by their contemporaries that,
though printing had not yet been invented, even the immense labor
involved in the manifold copying of large folio volumes by the slow hand
process did not suffice to deter them from multiplying the writings of
these men so numerously that they were preserved in many copies for
future generations, until the printing press came to perpetuate them.

Of this there is abundant evidence in the preceding pages as regards
medicine, and, above all, surgery, while a summary of accomplishments of
workers in other departments will be found in Appendix II, "Science at
the Medieval Universities."

At the beginning of the twentieth century, with some of the supposed
foundations of modern chemistry crumbling to pieces under the influence
of the peculiarly active light thrown upon our nineteenth century
chemical theories by the discovery of radium, and our observations on
radio-active elements generally, there is a reawakening of interest in
some of the old-time chemical observers, whose work used to be laughed
at as so unscientific, or, at most, but a caricature of real science,
and whose theory of the transmutation of elements into one another was
considered so absurd. It is interesting in the light of this to recall
that the idea that the elementary substances were essentially distinct
from each other, and that it would be impossible under any circumstances
to convert one element into another, belongs entirely to the nineteenth
century. Even so deeply scientific a mind as that of Newton, in the
preceding century, could not bring itself to acknowledge the tradition,
that came to be accepted subsequent to his time, of the absurdity of
metallic transformation. On the contrary, he believed quite formally in
transmutation as a basic chemical principle, and declared that it might
be expected to occur at any time. He had seen specimens of gold ores in
connection with metallic copper, and concluded that this was a
manifestation of the natural transformation of one of these yellow
metals into the other.

With the discovery that radium transforms itself into helium, and that,
indeed, all the so-called radioactivities of the heavy metals are
probably due to a natural transmutation process constantly at work, the
ideas of the older chemists cease entirely to be a subject for
amusement. The physical chemists of the present day are very ready to
admit that the old teaching of the absolute independence of something