Air, water and food from a sanitary standpoint / by Ellen H. Richards and Alpheus G. Woodman.

  • Richards, Ellen H. (Ellen Henrietta), 1842-1911.
Date:
[1904], [©1904]
Catalogue details

Licence: Public Domain Mark

Credit: Air, water and food from a sanitary standpoint / by Ellen H. Richards and Alpheus G. Woodman. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    after being made several hours. To 50 c.c. of the water, placed in a four-inch porcelain dish, add two drops of the haematoxylin solution, allow the solution to stand for one or two minutes, then add a drop of 20 per cent, acetic acid. The standards are prepared at the same time, using 50 c.c- of distilled water and the required amount of a stand- ard alum solution. The comparison must be made imme- diately, since the color fades on standing. In this way the presence of one part of aluminum sulphate in five million can be determined directly in the water and with ease. Logwood may be used instead of the haematoxylin, the solution being prepared as above. ATotes.—This test will show the presence of all soluble salts of aluminum which enter into combination with the coloring matter of the logwood to form a lake. The alkalies and alkaline earths give a purplish color with logwood extract, hence the test for alum can be made only in acid solution. Determination of Lead.—Lead in the minute quantities in which it ordinarily occurs in water is best estimated by comparing the color of the sulphide with standards. Directions.—If the water is colorless, acidify the clear solu- tion, concentrated if need be, with two or three drops of acetic acid, and pass in hydrogen sulphide to saturation. If a color is produced, compare it in a 100-c.c. tube with the color given by varying quantities of a standard lead solution. If the water is too highly colored to estimate the lead di- rectly, evaporate three or four liters in a porcelain dish to about 25 c.c, add 10 c.c. of ammonium chloride solution and a considerable excess of strong ammonia. Then add hydro- gen sulphide water and allow the dish to stand some hours. Boil the contents of the dish for a few moments to expel the