50 PRESIDENT’S ADDRESS—SECTION B. 
of their cells, and it is pleasant to reflect that the Church, 
which has had so many stones cast at it on account of its 
treatment of unorthodox investigators, gave asylum to such 
numbers of those who kept alight the torch of patient investiga- 
tion at a time when all the outside intellectual world was fight- 
ing about dogma, or pummelling each other with philosophical 
disputations. 
With regard to the theoretical side of the alchemistic problem, 
a very few words will suffice. 
The problem of how to convert metals into gold demanded 
some theory as to the constitution of metals. 
Such a theory was advanced by one of the earliest of the 
Arabian writers, Geber, about the middle of the 8th century, and 
was accepted by all the later alchemists with hardly any 
variation. 
Indeed, this blind and unquestioning acceptance of the state- 
ments of previous authorities is one of the characteristics of the 
alchemists. This theory enunciated, after the most approved 
Aristotelian style of reasoning, that all metals contained two 
principles—the fixed and the volatile, represented by mercury 
and sulphur. 
PARACELSUS AND THE IATRO-CHEMISTS. 
We now come to the next development of chemistry, namely, 
as the healer of disease. Already amongst the alchemists the 
philosopher’s stone was credited with all the wonderful 
qualities which fabulous things naturally assume. It was 
not only to convert metals into gold, if absolutely pure, 
and if impure, to convert them into silver. It was to be a uni- 
versal solvent, dissolving and purifying everything. It was to 
give the finder the fulfilment of every wish and to procure for 
him indefinite length of life, it was to be the elixir of life, to 
rejuvenate the old, and give man immortality in the flesh. 
This idea, a natural development of the other, was first given 
practical effect to by Paracelsus early in the 16th century. He 
announced the discovery that the aim of chemistry was not to 
make gold, but to prepare medicines. 
This extraordinary man attacked the alchemists with tremen- 
dous vigour, and founded the school of Iatro-chemists, the pre- 
cursors of the physicians of the present day, who forsook the 
elusive art of making gold directly, and fell to preparing strange 
drugs, from many of which we suffer to-day. Chemistry became 
a handmaid to medicine, and chemists merely apothecaries. 
Paracelsus appears to have regarded everything in Nature as a 
possible drug, and he did not scruple to dose his contemporaries 
in the most outrageous manner with substances known to be 
poisonous, and herbs of whose action he knew nothing. 
