287 



lected at the cathode, which floated upon the liquid, and which, 

 when washed and dried, was analysed l3y heating in a tube retort ; 

 five grains of the zinc compound gave 0"73 of a cubic inch of perma- 

 nent gas. which on examination proved to be nitrogen with one- 

 fourth hydrogen. The same quantity of the cadmium compound 

 gave 0'207 cubic inch of nitrogen with no admixture of hydrogen. 

 A like weight of the copper compound gave 0'107 of nitrogen. 

 No ammonia was evolved from either; and the author is inclined to 

 think that the hydrogen yielded by the zinc compound resulted from 

 the reaction of the metal upon combined water. The specific gra- 

 vity of specimens of these substances which the author tried were 

 respectively 4, 6, 4, 8, and 5, 9. A mixed solution of chloride of 

 gold and hydro cUorate of ammonia, electrolyzed vnth platinum elec- 

 trodes, gave a black powder of the specific gravity 10"3 ; five grains 

 of which, being heated, gave only 0*05 cubic inch of gas. The 

 author proceeds to observe, that the similarity in appearance and 

 mode of formation of these compounds and of the mercurio-ammo- 

 niacal amalgam, is strong evidence of identity of constitution, and that 

 the non-permanence of the latter substance is due to the mobihty of 

 the mercury ; for if we place the compounds in similar circumstances, 

 that is, solidify the mercurial one, or liquefy those of the other me- 

 tals, the phaenomena are perfectly analogous. The experiments 

 also bear immediately upon those of Thenard, Savart, and others, 

 where ammonia, passed over heated metals, was found to be decom- 

 posed more completely by the oxidable than by the inoxidable me- 

 tals, and to alter their physical characters without materially in- 

 creasing their weight. On examining papers connected with this 

 subject, the author found that Mr. Daniell had cursorily noticed a 

 deposit somewhat analogous to those here treated of, which was 

 formed upon the negative plate of his constant battery when this 

 was charged on the zinc side with hydrochlorate of ammonia, and 

 the nature of which that gentleman observed was worthy of further 

 examination, but had not had time to investigate. 



February 11, 1841. 



The MARQUIS OF NORTHAMPTON, President, in the Chair. 



The Right Hon. Sir Richard Hussey Vivian, Bart., G.C.B., &c., 

 and Samuel Cartwright, Esq., were balloted for, and duly elected 

 into the Society. 



A paper was read, entitled, " Contributions to Terrestrial Mag- 

 netism, No. 2." By Major Edward Sabine, R.A., V.P.R.S. 



This paper is the second of a series, in which the author purposes 

 to communicate to the Pvoyal Society the results of magnetic ob- 

 servations in different parts of the globe, having for their object to 



