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attempts to transmute owing their origin to superficial obser- 
vation and probably to the teachings of Aristotle and the 
famous Arabian alchemist, Geber, of the seventh century. 
Aristotle regarded the four elements, earth, air, fire, and 
water, as one original substance simply possessing different 
properties which he assumed could be altered, and from that 
he deduced that substances could be transformed. The 
actual methods of transformation differed of course in the 
various teachings. Geber taught that all metals were different 
mixtures of mercury and sulphur, the noble metals being 
rich in mercury, the base ones in sulphur, and transmutation 
meant the increase of mercury or the decrease of sulphur. 
It may be mentioned that the colours of the metals played 
an important part in these alchemistic theories. It was a 
great achievement when they had made a metal to look like 
gold. A deposit of copper on iron left in a solution of a 
copper salt was considered a transformation of the 
iron into copper, an observation of the most superficial nature. 
Transmutations of this kind required, of course, so-called 
“ medicines ” of different order and strength. The philos- 
opher’s stone, the “ great elixir,” or “ the magisterium,” 
was one of such “ materia prima,” and we find early chemists 
working up in every conceivable way all kinds of imaginable 
substances with a view to the discovery of a philosopher’s 
stone. The knowledge of the stone was kept a profound 
secret. In its description by the alchemists, mystical drawings 
were used to prevent its supposed discovery by outsiders. 
The unsoundness of the theory is shewn by the assertions 
of a few of its most prominent champions from time to time. 
Roger Bacon (1214-1294) says “ It was able to transmute 
one million times its weight of mercury.” Others, more 
modest, said one hundred times. 
Raymond Lully (1235-1315) gave a most elaborate recipe 
for the successive transmutation of mercury into gold by 
means of the stone. Van Helmont (1577-1644) says that 
11 a quarter of a grain of the philosopher’s stone turned eight 
ounces of mercury to gold in 1615.” Shortly afterwards, 
Helvetius, Physician to the Prince of Orange, published a 
detailed account of transforming lead to gold by means of 
a small quantity of a certain preparation. The philosopher’s 
stone was supposed to preserve life and health, and the long 
lives of the patriarchs were explained by the assumption 
that they knew of this universal medicine. 
Towards the end of the middle ages the belief was taught 
that by means of the philosopher’s stone living beings could 
