If now we take the specific gravity of this as being approximately 5.6, and, assuming a specific gravity of 42 for the rutile, calculate what the specific gravity of the Fe(Ta, Nb)206 constituent should be, we get the value 7.3, which is approximately the specific gravity of a typical tapiolite, i.e., one containing only a few per cent of niobic oxide. It appears, therefore, that the Fe(Ta, Nb)206 constituent of the Piedmont specimen must be tapiolite, and if so it follows that this specimen is really representative of typical strüverite.

In stating the results of his analysis, Prior made it quite clear that he had not adequate quantitative data for stating the exact relative percentages of niobic and tantalic oxides present. These considerations do not seem to have been taken into account by Hess and Wells, who (loc. cit.) have rather hastily concluded that the Piedmont specimen is not a typical strüverite. The evidence detailed above proves their conclusion to be incorrect, if we accept the view, to which they subscribe, that strüverite is an isomorphous mixture.-Mineralogical Magazine, May, 1912.

THE NATURE OF THE ELECTRIC DISCHARGE. By Prof. NIPHER.

FORMER results of Prof. Nipher's work seem to point very strongly to the one-fluid theory. It would follow that the two waves which were shown to exist in the Wheatstone experiment were compression and rarefaction waves. The negative wave is in the nature of a supercharge which travels along on the outer surface of a thin outer film of the conductor. The positive wave is one in which a thin outer film of the wire is suddenly drained of the negative charge at the instant of passing of the wave. We had been led to suspect, as a result of recent experiments, that matter in this latter condition is explosive. The tests have been made on thin fuse wires sealed into long glass tubes through which the wire passes. The wires were sealed in by means of hard sealing-wax. A discharge from a battery of Leyden jars was passed through the wires. The disintegration of the wires is much greater at the positive end. The sealing-wax, wire, and glass tube, in almost every case, break down at that end. The lead is dispersed in a fine powder or dust.

Prof. Nipher remarked that he had just found in the London Phil. Mag., 1815, xlvi., pp. 161 and 259, an account of the work of De Nelis and Singer, who passed a positive discharge through a lead wire of oor inch diameter contained in an iron tube. The wall of the tube was usually about o'14 inch in thickness. In one case the tube was I inch in external diameter, with a small bore admitting a steel needle with wax insulation, and terminating in the short lead wire resting on the bottom. The lead wire was surrounded by oil. Such tubes were burst by repeated explosions of the lead wire, which required to be replaced at each discharge. The discharge was from a battery of Leyden jars, having an area of from 75 to 100 square feet. The needle and part of the liquid were thrown out at each explosion. In some cases the liquid was thrown to a height of 40 feet. The experimenters do not seem to have used the negative discharge. They attributed the effects to the expansive power of the electric fluid.

What they were doing was to suddenly drain that lead wire of the negative fluid. The atoms of lead then repel each other. Some of the effect is, of course, a heat effect. The question arises, however, will the negative discharge produce a like or an equal effect? Is it not possible that such molecular repulsion is primarily concerned in the formation of disruptive channels in air, and resulting in spark discharges and lightning?-Science, N.S., xxxv., No. 905.

THE DIRECT DETERMINATION OF SMALL AMOUNTS

OF PLATINUM IN ORES

AND BULLION.*

By FREDERIC P. DEWEY.

By the old method of determining platinum in ores and bullion, the silver-alloy first obtained in the regular course of assay is parted in strong sulphuric acid and the residual metal weighed. This is re-alloyed with silver by a second cupellation and parted in nitric acid, the residual metal being again weighed. Any difference shown between the two weighings is assumed to be, and is called, platinum. Sometimes it is so, and if any considerable amount of platinum be present there will be a decided difference between the two weighings; but a slight difference is no real evidence whatever of the presence of platinum. On the other hand, the second weight may equal or possibly exceed the first, even when traces of platinum are present. Again, other members of the platinum group may go into solution in nitric acid more or less. If present these would be called platinum and escape detection. The method does not provide any direct tests whatever as to the presence or absence of platinum. It is often indecisive and sometimes gives erroneous results. It is, therefore, quite unsatisfactory.

Being called upon many times to determine platinum in a wide variety of materials, particularly when present in very small amounts, I have realised the disadvantages and defects of this old method.

