122 
NA TORE 
[DECEMBER 10, 1903 
the Hindu Kush, and through the terrible passes and | cost of lighting by various illuminants on the basis 
defiles of Darél to the lower Swat Valley and to the 
monasteries and monuments of the Punjab. 
It would have been interesting, too, if something of | 
the northern art of Buddhist India had been illus- 
trated, as well as the sculptures of Sanchi. It.is in 
the north that the Greek influence is so marked in 
| 
sculptural art as to render it quite distinct in character | 
from the rude and riotous productions of the indigenous 
artist of the south, probably educated in Hindu schools. 
But it is impossible within the limits of a popular 
historiette to compass more than a cursory account of 
so astonishing a moral phenomenon in the world’s 
history as the rise of Buddhism and its marvellous out- 
spread; or to present a view of Indian existence other 
than that which marked certain phases of its career. 
Prof. Rhys-Davids has done invaluable service in illus- 
trating the earliest phase of Buddhist inception, and 
in giving to the world a far more lucid idea of the 
character of the three great Buddhist kings and heroes 
—Chandragupta, Asoka, and Kanishka—than is to be 
found elsewhere in the popular literature of the day. 
For it is only a great scholar who could have done 
this so well. 
The work is scholarly throughout, as well as popular, 
and fully maintains the high standard of the fascin- 
ating series of ‘‘ stories ’’ of which it forms a note- 
worthy unit. 
ACETYLENE. 
Acetylene: its Generation and Use. By F. H. Leeds 
and W. J. A. Butterfield. Pp. x+276. (London: 
C. Griffin and Co., Ltd., 1903.) Price 5s. net. 
’T*HE steady advance made during the past few 
years by this beautiful illuminant fully justifies 
the production of the practical handbook which 
Messrs. Leeds and Butterfield have now placed before 
the public. ; 
In this work they have described and explained the | 
physical and chemical phenomena attending the gener- 
ation and combustion of the gas, and also its employ- 
ment in the various directions in which it has of late 
been used. 
The subject is thoroughly dealt with, and the book | 
contains an enormous amount of information and 
common-sense advice, the only general criticism that 
can be urged against it being, perhaps, that of the 
occasional repetitions which are inseparable from dual 
authorship. 
In the introductory chapter, whilst considering the 
advantages of acetylene as an illuminant, the authors 
deal with a point which, up to the present, has been 
too much overlooked with regard to illumination by 
flames, and that is the importance of the action that 
these have in burning up and destroying considerable 
quantities of the organic impurities present in the air of 
an inhabited room, a function which is of the utmost 
importance, and the absence of which is a considerable 
factor in the unpleasant nature of the atmosphere often 
found in rooms lighted by incandescent electric lamps. 
An interesting feature is also to be found in the 
authors’ attempt to compare the relative merits and 
NO. 1780, VOL. 69] 
of illuminating effect rather than illuminating power. 
That this difference does exist as a most important 
factor in illumination has long been recognised, and 
a moment’s consideration will convince anyone that 
although a particular burner may yield a light of 25 
candles, it will not be in any way equivalent in its 
power of effectively lighting a room to 25 candles dis- 
tributed over the area of the room. If a satisfactory 
unit of comparison and an accurate method of deter- 
mining the results could be obtained, this method of 
comparison would offer enormous advantages over the 
ordinary photometric method. 
In compiling the table the authors have taken as 
the standard of a well-lighted room the being able to 
read with ease ordinary print in every part of it, but 
it is clear that so much depends upon the personal 
factor that whilst one observer may look up a train in 
Bradshaw with ease and comfort, another might find 
a difficulty in dealing with fair-sized print, and on such 
a basis it is hard to found a satisfactory unit of com- 
parison. 
In dealing with the physics and chemistry of the 
actions taking place between carbide and water in the 
generation of acetylene, the whole question is very 
carefully and thoroughly treated, but in referring to 
the power of water in dissipating the heat generated 
during the action, a little too much stress is laid on 
the power of water in keeping down the temperature. 
The statement that 
“if an excess of water is employed in an acetylene 
generator the temperature inside can never, except 
quite locally, exceed 100° C. however fast the carbide 
be decomposed ”’ 
is. although perfectly correct, a little misleading. The 
importance of reducing the temperature in an acety- 
lene generator to the lowest possible point is to prevent 
the formation of certain compounds which afterwards 
give rise to trouble in the consumption of the gas, and 
with a large generator of the type in which carbide is 
fed into water, although the water may be in very 
large excess, it is by no means unusual to find in the 
centre of the decomposing mass on the bottom of the 
apparatus a temperature capable of melting lead, this 
being due to the fact that when the carbide is fed in in 
large quantities, a crust of lime forms on the outside 
of the mass which becomes toughened by tarry pro- 
ducts formed by the heat on the acetylene generated 
in the interior of the mass, and this partly by acting 
as a non-conductor and partly by keeping the carbide 
away from the large excess of water, allows an undue 
rise of temperature, and the acetylene generated is 
found as a result to contain considerable amounts of 
products of polymerisation. 
In referring to the combustion of acetylene and its 
illuminating power, the authors conclude that it would 
be clearer to state the illuminating power of acetylene 
as 48 candles per cubic foot, rather than by accepting 
the arbitrary nomenclature of gas photometry to speak 
of it as 240 candles, inasmuch as in determining the 
illuminating power, the gas has to be burnt at the rate 
best suited for developing its light-giving properties, 
and the results so obtained calculated to a consumption 
of 5 cubic feet. 
