4. Brochantite.-A specimen of this mineral from Chili gave on analysis the following results, after deducting 445 per cent. of insoluble matter: 5. Pectolite.-A specimen of the so-called okenite from Disco Island gave on analysis SiOg. 52.86 CaO. Al2O3. 34.33 0.71 Na2O. K2O. H2O. Total. This is evidently pectolite, and probably resembles much that is called okenite from the same locality. 6. Scorodite.-This rare mineral has been found at the Horn Silver mine, at Frisco, Utah. A pure sample for analysis could not be obtained. Before the blowpipe, the mineral gives the reactions of arsenic acid, iron, and water. 7. Bismuthite.-A mineral from Casher's Valley, North Carolina, proved to be bismuthite. The analysis gave the following results: BiO2. CO2. H2O. Insoluble. Total. 99.80 Sp. gr. 7.45 The formula suggested is Bi2C30, + 2Bi2H2O.. Comparing this formula with that given by Weisbach for his bismutosphærite, it is found that they differ only in the hydration of the bismuth oxide. A new examination of bismutosphærite appears desirable, for it is curious that the loss in the analysis should be exactly equal to the amount of water required to make it the well-known mineral bismuthite. 8. The author also describes some hemimorphic crystals of barytes from De Kalb, St. Lawrence Co., New York, and some interesting pseudomorphs of cerargyrite after pyrargyrite occurring at the Horn Silver Mine, Frisco, Utah. B. H. B. Minerals of the Serpentine-Chlorite-group. By V. WARTHA (Zeit. Kryst. Min., 13, 71–72).—The author gives analyses of two rocks he found in the Montafun Valley, Vorarlberg. The first came from Grandau (Analysis II), and resembles serpentine. The second came from Tafamunt (Analysis III), and resembles chlorite-schist. As the Grandau rock closely resembles the so-called precious serpentine from Borostyánkö in Eisenburg County, West Hungary, the author also gives an analysis of this (Analysis I). The analytical results were as follows:: 100:31 SiO2. FeO. Fe2O3. Al2O3. MgO. H2O. CaO. Total. Sp. gr. 2:693 100-62 2.722 99.68 2.876 From these results, the author concludes that the Hungarian rock and that from Grandau are identical with Kenngott's pseudophite, whilst the Tafamunt rock is serpentine-schist. In conclusion the author gives a number of analyses of serpentines free from alumina, and compares them with the analyses of minerals of the pennine, ripidolite, and chlorite-groups. He concludes that the typical serpentine (massive serpentine from Zermatt and from Windisch Matrey) contains a certain quantity of alumina, and that, with reference to the percentage of alumina, there is always observable a transition from serpentine to pennine. Serpentine, in fact, is nothing else than a characteristic member of the chlorite-group, in which the percentage of alumina is eventually equal to nought. B. H. B. Imperfectly known Silicates. By E. SCHLUTTIG (Zeit. Kryst. Min., 13, 73-76).-Glaucophane.-An analysis of the glaucophane, described by A. v. Lasaulx, from the Pointe des Chats, Brittany, gave the following results: SiO2. Al2O3. Fe2O3. FeO. CaO. I. 56-65 12:31 3:01 4.58 II. 57-13 12.68 8.01 2.20 MgO. KO. Na2O. Total. 12.29 1.05 7.93 100.02 3.34 11.12 trace 7.39 99.67 A. v. Lasaulx' results (II) are added for purposes of comparison. Violan from St. Marcel in Piemont gave on analysis the following results: SiO2. Al2O3. FeO. NiO + CoO. MnO. CaO. MgO. K2O. 52.02 2.60 0.80 Na,O. 4.94 0.39 2.87 22.94 15.18 0.75 The mineral was of a violet colour, and was associated with quartz, tremolite, and piemontite. Sapphirine from Fiskenäs in Greenland gave on analysis the following results : 14.76 63.23 1.65 19.75 99.39 This agrees with Rammelsberg's formula (MgFe),Al10SiO23. Felspar in the Corsican Diorite.-This has hitherto been regarded as ancrthite. The author concludes that it is a labradorite, composed of albite (1 mol.) and anorthite (3 mols.) His analysis gave— SiO2. Al2O3. Fe2O3. CaO. MgO. K2O. Na2O. H2O. Total. 47.38 29.58 1.34 12.26 1.50 3.15 2.14 2:33 99.68 Sp. gr. 2.70 B. H. B. Plagioclase from Tynemouth Dyke. By J. J. H. TEALL (Zeit. Kryst. Min., 13, 96).-An analysis of a specimen of plagioclase from the rock of a North-of-England dyke gave the following results: SiO2. Al2O3. Fe2O3. CaO. MgO. K2O. 47.30 31.50 1.85 14.88 0.93 0:38 Na O. Loss. Total. 1.80 99.86 1.22 The crystals are porphyritic, and glassy in texture. A section parallel to the basal plane gave 55° 10' as the angle between the extinction positions of adjacent lamellæ. The corresponding angle in anorthite lies between 57° and 74°, and in labradorite between 10° and 14° 30'. B. H. B. Action of Heat on Clays. By H. LE CHATELIER (Compt. rend, 104, 1443-1446).-The author has investigated the behaviour of clays on heating with a view to determine their constitution, and if possible to devise a scheme of classification. The temperatures were measured by means of a thermoelectric couple consisting of pure platinum, and platinum containing 10 per cent. of rhodium, and were registered photographically by means of a reflecting galvanometer. It was found that when small quantities of clay are heated the rate of increase of temperature slackens considerably at the moment of dehydration, and this point can be used as a means of distinguishing between different classes of hydrated silicates. The position of this point is independent of the conditions and notably of the rapidity of heating. The phenomenon is due to the fact that as soon as the velocity of a chemical change attains a notable value it increases very greatly for small increments of temperature. During the heating of the clays, however, there is not only a reduction in the rate of increase of temperature due to dehydration, but sudden accelerations are observed which indicate the occurrence of changes accompanied by a development of heat. The examination of