HawortTu. | Detailed Geology. 103 
and, therefore, acted as an active corrosive agent. Water in 
mines bordering on limestone areas which had limestone in 
contact with mine water rarely, if ever, showed acid reac- 
tion. This led to the thought that sulphuric acid in the 
water was neutralized by its action on limestone. A few ex- 
periments were made by placing fragments of limestone in 
pools of water which gave strong acid reaction. It was 
found that within a few days each entire fragment became 
covered with iron rust, implying chemical action not only 
between free sulphuric acid and limestone, but also between 
iron sulphate held in solution and the limestone. 
From the above conditions it seems probable that owners 
of mines bothered with bad water could modify the water 
and probably entirely destroy its bad qualities by keeping 
masses of limestone in the water pools all the time. ‘This 
might be done at a very small expense. Surface pools sup- 
plied largely from the mines might have a few loads of lime- 
stone thrown into them, which could be replenished from time 
to time as they became dissolved away. Should their sur- 
faces become coated with iron oxide to such an extent that 
further action was prevented, it would be comparatively in- 
expensive to have them rebroken so that fresh surfaces would 
be produced. This process might be carried even to the ex- 
tent of sinking blocks of limestone into underground pools so 
that gradually the ground water would be modified before 
being pumped to the surface. This would destroy the corro- 
sive action of water on pumps and all mine and mill ma- 
chinery, but the water still would be unfit for boiler use on 
account of its holding so much solid material in solution. 
