NEWS of young Fellows representing the modern school of In moving a vote of thanks for the Address, Sir WILLIAM RAMSAY said he was inclined to think that the tendency was to trust too much to the results of examinations. He was of opinion that the aim of the examiners should be to ascertain if the candidates could converse freely and easily on their subject, and put it into practice. Mr. BERTRAM BLOUNT, in seconding, said that Sir William Ramsay had given a definition of a chemist. Speaking as one of the examiners for the time being, he could say certainly that the Board endeavoured to distinguish those candidates who could not only talk but do something. He endorsed the opinion of the President that it was well to have young Fellows on the Council so that fresh views were introduced, and he felt the time had come when the hitherto over-modest chemists were able to assert themselves and take a proper place among the professions. The vote having been put to the meeting by Sir William Ramsay, and carried, the PRESIDENT briefly replied, and declared the result of the election of the Officers and Members of Council. The following were elected Censors: -Prof. Percy F. Frankland, Mr. David Howard, Prof. J. Millar Thomson, and Sir William Tilden. The other Officers and Council were declared elected as follows: ROYAL SOCIETY. Ordinary Meeting, February 24th, 1910. "Colour Blindness and the Trichromatic Theory of = 2CO2+2C2H6+ 2H2O + C6H1004 (PO4R2)2 (2) C6H10O4(PO4R2)2+2H2O = C6H12O6+2PO4HR2. These were founded on-(a) The determination of the amount of carbon dioxide and alcohol produced by the addition of a known amount of phosphate in presence of excess of sugar; (b) the production of a hexosephosphate of the composition C6H10O4(PO4R2)2; (c) the occurrence of an enzymic hydrolysis of this substance with production of free phosphate. In order to obtain further experimental justification for this view, several additional determinations have been made, and these form the subject of the present communication. The results which have been obtained are as follows:1. When glucose or fructose is added to yeast-juice in presence of excess of phosphate, a period of accelerated fermentation occurs, during which the added sugar undergoes the reaction (1) quoted above, one molecule of carbon dioxide being evolved for each molecule of sugar added. 2. When the available phosphate of a mixture of ferment, coferment, and sugar is greatly reduced, the total fermentation produced becomes very small. The addition of a small amount of a phosphate to such a mixture produces a relatively large increase in the total fermentation, even after allowing for the amount of carbon dioxide equivalent to the phosphate added. President-George Thomas Beilby, LL.D., F.R.S. 3. A hexosephosphate when digested with yeast-juice is hydrolysed by an enzyme (hexosephosphatase) with production of free phosphate, and a sugar, which is capable of being fermented by yeast. As the result of this hydrolytic action the hexosephosphates when treated with yeast-juice or zymin are finally converted into carbon dioxide, alcohol, and free phosphate. In the light of these results it becomes necessary, in discussing the chemical changes which the molecule of sugar may undergo in the process of fermentation, to take into consideration the fact that two molecules of sugar are involved in the reaction. On the motion of Prof. J. MILLAR THOMSON, Seconded by Mr. W. T. BURGESS, a vote of thanks was accorded the retiring Officers and Members of Council. Dr. JOHN A. VOELCKER having replied on their behalf, the proceedings terminated. NOTICES OF BOOKS. Allen's Commercial Organic Analysis. Vol. I. Edited by HENRY LEFFMANN, M.A., M.D., and W. A. DAVIS, B.Sc., A.C.G.I. Fourth Edition. London: J. and A. CHURCHILL. 1909. In the fourth edition of the invaluable "Allen" practically only the general plan of the original treatise is preserved, the improvement of apparatus and methods and the discovery of new tests and processes having been so rapid that it has been found necessary to prepare a perfectly new work. In order to ensure the greatest possible efficiency the articles dealing with different subjects have been allotted to specialists in the various branches, and thus English and American authors have collaborated to produce the most complete and authoritative text-book on technical analysis in the English language. Volume I., which is to be followed as rapidly as possible by seven other volumes, deals with the alcohols and their derivatives, malt liquors, wines and spirits, carbohydrates and vegetable acids, and new sections have been added on yeast and on paper and paper-making materials. An introduction deals with general methods of analysis, and describes special apparatus used in technical analysis. The whole volume is characterised by great succinctness, while full references to original papers are always given, in case further information on any point is desired. 