In an article on the solubility of gold in nitric acid (Fourn. Am. Chem. Soc., 1910, xxxi., 323), I have briefly outlined a method of gathering a little gold out of a solution containing much silver, which furnishes the basis of tion of small amounts of platinum, and has the added an excellent method for the direct and absolute determinaadvantage that the metal weighed may be subjected to suitable tests to determine that it really is platinum, and to reveal the presence of other members of the platinum group.

In the regular course of assaying for the precious metals, gold is parted from silver by dissolving the silver in nitric acid. If platinum be present in small amounts only, it will readily go into solution in the nitric acid. If now a limited amount of hydrogen sulphide be added to the solution from parting, any platinum present will be precipitated as sulphide along with some silver sulphide. On filtering off the precipitate (which generally is sufficiently washed by the operations necessary to transfer it from the precipitating dish to the filter), the moist filter is transferred to a small porcelain crucible, dried at a low heat, and burned off by gentle ignition. This transforms the sulphide precipitate into a metallic sponge, which is wrapped in a small piece of thin lead-foil and cupelled. The resulting bead is then parted in strong sulphuric acid, when the platinum will be left as a dark residue, generally collected in spongy form, even when minute in quantity. This sponge, after re-boiling in fresh acid, if necessary, is suitably washed by decantation, annealed, and weighed.

Generally the final metal speaks for itself as being platinum, but if there should be any doubt it may be dissolved in a drop or two of aqua regia and gently evaporated. The solution obtained may be tested with potassium iodide, or a few small crystals of ammonium chloride may be added, when the characteristic precipitate will show itself. As a further test this may be filtered off and gently ignited to produce spongy platinum. If the amount of the final metal be considerable, the platinum may be determined by the double-chloride method. Any decided difference the platinum group, for which direct test could then be shown would indicate the presence of other members of

made.

Presented at the New York meeting of the American Institute of Mining Engineers, February, 1912, and published in the Bulletin of the American Institute of Mining Engineers, April, 1912, Serial No. 64.

July 5, 1912

9

It is also very satisfactory to use the general method of gathering gold in a precipitate of silver sulphide in determining minute quantities of gold in high-grade silver, such as that produced by electrolytic refining. It is comparatively easy to gather the gold from very large samples of silver, up to 100 grms. or more, into a decigrm. of silver, and then part by nitric acid as usual.

The amount of hydrogen sulphide required depends, of course, upon the amount of platinum present. If this should be roughly known or suspected, the amount used should generally be enough to precipitate the platinum and from three to five times as much silver. On an entirely unknown ore I should at first use I cc. of strong hydrogen sulphide solution diluted to 15 cc., and reserve the filtrate from the sulphides for re-treatment, if necessary. On an unknown bullion I should use 2 cc. of strong solution diluted to 30 cc., partly because bullions are liable to carry much more platinum than any ordinary ore, and partly because the volume of the silver nitrate solution from parting the gold must necessarily be larger. If, however, it is known that minute amounts of platinum are present, it is still necessary to use sufficient hydrogen sulphide to give a silver bead large enough to handle comfortably. For this reason I seldom use less than the equivalent of i cc. of strong hydrogen sulphide solution.

It may happen that the final metal shows the yellow colour of gold, due to the fact that exceedingly fine floatgold passed over in decanting the solution of silver nitrate from the gold. In such a case the metal must be re-alloyed with silver and the treatment repeated. When the proportion of gold to silver in the metal being parted is so small that the gold separates in a very finely divided state, it will often save trouble to filter the silver-nitrate solution, to separate any float-gold, before adding the hydrogen sulphide.

This method has been used with the utmost satisfaction in determining very minute amounts of platinum in various silver products directly. Much of our silver coinage, for instance, will show a few tenths of a milligrm. of platinum in 100 grms. of coin. Recently I examined samples from two purchases of fine silver. Very large samples were dis solved in nitric acid. The acid in portions was poured upon the samples and allowed to act at a gentle heat until exhausted. Finally, a small amount of residual silver was removed from the solution and dissolved in a small amount of fresh acid, the solution being then united with the main solution, and the whole evaporated nearly to dryness. It was then diluted to about 250 cc. and 5 cc. of strong hydrogen sulphide solution diluted to 50 cc. was poured in with constant stirring.

