THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
87 
THE MIDDLE LIAS OF NORTHAMPTONSHIRE. 
BY BEEBY THOMPSON, F.C.S., F.G.S. 
• (Continued from page 76.) 
Carbonate of lime in water decomposes about 10J times its 
weight of common yellow soap, and nearly 9 times its weight 
of white curd soap in the operation of washing. Other salts 
of lime or magnesia destroy an amount proportionate to the 
lime or magnesia they contain. The lime unites with the 
stearic, or other fatty acid present in the soap, forming the 
stearate or other salt of lime, and until the lime is so satisfied 
no lasting lather can be obtained. It follows, therefore, that 
the water is softened at the expense of the soap, and this is 
accompanied with the production of insoluble curdy bodies 
(insoluble soaps). 
Considering the large amount of soap used, a soft water 
is very desirable. Soft water is also much better for making 
tea, and for most manufacturing processes—brewing being an 
important exception. 
Where a hard water only is available, it would generally 
be both beneficial and economical to soften it by Clark’s 
process. I believe the Marlstone water might be so treated 
with advantage to'the town. After making large allowances 
on account of water used for purposes where hardness is of 
no account, the value of the process may be estimated by the 
following figures :— 
To soften the same amount of water by— 
£ s. d. 
Lime, 1 cwt. ... ... about 0 0 9 
Carbonate of Soda, 4f cwt. ,, 1 13 0 
Soap, 20J cwt. ... ... ,, 28 0 0 
To soften by boiling would be about as expensive as by soap. 
At Caterham a very hard water is reduced from 21-2° to 
4*4° at a cost of less than £1 per million gallons. 
Some waters are greatly benefited in other ways by this 
artificial softening, as will be explained further on. 
Excessive hardness .—A contaminated subsoil or water¬ 
bearing bed gives to water percolating through it the power 
to dissolve large quantities of salts, thus producing excessive 
hardness. According to recent investigations of Mr. War¬ 
rington*, the silica is not increased, and the quantity of 
carbonates but little. Lime is considerably increased, and 
* “ A Contribution to tlie Study of Well Waters,” by Robert War¬ 
rington, F.R.S. “ Journal of the Chemical Society,” June, 1887. 
