Untitled

Otago Witness, Issue 2429, 3 October 1900, Page 62

SCIENCE NOTES.

— " A wail of complaint has gone up from )he photographic societies, which finds expression in the phrase* ' too many developers.' Thi^f denunciation .cf needless repetition is well merited, and while new developers continue to be introduced which have the same characteristics and the same disadvantages as old-established predecessors, only irritation and confusion can result. There is, however, still room for a developer which is more energetic than pyrogallic acid, which produces clean negatives free from fog, and neither stains nor injure^ the fingers." So begins a little booklet published by "Messrs Griffin and Sons, who are the makers of " Kachin." It contains many practical hints on the use of thib new developer, and much information that will prove useful to every amateur photographer. From it we learn that " Kachin " is a highly purified benzol derivative obtained by a patented process. It is a clear white, beautifully crystalline substance, having a characteristic silky lustre, and is readily soluble in water. It is quite btable at temperature below that of boiling point, and may be stored in paper or in tins quite as effectively as in bottles; samples of it have been kept in paper bags •for more than two years Without showing the slightest signs of deterioration. The composition of " Kachin " has lately been so moditied as to admit of its being used in conjunction with carbonate of soda as an accelerator, instead of the more objectionable caustic alkali which was formerly the only accelerator with which it would work satisfactorily. 1 ihave tried a sample of 'wie new " Kachin," and like it much better than the old. Another peculiarity of "Kachin " is that potassium bromide hay little or no restraining action, upon it, and weak negatives are the result of over-exposure; however, borax has 'been found to fill its place in a very perfect '.manner, and enormously increased contrast can be secured by the addition of from 10 to 30 drops per ounce of a 4- per cent, solution of this cheap and easily obtained salt. This is a distinct advantage to those photographers who wi^h to use a gi^en quantity of develoipcr, which will take'up from each plate developed a considerable amount of bromide, and will yet yield normal soft re&ults, the additional re-strainer not affecting, as would usually be the case, the 'density of the negative. ■ — "Iris," in Leeds Mercury.

— Professor "Willc and Mr Aksd Evening have succeeded by thrur patented processes in making seaweed useful in different wayp, and in producing the lollowing articles from it — viz., .sodium is extracted through the aid of acids, and more sodium is got in this way than through the burning process, when considerable waste occurs. From the offal after making sodium can be produced, an admixture to so-called size paint (instead of using Iceland mops). This product is much cheaper, and can be made insoluble in water thi'ough a coating v/ith a special stuff, it can thus partly take tho / place of oil. Further, there

can be made from, seaweed a finish for use in cloth mills, and this same product can al«o be used as a glue for paper. The half-fluid like pulp can be made imo a kind of leather for binding books.

—M. Stanislas Meunier has observed the fact that' limestone rocks near Constantine, Algeria, are pierced with holes by snails, which use v cavities thus formed as a shelter from the summer heat.. In the same connection, M. Edouard Harle has xjbservod an aralogous fact at Salias-du-Salat, in France : calcareous rocks of compact structure or marble present here and there groups of cylindrical holes as large as the iLumb ; according to the inhabitants, these holes are made by a species of snail, and several of these were found lodged in .them. Cases of this kind have been already observed, and as far back as 1854- M. Constant Preyoat gave an account to the Academic dcs Sciences of a series of cylindrical holes made by snails in the limestone rocks at Monte Pelegrino, in Sicily. These holes are from three to four inches long and have diameters varying from one-fifth to two inches, according as they were made by young or adult specimens. Near Eoulogne-sur-Mer he observed hard limestone rocks which had been perforated with circular holes, grouped on the inner or less exposed faces of the rocks, these being from five to six inches deep and having a slight upward slope t.o prevent the accumulation of water. The snail in this case is the Helix hortensis.

