F. Every liquid which, after the addition of sulphuric acid, contains in every 100,000 parts by weight more than one part of free chlorine.
G. Every liquid which in every 100,000 parts by weight contains more than one part of sulphur, in the state of sulphuretted hydrogen or of a soluble sulphuret.
H. Every liquid having an acidity superior to that produced by adding two parts by weight of hydrochloric acid to 1000 parts of distilled water.
I. Every liquid having an alkalinity greater than that produced by adding one part by weight of caustic soda to 1000 parts of distilled water.
J. Every liquid exhibiting on its surface a film of petroleum, or hydrocarbon, or containing in suspension, in 100,000 parts, more than 0.5 of such oils.
But to arrive at a fair and impartial conclusion, authorities now agree that analyses and investigations must be often, and for a prolonged period of not less than one year. The aim of modern scientists, in their analyses, is to detect the amount of organic (especially sewage) contamination. Dr. Frankland’s method is by the estimation of organic carbon and nitrogen, while Wanklyn, Chapman, and Smith reach their conclusions by estimation of nitrogenous organic matter, by breaking up the organic bodies and separating their nitrogen in the form of albuminoid ammonia. Ammonia is the measure of that portion of organic matter not decomposed but in state of or capable of undergoing putrefaction.
The maximum amount of free ammonia permissible in good drinking water is .5 of a grain per 1000 gallons, and of albuminoid ammonia .9 of a grain per 1000 gallons.
Upon the above basis the relative merits of the following waters may be formed:
Number of Grains of Sewage in Each Thousand Gallons.