Ell 
76 _ SCIENCE. 
nerves; nor the researches of Weir Mitchell on the 
functions of nerve-centres, and the action of snake- 
poisons; nor, in later years, the researches of Wood on 
the physiology of fever; and on various subjects by 
Bowditch, Arnold, Flint, Minot, Sewall, Ott, Chitten- 
den, Prudden, Keyt, and others. But speaking with 
all the diffidence which one, who, at least by birth, is 
a foreigner, must feel in expressing such an opinion, I 
say, that considering the accumulated wealth of this 
country, the energy which throbs through it, and the 
number of its medical schools, it has not done its 
fair share in advancing physiological knowledge, but 
for one thing, which makes the world its debtor. I 
mean the discovery of anaesthetics. When Morton, 
in 1846, demonstrated in the Massachusetts general 
hospital that the inhalation of ether could produce 
complete insensibility to pain, he laid the foundation- 
stone of our laboratory, and of many others. No doubt 
the men whose instincts led them to physiological 
research, and who realized that by the infliction of 
temporary pain on a few of the lower animals they 
were discovering truths which would lead to allevi- 
ation of suffering, and prolongation of life, not only 
in countless generations of such animals themselves, 
but in men and women to the end of time, would 
have tried to do their work in any case. But the 
men who can steel their hearts to inflict present pain 
for a future greater gain are fewin number. The 
discovery of anaesthetics has not only led to ten physi- 
ological experimenters for each one who would have 
worked without them, but by making it possible to 
introduce into the regular course of physiological 
teaching, demonstrations and experiments on living 
animals, without shocking the moral sense of stu- 
dents or of the community at large, has contributed 
inealculably to the progress of physiology. 
On the occasion of the opening of the old labora- 
tory I used these words:} — 
‘‘Physiology is concerned with the phenomena going on in 
living things, and vital phenomena cannot be observed in dead 
bodies; and from what I have said you will have gathered that I 
intend to employ vivisections in teaching. I want, however, to 
say, once for all, that here, for teaching purposes, no painful 
experiment will be performed. Fortunately the vast majority of 
physiological experiments can nowadays be performed without 
the infliction of pain, either by the administration of some of the 
many anaesthetics known, or by previous removal of parts of the 
central nervous system; and such experiments only will be used 
here for teaching. With regard to physiological research, the 
case is different. Happily here, too, the number of necessarily 
painful experiments is very small indeed; but in any case where 
the furtherance of physiological knowledge is at stake — where 
the progress of that science is concerned, on which all medicine 
is based, so far as it is not a mere empiricism —I cannot doubt 
that we have a right to inflict suffering upon the lower animals, 
always provided that it be reduced to the minimum possible, and 
that none but competent persons be allowed to undertake such 
experiments.” 
Those words were a declaration of principle and a 
pledge given to this community, in which I was about 
to commence my work. That the work has been 
carried on for seven years among you, without a mur- 
mur of objection reaching my ears, is sufficient proof 
that Baltimore assents to the principle; and, grati- 
1 Pop. sc. monthly, November, 1876. 
fying as the building of our new laboratory is to me 
from many points of view, there is none so grateful 
as its witness, that, in the opinion of our trustees and 
of my fellow-citizens, I have carried out my pledge. 
There has been no hole-and-corner secrecy about the 
matter: the students in the laboratory have been no 
clique living isolated in a college-building, but either 
your own sons, or boarders scattered among dozens 
of families in this city; and no room in the labora- 
tory has ever been closed to any student: what we 
have done has been open to all who cared to know. 
On this occasion, when we formally make a fresh 
start, I desire to re-assert the principle, and repeat the 
pledge. 
(To be concluded.) 
BERTHELOT’S EXPLOSIVE MATERIALS. 
Explosive materials, a series of lectures delivered by 
M. P. E. BerTHetor ; translated by Marcus 
BENJAMIN. A short historical sketch of gunpowder, 
translated from the German of KARL BRAUN by 
Lieut. Jonn P. WisserR, U.S.A. A bibliography 
of works on explosives; reprinted from Van Nos- 
trand’s magazine, No. 70. N.Y., Van Nostrand, 
pe (Van Nostrand’s science series.) 180 p. 
TueE lectures of Berthelot, which form the 
more important part of this collection, are de- 
voted to a popular exposition and amplifica- 
tion of the theories which he has from time to 
time advanced, concerning the constitution and 
mode of action of explosive substances. The 
principal topics treated are, the force of ex- 
plosives; the origin, duration, and speed of 
propagation of the explosive reactions ; inflam- 
mation and detonation as modes of inducing 
explosions ; and explosions by influence. 
The force of an explosive may be under- 
stood in two ways: it may be considered either 
as.the pressure developed or as the work accom- 
plished. The pressure depends principally 
upon the nature of the gases formed, their vol- 
ume, and their temperature. The work, on the 
other hand, is principally dependent upon the 
amount of heat given off in consequence of 
the chemical decomposition. In practice, as, 
for instance, in guns, the transformation of this 
heat into useful work is never complete, since 
heat is absorbed by the gun, gases, and projec- 
tile, and a portion of the work produced is lost 
in moving the gases and air projected. Taking 
all these facts into consideration, it has yet been 
difficult to explain the great differences which 
result from the different methods employed for 
inducing explosions. Berthelot holds that this 
diversity depends upon the rapidity with which 
the explosive reaction propagates itself, and the 
more or less intense pressures which result from 
it, and he illustrates it as follows : — 
