. M. Lambe in the 
Ottawa Naturalist for December, 1913 (vol. xxvii., 
pp. 109-16, plates x.—xii.). It was found by the well- 
known collector. Mr. C. H. Sternberg, last summer. 
The skull is long, depressed, and wedge-shaped, with 
a single nasal horn of somewhat unusual shape; but 
its chief peculiarities are the large size of the supra- 
temporal fossze, and the production of the hind border 
of the great occipital flange into four pairs of spines, 
of which the three innermost on each side are very 
long. Although the Alberta horned dinosaur may 
be generically identical with an imperfectly known 
species from the Cretaceous of Montana, referred by 
Cope to the genus Monoclonius, under the name of 
M. sphenocerus, it is considered that the two are 
specifically distinct. 
According to an article by Mr. C. Schuchert on the 
dinosaurs of German East Africa, published in the 
American Journal of Science for 1913 (vol. xxxv., 
pp. 33-8), the largest representative of the genus first 
described as Gigantosaurus, but now known, on 
account of the preoccupation of the original name, as 
Tornieria, is believed to have been about twice the 
length of Diplodocus, or at least 150 ft. The neck 
appears to have exceeded that of the American species 
by a length of about 15 ft. It is hoped to set up a 
skeleton of this gigantic reptile in the Berlin Museum. 
At the conclusion of a note on the relationship 
between the Permian reptiles of South Africa and 
those of Russia, published in the Journal of Geology 
for November and December, 1913 (vol. xxi., pp. 
728-30), Dr. R. Broom expresses the opinion that the 
dicynodonts of the Durna valley represent the Ciste- 
a 
= =e 
——— os 
