a. The layer of turquoise mineral, from which the rock or vein-stuff had been detached as far as practicable, was found to contain phosphoric acid, alumina, oxide of copper, oxide of iron, and water; which occur in turquoise. b. After the layer a had been separated, a fair average sample of the rock was found to contain 1.69 per cent. of metallic copper. It was also assayed and found to be free from silver[EN#7] and gold. No. 27. "G." A variety of jasper, having a somewhat polished, and irregular and deeply indented surface, the result of sand-action. The fractured surface was red, with patches of yellow. It was found to consist chiefly of silica, coloured with oxides of iron. No. 28. "H." Lump of "sard," of a pale-red flesh colour. A variety of chalcedony. It was found to consist almost entirely of silica[EN#8]. No. 29. "I." Lumps of pure ironstone. A small lump of metal[EN#9], supposed to contain antimony[EN#10] and platinum, was brought for examination by Captain R. F. Burton. It was submitted to analysis, and found to be iron and combined carbon, or white cast-iron, containing small quantities of lead, copper, and silver, and free from antimony, platinum, and gold. It is evidently the product of a fusion operation. A few "shots" of lead were attached to the surface of the metal[EN#11]. Dr. Percy concludes the assays in these words:-- Three of the specimens (Nos. 14, 15, and 19) from the same locality contain gold. The amount of gold, however, is small. I consider these indications of the presence of the precious metal not altogether unsatisfactory; and certainly to justify further exploration. My conviction is, that the ancients were adepts in the art of extracting gold, and that, owing to the small value of human labour, they could get out as much of the metal as could now be done. They knew perfectly what was worth working and what was not; and I think it likely that what you have brought home, had been rejected by the ancients as unworkable[EN#12]. Further search may lead to the discovery of workable stuff; but would doubtless require a good deal of time, unless lucky accident should intervene. The specimens Nos. 2, 3, 5, 22, and 23 contain sufficient iron to render them available as iron ores, provided they occur in large quantity. The copper present in No. 21a is too small in amount to render it available as a source of that metal [Footnote: Analyses of copper ore from Midian at the Citadel, Cairo, gave in certain cases forty percent.]. If it is practicable on a large scale, by hand-labour or other means, to separate the "copper mineral" (as in b), it would be sufficiently rich in copper, provided the cost of the transit were not too great. The specimen No. 17 is only of scientific interest, as it gives off an acid vapour when heated; and this substance may have been used by the ancients in the separation of silver from gold by the process termed "cementation." I remain, dear Sir, yours very truly,