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Vapour-density of Zinc. By J. MENSCHING and V. MEYER (Ber., 19, 3295-3298). In their paper, the authors describe the method used by them in the determination of the vapour-density of zinc, and give details of the furnace employed, with which a constant temperature of about 1400° was obtainable under the conditions of working. The porcelain experimental tube was filled with nitrogen carefully freed from every trace of oxygen by slow passage over red-hot copper turnings, and through chromous chloride and alkaline pyrogallate. Two experiments were made, one at a temperature lower than the maximum, the second at the maximum temperature of the furnace, and the numbers obtained for the density were 2:41 and 2:36 respectively, compared with 2:25, the theoretical density of monatomic (Zn) zinc vapour. Experiments were also made with magnesium, but so far without success, since it has not been found possible to volatilise the metal in hydrogen. W. P. W.

Ammonio-mercuric Chromates. By C. HENSGEN (Rec. Trav. Chim., 5, 187-198).-On dissolving mercuric oxide in ammonium dichromate, Hirzel obtained a compound to which the formula (NHg2,OH)2,4HgCrO,, was ascribed, although based only on determinations of the mercury and chromium. In this paper, it is shown that mercuric oxide dissolves readily in a saturated solution of ammonium dichromate; golden, crystalline leaflets or needles separate out; these are insoluble in water, alcohol, and ether, very soluble in hydrochloric acid, but only sparingly soluble in dilute nitric or sulphuric acid. Analytical results showed the atomic ratio Hg: N: Cr= 1: 2: 2, and that three-fourths of the total nitrogen was in the form of ammonium and the remainder in an amido-group, results which point to the composition (NHg2, H2O), Cr2O,3(NH)2Cr2O,. These crystals when treated with excess of ammonia yield a canary-yellow powder, which no longer contains nitrogen in the form of ammonium, and to which the formula (NHg2, H2O)2CrO, is ascribed. If mercury chromate be digested with a warm, concentrated solution of ammonium dichromate, a brown solution is obtained, from which, on pouring into an excess of cold water, a yellow powder is deposited; the composition of the substance is (NHg2, H2O)2CrO4, the analogue of the selenate (NHg2, H2O),SeO1. V. H. V.

Water of Crystallisation of Alums. By E. MAUMENÉ (Compt. rend., 103, 1140-1141).-Ordinary potassium-alum, containing according to the author 28.73 mols. H2O, was dried for several months over sulphuric acid almost completely free from water. It never shows any condition of equilibrium corresponding with the formation. of a hydrate containing 24 mols. H2O. Towards the end of the operation, dehydration took place very slowly. The product contains 3.5 mols. H2O, and seems to have attained a condition of equilibrium. C. H. B.

Chemical Composition of some Ancient Ceramics from Brandenburg. By E. JENSCH (Ber., 19, 2850-2853).-Fragments of urns from various ancient burying places were analysed. The following may be quoted as examples:-I. From the urn field between.

Reichersdorf and Küppen, Jessnitz N/L. II. Fünfeichen, Fürstenberg a/O. III. Platkow, Gusow, in the Lebus district.

The specimen II was taken from the sides, which were covered with a thin glaze, I and III were taken from the bottom of the urns. Specimen II was coarse-grained and porous. Dried at 105° the loss of weight varied between 0.6-5.3 mean 1.95 per cent., an additional loss of 1.5-94, mean 40,2 per cent., occurring when the temperature was raised to a red heat.

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Owing to the unusual amount of phosphoric acid, analyses of five other fragments from the two urns containing the highest amount were made, with a result that a variation of 0.26-0.85 per cent., and 0.12-0.97 per cent. respectively were found. This is in all probability accounted for by imperfect admixture of bone-ash or some material rich in phosphorus with the red clay of the district which was most probably used in the manufacture of the urns. The clay accompanying the urn from Linderode had the composition SiO2, 62-67; AO, 29-34; FeO and Fe2O3, 356; CaO, 1.17; MgO, 0·53; Alkalis, 2:02. W. P. W.

