APRIL 5, 1901.] 
teachings of Aristotle and Galen, boldly 
asserted that the true use of chemistry is 
not to make gold, but to prepare medicine; 
and he and his follower Van Helmont, in 
addition to attaining fame for skill in com- 
pounding remedies, were amongst the first 
to appreciate the true import of the proc- 
esses of analysis and synthesis which 
came to be called in their day the spagyric 
art. Then followed the doctrine of the 
mutually neutralizing substances, acid and 
alkali; the fruitful hypothesis of elective 
attractions, or affinities; the ingenious, if 
erroneous, theory of phiogiston, and the 
more permanent theory of oxygen. All these 
led up through more and more searching 
experimentation to the first great epoch in 
the history of chemistry—the epoch of 
Lavoisier. 
Among the early workers in the century 
preceding the epoch of Lavoisier the names 
of Becher and his disciple Stahl deserve es- 
pecial mention, not only by reason of their 
introduction of the theory of phlogiston, 
but also by reason of their enthusiastic and 
steadfast devotion to science without hope 
of pecuniary reward. In his remarkable 
treatise entitled ‘ Physica Subterranee,’ 
published in 1681, Becher defends the sci- 
entific pursuit of chemistry as not less 
worthy of attention than philosophical and 
theological studies. He insists especially 
on the need of careful observations and on 
the necessity of constantly verifying theory 
by experiment. With true scientific en- 
thusiasm he describes the chemist as one 
willing to work amid the flames and fumes, 
and, if need be, the poisons and poverty of 
the laboratory. He has no patience with 
the charlatans, of which it appears there 
were still many in his day, who are looking 
chiefly for ways and means of extracting 
the precious from the baser metals. As for 
himself, he says: “‘My kingdom is not of this 
world. I trust that I have got hold of my 
pitcher by the right. handle—the true 
SCIENCE. 
527 
method of treating this study; for the 
pseudo-chemists seek gold, but the true 
philosophers, science, which is more pre- 
cious than any gold.” 
It is a peculiarly noteworthy fact that 
while much attention was given to chem- 
istry during ancient and medieval times, 
comparatively little “attention was given 
to the other branches of physical science. 
Our knowledge of heat, light, electricity 
and magnetism is almost;wholly a develop- 
ment of modern times. The Greeks were 
acquainted with a few of the more ele- 
mentary phenomena of electricity and 
light; and Ptolemy and Alhazen came 
near discovering the law ‘of optical re- 
fraction; but there was no contribution 
made to either of those physical sciences 
comparable with the discoveries of Hip- 
parchus in astronomy until the epoch of 
Galileo. What a marvelous increase in 
the rate of scientific progress began with 
this epoch is shown on nearly every page 
of the subsequent history of science. Galileo 
and his contemporaries may be said to have 
established the methods of observation and 
experiment. Their systematic application 
has borne fruit in every science. Almost 
every step forward has led to additional 
advances, until now each of the physical 
sciences has its wide’array of determinate 
facts correlated under a great theory. In 
the domain of light, for example, the only 
solid contribution of the ancients is the 
obvious fact of radiation in straight lines. 
After nearly sixteen hundred years of our 
era had elapsed, there came Galileo’s inven- 
tion of the telescope, and about the same 
time Snell’s discovery of the law of refrac- 
tion. ‘To the telescope was soon added the 
microscope and the camera obscura. Then 
followed Newton with explanations of the 
rainbow, dispersion and kindred phenom- 
ena; Hooke with his discovery of the 
colors of thin plates; Dolland with the 
