# Popular Science Monthly/Volume 50/December 1896/Minor Paragraphs

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Gelatin has the curious property of becoming insoluble and stiff when exposed to formic aldehyde, while it resists the action of water, acids, and alkalies. In this stiffened condition it is like celluloid without being inflammable. Advantage is taken of this property in making statuettes and trifles of the carver's art. To make these objects, gelatin, having stood overnight in water, is melted in the marine bath, then mixed with formic aldehyde, and poured into molds of plaster, clay, or metal, cooled, and, when taken out of the mold, dipped in a concentrated solution of formic aldehyde, or, if large, painted with it. The transparency of the gelatin is remedied by adding, previous to molding, a little zinc white in water and alcohol, with which, if it is desired, coloring substances may be incorporated.
Twenty or more industries are enumerated in the report of a committee appointed by the British Home Secretary to inquire into the subject as "dangerous trades." Each of them has its special risk, ranging from discomfort that ultimately works harm to immediate peril. In the manufacture of India rubber the constant and all-pervading presence of naphtha, in which all the material has to be dissolved, is an effective agent of mischief. Still, no special illness is known to be produced by the fumes of naphtha, but, besides being unpleasant, they tend to undermine the constitution. The bisulphide-of-carbon process for vulcanizing India rubber is more positively dangerous, and sometimes, according to the report, leads to insanity. Other dangerous trades mentioned are that of "dry cleaning," in which fire and the inhalation of volatile spirits are elements of peril; working in bronze, which induces skin disease and slow poisoning of the system; mica-dusting, at which a boy seldom continues more than six weeks; and the manufacture and use of inflammable paints.
In order to determine whether calm sea air contains appreciable quantities of salt, M. E. Chaix, of Geneva, visiting the island of Jersey, drew air in quantities of one thousand litres at a time and stirred it in a solution of nitrate of silver. The solution was not made turbid in any of the experiments. The air, therefore, held no salt. Hence it seems certain that all the salt that may be floating in the atmosphere is that derived from the spray blown in by the winds and held temporarily in mechanical suspension. It does not volatilize in the air, and never becomes a real constituent of it. Persons going to the seaside "for the sake of the salt air" would therefore do well to avoid the calm, quiet places, and seek those which are more or less windy.
Believing that the current estimates of the velocity of flight of pigeons were not founded on sufficiently accurate data, Mr. G. B. Keene adopted the plan of having the birds released at a given distance away and a given moment, and observing the time of their arrival at their home. He found that, while some birds could maintain a speed of about 1,170 yards a minute, the speed of the majority, or 73 per cent of those observed, was between about 860 and 1,170 yards a minute. The highest speed observed by him of young pigeons was about 1,362 yards a minute. M. Felix Rodenbach, who has ​also made careful observations, believes in the possibility of pigeons flying 72 miles an hour. Observation shows that they fly perceptibly faster than the best express trains. Their speed, in M. Rodenbach's view, is even much greater than it appears; for they can not fly in a straight line as the express train runs, but are obliged to make zigzags and detours, as they meet or are turned by varying currents in the air.
The Gas Exposition to be held in Madison Square Garden during the two weeks beginning January 25, 1897, will be the first affair of the kind attempted in this country, although such displays are a regular feature of the year's entertainments in some European countries. The exhibition will be managed by a board of directors composed of men well known in the commercial and financial world—many of them connected with gas enterprises, and some distinguished in science and public life—assisted by an executive committee. It is represented that a large and increasing interest is being taken in the project by men and firms whose cooperation is desired, and who might be counted upon to become exhibitors. It would be impossible to name all or even a considerable fraction of the features which could find an appropriate place in such an exhibition. Great improvements are being made in the use of gas for light and fuel and the appliances, and these will, of course, be shown.
Mr. Amos W. Butler, the well-known ornithologist, gives, in his address as retiring President of the Indiana Academy of Sciences, an interesting and valuable contribution to our knowledge of contemporary evolution. The address, published by the Academy, treats of "a century of changes in the aspects of Nature" in Indiana. The disappearance of the great forests, the extinction of the Indian and the large mammals, have been accompanied by corresponding changes among the smaller animals. Especially notable has been the loss of the hosts of passenger pigeons. In the days of Wilson and Audubon the sky was literally dark with these. Now the species is but a memory, so far as Indiana is concerned. The future will record changes as the past has done. "But at no time in the future will the changes in the aspects of Nature be so noticeable, so incomprehensible, because of their vastness, as have those of the century just closing."
Following the protest which some time ago appeared against the illustrations of impossible icebergs comes one against impossible volcanoes. Mr. Oliver C. Farrington writes to Science, sending a reproduction of a school geography's picture of Popocatepetl, and by the side of it an outline of the actual mountain. The difference is quite startling. The slope of Popocatepetl was found by Mr. Farrington to be never more than 30°, while the picture represents a snow-capped peak with a slope of from 40° to 50° "A tall cross, such as no traveler in Mexico ever saw, and luxuriant palms, such as never grow at the altitude from which Popocatepetl can be seen," furnish a fitting foreground.