granite or any other known rock. With the view of testing in some degree the accuracy of this opinion, Leonhard requested of the celebrated chemist C. G. Gmelin, who has published so interesting an account of the composition of Phonolite or Clinkstone, to examine basalt in the same manner as he had phonolite. Leonhard, in his great work on Trap-rocks, now in the press, tells us that Gmelin readily agreed to undertake the analysis, and had already communicated to him the following examination of basalt.

Analysis of Basalt, by Professor C. G. Gmelin.

The analysis was conducted in the same way as that of phonolite.

Basalt from Stetten, a Conical Basaltic Rock in Hegau.

100 parts of the gelatinizing mass

100 parts of the not gelatinizing

The mass which does not gelatinize yields, when what appears to be magnetic iron is abstracted from the oxidulated

This result does not agree precisely with that of any other mineral, with respect to the component parts, but it approaches, in some measure, to anorthite, a species of felspar discovered by G. Rose. Anorthite is entirely decomposed by concentrated muriatic acid. It likewise contains a considerable quantity of magnesia, but what particularly deserves notice is, that no other fossil containing much magnesia gelatinizes with acid. The quan. tity of silica and lime in that part of basalt which gelatinizes with acids, agrees completely with that contained in anorthite. But, on the other hand, anorthite contains a far greater quantity of aluminous earth, considerably less magnesia, and no alkali. On the whole, it appears that that part of basalt which gelatinizes with acids, is the regular mass from which the various crystals are developed, that occur so frequently in basalt. For example, it is easy to perceive, that in consequence of the disappearance of magnesia, Labrador felspar, that universal component part of dolerite and syenite, as well as of many meteoric stones, stilbit so frequent in basalt, as well as chabasie, prehnite and arragonite, will be found in the mass.

The portion which does not gelatinize has nearly the same component parts as augite.

The analysis of basalt from Hohenstoffeln in Hegau is not yet quite completed. The proportion of the gelatinizing part to that which does not gelatinize is 6.197:3.303, and it deserves to be noticed, that it approaches very nearly to the basalt from Stetten.

=

Without doubt that part which does not gelatinise is completely analogous in its composition to the basalt from Stetten.

The gelatinous portion of basalt from Sternberg near Urach, has likewise the greatest analogy in its composition with the preceding. In this basalt the portion that gelatinizes is very remarkable: its proportion to that which does not gelatinize

100.14.

100 parts of the gelatinizing mass consists of

=

This basalt exhibits a very distinct decomposition on its surface, consisting of two to four lines of bluish-grey, and where the decomposition has proceeded farther, of a light yellow colour. In this instance, the decomposed part, as well as that which is undecomposed, requires examination. Of the former, a part of that which was most completely decomposed was employed. The principal result was anticipated, as might be expected, namely, that the decomposition diminished the relative proportion of the gelatinizing mass.

The gelatinizing mass in proportion The undecomposed Basalt, = 067,47·1 to that which did not gelatinize, The decomposed Basalt,

{The

=

031,10.1

100 parts of the gelatinizing mass of the undecomposed ba

The portion which did not gelatinize exhibited a peculiar composition; but the analysis must be repeated, as the loss is so considerable :

The quantity of alkali is remarkable, and it might be supposed that it was acquired in consequence of the silica in the gelatinizing portion being separated from that which did not gelatinize by the carbonate of potash; but that cannot be the case, because the powder was first of all acted upon by diluted muriatic acid, and then carefully washed.

The result of the investigation of the decomposed mass was, that the quantity of silica, titanium, lime, magnesia, and the alkalis was diminished, while that of the oxide of iron was considerably increased.

Chrome has been found in all analyzed basalt; without doubt it is contained in olivine, and perhaps the chromate of iron is

likewise to be found. Professor Bugengeiger of Freyburg has long since discovered chrome by means of the blowpipe.

Nothing was discovered after repeated experiments with muriatic acid, nor with sulphuric acid. Lithia has not been discovered. Strontian was by no means always found; but it was decidedly discovered in the basalt from Stetten.

On the Cholera Animalcule.

Ir is a very generally diffused opinion, although supported by no positive facts, that those animated creatures belonging to the lowest classes to which, on account of their minuteness, the name of Microscopic Animalcules has been given, are formed by the simple aggregation of the so-called organic molecules; and Dr Hermann has endeavoured to explain the contagious nature of cholera upon this supposition. As similar views have been more than once suggested, and it is to be feared that their plausibility may gain for them a more extended credence; the opinion of a naturalist deeply versed in microscopic inquiries, and who has personally observed the oriental plague, a disease not dissimilar in some of its characters to cholera, merits consideration. Professor Ehrenberg, in a late fugitive piece, has expressed himself in the following terms upon this subject.

To the doctrine of the similarity of the contagion of plague and of cholera, is connected with another which has lately found its way into the public journals, and which is merely a revival of the old and antiquated idea of small invisible insects which generate this contagion by their irritation, poison, &c., and propagate it by their increase and migrations. Similar stories are to be found in the traditions of various people as well as those of the poisonous look of some human faces, of the dragon, of witches, magicians, the second sight, &c., formerly so seriously believed, but now only thought ridiculous. Linné, the great reformer of natural history, first took this fabulous animalcule into the domain of natural history, probably only with the view of directing the attention of naturalists to the subject.