Page:Proceedings of the Royal Society of London Vol 1.djvu/428

Rh Among the nebulae that have been formerly observed by the author, he refers to seven, which he considers as having approached very near to ﬁnal condensation; and of these he observes, that we see only a superﬁcial lustre, resembling that of planets, which are opake bodies, and not such as might be expected if the nebulous matter had no other quality than that of shining, and were perfectly transparent.

The author observes, that the spheroidal form which prevails among nebulae, is another circumstance of resemblance to planetary bodies, from which also their rotation on their axes may be inferred.

That nebulae do really undergo successive changes, the author de- duces not only from a comparison of diﬂ'erent nebulae with each other, but from a comparison of his own observations, made upon the ne- bula in Orion at this time, with those which he himself made thirty- seven years since.

The ﬁgure of it, at that time, he also then observed to differ from that given by Dr. Smith in his optics; and he now remarks, that it (ﬁllers from the delineation given by Huygens in his Systema Sa- turnium.

In the course of the gradual contraction of this nebula, Dr. Hers- chel has also observed certain stars which had appeared nebulous to become distinct by removal of anebulous covering, and thence infers that this nebula is certainly nearer to us than stars of the seventh or eighdth magnitude, and possibly not more distant than those of the thir.

Notwithstanding, therefore, the extreme dissimilitude between the appearance of diffused nebulosity and that of a star, they seem to have a natlu'al connexion by the several intermediate gradations that have been described. A nebulosity may be conceived so dilute as to be invisible till partially condensed; a nebulosity may become con- verted into a planetary nebula. The planetary nebula with uniform light may, by gradual condensation of its centre, be converted into a stellar nebula with bright central nucleus, surrounded by a more di- lute bur; and this at last assumes the appearance of a complete star, by condensation of so large a portion of its nebulous matter, that the remainder is no longer visible by the best telescopes.

An opinion having been entertained by many persons, that alcohol which has been distilled from wine does not exist ready formed in the liquor, but is generated during the process of distillation, Mr. Brande undertook a repetition of Fabroni’s experiment, on which this opinion is principally founded; but when he added four ounces of dry subcarbonate of potash to eight ﬂuid ounces of port, no alcohol was separated, although some of the same wine had previously been