The theory and practice of hygiene (Notter and Firth) / by J. Lane Notter ... and W. H. Horrocks.
- James Lane-Notter
- Date:
- 1900
Licence: In copyright
Credit: The theory and practice of hygiene (Notter and Firth) / by J. Lane Notter ... and W. H. Horrocks. 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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![of its surface. Tims in glass and jwrcelain vessels with very smooth sur- faces water boils at a temperature 1 or 2 degrees liigher than in metalli(5 vessels with a rough siu-face. Water has a remarkable power of dissolving substances, and is the most universal known solvent. It dissolves or retains all the known gases, and there are only a few solid substances that do not gradually yield to the solvent action of Avater, assisted as this is by the gases present in all natural waters. The solubility of different substances is, however, very unequal. <Tenerally, the solubility of any particular body is increased in proportion as the temperature is raised, but there are exceptions to this rule; for example, water at 0° C. dissolves nearly tM'ice as much lime as water at 100° C. In ■the case of gases, the amount which water can dissolve is largely depend- ent upon the pressure; and under ordinary pressure it is generally larger in pro])ortion as the temperature is lower. ° The aqueous solutions of solid substances and of certain liquids and o-ases Iiave a higher density than ordinary water. The freezing point of water- solutions IS lower than that of water; thus sea-water, Avhich is largely a solution of various salts of magnesium, sodium, and potassium, freezes less readdy than fresh water. The boiling point of Avater is raised when it •contains solid substances in solution. Liquid and gaseous substances dis- solved in water sometimes cause a rise and sometimes a depression of the boilmg point. 0]ST THE QUANTITY AND SUPPLY OF WATER. In estimating the quantity of water required daily for each person, it is 3iecessary to allow a liberal supply. There should be economy and avoidance ofwaste; but still, any error in supply had far better be on the side of ■excess. In England many poor families, either from the difficulty of •obtaining water, or of getting rid of it, or from the habits of uncleaiiliness thus handed down from father to son, use an extremely small amount. It ^oul.l be quite incorrect to take this amount as the standard for the com- mnnty at large or even to fix the smallest quantity which will just suffice ilpn^r cleanliness. It is almost impossible to give a definition of -Cleanliness ; nor perhaps is it necessary, since there is a general understand- ing of what IS meant. It must be clearly understood for what purposes water is sui.i)lied. It ntlJu '^Tl '^'i^'^- cooking, and ablution of persons, clothes, tle l'v'^' houses; for cleansh.g of closets, sewers, and streets; for f r '''^ ^y^^limg of animals, washing of carriages and stables ; baths, &c ^''P^^'''' extinguishing fires; for public fountains or v.n.Jn^^'^T'i the quantities necessary for different communities must in lurnSf : ' ^^''^^f^;'}^ live together in towns or are scattered •drai^nl ' r'^f' '^'l ■'^^^^'g as there may be or may not be systems of araiiiage or trades and manufactures. . diviflp nil, f fPl''^? byAvatcr companies, the usual mode of reckoning is to . express ft ^f^ 'T'^^. g^^'^^ total population, and to cxpi( s!, the amount per head per diem. 1 reckoned Z \^^^A oi o ^^'^ Poplation of the MetropoTs and suburbs was ialirnVZ! i T ^'^S ^'''ll''''^' representing a daily consumption of 35-09 .gallons per head, or 236 gallons per house, for all inirposes. The,average](https://iiif.wellcomecollection.org/image/b2135764x_0025.jp2/full/800%2C/0/default.jpg)
