Sanitation in daily life by Ellen Henrietta Richards

Author:Ellen Henrietta Richards
Language: eng
Format: epub, pdf
Publisher: Whitcomb & Barrows

ber ending and punch cork. Fill it four-fifths full with the sample of soil to be tested, put a fine wire gauze at the bottom and some coarser gravel so as to furnish good drainage, then the sifted earth. It adds to the interest to weigh the dried earth used and then to measure the water added at the top and note the amount the earth from different sources will take up. Some clayey soil for contrast should be obtained.

(a) Prepare test solutions as follows: Weigh 0.165 gram salt (pure, dry NaCl). Make up to a liter. 1 c.c. = 0.001 gram CI.

(b) Weigh 0.072 gram KnOs. Make up to a liter. Measure out 100 c.c. of this and make up to a liter. 1 c.c. — 0.000001 nitrogen.

(c) Weigh 0.315 gram NH4C1. Make up to a liter. Measure out 100 c.c. of this and make up to a liter. 1 c.c. = O.00001 nitrogen.

It is desirable to prepare fresh for experiments,

(d) A solution containing 1 c.c. skimmed milk in a liter.

(e) A solution containing 1 c.c. urine in a liter. Varying quantities of these solutions and mixtures of

them may be made by the class, each for his own filter, and tests of the filtrate made. There may be shown the following facts: That the salt goes through unchanged whatever the mixture used, and therefore that the test for chlorine is a universal one, and its presence above the normal for the region is a certain indication of past pollution. That passed through clean sand or earth, nitrates go through unchanged; but in the presence of considerable organic matter, milk solutions, for instance, they are reduced to nitrites. Ammonia and urine solutions may be converted into nitrates by slow passage through unsterilized loam or garden soil, but they are not changed by clean washed sand. Nitrates therefore show a previous contamination, ammonia and nitrites show present contamination.

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