a large number of clays shows that these substances are much less complicated than was believed. They may be divided into five well-defined groups, typical members of which are halloysite from Miglos; allophane from Saint Antoine; kaolin from Red Mt., Colorado; pyrophyllite from Beresow, and montmorillonite from St. Jean de Cole respectively. The first group shows a feebly marked reduction in the rate of increase at 150-200°; a second wellmarked reduction ending at 700°, followed by an acceleration at 1000°. The second shows well-marked reduction at 150-220°, followed by acceleration at 1000°. The third shows a reduction at 770°, followed by a slight acceleration at about 1000°. The fourth shows a well-marked reduction ending at 700°, and a second less strongly marked reduction at 850°. The fifth shows a well-marked reduction at 200°, a second less strongly marked at 770°, and a doubtful reduction at 950°. C. H. B. Constitution of Clays. By H. LE CHATELIER (Compt. rend., 104, 1517-1520).-When hydrated silica is gently heated it shows a diminution of the rate of increase of temperature between 100 and 200°. Alumina under the same conditions behaves differently according to the method by which it has been prepared. If precipitated from sodium aluminate it shows a first diminution below 200°, and a second ending at 360°; if precipitated from aluminium salts or prepared by calcination of the nitrate at a moderate temperature it shows the same reductions followed by a sudden acceleration in the rise of temperature at 850°; bauxite shows a diminution at 700°. VOL. LII. 39 From these facts it follows that the author's experiments (preceding Abstract) cannot be taken as showing the presence of free silica in clays, and they indicate that the first two hydrates of alumina cannot exist in any of the clays examined, whilst the hydrate present in bauxite can only be present in halloysite if in any. The evolution of heat at high temperatures is due to a molecular change in the alumina, which beyond this point becomes insoluble. Free alumina does not exist in clays, but is liberated by their decomposition on dehydration. Clays belonging to the montmorillonite-group have the composition 4SiO2, Al2O,H2O + Aq, whilst halloysites have the composition 2SiO2,Al2O3,2H2O, and in this respect are identical with kaolin. They are, however, distinguished from the latter by their behaviour during dehydration, and their solubility in acids after heating. C. H. B. River Waters of La Plata. By R. SCHOELLER (Ber., 20, 17841788).-I. La Plata water near Buenos Ayres. Water of brownish colour and slightly turbid. II.. Uruguay water, from about 3 miles above Fray Bentos; it was of pale brown colour and slightly turbid. III. Rio Negro water from above Mercedes; it was clear and nearly colourless. The results of the analyses of the filtered waters were as follows (grams per kilo.). Potassium was not detectable with the spectroscope in any of the waters. A. J. G. Organic Chemistry. Iodoform and Bromoform. By F. GÜNTHER (Arch. Pharm. [3], 25, 373—394).-Most of the methods given in text-books for the preparation of bromoform yield either none of that compound or very little. Methyl alcohol under the action of alkali and bromine gives no bromoform unless the alcohol be impure, formic acid being obtained. Ethyl alcohol under the same conditions gives acetic acid. If, however, the compound analogous to bleaching powder is prepared with bromine and milk of lime, this when heated with ethyl alcohol and then distilled gives bromoform. The best raw material is acetone. This when mixed with ten times its weight of a 20 per cent. soda solution heated at 50°, and treated with bromine in the smallest possible portions at a time, gives a yield of 81 per cent. of the theoretical amount of bromoform. The process goes quietly but lasts for some days. Caustic alkali in place of the carbonate accelerates the process, but the yield falls to 62.5 per cent. Acetaldehyde in presence of an alkali and bromine gives no bromoform. Anhydrous aldehyde under the action of bromine gives as one product a substance having the empirical formula C,H,BrO2, but whose constitution is quite uncertain; when heated with aqueous alkalis it yields bromoform and what seems to be a true resin. Iodoform.-Alcohol containing 20 to 25 per cent. aldehyde is the most suitable raw material for the production of this compound. It is mixed with ten times its weight of soda solution, iodine is added, and the mixture stirred round from time to time; the iodoform gradually and quietly separates out. The process is completed in the cold. Some sodium iodide may be added with advantage, to increase the solubility of the iodine. As bye-product, sodium iodide nearly free from iodate is obtained. J. T. Products from the Residues of Compressed Gas. By A. COLSON (Compt. rend., 1286—1289).-The residues from compressed gas were heated at about 35°, and one part of the evolved gases was condensed in a flask by means of a freezing mixture, whilst the remainder was absorbed by bromine, the bromides being afterwards fractionated. The fraction boiling at 148° is isobutylene bromide, about 100 gram s being obtained from 6 litres of gas oil. The fraction at 156-159 is smaller, and consists of diethylidene bromide, but the greater quantity of the brominated product consists of ethylvinyl bromide boiling at 167°. The portion of the gas condensed by the freezing mixture contains a certain quantity of the three butylenes, but consists mainly of hydrocarbons richer in carbon (b. p. 11-30°), and when treated with bromine yields the erythrene bromide described by Caventou. This bromide is soluble in boiling concentrated nitric acid, and is deposited unchanged on cooling. It is very slightly attacked at 180° by a solution of lead acetate in benzene. If powdered silver nitrate is |