i6‘ Dr. Pearson's Experiments and Observations 
The experiments of the alchemists also made it appear, that 
earth was only a part of the matter of concretions. It was 
probably the observation of the deposition and crystallization 
of saline bodies, which suggested the notion of urinary calculi, 
being of the nature of tartar. Such was the opinion of Basil 
Valentine, and after him of Hochener, better known by the 
name of Paracelsus ; but, whether the latter adopted the de- 
nomination Duelecb from its import, or from caprice, has not 
been explained. Van Helmont, a century after his proto- 
type Paracelsus, being struck with the experiment in which 
he discovered the concretion of salts in distilled urine by al- 
cohol, was led to depart from his adored master s opinion, 
with respect to the nature of calculi ; although he acknow- 
ledges the merit of Paracelsus, in having discovered the sol- 
vent Ludus, (a calcareous stone also called Septarium,) which 
Van Helmont says is preferable to alkaline lixivium. He also 
says, that when the archeus spirit of urine meets with a vola- 
tile earthy spirit, and does not act in a due manner, a con- 
cretion will be formed ; but, in a healthy state, although all 
urine contains the matter of urinary calculi, no concretion can 
take place, because the archeus, or vital power of the bladder, 
counteracts its formation. 
As to the kind of earth composing calculi, the only distinc- 
tion of earths, till about the last half century, was into absor- 
bent and non-absorbent ; but, since the absorbent earths were 
distinguished into calcareous, magnesia, and alumine or clay, 
the calcareous was considered to be the earth of urinary con- 
cretions ; apparently however for no other reason but its ob- 
vious properties, and its extensive diffusion through the whole 
animal kingdom. 