Heating and Cooling of Fused Steel. By OSMOND (Compt. rend., 103, 1135-1137).-Iron containing 0.16 per cent. of carbon shows a feeble perturbation at 749° (this vol., p. 14), but the modification of the iron takes place mainly at a higher temperature. In the cooling of the fused metal, there are in fact three points at which the rate of cooling diminishes. Between 863 and 820°, the maximum effect being observed between 845° and 839°; between 775° and 736°, the maximum being between 763° and 749°; and between 693° and 669°. The first change indicates the return of the iron from the 3 modification which is stable at high temperatures, to the ordinary modification stable at the ordinary temperature, this return being retarded by the presence of the small quantity of carbon. The first diminution in the rate of cooling corresponds with a development of +38 cal. and the second with a development of +13 cal., the total 51 agreeing closely with Pionchon's determination +53 cal. On reheating, the second and third perturbations become coincident.

With steel containing 0.57 per cent. of carbon, the two perturbations at the highest temperatures become merged into one which takes place at 736-690°, but is still quite distinct from recalescence. If the steel contains 1.25 per cent. of carbon, the temperature at which alteration takes place is still lower, and in fact coincides with recalescence at

704°. It is evident that during cooling the presence of the dissolved carbon retards the alteration of the iron the more completely the greater its quantity.

Steel containing 0.16 per cent. of carbon shows the same perturbations in an atmosphere of hydrogen as in nitrogen. Steel containing 1.25 per cent. of carbon when cooled in hydrogen from 800° shows much enfeebled recalescence, a result probably due to the fact that hydrogen, as Forquignon has shown, has a strong attraction for the carbon in steel, and thus diminishes the proportion of carbon which combines with the iron. In another experiment, however, cooling from 1100°, no anomalies were observed.

No noteworthy differences are observed in an atmosphere of coal-gas. C. H. B.

Influence of Silicon on the Condition of Carbon in Castiron. By F. GAUTIER (Compt. rend., 103, 1137-1140).-The author has repeated Stead and Wood's experiments in which white iron was converted into grey iron by melting with a certain proportion of iron rich in silicon. His results were precisely the same, and show that in presence of not less than 2 per cent. of silicon the combined carbon is almost completely changed into graphite. He points out that the reverse change takes place in the Bessemer process. About half the silicon is removed before the amount of carbon has appreciably diminished, and it is then found that the iron has become white. The presence of manganese interferes with the conversion of combined carbon into graphite, owing to the tendency of the manganese to combine with carbon.

Grey iron prepared indirectly in this way is more homogeneous and has greater tenacity than grey iron obtained in the ordinary way.

C. H. B.

A New Class of Cobaltic Salts. By F. KEHRMANN (Ber., 19, 3101-3103).-Potassium cobaltic oxalate, K&Co(C2O1) + 6H2O, is obtained by mixing cobaltic hydroxide, potassium oxalate, oxalic acid, and water to a thick paste, and allowing the mixture to remain 14 to 21 days. After recrystallisation, &c., the salt is obtained in nearly black, well-formed, seemingly monosymmetric crystals, which in thin lamellæ show distinct dichroism (dark blue and emerald-green).

When treated with cold saturated sodium chloride solution, the sodium potassium salt is obtained crystallising in beautiful pyramids. The barium salt crystallises in sparingly soluble, green needles. The solutions of these salts are stable in the cold, but quickly decompose on heating with evolution of carbonic anhydride and formation of cobaltous salts. Corresponding nickel compounds could not be obtained. A. J. G

Mineralogical Chemistry.

Occurrence of Free Iodine in a Mineral Water. By J. A. WANKLYN (Chem. News, 54, 300).-The water from Woodhall Spa, near Lincoln, is exceptionally rich in bromides and iodides, and, moreover, contains iodine in sufficient quantity to give it a brown tint. On agitating it with carbon bisulphide, the water is decolorised, the bisulphide becoming violet. D. A. L.

