NovEMBER 8, 1906 | 
INEACTA CREE: 
47 
From Continental contemporaries we note the following 
recent appointments :—Prof. H. Rubens, professor of 
physics at the Technical High School, Berlin, to be pro- 
fessor of physics at the University of Berlin and director 
of the Physical Institute; Prof. Arthur Wehnelt, professor 
of theoretical and applied physics of the University of 
“rlangen, to be a professor and departmental director in 
1.2 University of Berlin; Dr. Joseph Griinwald, privat- 
‘scent at the University and the Technical High School 
vf Vienna, to be extraordinary professor of mathematics 
in the University of Prague; Dr. H. Mache, privatdocent 
of the Vienna University, to be extraordinary professor of 
physics in the University of Innsbruck; Prof. Czsar 
Pomeranz, extraordinary professor of chemistry in the 
Vienna University, to be professor of chemistry in the 
University of Czernowitz; Prof. Karl Zsigmondy, pro- 
fessor of mathematics in the Technical High School, 
Prague, to the chair of mathematics in the Technical High 
School, Vienna; Prof. Reissner, privatdocent in the Tech- 
nical High School, Berlin, to be professor of mechanics 
in the Technical High School, Aachen; Prof. Zdenko 
Skraup, professor of chemistry in the University of Graz, 
to the chair of chemistry in the University of Vienna; 
Prof. Franz Streintz, privatdocent of the University of 
Graz, to be professor of physics of the Technical High 
School in Graz. 
SOCIETIES AND ACADEMIES. 
LONDON. 
Royal Society, May 31.—‘‘The Viscosity of the Blood.” 
By Dr. A. du Pré Denning and John H. Watson. Com- 
municated by Prof. F. Gotch, F.R.S. 
It is urged that the full import of a knowledge of the 
variations in the viscous resistance to be overcome by the 
blood in circulating through the capillaries and smaller 
vessels of the system, and the significance of such data to 
‘he more exact consideration of a large number of normal 
ind pathological conditions, especially those of the circu- 
latory system, have not been fully realised by either 
clinicians or physiologists. Experiments have been under- 
taken to observe the influence of the number of the cor- 
puscles present upon the viscosity of the blood under vary- 
ing conditions of pressure and temperature, the rate of 
flow through capillaries of different sizes under the same 
conditions, and the alterations caused by the additions of 
certain salts and other substances; one important result 
of the experiments was to show that the decrease in 
viscosity for each degree rise of temperature for a blood 
rich in corpuscles is considerably greater than for a blood 
poor in corpuscles, especially when the flow is through the 
finer capillaries, or, in other words, the flow of blood does 
not follow the fourth power of the radius as required by 
the Poiseuille formula. An attempt is made to indicate 
briefly the import of the results obtained in a consider- 
ation of the mechanism of the circulatory system. At the 
end of the paper an account is given of a clinical viscosi- 
meter which the authors have devised for determinations 
of blood viscosities with but a few drops of blood; such 
viscosity determinations, it is claimed, are necessary supple- 
ments to haeemacytometer observations. 
June 21.—‘ On the Behaviour of Certain Sub- 
stances at their Critical Temperatures.’’ By Dr. Morris 
\V. Travers, F.R.S., and Francis L. Usher. 
Traube, de Heen, and others have recently suggested 
that the simple theories of Andrews and Van der Waals 
may be insufficient to account for the changes which take 
place in pure substances at their critical temperatures. 
Their evidence appears to show that in the case of such 
substances as ethyl alcohol and ether the Cagniard-Latour 
temperature is dependent on the relative volumes of the 
two phases, and to account for this they have suggested 
the existence in the system of complex molecules. 
The authors have carried out investigations with ether 
and with sulphur dioxide, and have found that the 
Cagniard-Latour temperature is independent of the con- 
ditions under which the experiments are carried out. 
Particular precautions were taken to obtain the liquids 
pure and to maintain steady temperatures, the measure- 
ments of which were certainly accurate to within 0°-05. 
