288 Chronicles of Science. [April, 



ton of coals will be 4s. Gd. The works have been made to supply 

 950,000,000 cubic feet of gas annually, or at the rate of 2f millions 

 of cubic feet daily. 



Electricity. — A therrno-electrical apparatus, with galena and 

 iron, has been made by MM. Mure, Clamond, and Grarffe. Ac- 

 cording to the results of their experiments, this apparatus deserves 

 the attention of all who require galvanic batteries, since regularity 

 and steadiness of action are here combined with economy and the 

 absence of inconvenient vapours. 



For telegraphic work or domestic purposes, where a constant 

 galvanic current is required with little trouble (electric bells, fire and 

 thief detectors), the writer has found the new battery known as the 

 Leclanche cell to be most perfect in action. The main feature is 

 that peroxide of manganese is used with zinc (not amalgamated) and 

 an aqueous solution of an alkaline salt, chloride of ammonium being 

 preferred. The cells are of three sizes : the smallest, with a porous 

 pot 4 • 3 inches high, can accomplish an annual electric work which 

 maybe represented by 620 grains of copper reduced in the voltameter; 

 the medium size, with a 6 -inch porous pot, can reduce from 950 to 

 1000 grains; while the large size gives a work equal to 1500 or 

 2000 grains. 



F. Zaliwski has described a galvanic element with three fluids. 

 This contrivance consists of two porous cells placed one inside the 

 other, and surrounded by another suitable vessel. The inner vessel 

 contains nitric acid and a piece of carbon, the intermediate vessel 

 contains sulphuric acid, and the outer vessel a solution of sal-ammoniac 

 in water and a piece of zinc. This author states that this arrange- 

 ment is superior to a Bunsen cell. 



The phenomena of atmospheric electricity at the island of Haiti, 

 or St. Domingo, as it is also called, are of a very striking character. 

 According to Mr. Ackermann, who has during a series of five years 

 made meteorological observations at Port-au-Prince, there have, on 

 an average, been 129 days of each year either severe thunderstorms 

 or other very marked electrical phenomena, especially during the 

 months of May, July, August, and September. Severe thunder- 

 storms more frequently occur during day than night-time. The 

 year 1868 was especially remarkable for severe thunderstorms; 

 during one of these, lasting for forty-five minutes, 400 lightning 

 flashes were distinctly seen. 



A company has been formed in America with the view of cover- 

 ing other metals, by galvano-plastic means, with a more or less thick 

 coating of pure nickel. Since that metal is very hard, it resists, 

 even in thin layers, rather rough usage ; it is not oxidized, even in 

 contact with water, at the ordinary temperature., and the metal as- 