1909. Year-book of Pharmacy. Edited by J. O. BRAITHWAITE. London: J. and A. Churchill. THE Year-book of Pharmacy for 1909 contains abstracts of all papers relating to pharmacy, materia medica, and chemistry which have appeared in British and foreign journals between July 1, 1908, and June 30, 1909. A list of subjects suggested for investigation should stimulate the activity of the year-book's readers, and the fund which is devoted to giving grants for such researches should prove a valuable factor in aiding original work. The book also includes the transactions of the British Pharmaceutical Conference, the forty-sixth annual meeting of which was held in Newcastle last summer, and the papers read at the meetings are reproduced, together with the discussions on them. Papers on the Conservation of Water Resources. Washington: Government Printing Office. 1909. NEWS Radio-activity of Halogen and Oxyhalogen Compounds of Thorium.-J. Chaudier and Ed. Chauvenet. The radio-activity of the halogen and oxyhalogen compounds of thorium for quantities of substance containing more than about 10 mgrms. of thorium varies with the nature of the associated elements; the intensity of the increases. radiation diminishes as the atomic weight of the element This variation seems to be due to the absorption of the radio-active radiation by the elements which are contained in the molecule. The radio-activity curves of compounds of thorium resemble that of thorium, and coincide with it when the quantities of material are small enough. With less than 10 mgrms. of thorium all the curves coalesce to form one, which shows that the radioactivity of thorium is an atomic property, as Mdme. Curie has stated. Action of Carbon Tetrachloride on some Minerals. Pierre Camboulives.-Carbon tetrachloride acts on the majority of natural metallic oxides, transforming them into chlorides, provided that they are in a sufficiently finely divided state. Corundum is an exception, though artificial alumina is readily converted into the chloride at 390°. Silica is not attacked by vapours of carbon tetrachloride, and thus this reaction provides a method of determining the free silica in minerals, and carbon tetrachloride must be regarded as a valuable reagent in analytical separations. "The MONDAY, 14th.-Royal Society of Arts, 8. (Cantor Lectures). In this pamphlet various papers written by the members of the United States Geological Survey for the report of the National Conservation Commission are reproduced. The THURSDAY, 17th.-Royal Institution, 3. "Turner," by A. J. Finberg. papers, which summarise results of investigation and statistics which have been collected by the department during the last twenty years, deal with the distribution of rainfall, the increase of floods, the development of water-powers, irrigation, &c., and the conclusions which the members of the Survey have drawn on these subjects are given in detail. "The Royal Society, 4.30. (Bakerian Lecture). Chemical, 8.30. "Organic Derivatives of Silicon Chemical, 5. (Annual General Meeting). Presidential Address," The Union of Hydrogen and Oxygen in Flame," by Prof. Harold B. Dixon, F.R.S., &c. SATURDAY, 19th.-Royal Institution, 3. "Electric Waves and the Electro-magnetic Theory of Light," by Prof. Sir J. J. Thomson, F.R.S., &c. NEWS I grm. of hydrogen occupies 11160 cc.), is given by THE CHEMICAL NEWS. (dvapour-density)— NEWS.(dvapour-density VOL. CI., No. 2625. A NEW METHOD FOR DETERMINING VAPOUR- DENSITIES.* By PHILIP BLACKMAN. Apparatus. A LONG glass measuring-tube (a disused burette serves the purpose excellently) has one end sealed off, and the other open end has a projecting rim or lip (Fig. 1). A one-holed rubber stopper, to fit the measuring-tube, is fitted with a glass N-tube of narrow bore (2 or 3 mm. internal diameter) of the shape shown in Fig. 2; its end must be flush with the stopper as shown. A small glass-stoppered weighingbottle, best of the shape and size shown in Fig. 3, because it will lie conveniently across the measuring-tube without jamming (it is supplied by Messrs. F. E. Becker and Co., Ltd., 17-27, Hatton Wall, London, E.C.) is used for weighing out the substance to be experimented upon. Method. 1. The measuring-tube, placed upright, is filled with dry clean mercury, and any air-bubbles are carefully removed. 2. The stoppered weighing bottle, completely filled (to exclude air) with the known weight of the substance to be experimented on, is placed upon the mercury in the measuring-tube, and the rubber stopper, fitted with the N-tube, is forced into the neck. The weighing-bottle is thus forced inwards, causing the excess of mercury to fill the N-tube and some to escape (Fig. 4). The stopper should be tied on to the lip round the neck of the measuringtube with a little soft wire. 3. The whole is now inverted. If the weighing-bottle does not rise upwards, gentle tapping on the tube-wall will cause it to do so. 4. The tube is next surrounded with a suitable heating jacket, and heated in the vapour of some liquid boiling at a temperature above that at which the substance vaporises at ordinary atmospheric pressures (Fig. 5). 