INTRODUCTION. 5 
the present day a great number of substances are 
known to possess the same singular property. 
In 1663, the celebrated English chemist Robert 
Boyle announced to the world that the Diamond 
possessed the same luminous property as the Bo- 
logna Stone; and what we have just told of Cas- 
cariolo’s labours has its parallel in the discovery 
of another luminous body, far more remarkable 
than either. 
In the seventeenth century there lived at Ham- 
burg an alchemist named Brandt, who having en- 
deavoured for many years, but in vain, to convert 
other metals into gold, was struck one day with 
the golden colour of urine, and doubted not but 
that this liquid contamed some substance that 
would realize his dreams. Brandt thought that by 
acting upon the metals he wished to convert into 
gold with a blackish extract he had prepared by 
concentrating and evaporating urine, he would 
certainly operate the desired transmutation. He 
therefore introduced this black extract into a re- 
tort with the metals in question, lighted his fur- 
nace, and watched intently the progress of the 
operation. The result was negative: the metals 
after the experiment remained unchanged. How- 
ever, one evening, after having distilled a consi- 
derable quantity of urme over some metal or other, 
and having pushed the distillation as far as pos- 
sible, he was surprised to find that a peculiar shi- 
