Hg + Mg + 2NaC2H5 = HgNa + Mg(C2H5)2. the magnesium-ethyl forming a compound with the zinc-ethyl previously in union with the sodium-ethyl. Mercury, Copper, and Sodium-Ethyl.-Mercury, Iron, and SodiumEthyl-Mercury, Silver, and Sodium-Ethyl. The result in each of these three cases is mercury-ethyl and sodium-amalgam, the presence of the copper, or iron, or silver appearing to have little or no influence on the course of the reaction. The foregoing reactions exhibit sodium-ethyl in a new light. It is a sodium compound which possesses the very singular property of giving up its sodium to mercury. In conclusion, I would remark that since the organo-metallic bodies are liable to be attacked by mercury, very little reliance can be placed on those vapour-density determinations of organo-metallic bodies which have been made by the method of Gay-Lussac, involving, as it does, the employment of mercury in contact with the organo-metallic body in a state of vapour. Most probably the anomalous results obtained by Buckton and Odling, viz., that the vapours of aluminum-methyl and aluminum-ethyl do not expand regularly, depend upon the decomposition of those compounds by the mercury of the bath. And most probably vapour-density determinations of these compounds will be found to yield perfectly intelligible and normal results when the method of Dumas instead of the method of Gay-Lussac is employed. XIII.-Chemical Researches on New and Rare Cornish Minerals. By A. H. CHURCH, M.A., Professor of Chemistry, R.A. College, Cirencester. (Continued from vol. III., new series, p. 259.) IV. A New Hydrated Cupric-aluminum Sulphate. I HAVE been engaged for some time in analysing certain chrysocollas containing aluminium, similar to the Tuscan specimens described by Delesse. But no definite composition was presented by these bodies; indeed they were evidently mixtures in most instances. In some of the specimens, I found, as Berthier had previously stated, much sulphuric acid, and at last I have obtained from Mr. Talling some specimens of a mineral almost free from silica and containing over 13 per cent. of sulphuric acid. I noticed it in Mr. Talling's collection, was struck by its appearance, and at once secured a few fragments. The analyses proved satisfactory and accordant, and showed the mineral to be a new and undescribed species. I purpose naming the mineral Woodwardite after my valued friend, the late Dr. S. P. Woodward. I shall be glad if this slight act of homage to the memory of an eminent man of science, serve to recall the labours of a palæontologist who was well versed likewise in chemical geology. Woodwardite occurs in stalactitic forms consisting of minute botryoïdal aggregations. It often constitutes a crust about th of an inch in thickness, and possessing the peculiar rippled appearance well seen in some specimens of langite. Woodwardite presents a most striking appearance when viewed with an 1 inch objective in the microscope, the mammillary or botryoïdal aggregations being arranged in irregular columnar masses. No trace of crystalline structure has yet been detected. The mineral is perfectly uniform in appearance, and evidently free, except where in contact with its matrix, from all admixture. To the unassisted eye, Woodwardite appears nearly opaque, but under the microscope the globules of which it consists are seen to be translucent. The lustre is between waxy and dull. The colour of the mineral is a rather greenish turquoise-blue. The streak and powder are pale blue. The mineral, though it readily falls to a coarse powder, presents a peculiar toughness and tendency to cohere under the pestle, resembling camphor and sal-ammoniac in this respect. The hardness is about 2. The specific gravity is about 2:38. This determination is approximative only; it was made with a specimen freed from interstitial air, but containing a large quantity of hygroscopic or accidental moisture, about 13 per cent. in all probability. Woodwardite is tasteless and without odour. It dissolves readily in dilute acids, a minute residue, about 1 per cent., of gelatinous silica remaining unaffected. Heated in a bulb-tube before the blow-pipe, it gives