Page:Popular Science Monthly Volume 28.djvu/443

Rh believes that a good place to look for the origin of cholera may be in the volatile ptomaines, or alkaloids of putrefaction emitted by organic substances in the later stages of decay. The ptomaines developed in the earlier stages of putrefaction appear according to his researches to be usually solid or liquid, and much less dangerous than those which escape at a later stage, and which, being volatile, have thus far eluded examination. But these last, when taken into the system by the breath, produce deadly effects. M. Le Hon's conclusions on this subject have been derived from observation of the progress of cholera at Kombakonum, in Southern India.

has made experiments with animals of the classes of vertebrates, articulates, mollusks, and worms, from which he has determined that the sense of color and the power of perceiving light are more widely distributed than has generally been supposed. The variations in the sense of color among animals are very great.

on the Norwegian frontier, in latitude 67°, 6,000 feet high, and Parjektjàkko, in Swedish Lapland, 1,000 feet higher, have in turn been put forward as the highest mountain in Sweden. They both have now to give place, on the testimony of Dr. Svenonius, to Kebnekaisse, in Lapland, which is 7,300 feet above the level of the sea.

indicates as probable sources of nitrogen in soils, and serving as food for plants, the dead bodies of insects, excreta of living insects, invisible spores, microbes, and particles of organic fluff which are always floating in the air and liable to adhere to the moistened surface of the soil and of the leaves of the growing plants. To prove the existence of such deposits on leaves, moisten a white pocket-handkerchief and gently rub it over the surface of the leaf of any growing plant in dry weather. No matter how far from the smoke of towns, the soiling of the handkerchief will show a deposit of solid matter, of which a considerable proportion is organic.

in the color-blind test is now obligatory on candidates for masters' and mates' certificates in the British mercantile marine. Failure to pass the test does not now prevent the candidate receiving his certificate, as it did when the examinations were first instituted, but the certificate is given with the indorsement, "The holder has failed to pass the examination in colors." This examination is not yet made obligatory on pilots and men on the "lookout," and this ought to be regarded as a serious omission; for collisions are certainly more apt to occur off the coasts, when the vessels are under the charge of pilots, than out at sea, where they have been given over to the masters and mates.

of Copenhagen, has published the results of a sanitary inspection of the schools of that city, from which it appears that about one third of the pupils are sickly. With respect to the girls, the fact is brought out that "between the ages of twelve and sixteen the number of sickly girls increases till it exceeds that of healthy by ten per cent, except at the age of fourteen, when the figures are equal." Dr. Hertel also made inquiries into the condition of some German schools, and brought out the fact that in a single group of them three fourths of the pupils of the highest class have defective eye-sight.

Japanese have promulgated a patent law, which seems to be a compilation of various provisions selected from the laws of other countries. The term of protection is fifteen years. Articles "that tend to disturb social tranquillity, or demoralize customs and fashions, or are injurious to health," and medicines, arc excepted from its benefits. Among the conditions on which patents are granted, it is prescribed that the articles must have been publicly applied within two years, and that the patents shall become void when the patented inventions have been imported from abroad and sold.

claims to have employed a process for electroplating with aluminum, by which the deposition of that metal is effected as easily as is that of copper or silver, he uses a saturated solution of sulphate of aluminum and a solution of chloride of sodium, keeping them separated by a porous vessel. Under the action of the galvanic current a double chloride of aluminum and sodium is formed, which decomposes at once, the aluminum being set free and depositing itself at the negative electrode upon whatever object may be placed there to receive it.

in his studies of compound eyes and multiple images, remarks as a curious peculiarity of the eyes of the horse-fly that the lenses of the upper and anterior part are much larger than those situated below a median line, the larger facets having at least twice the diameter, or four times the superficial area, of the smaller. The larger lenses form pictures at a plane considerably above the focal plane of the smaller ones. Thus these insects are furnished with eyes of two varieties, corresponding to our long sight and short-sight spectacles; in other words, with telescopic and microscopical eyes, the telescopic looking upward and forward and the microscopical downward.