PHYSICAL FACTORS OF WATER COMPARED WITH OTHER SUBSTANCES (PER UNIT WEIGHT). ================================+=================================== Capillary ascent in glass tubes | Specific Heats. of one mm. diameter. | | Water 14 mm.| Water 1.000 Alcohol 6 mm.| Ice .502 Olive oil 1 mm.| Steam .475 | Clay, Glass .180-.200 | Charcoal .241 HEAT RELATIONS. | Wood .032 Density. | Gold, Lead .032-.031 | Zinc .096 Water at 0° C. (freezing | Steel .119 pt.) .99988| Water at 4° (Maximum | Heat of fusion. density) 1.00000| Water (Ice) 80 Cal. Water at 15° C. (ordinary | Metals 5-28 “ temperature) .990 | Salts, (incl. silicates) 40-63 “ Ice at 0° (freezing pt.) .92800| --------------------------------+----------------------------------- +=================================== | Heat of Evaporation. | | Water at 20°C. 613 Cal. | “ “ 100°C. 637 “ | Alcohol 209 “ | Spirits of Turpentine 67 “ +----------------------------------- Summarizing the meaning of the data given in the above table with respect to organic life, we see, first, that water rises higher both in the soil and in the tissues of the plant than any other liquid. Second, that as its density decreases in cooling after a certain point is reached, it freezes at the _surface_ instead of at the _bottom_, as other liquids do; and as solid water (ice) is lighter than fluid water, ice stays at the surface and is readily melted when spring comes. Third, since its temperature changes more slowly than that of any other liquid, it serves to prevent injuriously rapid changes of temperature in plants and animals as well as in soils. Its high “heat of fusion” also serves to prevent quick freezing of plant and animal tissues, so that the brief prevalence of a low temperature may be more readily borne. Finally, the large amount of heat absorbed in evaporation of water serves to keep both plants and animals cool under excessive external temperatures which would otherwise quickly destroy life.