Photography and Science.

New Zealand Graphic, Volume XL, Issue 11, 14 March 1908, Page 45

Photography and Science.

PLATINUM PRINTS. There has been some talk of late as to the unpopularity of the platinum process. For some time 1 thought the decline was only to be brief, and that as soon as the temporary tyranny of the “boiled” bromide was over there would be a revulsion of feeling in favour of platinum printing, remarks a Home writer. But it certainly looks as if the unpopularity is settled, and we have to seek the cause. The cost of the paper i certainly high, but the chemicals required are cheap. A little healthy competition between manufacturers might lower prices somewhat without lowering the quality, but even then it could scarcely be possible to retail a thoroughly good paper at so-called “popular” prices. 1 must say that I cannot agree with those who assert that you can get the same effect with other cheaper processes. Only th? expert bromide worker could produce a print that would deceive the trained eye for a moment, and there are only a very few makes of bromide paper that in any way justify their claims in this direction. The bromide process is excellent in its way; but there is a very distinct difference between it and platinum. I am afraid that the unpopularity of platinum planting does not show that the .public is averse to paying extra money for an extra good thing, but rather leads us to conclude that the majority of the photographic public are too careless and uncritical to appreciate th? good points of the process. Perhaps, too, it suggests that the rank and file of photographers cannot produce negatives good enough for platinum. If you want a good thing, you must pay the price 1?/ it. If you want platinum quality, you cannot get it by cheaper methods than platinum printing. Perhaps on the whole it is as well that so beautiful a process is neglected by those who, with any sort of a subject and any sort of a negative, would get as poor results with platinum as with any other printing paper. All the newer printing processes are supposed to give prints indistinguishable either from carbon or from platinum. Some of the imitation “carbons” are feeble enough; but the peculiar quality of platinum has so far, 1 maintain, defied imitation. Quite apart from the question of permanency, a quality which may or may not be highly valued, the photographer who wants platinum or carbon effects will do well to employ the genuine and direct processes. ♦ ♦ ♦ 1 KEEPING WARM WITH ICE. To keep from freezing by the use of ice seems a novel way of turning ordinary usage upside down. Yet a Government expert has devised such a peculiar method of heating. It consists in keeping out cold, not by the use of fire, but by the intervention of ice. A car, double-lined, is fitted at each end with four galvanised iron cylinders, Teaching from the floor almost to the top. In summer these cylinders are filled ■with iee and salt in order to keep the car cold. The remarkable point, however, is that in winter- they are filled with ice to keep the contents of the ear from freezing. Ice is nominally at a temperature of thirty-two degrees Fahrenheit, and it is a substance that changes its temperature reluctantly, being a bad conductor of heat or cold. Consequently, when zero weather prevails without, the cylinders of relatively warm ice prevent the escape of heat; in other words, they (maintain the temperature within the car. Another device whereby ice is employed for protection against cold consists in throwing on the ear when the weather is near the zero point a plentiful stream of water, which freezes nt once and forms a complete coat over the vehicle. The action of the ice is the same as in the other case. A similar plan is frequently adopted In the transportation of bananas, a fruit which is particularly susceptible to cold. The fruit is put in paper bigs inside of heavy canvas bags, and covered with salt hay when the temperature is dangerously low.

