JUNE 14, 1901.] 
blood corpuscles, and oxidizing and cata- 
lyzing organic substances. We see, there- 
fore, that the organism develops its enor- 
mous surfaces in the tissues and colloidal 
ferments not only because it requires os- 
motic processes, but on account of the very 
great catalytic activity of such surfaces. 
If, as Boltzmann says, the war for existence 
which living matter must wage is a war 
about free energy, certainly, of all the forms 
of free energy the free energy of surface is the 
most important for the organism. 
‘Tn conclusion, I need scarcely state that 
Ido not maintain that there is any mysteri- 
ous identity between the metals and the en- 
zymes. But, without exaggerating the over- 
whelmingly large number of analogies, we 
are compelled to regard the colloidal solu- 
tions of the metals, in many relations at 
least, as inorganic models of the organic en- 
zymes.” 
Harry C. Jonzs. 
} SCIENTIFIC BOOKS. 
Electric Lighting. By FRANCIS B. CROCKER, 
_ E.M., Pa.D., Professor of Electrical Engi- 
neering in Columbia University, N. Y., and 
Past President of the American Institute of 
Electrical Engineers. New York, D. Van 
Nostrand Co.; London, E. & F. N. Spon. 
This book is the second volume of a work, 
the earlier of which appeared in 1896. The 
complete work is intended to be a practical 
treatise on electric lighting for engineers, stu- 
dents and others. The prior volume dealt 
mainly with the establishment and equipment 
of electric lighting stations, including locations, 
buildings, power, dynamos, accumulators, 
switchboards, measuring instruments, lightning 
arresters, etc. The present volume, on the 
other hand, is devoted to that part of an elec- 
tric light installation which includes the distri- 
bution of current and its utilization in various 
forms of lamps for light. As the author points 
out in his preface, the space available would 
not permit the more abstruse consideration of 
~the several divisions of the subject, and this 
may well be admitted. A glance shows, in- 
SCIENCE. 
943 
deed, that the volume has no waste space ; the 
descriptions are brief, and the data compact and 
apparently quite accurate. In these respects it 
is excellent. 
The book is eminently practical, but does 
not neglect the full consideration of principles 
necessary to a full understanding of the topics 
treated. It will be valuable as a reference 
book for engineers on account of the inclusion 
within its pages of many useful tables and 
examples. 
Beginning with a chapter upon the physical 
properties of conductors, which includes the 
application, under limitations and modifica- 
tions, of the so-called Kelvin’s law, and the 
maximum carrying capacity, there follows a 
thoroughly adequate treatment of the various 
systems of electrical distribution in several suc- 
ceeding chapters. The series systems, parallel 
systems, three*wire and five-wire distribution, 
direct current transformer systems and net- 
works of electrical conductors, share the space 
alloted, in accordance with their importance in 
actual practice. 
Chapters VII. and VIII. contain brief, but 
very lucid, expositions of the principles of alter- 
nating currents and polyphase currents respec- 
tively, after which follows a chapter devoted to 
a similar treatment of that very important ad- 
junct, the alternating current transformer. 
The two succeeding chapters relate to alternat- 
ing current systems of distribution and the 
calculation of such circuits. The matter ap- 
pears to be well put together, and is amply 
elucidated by diagrams. The part of the work 
devoted to the distribution of delivery of energy 
to the place desired is concluded by a full and 
judicious consideration of overhead and under- 
ground conductors. » Here may be found ample 
details of line construction, conduits, etc., as 
exemplified in the most recent construction, 
particularly in America. 
The remaining portion of the volume proper 
is devoted to the utilization of the energy for 
lighting, as in are lamps and in incandescent 
lamps, in addition to the accompanying interior 
wiring, and electric meters. The work con- 
cludes with appendices, one of which contains 
the National Electric Code of the Board of Fire 
Underwriters, and the report of the Committee 
