SCIENCE, MECHANICAL INVENTIONS, ETC.

New Zealand Herald, Volume XXXVIII, Issue 11692, 29 June 1901, Page 4 (Supplement)

SCIENCE, MECHANICAL INVENTIONS, ETC.

THE UGHTIJfG OF THE GLASGOW EXHIBITION". At the close of an article on the Glasgow Exhibition, which, appeared on. May 8, the special correspondent of the Times referred to the lighting in the following terms: " One word about the lighting, which is a feature of the Exhibition. There is no attempt to rival the effects produced in Paris, but the opportunity lias been taken to institute a practical and interesting comparisn between the most modern systems of lighting. There is electricity of various kinds, acetylene gas, compressed oil, and compressed gas. I do not know to which the palm should be given; but there is no doubt that electricity is quite eclipsed by compressed incandescent gas. Two systems of the latter are installed Welsbach, in which the gas is compressed at a central station, and the ingenious Scott-Sneli system, in which each lamp is made to compress its own gas by the heat generated by itself. It is an interesting comment on the rapidity with which things move that electricity— yesterday the latest-born and best-beloved offspring of physical science—is already being displaced by younger rivals."

LEFT AND lUGHT-lIANDEDXESS. In a paper on "Left and Right-Han ness" Dr. Lueddeckens gives some interesting information regarding this subject. It has: been a well-known fact that the stronger activity of the nerves of the right half of the body (for not only the hand .is concerned) must be ascribed to a preponderance of the left side of the brain, whose finer development, especially as the seat of the centre of speech, is a matter of common knowledge. In the said paper, according to tho German periodical Woche, the question regarding the cause of the unequal working of the two hemispheres of the brain has been solved. A sketch dwelling on the history of evolution leads from the original symmetry of the organism to a subsequent asymmetrical arrangement of the heart, and the large blood vessels, from which may be inferred quite naturally that the two halves of the head are not placed on an equal footing as regards the quantity of blood supplied and consequently of the blood pressure, and that on the contrary there must be under normal conditions a stronger pressure in the arteries of the left side of the head. This theory is supported by the well-known experiences of anatomists and pathologists and a series of interesting observation. Of especial interest is the effect of the greater blood pressure upon the loft eye. Dr. Lueddeckens found in the latter, as compared with the right one, in a surprisingly large number of cases, a narrower pupil, in consequence of a more fillcd-up condition of the vessels of the iris, and upon closer examination a shorter construction of the eyeball. .This furnishes the hitherto unknown reason for the fact that in a large number of persons the left eye is the better one. Thus, the finer development of the left half of the brain is explained very simply by the fact that it is better supplied with blood, and the question why it is the seat of the speech centre and why most people are right-handed is solved in the most natural manner. It is most remarkable how truthful a reflection of the above-described conditions is afforded by the examination of left-handed persons. In a large number of cases a moro florid colour was perceptible on the right side of the face; the right eye was built shorter, its pupil narrower; in short, everything pointed to a better blood supply on the right side of the brain, which in consequence imparts to the left side of the body the preponderance over the right one, a condition styled left-handedness. In relation thereto stands the habit of most left-handed persons, in opposition to other physiological laws, to sleep on the left side, in 'the unconscious endeavour to relieve the right half of their brain, which contains a larger amount of blood during the day. For the same reason the position on the right side is the normal one for right-handed persons. SUBSTITUTE FOP, CELLULOID, PARCHMENT, ETC. A process for the transformation of vegetable fibres, especially cotton tissues, into a parchment-like product has been patented in Austria. A cotton fabric, such as calico, is treated with sodium lye and carbon sulphide, the latter, however, not in the liquid, but in the vaporous srate. The sodium lye used for this purpose, with which the cotton fabric is worked through and then pressed out, must not exceed 25 per cent, in strength. The whole is now left alone for three days in a closed receptacle and then suspended in an atmosphere of carbon 'sulphide vapours till it has changed into a vellowish-brown, translucent mass. The fabric is now rinsed in water; this causes it to swell; then it is pre-dried on plates ; loosened from the plates, it is allowed to finish drying at lOOdeg. C., whereby shrinking and a brown colouration is effected. The fabric thus hardened can be rendered pliable again by several hours' immersion on 5 per cent. acetic'acid, which is generally done; subsequently it is washed and likewise dried again. The product obtained in this manner consists of a firm, translucent mass, which becomes mouldable, and softens on being heated to lOOdeg. C., so that it may be provided with any desired patterns by pressing between plates and rollers. The product may then be completely bleached by the .use of chloride of lime, or may be dyed as desired. It is excellently adapted as a substitute for celluloid, parchment, gutta percha, and caoutchouc.

PHOTOOP.APHIC prints. To. glazing photographic prints, 'first clean some sheets of patent plate-glass or ferrotype plate (which should be somewhat larger than the prints) with soap and water (says a writer in the May part of Work). If the highest gloss is required, glass should be used. When the glass is dry?rub it over with a/Solution made by dissolving a little white wax in turpentine, as used in the-car-bon process. Soak the prints and lay 'them face down on the glass (several, may bo laid on tbo same sheet of glass if it is large enough), cover with a sheet of ■ iluflleus blot-ting-paper, and squeeze tho prints into close contact with the glass, forcing out any air bubbles. It' the glass is placed a yard or so from the lire? the prints should dry off quickly, and will often come away spontaneously; otherwise, lifting one corner of the print with a penknife usually suffices. At times, however, the" print fails to; come off, ami therefore the alum bath had better be used, but not until after toning, nor must any of the alum remain in the print v.'hen it is placed in the fixing bath, as hyposulphite of soda is decomposed by the alum, and fading of the print will result. Chloride of soda is merely used to convert any free nitrate into chloride, and thus to avoid trouble in the toning bath. Glazed prints lose their polish on being wetted with paste when mounting, but if before the prints ale thoroughly dry they are backed with a piece of waterproof paper while still on the glass, the print and its backing will leave the glass together, and the print may be mounted with gelatine.

ELECTRICITY NOW USED FOR TANNING. Electricity is now being used to ''uiihair" and tan the skins of animals. The hides being placed in a tank of chemical solution, a current is passed through for twenty minutes, and, after a subsequent soak of an hour or so the skins are in condition to be removed and deprived of their hair. Such, at all events, is the claim of the people who own the process, and they say that by this means results are accomplished in a couple of hours which hitherto have required from ten days to three weeks. After they have been "unhaired." the skins are tanned by placing them in a tank containing the proper bark extracts, and passing tho current of electricity through them. The current has a tendency to open the pores and allow the extracts to penetrate the hides thoroughly, thus accomplishing the tanning process "in a rapid and econo" mical way. The same idea is applied to the extraction of essential principles from coffee, nuts, and other substances, the raw material being placed in a tank of chemical solution, which is caused to boil by means of a current of electricity. The solution absorbs the extractive properties, and all vapours are conducted by a, pipe ito a condenser, so as to save them. The notion of nnhairing and tanning hides while you wait, so to speak, is distinctly novel, and the process is said to save money as well as time. Even a'saving of a few cents on each skin is of great importance, as may be judged from the fact that there bbare slaughtered in America annually something like 800,000,000 sheep and cattle, nob to count calves and goats.. ' ' v,