MODIFICATION OF THE CLARK SOAP-TEST.
The Cedar River, during its normal flow in summer, contains about ten grains of solid matter, mostly calcium carbonate, to the American gallon of 58,373 grains. This I considered good boiler-water, and made it the standard of comparison for my tests. Beside the shop, there is a well, which the people who built the road dug for supplying boiler-water; although the Cedar ran a few rods distant. This well-water contained about forty grains of solid matter to the gallon, one-fourth of the impurity being sulphate of lime. This water I made my “awful example” standard of comparison, so that water approaching this in hardness was condemned.
The soap-solution I made by dissolving seventy grains of castile soap, or white soap-powder, in a pint of alcohol. Care must be taken that all the soap is dissolved, and then it is best to keep the mixture in an even temperature not below 60° Fahr. The tests can be made more accurately by having the water under examination brought to the same temperature as the soap-solution.