NO. 1932, VOL. 75 | 
The second part of the paper deals with the phenomenon 
of opalescence which is observed in pure liquids at their 
critical temperatures. If varying quantities of a pure 
liquid are heated in sealed glass tubes, provided that the 
liquid ‘neither disappears. nor completely fills the tube 
before the critical temperature is reached, the surface 
separating the two phases may sink and disappear near 
the bottom of the tube, or it may remain stationary about 
the middle of the tube, or, lastly, it may rise and vanish 
near the top. In all three cases, if the temperature is 
raised so slowly that equilibrium is attained without 
ebullition of the liquid phase, the contents of the tube 
become opalescent at a temperature slightly below that at 
which the surface vanishes, the effect being similar to 
that produced by the action of oxidising agents on a solu- 
tion of sulphuretted hydrogen. When the surface is falling 
the opalescence appears in the space below it, and when 
the surface is rising, in the space above it. In either case 
the opalescence is confined to the space in which it first 
appeared by the moving surface, and its intensity is in- 
versely proportional to the volume it occupies. Although 
it is fairly evenly distributed through the space it occupies, 
it is usually more intense very near to the surface, and 
when the latter disappears gradually becomes diffused 
through the whole tube. 
In the case where the surface appears to remain 
stationary, the tube appears slightly and evenly opalescent 
throughout its whole length, and if, when this is the case, 
the volume of the space containing the substance is jn- 
creased or decreased, opalescence appears below or above 
the surface itself, and its intensity is inversely proportional 
to the space it occupies. The effect persists over a finite 
range of temperature. In the case of sulphur dioxide it 
sets in at o°-1 below that at which the surface vanishes, 
attains a maximum at about 0°-05 above it, and completely 
disappears at a temperature o°-1 higher. In the case of 
| ether the effect persists over about 2°. 
The conditions necessary for the existence of complexes 
in a liquid-vapour one-component system in the neighbour- 
hood of the critical temperature were given by Donnan at 
the British Association in 1904. He suggested that at the 
critical temperature the interfacial tension becomes zero 
for ordinary values of the radius of curvature, but remains 
positive for very small values, for which it does not be- 
come zero until the critical temperature is passed. Hence 
it may be assumed that at temperatures slightly below 
the critical the interfacial tension is greater for very 
small radii of curvature than for ordinary curvatures. If 
over a range of temperature, including the critical tempera- 
ture, limited above by the temperature at which the inter- 
facial tension for very small curvatures becomes zero, and 
below less sharply, small non-molecular aggregates can 
be formed, it follows that these will be differentiated from 
either the liquid or vapour phase, and will have a stable 
existence. To such aggregates is attributed the pheno- 
menon of opalescence, and the range of temperature over 
which it is observed, and the manner of its appearance 
and disappearance, are in agreement with the assump- 
tions. 
Paris. 
Academy of Sciences, October 29.—M. H. Poincaré in 
the chair.—A new and rapid method for the determin- 
ation of the errors of division of a meridian circle: M. 
Loewy. A more detailed discussion of a method described 
in outline in an earlier paper.—The moth of the beetroot, 
Lita ocellatella: Alfred Giard. The author has recog- 
nised by a further study of this parasite that he was in 
error in identifying it as belonging to the species Loxostege 
sticticalis of American naturalists, or Phlyctoenodes or 
Eurycreon sticticalis, according to the European nomen- 
clature. The author points out the remarkable facility 
with which the larvae escape through small apertures, and 
the danger through this cause of sending live specimens 
through a district not subject to this pest.—Observations 
on the sun made at the Observatory of Lyons during the 
third quarter of 1906: J. Guillaume. The results are 
summarised in three tables, giving the surfaces of the 
sun-spots, their distribution in latitude, and the distribu- 
tion of the facule in latitude——The deformation of 
quadrics: Luigi Bianchi.—The transformations of ‘some 
linear partial differential equations of the second order : 
