486 SCIENTIFIC RECORD FOR 1884 



metnl and electrolyte has a diiferent class of motions, and in conse- 

 quence of this they also, by contact alone with each other at the same 

 temperature, become electro-polar. The molecular motion of each dif- 

 ferent substance also increases at a different rate by rise of temperature. 

 {Nature, January, 1884, xxix, 300.) 



Hammerl has studied the conditions of accuracy in the copi)er vol- 

 tameter, and finds them to be as follows : (1) The liquid should not be 

 heated above 40°, for fear of oxidizing the deposit; (2) the plates should 

 be nearly rectangular, preferably circular, parallel, and varnished on 

 the back ; (3) if they are not less than l.S'^'" apart, the density of the 

 current for exact measurement should not exceed 7 amperes per square 

 decimeter. (J. P%s., April, 1884, II, iii, 178.) 



Mascart has repeated his determination of the electro-chemical equiv- 

 alent of silver, and now flndj that a coulomb will deposit 1.1156 milli- 

 grams of silver and will decompose 0.09303 milligram of water. The 

 values found by Kohlrausch were 1.1183 and 0.09325, respectively. {J. 

 Pliys., July, 1884, II, ni, 283.) 



Eayleigh has also determined the electro-chemical equivalent of sil- 

 ver and finds 1,118x10-^ for its value in C. G. S. units. One ampere- 

 hour deposits 4.025 grams silver. {Proc. Boy. Soc, March, 1884; J. 

 Phys., July, 1884, II, in, 307.) 



Lodge, in a paper on storage batteries, concedes that at the present 

 time it is i^retty generally felt that no existing form of storage battery 

 is perfect, and that on the whole such batteries are extravagant and 

 wasteful to an extent sufficient to more than compensate for their un- 

 deniable convenience. " It is perfectly certain," he says, " that their em- 

 ployment has not become at all general, and that they have failed to 

 realize the somewhat sanguine hope of their early promoters." Storage 

 batteries would be useful, he thinks, (1) to economize now wasted power, 

 like water-power; (2) to obtain regular from irregular action, as wind 

 and tides; and (3) to obtain strong but short — from long-continued 

 though weak action. {Nature, October, 1884, xxx, 585.) 



NECROLOGY OF PHYSICISTS, 1884. 



GiNTL, J. WiLHELM, professor emeritus of mathematics and physics at 

 Gratz, a telegraph engineer and inventor of a duplex system of tele- 

 graphy. Died at Prague December 2B, 1883, aged 80 years. 



Mereifield, 0. W., principal of the royal school of naval architecture, 

 South Kensington. Died at Brighton, Eng., January 1, 1884, aged 

 56 years. 



Dallmeyer, John Henry, physicist and optician, celebrated for his 

 photographic lenses. Died in London in January, 1884, aged 53 

 years. 



Du MoNCEL, Theodore, electrician and physicist, editor of La Lu- 

 mi^re Electrique. Died in Paris February, 1884, aged 03 years. 



