Lessons in Practical Hygiene. By Alice Ravenhill. (E. J. Arnold
and Sons, Leeds and Glasgow. 5s. net.)—Miss Ravenhill, who can draw on a very large experience in dealing with her subject, uses an eminently practical method. She begins with lessons on life, air, and water. The fourth on life, " Conditions by which Life is Affected," is in two sections, " The Influence of Nutrition " and "The Influence of Environment." The second of these is illustrated by a very simple experiment. Sow mustard and cress on pieces of flannel, very thickly on one, sparsely on the other. Examine after a fortnight specimens from each, and record results of overcrowding. The properties and qualities of air are then investigated and illustrated by experiment. Here is one on air pollution. Pour clear lime-water into a tumbler, shake it well, and note result. Then breathe repeatedly into the tumbler through a glass tube, and observe results. Then we have water. Here, taking again the section which concerns pollution, we have experiments to prove the uselessness, and even mischief, of the common filter. They show that substances larger than the pores of the paper will not pass through, and that though the smaller suspended matters may be separated, the dissolved are not. Many people doubtless suffer from an unjustified faith in the filter. Part II. is concerned with the human body, its systems, nervous, circulatory, &c. ; constituents; digestive process; organs of excretion ; the skin, eye, ear, and throat. Taking the eye, we find tests of sight-power, and a test for astigmatism. Part III. is given to " Food," a division, as might be supposed, of great and varied interest. The term "caloric " is used to measure the value of food. A shilling's-worth of "refined cotton-seed oil" gives 16,750, fine flour 15,636, oatmeal 10,984, margarine 8,625, butter 2,884, apples 1,529. A man in the prime of life, working hard, wants 3,000 (4) oz. of proteids, 21 oz. of fat, and 1 lb. of carbohydrates). The hard-worked German gets 3,370, the English 3,750, the American 4,060. Part IV. has to do with " Personal Hygiene," Part V. with "The Dwelling."
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