try. After Roger Bacon came Raymond
Lully, who wrote, in all, sixteen treatises on chemical subjects. At
about the same time, Arnold of Villanova was teaching medicine at
Paris and paying special attention to chemistry. From him there are
twenty-one treatises on chemical subjects still extant. Arnold of
Villanova died on the way to visit Pope Clement V., the immediate
predecessor of John, who lay sick unto death at Avignon.

It is evident, then, that there was no spirit of opposition to
chemistry gradually forming itself in ecclesiastical circles, and
about to be expressed in a decree by John. The chemists of the
thirteenth century had been among the most distinguished churchmen of
the period. One of them at least, Thomas Aquinas, had been declared a
saint. Another, Albertus Magnus, has been given the title of Blessed,
signifying that his life and {136} works are worthy of all veneration.
Pope John XXII. had as a young man been a student of these men at the
University of Paris, and would surely have imbibed the tradition of
their interest in the physical sciences. That he should have unlearned
all their lessons seems out of the question.

It remains, then, to see whether there was any diminution of the
interest in chemistry after the issue of this decree by John. In the
fourteenth century we find the two Hollanduses, probably father and
son, whose lives run during most of the century, doing excellent work
in science. They frequently refer to the writings of Arnold of
Villanova, so that they certainly post-date him. From them altogether,
we have some eleven treatises on various chemical subjects. Some of
these, especially with regard to minerals, have very clear
descriptions of processes of treatment which serve to show that their
knowledge was by no means merely theoretical or acquired only from
books.

Probably before the end of the fourteenth century there was born a man
who must be considered the father of modern pharmaceutical chemistry.
This was Basil Valentine, the German Benedictine monk, whose best
known work is the "The Triumphal Chariot of Antimony." Its influence
can be best appreciated from the fact that it introduced the use of
antimony into medicine definitely, and that substance continued to be
used for centuries, so that it was not until practically our own
generation that the true limitations of its usefulness were found.
Valentine described the process of making muriatic acid, which he
called the s