Page:Proceedings of the Royal Society of London Vol 4.djvu/257

Rh nights occur in the course of the two winters in which the formation of arches of the aurora is noticed and their direction recorded ; of these, ten are to the west, having their centres rather to the south- ward of west, the arches extending from N.W. to S.S.E. and S.E. ; seven are to the east, or more precisely to the southward of east, the arches extending from N.E. to S.E. and S.W. - Of the five others, four are said to be froni east to west across the zenith, and cannot therefore be classed with either of the preceding, and one is noticed generally as being to the north. The facts here recorded appear to afford an evidence of the same nature as those mentioned by M. Erman, as far as regards there being two centres of the phsenomena. In respect to the relative brilliancy of the east- ern and western aurora, nothing very decided can be irf erred from the register. If, as M. Erman supposes, that they may be referred respectively to " les deux foyers magnetiques de I'hemisphere bo- real," it is proper to notice that the position of Alten is nearly mid- way between those localities „

There can be no doubt that the frequent appearance of the aurora, and the peculiarities of the phsenomena observed there, ren- der it a most desirable quarter for a magnetical and meteorological observatory.

Edward Sabine. ' W. H. Sykes.

2. " Second Letter on the Electrolysis of Secondary Compounds, addressed to Michael Faraday, Esq., D.C.L., F.R.S., &c." By J. Frederic Daniell, Esq., For. Sec. R.S., Professor of Chemistry in King's College, London.

The author, in this letter, prosecutes the inquiry he had com- menced in the former one, into the mode in which the chemical ele- ments group themselves together to constitute radicles, or proxi- mate principles. He considers his experiments as establishing the principle that, considered as electrolytes, the inorganic oxy-acid salts must be regarded as compounds of metals, or of that extraor- dinary compound of nitrogen and four equivalents of hydrogen to which Berzelius has given the name of ammonium, and compound anions, chlorine, iodine, &c., of the Haloide salts ; and as showing that this evidence goes far to establish experimentally the hypothe- sis originally brought forward by Davy, of the general analogy in the constitution of all salts, whether derived from cxy-acids or hy- dro-acids. Some remarks are made on the 'subject of nomenclature, and the rest of the paper is occupied with the details of the experi- ments, all bearing on the important subject which he has under- taken to investigate.

The ballot for the Right Rev. the Lord Bishop of Norwich was deferred until the next meeting of the Society, there not being a sufficient number of Fellows present.