the various experiments to be carried on with this instrument, and explains the results arrived at. The different behaviour of various crystals is pointed out, the distinction between positive and negative crystals being very clearly shown. Those students who have little or no knowledge of mathematics or higher optics will no doubt find these few pages of considerable value. Two plates of figures add greatly to the lucidity of the text. rendering its special treatment necessary and desirable. | form the essential part; after which he gives details of That is happily no longer the case; the last edition of "Select Methods in Chemical Analysis," by William Crookes, F. R.S. (published by Longmans and Co.), goes very thoroughly into the subject. We note that emphasis is herein laid on the desirability of reporting that results have been obtained by a current of definite density, rather than by one yielding so many cubic centimetres of electrolytic gas per minute. We quite agree with the author that there is much to be said in favour of this recommendation. A current of 1 ampère equals 10'436 c.c. of oxy-hydrogen gas per minute, or 1969 m.grms. of metallic copper, or 67'1 m.grms. of silver, per minute. Results given with reference to ampères or decimal parts thereof are assuredly more easy of comprehension than those given in c.c. of gas. The sources of electrical energy may be briefly stated as, primary batteries, dynamo and magneto machines, and storage batteries or accumulators: of these we prefer the latter; the current is more constant, and this class of battery gives less trouble than any other. It may, of course, often happen that an accumulator cannot be used on account of there being no facilities available for recharging; in this case a bichromate battery will be found very convenient. The Leclanché cell is not of much use in this work, as the E.M.F. decreases so rapidly when a continuous flow of current is being used. By means of rheostats (several of which are described and illustrated) the strength of the current can be controlled with great accuracy. For measuring the currents used we do not favour the voltameter, though it is here said to be "the simplest and most convenient." Mechanical voltameters and ammeters for this purpose are now made so accurately that fractions of either unit can be easily read without any trouble beyond that of pressing a key. The first part of this book ends with a very interesting historical sketch of the inception and growth of electrolytic analysis. Gaultier de Claubry is credited with being the first to apply the electric current to the detection of metals in solution, in the year 1850, and, though many other workers have been constantly improving and adding to our knowledge, it is to the activity of the Aachen school, as represented by Classen and v. Reiss, that electrolysis owes the importance it now possesses in the eyes of the chemical public. The details of the more important methods devised by Classen and his fellowworkers are all mentioned under the headings of the respective metals to which they are applied. The second or special part of this excellent work is devoted to the separation and estimation of the various metals of common occurrence, each metal being taken in turn, all details of manipulation and apparatus being fully described and plentifully illustrated. CORRESPONDENCE. A NEW SULPHURETTED HYDROGEN To the Editor of the Chemical News. SIR,-In your issue for August 24th (CHEM. NEWS, vol. lxx., p. 95) is described a new form of H2S apparatus. It is no easy matter to fit the cork in such a way that there shall be no leak, under the great pressure caused by the rising of the acid in the funnel when the tap, E, of the wash-bottle is shut off. The following modification obviates this difficulty, and enables much slighter variations in E the pressure of gas, within the generating bottle, to force CHEMICAL An important and useful feature of this book is a list of the literature bearing on the particular subject, preceding the description of every process mentioned, thus enabling students, with very little trouble, to refer to the original articles and communications, should they wish it. In conclusion, we may add that it has not been considered necessary to include an outline of the electrolysis of minerals or alloys, believing that the experience gained in the analyses already described will enable the analyst NOTE.-All degrees of temperature are Centigrade unless otherwise to map out the proper course to be pursued as occasion arises. Notes on Polarised Light, for Students of Mineralogy. THESE notes have been prepared for the purpose of giving expressed. NOTICES FROM FOREIGN Comptes Rendus Hebdomadaires des Séances, de l'Académi des Sciences. Vol. cxix., No. 10, September 3, 1894. Assimilability of Potassa in Poor, Siliceous Soils by the Action of Nitrates.-P. Pichard.-Potassa which is in general sparingly assimilable, such as is found in siliceous rocks, in sandstones, and in sands, can suffice for the demands of plants which are exacting in this respect, by means of a suitable nitrification maintained in these soils, or by the addition of chemical nitrates. Nitric nitrogen is the excitant and the chief factor of all vegeta. tion. CHEMICAL NEWS, Sept. 28, 1894. Chemical Notices from Foreign Sources. New Gravimetric Determination of Glucose.