The Arkansaw traveler., 1884-08-30
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 SCIENTIFIC MISCELLANY.

SCIENTIFIC MISCELLANY.
 A French chemist has tound that, un- der certain conditions, an observation of the electric resistance of water seems to supply delicate sess of its purity.
 An establishment in the Hehndes which treats sea-weed for its iodine, ac- cording to Mir. Edward Sanford, F. (. & obtains an Illuminating gas as . bye product The process also yields . very light and porous charcoal, ammonia and tar.
 A simple sunshine recorder is made by Prof H. Macleod by placing . globular bottle of water befose camera in such a position that the focused ray falls oa a sheet of seasitized paper in .he camera box. AS the sun makes iss daily journey it produces a curved white hne oo the paper, and when clouds cross the sun the line stops.
 Some remarkable photographs of a pistol bullet in its Aight-under the illumination of an electric spark-have been secured by Prof E. Mach, of Pragae. He has Also photographed the air streams which one may SC over Bunsen burner placed in sunshine; and has even obtained pictures of waves of sound, these last being made visible by a method in which advantage is taken of the irregular refraetioo of light by the air set in vibration by sound.
 The temrsratures at which the com mon gases become ique6ed are given as follows by Prof. Dewar, the numbers ex- pressing degrees below zero Fahrenheit: Carbonic acid, II2; nitrous oxide. 90; ethyiene, the chief Illuminating consti- tutent of common coal gas, I54 I-2 oxy- gen, 2oo; nitrogen, gao; air, 3I4; car bonic oxide, SIS I-2. The greatest cold yet produced by man-3aS degrees be- low seso-was obtained by two Russian physicists by the use of liquid oxygen-
 Color Peroepion.-Lord Rayieigh has made some interesting investigations on color-blindness with an apparatus in which two specsra are overlapped 90 as to produce various mixtures of colors, which are examined and described by the person under test One of the things he has shown is that the majority of people require only half as much red in the mixed spectra to turn yellow into green as he does himself By far the most common form of coior-blindness is bind ness to red. Dr. Guthrie, who is SO afflicted, is more than usually sensitive to blue light and others have been found with an abnormally acute perception of red. One person appeared who suffered from the very rare defect of being color blind to green. These results have led an English astronomer to suggest that some of the startling changes of color alleged to have been noticed among the heavenly bodies have really never taken place, the suppesition of such changes having probably arisen from the differ ent eolor-perceiving power of different obseEvers.
 The Cholera Germ.-That the cause 2 cholera is a microscopic organism was first recognized in 1854 by Filippo Pacini, of Florence, the parasite being in ISS, classified by Tommasi-Crudelia among the schizomyceti, CT germs which multiply by simple division. Pacini supposed that the organism attacked the mucous mem brane of the intestines, but his doctrine was ndiculed or disregaTded until the same conclusion was reached by the com mission of eminent German patholoeisss which has just investigated the subject in Egypt. The cholera germ multiplies in the soil where the excretious Of cholera patients have found their way but it may also find an abiding place in bed-linen which has been fouled by such excretioas and washed without disinfectants, as was shown. in 1856, when a poor Tuscan woman died with cholera received from linen which had been infected an entire year before. Tommasi-Crudelir remarks that cholera in Europe IS always an im- portation from the east, never becoming acchmati.ed like smallpox, and that it becomes epidemic only when the excze- tions containing the germ find a soil favorabls so its multiphcaficn.
 Chinese Alchsmy.-An eastern writer declares that there is nov no reasonable doubt that the old Arabian alchemisss and others derived their ideas oo the of meals into geld and the belief in immunity from death by the use of the philosophers stone from China. Mercury is ssased to have been the philos- epher's stone of which Gebez and others