— One of the most interesting of the addresses delivered before the recent meeting of the American Medical Association, held at Atlantic City, was that by Professor Vaughan, of the University of Michigan, on the distribution of typhoid fever among the American soldiers in iB9B. Its chief interest, lay in the demonstration which it afforded of the practical certainty of typhoid fever arising within a couple of months or so of the assembly of an army in camp, and of the fact that the conditions of the camp and of camp discipline are the effective causes which determine whether or no the disease shall develop into an epidemic. He stated that not only did every regiment in the service develop-typhoid, but that more than 90 per cent, of the volunteer, and probably all of the regular regiments, developed the disease within eight weeks of assembling in the States camps. Another important point shown is that it did not require a very large aggregation of men to lead to this unlortunate result, ior the disease became epidemic both in the small encampments of not more than one regiment as well as in the larger ones of one or more corps ; in fact, so prevalent is typhoid fever in the States that it is more than probable that in any organisation, of 1300 men of military age, taken from private lite and held together for two months, one or more cas,es will develop however perieel the sanitary condition of the camp may bo. When, however, the disease has arisen all depends on the sanitary conditions of the campr. . . . The presence of typhoid fever in an army so greatly takes away from its utility as a fighting force that even from a merely military point of view no trouble would seem to be too great to take if by it such a scourge con be kept at bay, or even be diminished in its virulence. How great a scourge typhoid may bocome may be judged from the statement that about one-fifth of all the soldiers in the national encampments in the United States in 1898 developed typhoid fever.— The Hospital.

— Electricity has conferred innumerable benefits on mankind, but if It will — as Dr Frederick^ Giegler, of the Hygienic Institute of the University of Wtirtomburg has discovered — cure toothache, it ,vill have achieved a distinction which will, from the pom' of view of the average man, outweigh almost every other advantage it has bestowed on humanity. The method of application would seem to be exceedingly simple, and consists in merely putting the electrodes one on each side of the affected tooth, and passing a weak current through it. This sends what are described as " little darting arrow-like thrills " through the roots of the teeth, and in a very short time the pain cimdCo, while the microbes which have boon irritating the nerve or decaying the bony structure are killed. In this way, it is said, a really painless process of dentistry can be ensured, and, aa a rule, it is only necessary to keep up the electrical application from eight to 12 minutes, altliough in other cases as much as half an horn has been necessary to set a sufficient effect, 'incidentally, the work of the dentist is considerably

shortened, for what often requires an hour to do with the sensitive ca\ity of the tooth of a nervous patient can be done in 10 minutes when the cavity has been made absolutely painless by this means, which leaves no subsequent feeling of exhaustion or discomfort. — Liveipool Post.

— The novel process of pumping land out of the water is being carried, out not far from New York. According to daily press reports, land is now being literally pumped up from the sea. for the creation of a new suburb at Nassau Beach, on the shore of Jamaica. Bay, Long Island, not far from Brooklyn. " The salt mar&hes on this coast, which for centuries have been overflowed by the tides, and which, of course, while in this condition were utterly unfit for building purposes, are beingraised from four to six feet above high water by pumping up the sand, shells, and gravel which form the floor of the bay, and delivering this on to the land to be reclaimed. The process adopted to attain this end is as follows : A powerful suction dredger raises the material from the bed of the bay at the rate of 18,000 cubic yards a day, and with this five times the volume of wafer, which io sufficient to carry the sand and gravel along the 12in pipes which deliver it on the low land. The water flows off by ditches olong a more or le&s circuitous route back to the bay, the dredged material seettiing raid quickly drying, and forming solid land. The thickness of the material when firs.it deposited averages about Bft, but there is slainkago as it dries and consolidates. Tea acres have thu o beea raised since the pumping began a few months ago. A raised road and promenade two miles long and seventy feet wide and an electric railway will connect this new suburb with the railway to Brooklyn and New York."

— There are, naturally, a number of sweeping curves through the Urals, bin, all tunnelling has been avoided, ihe writer did not see a single tunnel in the Oral range. It is a remarkable fact that, dining the trans-Sibe-rian railway inspection, the writer did not observe a tunnel anywhere; and even after continuing the inspection right into the hea<l of Russia, about 2000 miles more of line had been covered before he sow the first tunnel. This was near Tyfa. not far from the illustrious Tolstoi's home ; and it was while responding to a pi'9-arranged invitation from le grand Russe, that the writer came across this, the first tunnel noted, after 6000 miles of overland railway inspection. The Russian railway engineer will sooner blow up a small mountain than make a tunnel, leaving a yawning chasm between die rocks, v/ith two "'strea'cs of rust" at the bottom thereof aa a souvenir of his activity. Or, if he finds that, after going to the mountain, the mountain is not likely to yield to him, his instructions are to circumvent it by a long detour. Anything to avoid tunnelling! The primary aversion to tunnels in Russia is not alone their fiist cost, but their subsequent cost ; tor tunnels, libs houses, always have "something the matter with them."— L. Lodian in Cassier's Magazine.