This operation concentrated the gold and platinum of the silver into a small amount of sulphide precipitate. This precipitate was filtered off, roasted, and cupelled. The resulting bead was parted in nitric acid and the gold determined. The silver nitrate solution was treated with dilute hydrogen sulphide solution, equivalent to about 1 cc. of strong solution, and the platinum parted from the silver by strong sulphuric acid.

These two samples yielded the following results :-
Gold found. Platinum found.
Mgrm.
Mgrm.
0.28

No.

I.. 2..

Silver taken. Grms. 122'32 125'47

O'12

0.67 0.18

In case we have a material containing a considerable amount of platinum, the well-known fact that platinum alloyed with silver is not entirely soluble in nitric acid must be considered. In such a case the gold from the first

Probably this method of precipitating a noble metal in solution, or removing it from suspension in a liquid, by adding hydrogen sulphide in the presence of silver in the solution, could be used to advantage in determining gold in metallic copper and similar materials.

PROCEEDINGS OF SOCIETIES.

ROYAL SOCIETY.

Ordinary Meeting, June 20th, 1912.

Sir ARCHIBALD GEIKIE, K.C.B., President, in the Chair. PAPERS were read as follows :—

"Investigation into the Life - history of Cladothrix dichotoma (Cohn). By DAVID ELLIS, D.Sc.

"Relation between Secretory and Capillary Pressure. I.-The Salivary Secretion." By LEONARD HILL, F.R.S., and MARTIN FLACK.

"Origin and Destiny of Cholesterol in the Animal Organism. Part IX. On the Cholesterol Content of the Tissues (other than Liver) of Rabbits under various Diets and during Inanition." By G. W. ELLIS and J. A. GARDNER.

"Note on the Protozoa from Sick Soils, with some Account of the Lite-cycle of a Monad Flagellate." By C. H. MARTIN, M.A.

"Further Observations on the Variability of Streptococci in relation to certain Fermentation Tests, together with some Considerations bearing on its Possible Meaning." By E. W. AINLEY WAlker.

"Chemical Action on Glucose of a Variety of Bacillus coli communis (Escherich) obtained by Cultivation in Presence of a Chloroacetate." (Preliminary Notice). By A. HARDEN, D.Sc., F.R.S., and W. J. PENFOLD.

The organism in question produces no gas when grown on glucose peptone water, aerobically, in a test-tube provided with a Durham gas tube; but when grown anaerobically in presence of chalk it yields an amount of hydrogen and carbon dioxide which is approximately 0.25-0.3 of that given by the normal organism. The amounts of alcohol and acetic acid are similarly diminished and that of lactic acid increased. The organism retains the power of decomposing formates.

It is probable that the normal organism decomposes glucose by the aid of at least three enzymes :

1. C6H12O6=2C3H6O3;

2. C6H12O6+ H2O=C2H4O2+C2H6O+H2CO2 ;
3. H2CO2 H2 + CO2.

The process of selection by means of chloroacetate leads to the survival of organisms containing relatively less of the enzyme conditioning reaction (2) than the normal organism.

It is hoped that the study of other organisms on similar lines may yield some information as to the nature of their characteristic fermentation processes.

July 5, 1912

Lipase from castor-oil seeds and emulsin from almonds possess a slow hydrolytic action on the hexosephosphate obtained by fermenting sugars with yeast juice in presence of phosphate. Autolysed ox pancreas has practically no action on hexosephosphate.

An extract of zymin hydrolyses hexosephosphate slowly. Autolysed yeast-juice possesses an enzyme which has a marked action on hexose phosphate, and which is precipitated in an active form by the addition of alcohol and ether.

"Oxydases of Cytisus Adami." By Prof. FREDERICK KEEBLE, SC.D., University College, Reading, and Dr. E.

FRANKLAND ARMSTRONG.

SOCIETY OF CHEMICAL INDUSTRY. (LONDON SECTION).

Ordinary Meeting, June 17th, 1912.

Mr. E. GRANT HOOPER in the Chair.

THE following papers were read and discussed :"Production and Polymerisation of Isoprene and its Homologues." By W. H. PErkin.

The results obtained by a group of English workers, of whom the author is one, are described in the paper.

