Page:Popular Science Monthly Volume 50.djvu/300

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in operation in the United States. We are within bounds in estimating the daily issues of the newspapers in the United States at more than 20,000,000 copies. If the publishers receive on the average as much as five dollars per year for their circulation from each subscriber or patron, we have more than $100,000,000 paid in from that source. Giving the weeklies an average of only 2,000, and we have nearly 25,000,000 subscribers to them, and at the average price of one dollar there is $25,000,000 more. We should think the total receipts from sales and subscriptions over rather than under $150,000,000. Now we come to the matter of advertising, which is probably nearly twice the amount paid in subscriptions—nearer $300,000,000 than $200,000,000. If it is only $250,000,000, we have an aggregate of $400,000,000 passing over the counters of the newspaper orifices of the country each year."


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