-Fernand Gaud.—In a porcelain capsule the author mixes 50 c.c. of cupro-potassic liquid, prepared at the very moment, and 50 c.c. of water. After boiling for two or three minutes it is set upon a boiling water-bath, and 25 c.c. of the saccharine liquid (made up to 1 per cent) is added at once. After 10 minutes the reduction is complete, the blue liquid is decanted, and the precipitate is washed with boiled distilled water. When the washings are neutral to phenolphthalein the precipitate is washed into a specific gravity bottle holding from 20 to 25 c.c. Its capacity at o must be known beforehand. The level is made up with boiling water and the bottle is weighed. Let P be the weight of the liquid and the precipitate, the total volume of which is equal to the capacity of the bottle at the temperature, t, of the experiment, i.e., vt = vo [1+3ẞ (t-to)]: Knowing also the specific gravity A 5.881 of dried cuprous oxide, and ₫ the specific gravity (found in the tables) of water at the teinperature of the experiment, t, we find the weight, p, of the precipitate by the formula = Consecutive Phenomena in the Dialysis of the Cells of Beer Yeast.-F. Onimus.-The author seeks to ascertain whether it is the immediate contact of beer. yeast or the products of its secretion which effect the phenomena of fermentation. His experiments show that beer-yeast certainly secretes a dialysable substance, and that the inversion of the sugar takes place before the new cells appear. No. 11, September 10, 1894. This issue contains no chemical matter. Bulletin de la Société Chimique de Paris. Series 3, Vols. xi.-xii., No. 13. Novel Muffle Furnaces.-Emile Aubin.-The construction of these muffle furnaces cannot be explained without the accompanying figures. As compared with ordinary gas muffle-furnaces they are said to effect a great economy of time and of gas. On the Emetics.-Paul Adam.- Boric, arsenious, and antimonious acids react upon the acids of the acid alcohols. For the lactate and the salicylate the formation of the ether is evident. The case of ordinary tartar emetic is less simple, because we cannot isolate the neutral antimonio-tartrate, but the analogies and the reactions must lead us to consider substances of this kind not as double salts, but as ether salts. Melting and Boiling-points of some Phenols, and of their Benzoic Ethers.-A. Béhal and E. Choay The authors give their results in the form of tables. The benzoates are all solid except that of orthocresol, which is liquid. They crystallise well and distil at the ordinary pressure, without any trace of decomposition. They are insoluble in water, but soluble in most of the organic sol vents. Compounds of Pyridin with the Permanganates. T. Klobb.-Ammonia and pyridin give two parallel series of derivatives. The parallelism is traced in the compounds of silver, copper, cadmium, zinc, and nickel. On Certain Derivatives of Campholic Acid.-M. Guerbet. This paper is not adapted for useful abstraction. Experiments on Coal Immersed in Water.-G. Arth. The author finds that for coal reduced into small fragments and immersed in water the variation of the composition of the organic matter is very slight whether the water flows or is at rest. In practice the modifications may be considered as negligible for a duration of twelve 161 months. The differences may become more important if the time is further prolonged or if the material is more comminuted. The action of air is more decided than that of water, but it is unimportant if the coal is placed in con. ditions such that it does not heat. The modifications observed do not ensue in the same manner in water and in air, nor are they alike in all kinds of coal. Chemical Composition of the Colostrum of the Cow.-L. Naudin.-The proportions of extract of lactose and of butter present nothing remarkable. The ash and the proteïc matter undergo simultaneously very important changes. The mineral matter is in much larger quantity than in normal milk; the insoluble ash, especially the calcium phosphate, is increased. Contrary to what we observe in normal milk, the serum obtained with the colostrum holds sulphates in solution. They may reach from 45 to 60 centigrms. per litre, and decrease gradually until the milk becomes normal. Universal Gas-Volumeter of Dr. G. Lunge.-An abstract of this paper would require the eleven accompanying figures. Disinfection by Electricity, a Study on the Hermite Process of A. A. Lambert.-We shall endeavour to notice this process at some length. MISCELLANEOUS. Schools of Chemistry, &c.-The following additional information is appended to that which appeared in the STUDENT'S NUMBER : MUNICIPAL TECHNICAL SCHOOL, MANCHESter. At this important Municipal School, with an attendance of upwards of 3000 students, there are organised Day Courses in Pure Chemistry, with applications to Dyeing, Bleaching, and Printing. In addition there are Evening Courses, not only in Pure Chemistry, but in Metallurgy, Iron and Steel Manufacture, Brewing, Oils, Colours and Varnishes, Oils and Fats, Soap Manufacture, Bleaching, facture, and Photography. The complete Syllabus (4d., Dyeing, and Printing, Coal Tar Products, Paper Manuby post 6d.) may be obtained on application to Mr. J. H. Reynolds, Director and Secretary, Princess Street, Man chester. Medical Education in the United States. - Ac cording to the Lancet Clinic, an American professional organ (quoted in the Medical Press), "In Ohio any five with it in six weeks, or six days, can grant a legal men can organise and obtain a legal college charter, and diploma." (!) Chemico Technical Study in England. - The blishments for higher education, the question of chemicoChemiker Zeitung observes that in certain English estatechnical instruction seems to be receding rather than advancing. Thus at University College, London, the separate Chair of Chemical Technology has been given up. All the arguments and warnings of authorities, such as Stanford and Watson Smith, seem to yield little fruit. On a Reaction of the Aldehyds; Differentiation of the Aldoses and the Ketoses.