The important early work of our fellow countrymen, the late Greville Williams and Tilden, and others, who observed that the polymerisation of isoprene under varying conditions results in the formation of a rubber-like body, is reviewed, and allusion is made to the experiments of Kondakow, Motiewsky, Thiele, Harries, Klages, and others on a variety of compounds containing the conjugated double linking -C-C-C-C-, which is usually connected with a tendency to polymerise. The observation of Dr. F. E. Matthews in September, 1910, that isoprene which had been left in contact with sodium since July of that year had turned into a solid mass of rubber, and the conclusion, based on further investigation, that sodium was a general polymerising agent, marked an important epoch in the history of the synthesis of rubber. Curiously, this observation was confirmed by the independent but later work of Carl Harries, who in publishing his discovery was unaware that he had been anticipated. The polymerising action of sodium is practically quantitative, and is not seriously affected by impurities. It will take place in the cold or in moderate heat, which is an advantage. This discovery renders the cheap production of rubber possible, if divinyl or erythrene, isoprene, di-isopropenyl, &c., or other similar compounds containing conjugated double linkings can be prepared cheaply. The great and fluctuating cost of turpentine are against its employment as a raw material. The only possible substances for rubber production at, say, Is. per pound, seem to be wood, starch or sugar, petroleum, or coal. Starch was chosen, and the formation from it of cheap fusel oil was made possible by a discovery of Prof. Fernbach, of the Pasteur Institute, who after long work found a suitable fermentation process by which the higher alcohols can be produced at a low cost. It has since been found that acetone can be produced very cheaply by fermentation. Specimens of Sir William Tilden's synthetic rubber and that produced by the new process were shown.

"Oxidation of the Drying Oils." By J. N. FRIEND and W. J. DAVISON.

The authors have studied the changes in weight undergone by the following oils during oxidation consequent upon exposure to the air in thin films :-Raw and boiled linseed oils, Chinese wood oil, cotton-seed oil, poppy-seed oil, hemp-seed oil, soya bean oil, walnut oil, and rosin oil. It is shown that all these oils, save rosin oil, at first rapidly increase in weight to a maximum, after which they

exceptional, exhibiting no setting power, but continuously losing weight, owing presumably to the escape of its more volatile constituents. Linseed oil sets to an elastic film when half the time has elapsed necessary to arrive at the maximum increase in weight. Hence, in giving two or more coats of paint to a surface, at least double the time required for each coat to set should elapse before the next coat is put on; otherwise the undercoat will continue to change in volume as it absorbs oxygen until the maximum point is reached, and will thus tend to tear away from and destroy the fresh coat above it. Whence once this interval has elapsed, however, further alteration in weight is so slow, relatively, that succeeding coats may be painted on

at leisure.

The initial stages of the setting of raw linseed oil are accompanied by the absorption of water, the so-called "drying" being in reality a moistening. In very dry air raw linseed oil sets extremely slowly, and it is suggested that if both the oil and air were perfectly dry no oxidation would take place.

In the case of boiled oil, the presence of moisture apparently makes no difference to the rate of setting. In an atmosphere of hydrogen, both the partially oxidised and the oils that had completely set remained permanent, suffering no disintegration or alteration in weight.

"A New Hand Photometer." By W. J. DIBDIN.

A convenient portable instrument for the determination of the light emitted in any direction by a lamp or any other source of light is described. It is designed to embrace (1) Maximum open scale readings; (2) convenience and accuracy in comparing lights of different colour; (3) reliability by reason of the facility with which its indications can be checked. The rays falling on a Leeson star disc as improved by the author, when the instrument is tilted at the desired angle at such a distance from the illuminant that they shall be normal to the disc, are measured against those emitted by an electric incandescent lamp, the illuminating power of which is varied by means of a rheostat so graduated as to give readings in foot candles. The readings compare well with those of standard photometers.

NOTICES OF BOOKS.

With 180

Spectroscopy. By E. C. C. BALY, F.R.S.
Illustrations. New Edition. London, New York, and
Calcutta: Longmans, Green, and Co. 1912.

