CHEMISTRY. 217 



sj'stera, and that the ideas advanced regarding the more general 

 application, as to private houses, villages, etc., are very similar to 

 those entertained by the editor after a careful consideration of 

 these reports from the Indian government." — New York Medical 

 Journal. 



STREET DUST LAID BY THE USE OF CHEMICALS. 



A patent was taken out in England, last September, by Mr. J. 

 W. Cooper, relating to the application of a compound of deli- 

 quescent salts to the prevention of dust upon roadways. This 

 season, extensive experiments have been made in the Parish of 

 St. Marylebone to test the value of the invention, and the results 

 seem very favorable. It is estimated that it costs 500,000 dollars 

 per annum to water the streets of London, and, notwithstanding 

 this enormous outlay, the dust -cannot be laid. The demand for 

 something more effectual has given rise to the invention referred 

 to. The composition used is from one-half pound to 1 jiound of 

 the mixed chlorides of calcium and sodium to 1 gallon of water. 

 The salts are put in the cart and the water is then taken in. By 

 the time the cart is full the salts are dissolved. Althoucrh we 

 have had sufficient rain in New York and Brooklyn, as well as in 

 other parts of the country, the season in England has been re- 

 markably dry, and consequently very unfavorable to the develop- 

 ment of the principle upon which this invention is based, namely, 

 the retention of moisture by the mixed chlorides. The reports, 

 however, are remarkably favorable. It produces a most impor- 

 tant effect upon the surfaces of macadamized roads, hardening and 

 concreting the material in such a manner that when it is perfectly 

 dry no dust arises from the passage of ordinary traffic. The light 

 dust always found upon a dry road surface, watered with plain 

 water, is not to be seen. The surface remains firm with the ab- 

 sence of detritus. The roads are thus rendered more durable, 

 while, the chlorides being anti-putrescent, a sanitary advantage 

 is gained, at the same time that economy in the use of water is 

 secured, — important considerations in all large cities. 



By the present system of deluging, three applications daily are 

 scarcely sufficient in warm, dry weather to prevent the dust from 

 blowing, whereas one application of Mr. Cooper's composition at 

 intervals of two or three days will, it is said, effectually accomplish 

 this object, and at a much less cost. 



The dust in the large rooms of warehouses and similar build- 

 ings might, doubtless, be effectively controlled by adding a little 

 of these salts to the water used. 



The shopkeepers, along the streets where this composition has 

 been used, have given their testimony in its favor. They state 

 that, instead of having' their shops filled with dust, they can 

 scarcely see a particle, and on Sundays, while other streets are 

 smothered in dust, they rejoice in immunity from this nuisance. 



The chlorides used are cheap, and obtainable in large quantities. 

 The chloride of calcium has not been in large demand heretofore, 



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