5. When the volume of the vapour in the measuring-tube remains constant, the position of the mercury-meniscus is noted, and the difference in height, m, measured in mm., between the mercury levels in the N-tube and measuringtube is measured. 6. The measuring-tube is removed, emptied of mercury, and, without removing the weighing-bottle, water is poured in from a burette to reach the position the mercury occupied; the volume, v, of the water represents the volume of the vapour. 7. The atmospheric pressure, p, measured in mm., the heating temperature, to, are required known. 8. w is the weight of the substance experimented on. Theory. and The volume of the vapour reduced to o° C. and 760 mm. pressure = 273 (pm)v 760 (273 + t) and the density of the vapour is therefore this quantity divided into w; or, the vapour density, compared with hydrogen at o° C. and 760 mm. pressure (taking that The author's descriptions of "A Simple Method for Determining Vapour-densities and for Analysing Binary Mixtures" in the CHEMICAL NEWS, 1909, C., 13, 129, 174, have met with such favour that he has yielded to several requests to compile this complete summary of his rather scattered papers upon the above mentioned subject which appeared in the Berichte, 1908, xli., 768, 881, 1588, 2487, 4141; and Journal of Physical Chemistry, 1908, vii., 679; xiii., 433. = d 11160X760 W (273+t) 273 (p±m)v (the formula to be used in practice)— A, The weighing bottle. B. Transverse section of the measuringtube, with the weighing-bottle lying on the mercury. Precautions and Observations. the various quantities, no difficulty should be found in 1. If every precaution be taken to measure accurately obtaining results practically in accordance with the required theoretical values. 2. A successful experiment should occupy forty-five to Sixty minutes. 3. When any substance, other than steam, be used as the heating medium it should be recovered by means of a suitable condenser and receiver in proper connection with the heating jacket. 4. If the N-tube be replaced by a short U-tube, and a long wide glass tube attached to it by aid of a short thick piece of rubber pressure tubing, mercury can be poured in so as to vary m (Fig. 6). 5. Still greater advantage will be obtained, though rather more difficulty in manipulation may be encountered, if the N-tube or U-tube be originally replaced by a straight tube, and joined on to a long wide glass tube by means of a thick rubber pressure tubing, when very great variations in m (m) can then be effected (Fig. 7). 6. If the measuring tube be properly graduated in cc. and tenths cc. (from the closed end), the volume of the vapour (less the volume of the weighing-bottle) can be read the curvature of the mercury-meniscus and for the expansions of the glass tube and mercury. 10. It is possible that through want of sufficient care a few air-bubbles may be found in the measuring-tube after it has been fitted up ready for heating. This does not at all necessitate the repetition of the operations. The tube is tapped slightly to cause all these air-bubbles to rise to the top; the position of the mercury meniscus is noted, so that, at the end of the experiment, the volume (v1) of this air can be determined (allowing, of course, i.e., minus, the volume of the weighing-bottle), or if the tube be graduated this quantity (v.) can be read directly; at the same time, the difference in height, mi, measured in mm., between NEWS A Study of some Reactions of Tellurium, Selenium, with Special Reference to the Tellurium Minerals. Tellurium and Gold Solutions.—In 1828, N. W. Fischer (Pogg. Annal., xii., 502) found that tellurium reduces the salts of gold, silver, platinum, and palladium, when introduced into their solutions. He considered the reduction as incomplete in all cases, but that the reaction of gold solutions was the most rapid, the reaction in this case being stopped by the tellurium becoming coated with metallic gold, which prevented further action, even at high temperature. It has been found (Lenher, Journ. Am. Chem. Soc., xxiv., 355) that when metallic tellurium is treated with a chloride of gold solution, metallic gold is deposited according to the equation 4AuCl3 +3Te=4Au+3TeCl4. The reaction is greatly accelerated by warming the solution, and if the gold chloride is in excess, and sufficient time is allowed, the tellurium completely passes into the solution, leaving fine gold as a precipitate. On the other hand, if tellurium is introduced into a gold chloride solution in greater quantity than that necessary to precipitate all of the gold, the yellow gold solution will soon become completely bleached, and on examination will be found to contain no gold. The action of the tellurium on the gold solution is fairly rapid; warming the solution a few minutes will bring down sufficient gold to colour the tellurium yellow, but in order to insure a complete reaction two or three hours continuous heating are necessary, or several days contact at room temperature. In order to obviate the difficulty of incomplete reduction noted by Fischer, it is only necessary to reduce the tellurium to a fine state of division and allow a sufficient time for reaction. When such conditions are fulfilled, the depositior. of metallic gold by elementary tellurium is quantitative from either acid, neutral, or alkaline solution. Tellurium and Silver Solutions.