SCIENCE NOTES.

Otago Witness, Issue 2082, 18 January 1894, Page 48

SCIENCE NOTES.

—Mr Jacksh, of Trieste, Moravia, as quoted by the Popular Science Monthly, names four sulphurets which become phosphorescent after a brief exposure to daylight—the sulphurets of calcium, strontium, barium, and zinc. The last compound has been obtained in a luminous condition only recently by distillation in a vacuum. Prepared in the usual way, by precipitating soluble salts of zinc with sulphurets, it shows no signs of phosphorescence. Sulphnret of barium gives a yellowish orange glow, but only for a few minutes after each exposure to the light, and is of as little use as the sulphurets of strontium and of zinc, the greenish glow of which disappears after about two hours. For practical uses the sulphuret of calcium of commerce is the only phosphorescent of value. Pure, it gives a faint yellowish light, but treated at a red heat, with the addition of a small quantity of a salt of bismuth, it is transformed into a substance giving a violet light and retaining its luminous quality for nearly 40 hours after an exposure of only a few seconds.

— The Indian Commission appointed by the Government for a fuller investigation on leprosy, haa now settled the question in the negative as to the hereditary transmission of the disease. This decision, arrived at after a very limited time of research, will find ready combatants in those persons who have given up the best part of their lives to the study of leprosy in its various bearings, and whose experience has not been such as to make them in sympathy with the ultimatum of this august body. The very natare of the complaint is one which demands exclusively a close personal investigation, extending over a number of years, before any opinion on the subject of its heredity can be conclusively formed. It is insufficient to trust too much to the testimony of the afflicted themselves, for to the Hindoo, as to the Eastern mind in general, the very fact that the disease is looked upon as a divine visitation for sin is provocative of a reticence on the part of its victims as to all past family history; hence it is manifestly evident, as we have said, that a lengthy personal study is necessary before any less conclusive evidence on the disease can be universally accepted. — Hospital.

— The heat being applied to the bottom of a vessel, the lowest layer of the water becomes hot first, and after a time some of it is converted into steam, forming a bubble, which rises into the upper psrt of the liquid. The upper part is still below the boiling point, and so the bubble collapses with a sharp, rattling noise called feimmering. When, however, the upper part has become sufficiently hot, the bubbles do not collapse, but escape at the surface. The water js thpn in a state called boiling. — A French architect, weary of the eter> iial ironwork supports and decorations of verandahs and balconies, and striving for something more solid and substantial in effect to harmonise with the substantiality of Btcme and brick buildings, has brought out a glas3 brick, with which he claims to tected by taste, upon an average, the twentieth part of a grain of gall, while the men detected the presence of the sixtieth part of a grain. The experiments were not comprehensive enough to demonstrate any decided superiority upon one side or the other, but the practical result of this investigation is the establishment of a reason why women bear physical pain with more fortitude than do men. It is, that the organs of senee being less active, " women are less easily affected by pain, or, indeed, any physical emotion.

— relative activity of the senses in men and women has been the subject of a strictly scientific investigation in Paris. The results of a series of experiments demonstrate conclusively that the senses are ordinarily from four to five times more acute in the male than they are in the female. The sense of smell in the men experimented upon was keen enough to detect trie hundredth part of a grain of prußsic acid. The women subjeeta only detected the poison by smell when the twentieth part of a grain was present. As to sight, it was proved that the men took in the general aspect of a scene at one glance, while in the women some striking

feature of the same view was apparently all that impressed them, and this sense was proved to be five times more acute in the males than in the females. The ticking of a watch was heard by the latter at the distance of only 2yds, while to the former it was distinctly audible at a distance of 10yds, and even more. A woman only deget handsome effects. Now that the brick is made he is working it in many other connections; thus the glass bricks can be built into walls where windows are desired, but where, according to Building Acts, they would be illegal. They are available for lining the wards of hospitals, for building baths, and even in such places as butchers' and fishmongers' shops they would be a cheap substitute for tiles. They can be prepared so as to lend themselves well to decorative effect.

— •• Marquetry" is a French term, which expresses what we call " wood inlaying," and wood inlaying of some description is an art of great antiquity. It appears probable that the art of inlaying was known to both the anoient Egyptians and Assyrians, and the Romans, besides their free use of mosaics for pavements, appear to have frequently employed veneers. But it is in Italy, in the fifteenth century, that we really come upon veritable wood inlay. This was a form of decorative work called " intarsiatura," in which designs and even pictures were built up by the juxtaposition oca number of small cubes of wood of different colours. While, however, these wooden cubes were comparatively thick, modern marquetry is cut out of very thin veneers.

— A curious discovery in science waß lately reported in the Electrical Review. If a beam of sunlight be passed through a prism so as to break it up into rainbow tints, and these be allowed to fall, one at a time, upon a glass vessel containing lampblack, coloured silk, or worsted, the vessel will give forth sounds varying according to the fabric employed and the colour of the ray which strikes it. Every kind of material gives forth some sound to some colour, and is silent to others.

— Writing to Industries, Mr A. A. Voysey gives an account of an apparently unusual cause of damage by lightning. In a room in a country house near Nottingham stood a table " ornamented by a fringe fastened securely to it by nails. This fringe bai been almost entirely burnt on the side of the table facing the room, and the burning had partially extended to one other side. The wood was charred to a depth of one-eighth to onequarter of an inch where the fringe was burnt. IE the table had been struck by lightning there must have been some marks in the room showing where the discharge had entered and where it passed to the earth. But not a mark or sign of any kind could be found, and the damage to the table was completely isolated. A rigid inquiry proved that no one had entered the room with a candle. The only possible explanation of the occurrence was suggested by an examination of the fringe. It was found to consist of a fluffy material, probably a mixtnre of cotton and wool, and certainly of an inflammable nature. Interspersed among the fluffy material were fine metallic threads. Now it is in this combination of inflammable material with the metal threads that the explanation lies. The metal threads were acted on inductively by the lightning discharges taking place near the house. This inductive aotion was sufficient to cause small sparks to fly between various threads, and the sparks set the inflammable material on fire. If the fire caused in this peculiar manner bad not quickly died oat, the whole house might have been destroyed, and no sign would have been left to point to the true cause. It is not unusual for fires to occur in connection with thunderstorms, and they are generally attributed to the direst action of a lightning discharge. Possibly a large percentage of such fires have been caused by induction, and the simple incident which has come to my notice is sufficient to show how easily the inductive action may cause a fire."

— To prevent collisions between railway trains, a Frenchman, Professor Pell at, has invented a machine by means of which every locomotive on the road registers its position electrically ever so often on a scroll of paper at the central office. The scroll is kept slowly moving over a cylinder. Electric contacts are made between points above and below it, which decompose some iodide of potassium in the paper, and thus cause a blue stain. This happens every time an engine passes over certain levers arranged be9ide the truck at intervals of a mile, more or less. By watchiDg the scroll a tiain despatcher can see in an instant where every train is, and if any two of them approach too closely he can stop any engine at the next post telegraphically. An electric signal may be picked up by the locomotive with a " brush " on one of the wheels when it touches the registering fixture.