Gold from Burmah. By R. ROMANIS (Chem. News, 54, 278— 279). The samples were found on the banks of the Meza, a tributary of the Irrawaddi, about 30 miles from the latter river, and to the westward of Katha. Sample A.-Large irregular fragments with quartz embedded in some of them. Iridosmine and crystals of chrome iron can be separated under a microscope. The composition is given below. The silver ore is a grey mineral which loses 49 per cent. on ignition. Sample B.-Fine smooth grains; about 17 per cent. insoluble in aqua regia, the insoluble matter consists of quartz, zircon, and about 7 per cent. of iridosmine in bright, flat grains mixed with a black mineral apparently a platinum ore.

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Preparation of Crystallised Insoluble Carbonates. By L. BOURGEOIS (Compt. rend., 103, 1088-1091).—0.5 gram of the amorphous carbonate is heated in a tube at 150-180°, with 20 c.c. of water and 2 grams of ammonium chloride, and then very slowly cooled. After the process of heating followed by slow cooling has been repeated four or five times, the carbonate becomes completely crystallised. The ammonium chloride is partially converted into carbonate, which decomposes into ammonia and carbonic anhydride. Part of the insoluble carbonate is thus dissolved, and separates in crystals during the slow cooling. When the heating is repeated, the

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same changes take place, and the crystals gradually increase at the expense of the amorphous substance. Calcite is obtained in simple rhombohedrons without admixture with aragonite; strontianite is obtained in short, rhombic prisms; witherite in long, thin, fibrous needles; cerusite in long, striated needles, which are always mixed with a variable proportion of a hydrated carbonate in nacreous, hexagonal lamellæ, with negative uniaxial double refraction, which is probably identical with hydrocerussite. Cadmium carbonate crystallises in rhombohedrons similar to those of calcite.

Lithium, magnesium, zinc, manganese, iron, nickel, cobalt, and copper carbonates yield only amorphous precipitates or indistinct spheroliths.

Almost identical results are obtained by heating the carbonates at 140° with a solution of urea, which is converted into ammonium carbonate by hydration. In addition, copper yields small prisms, which seem to be identical with malachite. C. H. B.

Occurrence of Iodine in Phosphorites and of Lithium in Psilomelane. By F. SANDBERGER (Jahrb. f. Min., 1887, 1, Mem., 95). -The author notes the remarkable manner in which elements occurring in rocks in very minute quantities become concentrated in certain products of the decomposition of the rocks. This is the case with iodine, which the author has detected in the staffelite from Brilon in Westphalia, separated out from decomposed diabase, and in the osteolite from the weathered basalts of the Kreuzberg on the Rhone.

Not less remarkable is the concentration of small quantities of lithium in psilomelane, a fact first observed in the Saxon Ore Mountains, but subsequently by the author in various places in the Black Forest. Lithium also becomes concentrated in the hexagonal variety of zinc sulphide, the so-called schalenblende. B. H. B.

Nephrite from Alaska. By A. B. MEYER (Jahrb. f. Min., 1887, 1, Ref., 6-8).—The author describes two axes procured from the Indians of South-east Alaska. The smaller has a sp. gr. of 2'96, and contains some magnetite; the sp. gr. of the larger being 2.92. The hardness of the latter is somewhat less than is usual with nephrite; the material being no longer quite unaltered. Analysis of the latter gave the following results:

SiO2. Al2O3. FeO. 51.63 4.31 4.82

CaO. MgO.
H2O. Total.
10.45 22.36 4.84 98.41

Under the microscope, it was found that this nephrite resembles most closely that from the river Kitoj in East Siberia. It differs from this, however, in the absence of all accessory constituents, except magnetite.

Green nephrite has been found in situ at the extreme north-west of Alaska. The raw material brought from Point Barrow in Alaska by Baird, proves on analysis to be neither nephrite nor jadeite, but pectolite. B. H. B.

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