Page:Popular Science Monthly Volume 19.djvu/253

Rh has marked characteristics which permit it to be distinguished very readily: the form of its crystals, particularly, is typical; it is of a light yellowish color, and appears under the microscope in the form of six-rayed stars derived from an hexagonal prism, of precisely the form of snow-crystals. The accompanying figures give photographic representations of the crystals as they appear under the microscope. Fig. 2 represents the crystals from pure water to which alcohol has been added in the proportion of one millionth; Fig. 3, those obtained from rain-water; Fig. 4, crystals from snow-water; and Fig. 5, those procured from cultivated soil. M. Müntz's first experiments were made about four years ago. He has since examined a



considerable number of samples of rain-and snow-water from Paris and the country. After each distillation the apparatus has been carefully cleansed by exposing it for some time to currents of vapor, and the analysis has been tested by repeating it in blank. More than eighty essays have given identical results. The quantity of alcohol contained in rain-, snow-, and sea-water may be estimated at from one to several millionths of the whole. Cold water and snow-water seem to contain a little larger proportion of it than warm water. Appreciable quantities of it are found in the water of the Seine; and the proportion is very sensibly increased in sewer-water. Vegetable mold appears to be rich in it; and it is probable that the natural alcohol originates in the soil from the fermentation of the organic matters contained in it, and is thence diffused as a vapor in the