362 
IN ADOT, 
[ FEBRUARY 15, 1904 
tinction between soma and sexual tissues comparable 
with that which in plants finds its expression in alter- 
nation of generations. 
On the other hand, the proposal to replace the ex- 
pression ‘‘ double fertilisation’’ by that of ‘‘ triple 
fusion ’’ strikes us as a good one. It is by no means 
certain that the process indicated is really of the nature 
of fertilisation at all, and until more evidence enables 
us to form a reasoned opinion as to the meaning of 
these remarkable phenomena that precede the form- 
ation of endosperm in a large number of cases, 
it is better to avoid taking up, even nominally, what 
may prove to be a totally untenable position. Indeed, 
we already know that endosperm may arise, in some 
instances, independently not only of the addition of the 
extra male nucleus but also even of the fusion of the 
two polar nuclei themselves. 
It is not possible to discuss the many points raised 
in this interesting worl in any detail. Every serious 
student of botany will certainly peruse it for himself 
and can form his own judgment on controversial 
matters. He will be aided in this by the copious 
references to literature which form not the least valu- 
able feature of this fine book. 
Here and there we note an occasional slip, e.g. the 
suggestion that the investigations which have led to a 
general disbelief in the occurrence of centrosomes in 
angiosperms originated in Germany. But as a general 
rule the statements are remarkably free from in- 
accuracy. It is not possible to conclude this notice 
without commenting on the excellent manner in which 
the book is got up. The text, and especially the illus- 
trations, both in character and execution, are all that 
could be desired. Ife 1835 Ise 
APPLICATIONS OF PHYSICAL CHEMISTRY. 
Physical Chemistry in the Service of the Sciences. 
By J. H. van ’t Hoff. Edited by Prof. Alexander 
Smith. Pp. xviii+126. (The University of Chicago 
Press, 1903.) Price 1.50 dollars. 
HIS handsome volume is based on a course of 
nine lectures delivered in 1902 at Chicago, where 
Prof. van ’t Hoff was the guest of the university; it 
deals with the extension of Avogadro’s law to solu- 
tions, and the thermodynamical principle of the con- 
servation of energy; the thermochemical and electrical 
methods of determining what chemical changes are 
able to do work, and the theory of ionisation; the 
application of the phase-rule in relation to the extrac- 
tion of pure salts from the Stassfurt deposits, and to 
the metallurgy of iron and steel; osmotic pressure in 
its physiological applications, and the catalytic action 
of enzymes; and the nature of the salts deposited by 
the evaporation of sea-water, and the reasons for their 
formation. The lecturer has thus, by carefully chosen 
examples, illustrated the bearing of modern physical 
chemistry on manufacture, on physiology, and on 
geclogy. 
Prof. van ’t Hoff tells a curious tale of the celebrated 
Kekulé, professor at Bonn, who thirty years ago took 
the pessimistic view that chemistry, as a science, had 
come to a stand, and that a Newton was necessary 
NO. 1790, VOL. 69 | 
before further advance could be made. It was an un- 
fortunate utterance, for no science has made greater 
strides within the last quarter of a century, and Prof. 
van ’t Hoff has done much to contribute to its advance. 
The fortunate conjunction of three men, van ’t Hoff 
with his magnificent powers of generalisation, 
Arrhenius with his keen insight, and Ostwald with 
his encyclopedic knowledge and rare gift of ex- 
position, has largely aided the rapid progress of 
physical chemistry. But the first step was taken by 
van ’t Hoffand Le Bel, in their simultaneously con- 
ceived theory of the representation of the molecule 
in three dimensional space. 
In discussing the aid which physical chemistry has 
given to pure chemistry, the author states :— 
“The most recent development of physical chemistry 
has been characterised rather by the establishment of 
comprehensive principles which fertilise the whole 
foundation of the science, and which promise to furnish 
nourishment for a large part of the chemistry of the 
future.”’ 
A short explanation of the nature and laws of 
osmotic pressure is then followed by a brief statement 
of the nature of a reversible cycle and its application 
to the case of carnallite. The ‘‘ principle of maxi- 
mum work ’’ is next considered, and the fallacy con- 
tained in it, and the suggestion is thrown out that all 
thermochemical work should be repeated, ‘‘ with the 
object of determining the ability of each reaction to 
do work.’? This suggestion is again illustrated by 
help of carnallite as an instance. At —21°, the 
temperature of equilibrium between carnallite and its 
components, 
MgCl, KCl.6H,0+6H,O = MgCl,.12H,O+ KCl, 
the possibility of doing work is zero. But above this 
te1iperature, the reaction can overcome a resistance 
such as a pressure; hence dE=—WdT/T, and a 
cyclic change is possible. For finite values 
E=—WaAt/T; hence, while at the transition tempera- 
ture where At=o, E=o, both above and below it the 
sign of E changes. Of course, at absolute zero, 
E=W, where At=—T, and the heat develeped will 
be a measure of the capacity to do work, and the fact 
that Berthelot’s principle of maximum work holds 
in many cases is merely due to the temperature of 
experiment being relatively low—only 273° above 
absolute zero. At 1ooo°, on the contrary, acetylene 
is formed with absorption of heat, and water decom- 
poses in spite of the fact that its formation is accom- 
panied by evolution of heat. This abridgment of 
van ’t Hoff’s argument will give an idea of the simple 
and clear method of statement. In a similar manner 
the connection of the capacity to do work with electro- 
motive force is explained, and illustrated by the ex- 
ample of a thallium—thallium chloride—-potassium thio- 
cyanate cell. Arrhenius’s conception of ions is thus 
introduced and shortly described. 
In dealing with the connection between physical and 
industrial chemistry, van ’t Hoff emphasises the 
circumstance that in Germany the most hearty co- 
operation exists between manufacture and science, 
alluding to the fact that it is not there expected that 
the physical chemists shall give ‘ tips’’ to the in- 
