Oxide of Iron

The present is not only a new but an instructive specimen. The crystals are secondary, but so perfectly distinct to every observer, that their derivation is truly evident. The grand vicissitudes and changes continually going on, even out of our sight, become in this instance very evident:—were the operations carrying on in our sight, we could not be more certain of them. Hæmatitic Iron, see tab. 56, is shown in this specimen, forming the concentric radii, in coats one over another, having lain over metastatic crystals of Carbonate of Lime; which being decayed, their place was filled up by a fresh supply of Oxide of Tron, with such exactness that the least attention to crystallization discovers the process. The moulding or coating in this manner is so sharp and accurate, that it may lead to a means of improving in such arts, especially as it is evidently a wet process, although it possesses so much the resemblance of fusion, as to have been actually thought so by some; but we herein see how the two processes resemble each other when completed.

Three different states of Oxide of Iron are visible in this; viz, the black-brown, the red, and the Roman Ochre; and I conceive an indefinite number of Oxides may be formed by the blending of these; nor do I think Iron is capable of taking oxygen from water, &c, in these different degrees which colour seems to represent; but when blueish or purplish, or any variety exists, it may depend upon Carbonic Acid, Hydrogen, Phosphorus, Manganese, &c., which may be known by their external appearance.