-The reaction (Hall and Lenher, Journ. Am. Chem. Soc., xxiv., 918) between silver salts and elementary tellurium results in the formation of silver telluride. Silver nitrate solution in contact with elementary tellurium which has been reduced to a fine state of division will in eight or ten days yield silver telluride according to the equation * From Economic Geology, 1909, iv., No. 6. The reaction pro 4AgNO3+3Te = 2Ag2Te+Te(NO3)4. ceeds more rapidly if the solution is kept boiling or is maintained at a temperature of 80°. Silver chloride dissolved in ammonia will on contact with tellurium produce silver telluride thus: 4AgCl +3Te = 2Ag2Te+TeCl4. In studying these reactions in ammoniacal solution it has been observed that if silver nitrate dissolved in ammonia is allowed to stand for several days, or if the solution is kept warm for a considerable length of time, a black deposit which is probably a nitride of silver separates out. When silver chloride in ammonia is used in this reaction an excess of ammonia is desirable, and the reaction is best carried out at room temperature. With silver nitrate in aqueous solution a greater range of temperature is possible; in fact, the solution can be boiled continuously. The resultant precipitate, if extracted several times with ammonia, will lose any silver telluride held mechanically or formed in the reaction. With due regard to the above precautions it is possible to obtain a good preparation of silver telluride by the action of elementary tellurium on silver solutions. Selenium and Gold Solutions.-Pure selenium acts with gold solutions in a manner similar to that of tellurium, the reaction being, however, very much moderated. The fused variety of selenium does not reduce gold at the ordinary temperature. Indeed, one experiment was made allowing the selenium to remain in contact with the gold solution for three months without visible change. At the boiling temperature the reaction proceeds nearly as rapidly as with tellurium, and takes place in a perfectly analogous manner, the reaction being expressed, 3Se+4AuCl3 = 3SeCl4 +4Au. In order to secure complete action it is necessary that the selenium shall be in a fine state of division, and that sufficient time shall be allowed in order that complete contact may be assured. It is necessary for the solution of the gold to be boiled with the selenium for six to eight hours, or the gold solution should be allowed to be in contact with the selenium for two or three days at from 70° to 80°. The reaction then between selenium and gold solutions results in the quantitative precipitation of metallic gold. Selenium and Silver Solutions.-Parkham (Chem. Cent., xxxiii., 813) observed that red selenium is blackened in a solution of silver nitrate, selenious acid being formed at the same time; after the latter had been removed by sodium hydroxide, the black powder remaining contained selenium and silver, but no unchanged selenium could be detected with the microscope. Senderens (Comptes Rendus, civ., 175) found that selenium would reduce a boiling solution of silver nitrate, either dilute or concentrated, with the formation of silver selenide and selenium dioxide. The statement of Parkham is obviously in error in regard to a precipitate of selenium dioxide in aqueous solution inasmuch as selenium dioxide is really soluble in water. The action of selenium on silver solutions is quite similar to that of tellurium, but is not as energetic. Selenium reduces solutions of silver nitrate or of the chloride in ammonia, either in the cold or on heating, with formation of silver selenide. As might be expected the reaction is materially accelerated by heat. Reaction of Tellurium Minerals with Gold Solutions.The tellurium gold minerals, calaverite, hessite, nagyagite, as well as native tellurium, all precipitate metallic gold from a solution of the chloride. In fact, they deport themselves toward gold solutions precisely as elementary tellurium does. When the tellurium mineral is in excess the yellow-gold solution is bleached to a colourless solution which contains no gold, while if the gold chloride is in excess, the amount of gold precipitated is in proportion to the quantity of tellurium and selenium present. It is obvious that these natural tellurides act toward gold solutions unlike chemical compounds of gold and tellurium, since we know of no true chemical compound that can precipitate one of its constituents in such a manner as takes place with the natural tellurides and gold solutions. (To be continued). |