WATER SUPPLY 221 
is discharged by hot springs and volcanic eruptions, which 
give forth vast clouds of steam that falls as torrential rain, 
According to Fouquet, Etna in 1865 discharged in about three 
months sufficient water to fill a reservoir a square mile in 
area and 26 feet deep. The view that such water is all 
derived from rain was supported by the claim of Ehrenberg 
that lavas contain the shells of diatoms, and by such reports 
as that Cotapaxi erupted fish; but the diatoms which 
Ehrenberg found in lava probably reached it during the 
dusting of his laboratory, and the arguments from sub- 
terranean fish are equally invalid. Much volcanic steam is 
probably of plutonic origin and is added to the surface water. 
Mining experience shows that water is constantly arising 
from the interior; thus below the zone containing meteoric 
water there is often a thick dry belt, in which are found, as 
at Bendigo, the Comstock Lode, and the St. Gothard Tunnel, 
springs of hot deep-seated alkaline water. The chemical 
composition of the water from many hot springs shows that 
it cannot be derived from the local rocks. The objections 
to the existence of plutonic water were abandoned after the 
experience at the Simplon Tunnel. Many workmen were 
scalded to death by irruptions of water far hotter than was 
expected from the depth. Some of this water was free from 
sodium chloride, which is universally present in meteoric 
water. Sir F. Fox (Proc. Inst. Civ. Eng. clxviii, 1907, 
p. 77) remarked of one spring, which discharged 3036 gallons 
per minute of water at 114-6° F. and contained 106 grains 
per gallon of mineral matter, that ‘ the complete absence 
of chlorine is believed to be unique, and seems to indicate 
that the water was possibly entirely plutonic, having never 
been on the surface of the globe.” There is no single abso- 
lute chemical test to distinguish between meteoric and plu- 
tonic waters; water is probably plutonic if it has no or but 
little chlorine, or contains boric acid where there are no local 
borates from former volcanic eruptions, or its constituents 
are not those that would be derived from the adjacent rocks. 
The deep-seated origin of the hot springs of Carlsbad in 
Bohemia was suggested by Geethe and proved by Suess. 
These springs have been flowing for at least seven centuries, 
for the Emperor Carl IV was cured at them of wounds re- 
ceived from English archers at the battle of Crecy (1346).