Some of the characters of coagulated and mechanically-filtered water / by Sheridan Delépine.

  • Delépine, Sheridan, 1855-1921.
Date:
1914
Catalogue details

Licence: In copyright

Credit: Some of the characters of coagulated and mechanically-filtered water / by Sheridan Delépine. Source: Wellcome Collection.

Provider: This material has been provided by London School of Hygiene & Tropical Medicine Library & Archives Service. The original may be consulted at London School of Hygiene & Tropical Medicine Library & Archives Service.

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    satisfactory. The seven essential desiderata indicated at the beginning of this paper can easily be met when the best types of pressure mechanical filters are properly worked. As to the conditions to which the author attaches little or no importance, some have been satisfied, while others have remained unsatisfied. He would, therefore, suggest, whether hard or soft water are in question, they should when treated satisfy the following conditions Essential conditions— 1. The water viewed in a 2 ft. tube shall be of a pale blue colour, or retain not more of any original yellow or brown discoloration than an amount capable of giving to the water a greenish blue colour. 2. The water viewed in a 2 ft. tube shall be elear. 3. The water when heated to 30° C. and to 100 C. shall be free from any appreciable smell. 4. One cubic centimeter of filtered water shall not contain more than 100 bacteria, capable of growing in three days on peptone bouillon gelatine (+ 10) incubated at 20° C. 5. Any quantity less than 10c.cs. of the filtered water shall not contain the bacillus coli communis. 6. The filtered water shall have no material action on bright pure lead after being in contact continuously for 24 hours at a temperature of 20° C. (By material action is meant an action causing the taking up by the water of more than one part of lead in 2,000,000 parts of water, when the lead is completely immersed, the water is protected from access of air or other gases while the test is carried out, and the ratio between the surface of lead and the volume of water is as one to four). 7. The amount of alumina in the filtered water sh 11