IN the above new edition Prof. Baly has brought together a large amount of information in connection with the rapidly extending field of spectroscopic research. The size of the work has been increased in the present edition to some 700 pages, and the half-tone illustrations are good. The scope of the work runs upon very practical lines, owing possibly to the fact that the author was associated with Sir William Ramsay during the period occupied by the discovery and investigation of the inert gases of the atmosphere, and thus, having been in touch with the work of other spectroscopists, has been able to give minute details of devices and manipulations otherwise inaccessible to the average worker. In spite of the fact that many of the illustrations of apparatus and instruments are of a highly complex character, and bear the names of prominent instrument makers, we are glad to note that in many instances instructions and drawings are given for the construction of useful apparatus: a case in point is that of a simple form of spectrograph that looks capable of doing useful work. Although the book is chiefly occupied with the practice of spectroscopy, the theory and mathematics involved are thoroughly explained. The work can scarcely fail to become a handbook in any laboratory where spectroscopic research is carried out.

CHEMICAL NEWS,! July 5, 1912

Water Analysis for Sanitary and Technical Purposes. By HERBERT B. STOCKS. London: Charles Griffin and Co., Ltd. 1912.

THIS handbook gives short directions for the analysis of samples of water for sanitary purposes, without going fully into the minutiae of a complete examination. Biological methods of investigation are not included, and the description of microscopic work is far too short to be of any practical use; in fact it consists of not much more than a list of a few names of organisms which might be present, and gives no help towards the identification of them. The chemical examination is treated much more fully, and ordinary methods employed in it are described in enough detail for a straightforward analysis to be carried out by any one who had had some little practice in elementary quantitative work. Only thoroughly tested methods are described, and the directions as to quantities, the time necessary for the completion of the experiment, &c., are precise and clear. Some data relating to average results are given as a guide for estimating the quality of any particular water, and full directions for the preparation of all the reagents required are included.

Cast-iron in the Light of Recent Research. By W. H. HATFIELD, B.Met., A.M.I.Mech. E. London: Charles Griffin and Co., Ltd. 1912.

RECENT research on the properties and nature of cast-iron and malleable cast-iron is admirably described in this book. The author's own work occupies a good deal of space in it, but he has by no means neglected the investigations of other metallurgists, either English or foreign, and his attitude towards opinions which he does not share is very impartial and restrained. At the same time his criticisms are shrewd and incisive, and his suggested explanations of some results show great ingenuity and resource. He bases his study of the subject upon the equilibrium diagram of the iron-carbon system, which is discussed in detail after a short historical introduction. The influence of silicon, phosphorus, sulphur, manganese, and other elements upon the properties of cast-iron is critically discussed, and the effects of casting temperature, superheated steam, and shrinkage and contraction are the subjects of later chapters. The student will find some suggestions in the work for profitable research work, and the engineer and metallurgical chemist will be able to obtain from it a thorough knowledge of recent investigations of cast-iron.

A Text-book of Rand Metallurgical Practice. By the following authors: RALPH STOKES, JAS. E. THOMAS, G. O. SMART, W. R. DowLING, H. A. WHITE, E. H. JOHNSON, W. A. CALDECOTT, A. McA. JOHNSON, C. O. SCHMITT. Volume I. London: Charles Griffin and Co., Ltd. 1912.

THIS book, each of the two volumes of which is complete in itself, has been produced by the collaboration of a number of metallurgists, works managers, &c., who are actually engaged in metallurgical work upon the Witwatersrand, and who, from the important positions they fill, may safely be regarded as writing authoritatively each upon his special subject. As a guide for other practical men working in similar conditions, and for students, this very definite and detailed account of metallurgical practice on the Rand will have considerable value, giving students especially an insight into actual working methods and the routine and difficulties of every day work. The book is mainly concerned with actual practice, and hence does not go into questions of research or yet unsolved problems. Each division of the subject-Sorting, Stamp Milling, Tube Milling, Treatment of Slime, Assaying, &c., is discussed in a separate chapter, and the bibliographies given are more than mere lists of works, often providing a short abstract of the papers or articles tabulated.

THE tables in this book, which is published under the direction of an International Committee appointed by the Seventh Congress of Applied Chemistry, have been collected from more than 300 periodicals by a special staff of abstractors, and are printed in English, French, German, and Italian. The data given relate to chemistry, physics, and technology, and have been brought down to the end of the year 1910, it being the intention of the Committee to issue a new volume during the present year if possible. The arrangement of the book seems to be systematic and in every way convenient for reference, and the volume will be a useful addition to the library of the chemist and technologist.

The Measurement of High Temperatures. By G. K. BURGESS and H. LE CHATELIER. Third Edition. New York: John Wiley and Sons. London: Chapman and Hall, Ltd. 1912.