-A. Villiers and M. Fayolle.-The authors have made use of a very sensitive reagent (aqueous solution of magenta decolourised by means of sulphurous acid), i.e., prepared without excess of sulphurous acid. They consider that every urine containing acetone must produce the re-colouration of the magenta. The use of the solution of magenta decolourised with sulphurous acid enables us to verify the purity of acetone. The same reagent serves to differentiate the aldosic from the ketosic sugars. Glucose, invert-sugar, and galactose redden the reagent as well as the aldehyds; it is the same with the reductive dextrines. Two samples of pure levulose and sorbine give a completely negative result.-Bull. Soc. Chim. de Paris, xi.-xii., No. 14. The Zurich Exhibition.-According to the Chemiker Zeitung the distribution of prizes at this Exhibition has been over-liberal. Of the 1300 exhibitors no fewer than 1199 have received prizes. In the department of Chemical Industry the three highest distinctions have been awarded to the manure-works, Grüze; the gelatinworks-both of Wintherthur; and the soap-works of Steinfels, of Zurich. The Cantonal chemist of the Pays du Vaud (F. Sciler) notices that the minimum limit of fat in milk in that district (3 per cent) is too low, as it allows of the removal of a portion of the cream. An examination of meat, which had occasioned NEWS MESSRS. MACMILLAN & CO.'S BOOKS FOR CHEMICAL STUDENTS. THORPE, F.R.S., Professor of Chemistry in the Royal College of TIMES TO THE PRESENT DAY. BY ERNST VON MEYER, eighty EXPERIMENTAL PROOFS OF CHEMICAL THEORY attacks of sickness and two deaths, led to the detection of an extremely pathogenic bacterium, not previously described. THIRD EDITION, RE-WRITTEN AND ENLARGED. 8vo., Price One Guinea, net. SELECT METHODS IN CHEMICAL ANALYSIS (CHIEFLY INORGANIC). BY WILLIAM CROOKES, F.R.S., &c., Editor of the Chemical News. WITH 67 WOODCUTS FOR BEGINNERS. By WILLIAM RAMSAY, Ph.D., F.R.S. CHEMICAL THEORY FOR BEGINNERS. BY LEO- OUTLINES OF GENERAL CHEMISTRY. By Prof. Translated by J. WALKER, D.Sc., Ph.D. WILHELM OSTWALD. 8vo., 10s. net. A INORGANIC AND ORGANIC CHEMISTRY. Complete Treatise on Inorganic and Organic Chemistry. By Sir H. E. RoscoE, F.R.S., and Prof. C. SCHORLEMMER, FR.S. Illustrated 8vo. Vols. I. and II. Inorganic Chemistry. Vol. I. The Non-Metallic Elements. 215. Vol. II. Part I. Metals. 18s. Vol. II. Part II. Metals. 18s. Vol. III. Organic Chemistry. Parts 1., II., IV., and VI., 215. each. Parts III. and V. 18s. each. INORGANIC CHEMISTRY FOR BEGINNERS. By Sir HENRY ROSCOE, F.R.S. Assisted by JOSEPH LUNT, B.Sc. Globe 8vo., 2s. 6d. LESSONS IN ELEMENTARY CHEMISTRY, INORGANIC AND ORGANIC. By Sir H. E. 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BY RAPHAEL MELDOLA, F.R.S., Professor of Chemistry, Technical College, Finsbury. Cr. 8vo. 6s. MACMILLAN & CO., LONDON. CHEMICAL NEWS, Sept. 28, 1894. Advertisements. iii HERIOT-WATT COLLEGE, EDINBURGH. | To MANUFACTURING CHEMISTS, DYE and COLOUR F. GRANT OGILVIE, M.A., B.Sc., F.R.S.E.-Principal. DAY CLASSES-SESSION 1894-95. MANUFACTURERS, and OTHERS. MESSRS. FULLER, HORSEY, SONS, and CASSELL are instructed to SELL by AUCTION, in Lots, on the Premises, No. 285, WANDSWORTH BRIDGE ROAD, FULHAM, S.W., on WEDNESDAY, OCTOBER 17TH, at 12 precisely, PLANT AND MACHINERY, including 4 copper The SESSION extends from TUESDAY, Jacketted pans, 55 wrought and cast iron pans, 10 mixers, 30 tanks The OCTOBER 9th, 1894, to FRIDAY, MAY 31st, 1895. These Classes provide Courses of Study extending over One or more Years, suitable for Students who have previously passed through the Curriculum of a Secondary School. The PRINCIPAL COURSES are:-PHYSICAL and CHEMICAL: MECHANICAL ENGINEERING and ELECTRICAL ENGINEERING. There are also Classes in French, German, Drawing, and Practice of Commerce. Session Fee, £10 10s. An extract from the Calendar of the College, giving particulars of the Day Classes, and of the various Appliances, Laboratories, and Workshops available for instruction, may be had on application to the LIBRARIAN at the College, or to the TREASURER of George Heriot's Trust. DAVID LEWIS, Treasurer. Treasurer's Chambers, 20, York Place, FOREIGN BOOKS AT FOREIGN PRICES. (up to 15 feet diameter), 3 sets paint rolls, pair 36-inch millstones, pair of edge-runners, centrifugal machine, hydraulic press, 12 pumps, Lancashire boiler, egg-ended and vertical boilers, three horizontal engines, shafting, 5-cwt. weighing machine, set of shear - legs, printing press, 2 iron safer, office fittings, quantity colour and chemicals, and other effects. 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