off a large amount of water with a slightly acid reaction, the residue becoming olive-brown, and, finally, black. Heated to 100° the blue tint of the mineral thereby becomes richer. In vacuo over oil of vitriol woodwardite loses a somewhat variable amount of water. Like many other uncrystallized minerals, it is hygroscopic, and if dried merely between pieces of filtering paper would be found to give a different formula on a dry and on a damp day. One determination of this accidental water gave 13.33 per cent., another a considerably smaller proportion. But the vacuum-dried mineral loses a constant amount of water at 100°; while the mineral dried at 100° suffers a considerable and perfectly definite further loss at a temperature below redness. Woodwardite contains traces of phosphoric acid, lime, and magnesia; the percentage of phosphoric acid has been determined, the lime and magnesia do not exist in sufficient quantity to be estimated. The analysis of the mineral offers no difficulty: in one instance (Anal. III) the sample for analysis was thoroughly washed before being employed. The wash waters contained a minute trace of copper. Analyses I and II were made by my assistant Mr. R. Warington, Junior. I. 5.47 grains of the mineral dried in vacuo gave : ⚫06 grain of SiO2. 21 grain of H2O at 100°. 2.56 grains of CuO. 100 grain of Al2O3. 2.00 grain of BaSO. : II. 10-19 grains dried in vacuo lost at a red heat : 2.41 grains of H2O; and gave 3.67 grains of BaSO4. III. 4 gramme, dried at 100°, gave :— 005 gramme of SiO2. 073 gramme of H2O, at a low red heat. 191 gramme of CuO. 071 gramme of Al2O3. •1605 gramme of BaSO4. IV. 5725 gramme dried in vacuo gave :— 0035 gramme of SiO2. 0300 gramme of H2O at 100°. 0955 gramme of H2O at a low red heat. 099 gramme of Al2O3. •209 gramme of BaSO4. V. 246 gramme dried in vacuo gave :- VI. 271 gramme dried in vacuo gave : ⚫015 gramme of H2O at 100°. The preceding analytical results point without doubt to a definite formula for the mineral, not only after it has become of constant weight in vacuo, but after drying at 100° C. To analyse the mineral, indeed, exactly in its natural condition of moisture would be useless, for as the atmospheric water increases or diminishes so does that of the mineral. But in vacuo over oil of vitriol, Woodwardite acquires in the course of an hour or two a perfect constancy of weight and composition. The formula which suggests itself for the mineral in this state is 2Cu"SO4.5Cu′′H2O2.4Al′′H ̧O3.4H2O. This formula demands the percentages given below: The numbers required by theory agree well with those furnished by experiment, except in the case of the SO, in which there is a deficiency of nearly one per cent. in the amount found. This may be accounted for by the occurrence of a small quantity of silicic acid in the mineral. The formula of the mineral, after it has been dried at 100° C., is 2Cu❝SO4.5Cu"H202.4Al”H3O3. This formula demands these percentages VOL. XIX. L This new mineral, though physically and chemically distinct from Lettsomite, is near that species. Woodwardite is more basic than Lettsomite, both in regard to the cupric and aluminic oxides. The difference is most strikingly seen in the percentage of alumina ; in Lettsomite this amounts to 11.06 per cent. only, according to Dr. Percy's analysis: in Woodwardite it is nearly 18 per cent. It is possible to regard the new mineral as a compound of brochantite and gibbsite. A trace of copper is removed from Woodwardite by digestion in cold water. Analysis IV. was made with a specimen so purified. The following percentages are those deduced from analyses I., II., IV., V., and VI. Before calculating the results, the small amount of silica found, about 1 per cent., has been subtracted in all the analyses but II. In analysis I. the phosphoric acid, which was found in the alumina, has also been deducted: 03 of a grain of Mg P2O, was obtained, corresponding to 0192 of P205 :Analysis of Woodwardite dried in vacuo :— 2 The following percentages are based on analyses I., III., and IV., the weights taken being those of the mineral dried till constant at 100° C. Analyses of Woodwardite dried at 100° C : |