When, in the year 1798, I presented to the Royal Society, in conjunction with Mr. Greville, a Paper on the Corundum Stone, I gave some hints of an opinion which l,as well as Mr. Greville, had already formed, namely, that the said stone was absolutely of the same nature with those stones or gems which mineralogists, following the example of the jewellers, had hitherto distinguished by the epithet
oriental
. This opinion was founded upon circumstances which appeared to me perfectly satisfactory; but these circumstances had not yet been sufficiently examined, nor were they sufficiently striking, to obviate every possible objection; and, consequently, my opinion was not yet in a state fit to be presented to the Royal Society, as an established truth. Since that time, I have never lost sight of this object, nor have I neglected any means in my. power, which could conduce to the end I had in view; and I may say, that my success has far surpassed my expectations. The specimens of corundum that have been lately sent from India, joined to the very considerable collection of oriental gems, in their perfect crystalline forms, which I have been able to procure, have afforded me the most satisfactory demonstration that a mineralogist can wish for; and nothing was now wanting to fix, in a complete and decisive manner, the general opinion respecting this stone, except to give it that additional support which is furnished by chemical investigation. Mr, Klaproth indeed had already published an analysis of the corundum stone, and of the sapphire; but he had not submitted to the same scrutiny, the perfect red corundum or oriental ruby; it is possible also, that the specimens of corundum he made use of in his analysis, which had been taken from among the first specimens of this stone sent from India, were not so pure as might have been wished, and that this impurity was the cause of the difference, (which however was very trifling,) between the result of their analysis and that of the sapphire. I there fore chose, from among the specimens of corundum which had been sent from China, from the kingdom of Ava, from the Carnatic, and from the coast of Malabar, such pieces as appeared to me the most pure; and, after having added to them a quantity of oriental rubies and sapphires, sufficient for many repeated analyses, I requested Mr. Ch e n e v ix, whose chemical labours are so useful to mineralogy, by his constant application of them to that science, to have the kindness to join with me in the investigation I had undertaken. The Royal Society will perceive, in the detail given by Mr. Chenevix himself, of the analyses which he has made, not only of the different varieties, of corundum, but also of the substances which accompany this stone in its matrix, how very satisfactory to science are the results of those analyses; insomuch, that I can now offer to the Society, as one of the best established truths, what, in the year 1798, I mentioned merely as a suspicion which had great probability in its favour; and can also, in consequence of the particular study I have made of all the varieties of stones that I have here joined together, under the general denomination of corundum, present to the Society a collection of facts, for the most part unknown, which, altogether, may be considered as forming a mineralogical history of this substance. Although the epithet oriental has been for a long time used by the lapidaries, to express, in gems or precious stones, a degree of hardness superior to that of other stones, (the diamond excepted,) which made them capable of taking a more brilliant polish; and although, following the example of the lapidaries, naturalists had employed the same term by way of distinguishing them, there still remained a great uncertainty, respecting the nature of the analogy which really existed between the various stones to which the above epithet was applied.
IV. Contributions towards the history of the monamines
