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POPULAR SCIENCE MONTHLY. 



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 pub- 

 lishers 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 dol- 



lar there is $25,000,000 more. We should 

 think the total receipts from sales and sub- 

 scriptions over rather than under $150,000,- 

 000. Now we come to the matter of adver- 

 tising, 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 ofifices of the country each 

 year." 



MINOR PARAGRAPHS. 



Gelatin has the curious property of 

 becoming insoluble and stiff when exposed 

 to formic aldehyde, while it resists the ac- 

 tion of water, acids, and alkalies. In this 

 stiffened condition it is like celluloid with- 

 out 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 transpar- 

 ency of the gelatin is remedied by adding, 

 previous to molding, a little zinc white in 

 water and alcohol, with which, if it is de- 

 sired, coloring substances may be incorpo- 

 rated. 



Twenty or more industries are enumer- 

 ated 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 mate- 

 rial 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 rub- 

 ber is more positively dangerous, and some- 

 times, according to the report, leads to in- 

 sanity. Other dangerous trades mentioned 

 are that of "dry cleaning," in which fire 



and the inhalation of volatile spirits are ele- 

 ments 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 experi- 

 ments. 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 sufiiciently 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 