IN 1898 Prof. Le Chatelier, who was one of the pioneers in the investigation of the measurement of high temperatures and the construction of pyrometers, delivered a course of lectures on the subject at the Collège de France. In this course he not only gave a full account of his thermo-electric and optical pyrometers, but also summarised all hat was then known of pyrometry. These lectures were translated into English by Mr. G. K. Burgess lation met with such a large demand that a second edition of the Bureau of Standards at Washington, and the transwas soon called for. Since its appearance the theory and practice of pyrometry have very rapidly extended, and so many new instruments have been devised and new methods perfected that Mr. Burgess, in preparing a third edition, has been forced practically to re-write the book. It deals more with the principles of the measurement of high temperatures than with the various types of instrument employed for the purpose, although these are usually fairly fully described, and it is intended for the use of the student and the engineer rather than that of the investigator, who, however, will find that the very complete bibliography will give him all the information that he is likely to require as to original English and foreign publications, both books and periodicals.

Notions Fondamentales d'Analyse Qualitative. ("Fundamental Principles of Qualitative Analysis"). By V. THOMAS and D. GAUTHIER. Paris: Gauthier-Villars. 1912.

THIS book is not intended for the use of candidates for examinations, but for those who wish to acquire a real knowledge of the principles of qualitative analysis and of the reactions of acids and bases. The authors have aimed specially at thoroughness, believing that in analysis a half-knowledge is very much worse than complete ignorance. Though writing for beginners they enter into the fullest details of the reactions they describe, and frequently give quite a considerable choice of methods of detection and confirmation, since they argue that success with a particular experiment depends very largely upon the personal factor as well as the skill of the experimenter. After discussions of the general operations of qualitative analysis, including some microscopic and spectroscopic work, the reactions of the individual bases are discussed in detail; the similar treatment of the acids follows, separations and systematic analysis being left for the last quarter of the book. The general style of the work suggests that the authors had in their minds the training of the research chemist, and for thoroughness and attention to detail the course that they suggest would appear to be admirable.

SOURCES.

Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Vol. cliv., No. 20, May 13, 1912. Action of Hydrogen Peroxide on Lactic Acid and Glucose.-Jean Effront.-By the action of hydrogen peroxide lactic acid is readily converted into acetic acid according to the equation

CH2.CH.OH.COOH + O2 = CH3COOH + H2O + CO2. The theoretical yield is very nearly obtained. A small amount of alcohol is always formed. With glucose hydrogen peroxide gives formic, acetio, and oxalic acids and some alcohol.

Bulletin de la Société Chimique de France.
Vol. xi.-xii., No. 8, 1912.

Knævenagel's Method of Preparing Glutaric Acid. -H. Gault.-Knoevenagel's method of preparing glutaric acid consists in condensing two molecules of ethyl malonate with one molecule of formaldehyde in presence of small quantities of diethylamine or piperidine, and saponifying the methylene dimalonic ether formed. The yield of the latter, and therefore of the glutaric acid also, can be very considerably increased by using four molecules of ethyl malonate to one of formic aldehyde, and a yield of 81 to 82 per cent can thus be obtained.

The

Cyanhydrines, Benzoyl-amides of Aldehydes and the Corresponding Alcohols.-J. Aloy and Ch. Rabaut. -When benzoyl chloride acts on aldehyde phenols in presence of potassium cyanide, cyanhydrines are obtained containing two benzoyl groups, of which one is attached to the phenol function. Two molecules of chloride and two of cyanide have to be used to one of aldehyde. corresponding benzoyl amide can sometimes be prepared by simply leaving the cyanhydrine in contact with fuming HCl at the temperature of the laboratory. In other cases it is better to heat in a sealed tube to 100°. The saponi. fication of the benzoyl amides gives the corresponding acid alcohols and acid phenols.

Preparation of Crystallised Quinine.-J. Ville. Anhydrous crystallised quinine can be easily and rapidly obtained by passing a current of air containing ammonia through a solution of hydrobromide of quinine heated on a water-bath. The quinine is thus precipitated in the form of white anhydrous crystalline lamellæ. When a solution of the hydrobromide is made alkaline with ammonia, and is allowed to evaporate after the addition of acetone, long silky needles of the hydrate containing three molecules of water separate. This hydrate is efflorescent, and loses some of its water of crystallisation at the ordinary temperature. Dehydration is rapid in a dry vacuum.

