with the theory of the aqueous formation: but the objection on this ground has been urged before. In one a crystal of schorl passes through the centre of a garnet, and the whole is suspended (if I may use such a phrase) in the quartz. In others the crystals of schorl are simply suspended in the quartz or felspar, and have perfect terminations. It is evident in the first, and strongest case, that the schorl crystals must have been supported in a fluid of equal gravity, possessing no action chemical or mechanical on it, while a garnet was allowed to crystallize round it, and that this extraordinary state of things must have continued during the time which it would require to deposit a mass of quartz from a watery solution around the whole, a period, which if we may judge from the slow formation of chalcedonies from water, involves a supposition little short of miraculous.
Such are the difficulties which beset this very simple and probably very common occurrence. I do not mean by adducing it, to say, that no theory is worthy of attention which cannot explain all the phenomena. My wish is rather to excite the industry of those who cultivate geology, to the investigation of the still recondite chemical actions, from which alone we can hope for the solution of these and numerous other difficulties which attend us.
Loch Laggan.
I am merely desirous of pointing out under this title a bed of limestone, lying in a country so little visited, that it has not yet been observed by mineralogists, and of sufficiently rare occurrence to render it an object of notice.
The whole country about Loch Laggan is of that composition which forms the far larger part of the highland districts, namely micaceous schistus.
3 i 2
