599 
NATURE 
[AUGUST I, 1912 
(who contributes an introduction), we think that 
many may conclude to reserve judgment for the 
present. The book is an ex parte statement of the 
merits of the engine, and we are inclined to think 
that the author has somewhat overstated his case. 
It is, however, a very readable work, dealing as 
it does with much that is new and which has an 
element of originality and novelty doubly welcome 
in works dealing with heat engines. Much of it 
is given up to interesting mechanical detail of 
engines actually constructed, and those who appre- 
ciate the mechanical difficulties incident to high 
compression and temperature will admire the 
ingenuity displayed in overcoming the troubles that 
would otherwise prevent the extensive adoption of 
the engine. And to a great extent the difficulties 
for small engines have been overcome to a degree 
which the reader will appreciate. 
After an outline of the various cycles and 
efficiencies of heat engines, the action and working 
of the Diesel engine is described. Apparently 
experience does not yet point to the exclusive 
adoption of either the two- or four-cycle engine, 
but it is stated that for powers up to 600 or 700 
horse-power the four-cycle engine will be employed 
for land purposes, and above that power the two- 
cycle. But perhaps the chief interest in the engine 
centres in its use for marine propulsion, and the 
latter half of the book is devoted to this applica- 
tion. -With a fuel consumption of about half a 
pound per horse-power, it becomes a serious rival 
to the steam engine. Nor does the fuel consump- 
tion per horse-power increase for partial loads to 
such an extent as with steam engines according to 
figures quoted. The saving of space, always of 
importance on board ship, will necessarily depend 
upon the horse-power per cylinder of the engine, 
but notwithstanding the auxiliaries required in the 
form of air compressors for injecting the fuel and 
those installed fer scavenging in the two-cycle 
engine, a considerable saving of space otherwise 
taken up by boilers might be expected. The issue 
of this book is timely, coming as it does so soon 
after the arrival of the Diesel-engined vessel 
Selandia in the Thames while we were in the midst 
of a coal strike. 
(3) To deal with the numerous papers read 
before the American Institute of Chemical 
Engineers which are recorded in this volume would 
take us too far, for they cover a wide range of 
subjects under the generic title » of 
“chemical engineering.” The president, Mr. 
McKenna, contributes an interesting paper on the 
evolution of Portland cement processes, in which 
the stupendous change brought about by the intro- 
duction of the rotary kiln is shown, both by the 
amount of cement made and its quality. Those 
NO. 2231, VOL. 89] 
embraced 
who recall the days of the bottle kiln in the 
United States, with its intermittent operation, 
can appreciate the advantages of the rotary kiln, 
with its continuous process and uniform 
product, as used in the great cement works of 
that country. The quality and price of the 
Portland cement thus made are such as to 
enable it to compete successfully with “natural” 
(or “Rosendale ”) cement, when the lower tensile 
strength of these latter cements is considered. 
But perhaps even more interesting is the conversion 
of the slag heaps from blast furnaces into cement, | 
which has been rendered possible by the high heat 
of the rotary kiln. It is stated that the manu- 
facture of cement by the United States Steel Com- 
pany is so large that it is rapidly becoming the 
largest factor in the business. The education of 
the chemical engineer is made the subject of a 
report by a committee. One observation bearing 
upon technical education in the United States and 
Germany is worth recording, viz., that “wits ” are 
worth more than technical knowledge generally, 
and “that too much effort is devoted in the schools 
to training the mind in a philosophical way, and 
too little in training what we are to call the wits.” 
Incandescent lamp manufacture is treated by 
Mr. Myers in a paper describing the manipulation 
of refractory elements. These refractory elements, 
particularly tungsten, are employed for the reason 
that the intensity of the light emitted varies as 
the twelfth power of the temperature, while the 
energy supplied varies only as the fifth power, so 
that better efficiency can be obtained from a sub- 
stance that can be burned at high temperatures. 
Carbon has the disadvantage that the vapour ten- 
sion resulting at high temperatures is such that the 
operating temperature mist be reduced to such a 
point that the efficiency is less than half that of the 
best metallic filament. 
In a paper on the manufacture and industrial 
applications of ozone, Mr. Linder describes the 
Berthelot process used for the commercial pro- 
duction of this gas. Electric ozonisers produce 
ozone theoretically in direct proportion to the 
wattage of the discharge per unit of air ozonised, 
but the destructive action of the heat on the ozone 
makes the production less. It is only at about 
8000 to 10,000 watts that the production of ozone 
becomes economical. The author believes that 
ozone will ultimately supersede formaldehyde in 
hospitals as a disinfecting agent, as recent experi- 
ments have shown it to be so suitable for the 
purpose. Experiments have shown that milk, 
cream, and butter can be completely sterilised, 
also other articles subject to decay. A paper on 
the loss in coal due to storage of (1) change in 
calorific value, (2) change in weight, and (3) ten- 