Action of Mercury and its Salts on Aluminium. Paul Nicolardot.-When aluminium foil is left in a solution of mercuric chloride the water is decomposed by the aluminium, and if there is sufficient chloride the oxidation is complete. Alloys and impure aluminium (98 per cent) are not attacked, and it is thus possible to distinguish between a utensil made of pure aluminium and another made of a copper alloy. The fact that aluminium, when rendered oxidisable by mercury or its salts, attacks water, may be used to determine the alkaline or alkaline earth metals which may be present in the aluminium employed. After the action is over the alumina may be filtered off and the lime precipitated with ammonium oxalate, while the sodium is determined in the filtrate from the calcium oxalate.

Detection of Arsenic and Lead in Wines.-P. Carles and L. Barthe.-When the vines are treated with an excess of lead arsenate the wines obtained from them contain negligible traces of arsenic and lead; if the vines are treated with a normal amount of lead arsenate neither

cases the dregs contain quantities of arsenic and lead which are not negligible.

Reactions of Salicylic Acid.-E. Barral.-When 10 per cent sodium nitrite is added to a solution of a salicylate containing concentrated sulphuric acid an orange coloration, finally turning red, is obtained. If a solution of salicylic acid is heated with ammonium persulphate the liquid turns yellow and then brown, and gives a brown or black precipitate. On cooling the precipitate separates from a colourless or yellowish liquid. A blue coloration is obtained when Mandelin's reagent is added to a solution of salicylic acid.

Atti della Reale Accademia dei Lincei.
Vol. xxi., No. 7, 1912.

Transformation Constant of Radium D.-Paolo Rossi. From measurements of the activity of a specimen of mineral containing radium D and its derivatives, the author has found that the half period of transformation of radium D is approximately seventeen years.

Formation of Solid Solutions of Sodium Halogen Salts at High Temperatures.-M. Amadori.-The crystallisation of the system NaCl-NaBr has a minimum at 744°, i.e., about 4° below the melting-point of NaBr, and that of the system NaBr-Nal a minimum at 645°, 17° below the melting-point of NaI, but for both potassium and sodium the systems chloride-bromide and bromideiodide show complete solubility in the solid state. For the system chloride-iodide the solubility in the solid state is limited, and a eutectic-point occurs at a concentration of 49 molecules per cent of chloride for the potassium salt In both and 37 molecules per cent for the sodium salt. cases the eutectic temperature is a little lower than the solidification-point of the iodide.

MISCELLANEOUS.

Royal Institution.-A General Meeting of the Members of the Royal Institution was held on the 1st inst.; Sir James Crichton-Browne, Treasurer and Vice-President, in the Chair. Mr. J. S. Highfield and Mr. W. Judd were elected Members.

Ozonair Portable Apparatus. We have received from Messrs. Ozonair, Ltd., 96, Victoria Street, Westminster, London, S. W., a copy of the new edition of their catalogue No. 1 "Ozonair Apparatus for General Purposes.' This catalogue contains illustrations, prices, and other particulars of Ozonair portable generators for purifying the air in rooms of from 3000 to 12,000 cubic feet capacity, for connecting the supply circuits or to portable accumulators. These apparatus are made in a variety of patterns; for standing on the table (horizontal or vertical current of ozonised air), for fixing on the wall, with medical fittings, &c. They are of handsome and compact design, and the consumption varies from only 10 watts to 130 watts, so that in all cases, where intended for use on a supply circuit, they can be connected to any lampholder or plug. The makers claim that their Ozonair apparatus, as compared with other methods of producing ozone, are noiseless and generate pure ozone, free from the oxides of nitrogen. The catalogue also contains some very interesting information regarding the nature of ozone and the many public and industrial purposes to which Ozonair apparatus can be applied, such as ventilation, water and food sterilising, brewing, bleaching, deodorising, &c. That these are not hypothetical is proved by a list of important users, not only in Great Britain, but on the Continent and in other parts of the world, comprising public buildings, breweries, slaughter houses, cold storage, waterworks, laboratories, and so on. Messrs. Ozonair, Ltd., will be pleased to send a copy of the catalogue to all those who are interested in the subject.