AN EFFICIENT AND SAFE NEGATIVE R~VCER. Considering the capriciousness of the ammonium persulphate reducer, and the liability to stain which some workers seem to experience with the ferricyanide and hypo solution, it is surprising that that known as Labaraque’s process or hypochlorite solution is not more often employed. It is made as follows: — Chloride of lime 1 ounce, water 6 ounces. Shake well and add—Carbonate of soda 2 ounces, water Bounces. This forms a thick white cream which should be poured on to a filter paper or tuft of wetted cotton wool in a funnel, and allowed to drain through. The precipitate in the funnel should be washed with water as soon as it ceases to drop, till the clear solution that runs through measures twelve fluid ounces. Tne actual reducer is-—Labarraque’s solution, as above, 1 ounce, chrome alum 20 grains, water 10 ounces. It is best to dissolve the chrome alum in ounces of water, and add to the hypochicride, and then dilute with three parts of water just before use. The negative need not be soaked in water first; it can, if necessary, he .put in the reducer dry. It is not even necessary to see that the negative is absolutely free from hypo, as the above solution immediately destroys the hypo left in the film. After the negative has been immersed in the solution for a short time it should be removed, and the surface rubbed with a pledget of cotton wool wetted with the solution, holding the negative up to th? light so as to be .able to gauge the reduction. The friction practically wipes off the top layer of the film of gelatine and silver, and consequently, by applying mor,? friction in one place than another, it is possible to locally reduce. It must be noted that the c**oride of lime mentioned, is the so-called chloride of lime, and not calcium chloride, which is useless. The solution will keep in good condition for practically any length of time, and may be used repeatedly; but as it is very cheap it will be wise not to try its endurance too much. ♦ ♦ A NOVEL WATERPROOF COVER. A natty little device which will be appreciated by book-lovers who desire to keep the boards of their books clean when travelling, has been invented by an Edinburgh bookseller. It is waterproof, and by means of inner pockets it slides firmly over the edges of the boards, while at the same time it can be adapter to books of varying thicknesses. Once attached—a matter of two or three seconds—it remains in a tight position until released, and it is impossible for the book-cover to become .soiled through handling or wet. FUEL FROM HOUSE REFUSE. To the more economical ami useful utilisation of the contents of the humble dust-bin there appears to be no end. The latest development is the production of a fuel known as ‘coalescine,’ primarily intended for industrial use, as distinct from the open-grate. The process of preparation, which is th?* invention of an English borough surveyor, comprises the pulverisation of the organic and inorganic matter contained in the dust-bin, and its subsequent admixture with tar or tar-and pitch, after which it is pressed into briquettes. The fuel is stated to burn with a high efficiency in ordinary boilers, is perfectly hygienic, and can be manufactured very cheaply. The calorific qualities of such refuse is well known to be very high, as is evidenced by its wide utilisation in municipal dust-destructors for the generation of steam for driving electric machinery. The now system should directly to those smaller towns where the exigencies do not warrant the heavy expenditure incidental to th? installation of a dust-destructor, since the apparatus for preparing the furl is of simple design and inexpensive to lay down, while the revenue reaped from the sale of the article should render it at least practically self-supporting.

Walking for Girls. “Charmed to have your society, of course, my dear, but”—the Grandmother paused in polite doubt —“are you quite certain that you can keep up with my pace? Now don’t look indignant. The fact that you are forty-five years younger than I am does not prove that you can walk four miles without pausing to rest. Some young girls consider half that distance a long walk, and it is, at a dawdling gait. ‘‘There is so much character in a walk, don’t you think? Have you noticed how some women loiter along as though half dead and alive? And that others start oil’ briskly, their manner full of energy, ambition and enterprise that will probably distinguish them throughout life? Though no one should hurry unduly,” amended the Grandmother, “for that also will become a habit, and undue haste causes people to appear excited. “The first consideration when preparing for a real walk is the clothing. It should be warm, but not heavy, and, above all, loose, for any garment that is tight retards air circulation. The slsrt should be four inches from the ground, and the shoes should have thick, wide soles and low broad heels, else the pedestrian will soon tire. It is absurd for a woman to attempt to travel several miles on heels two inches high. By doing so she runs the risk of turning an ankle, and in time will acquire the vulgar heel lope, which is also the gait of the kangaroo. Long distance shoes must be large enough to allow for the natural expansion of the ieet induced by the exercise, otherwise they will crowd the shoes too much and their wearer will have that still’ motion produced by cramped feet. "When walking do not make ton desperate an effort to keep the toes turned cut. American Indians, who are the most graceful pedestrians in the world, keep their toes straight ahead. Learn what is the correct length of step for your height and adopt it. instead of toddling along like a high caste Chinese woman. And remember that if you keep the back straight, the head, neck and chest up. the shoulders will take care of themselves. They need not be squired or held with a palpable effort, but carried in their natural manner. “Sometimes,” confessed the Grandmother. “I literally take a little run in the Park, albeit in a secluded place, having a due regard for the proprieties. Nevertheless 1 am proud of the accomplishment. How many girls go you know who can really run? Yet no exercise will render one more graceful, and it may readily be learned if one knows how to breathe properly. Practise breathing by standing erect, with chest thrown forward and shoulders well back. The respirations snould be long and deep and oft. repeated, until they become a habit. Yes, it is nice to bo able to run. but don’t try to do a mile all at once. Begin with a few rods, and that at a slow gait, without allowing the heel to touch the ground. The practice will help to form that swift, gliding motion of walking which is tn? acme of grace.”