riment was made, with a view of ascertaining whether the circuits could be increased in length to a considerable degree without diminishing the apparent value of the lights on such circuits. The Westminster and Waterloo circuits that is to say, the two at each end of the line were thrown into one, the total length of wire being 7063 feet, three of the lights being at the Westminster end and the other two at the Waterloo end. The lights burned with apparently equal brilliancy as when shortcircuited, and on the following day the length of the line was increased to 8815 feet, or 1.66 mile, but still without any perceptible effect on the light. We believe this is the longest circuit ever attempted to be used with an alternating current machine, and the success of the experiment has a very important bearing on the general question of electric lighting. We have said before that the cost of a plant necessary for working twenty Jablochkoff lights is £990. The interest on this at 5 per cent would be £49 10s., and taking wear and tear at 10 per cent, £99, we get a total of £148 IOS. Taking the whole time during which the lamps are lighted in the year at 3600 hours, say 10 hours a day, the cost of use of plant for each light per hour is 0'49d. To this we must add 3.24d. per light per hour for the cost of producing the light, and 2d. per hour per candle, making a total of 573d. per light per hour all the year round. Let us now compare the cost of gas with the latter figure. The light in the opal globe, as given above, is in round numbers equal to 155 candles, and in the granulated globe to 265 candles. To produce a light equal to 125 candles, one of the larger Sugg burners consumes 48 cubic feet of gas per hour, while to produce a 265-candle light we should require 83 cubic feet per hour. The cost of the former quantity of gas may be taken at 2d., of the latter at 3'5d., or, to put the matter more plainly,The cost of the electric light is 5'73 per hour. Gas equivalent to electric light in opal globe Ditto ditto, frosted globe.. .. 2'00 3'50 ད We have therefore, at last, a series of figures on this important subject which cannot possibly be doubted. The experiments which have yielded them have been carried out with the greatest care, and every precaution has been taken to render them so correct that all future cavil or controversy will be avoided; the practical outcome of the matter being that, used in the best possible manner, the amount of illumination in both cases being equal, the electric light costs 13 times as much as gas. PROCEEDINGS OF SOCIETIES. PHYSICAL SOCIETY. Ordinary Meeting, May 24, 1879. Prof. W. G. ADAMS, President, in the Chair. NEW members :- Mr. R. Sedley Taylor, M.A., and Mr. Walter Emmott, A.S.T.E. Mr. W. J. WILSON exhibited a new harmonograph and figures drawn by it. The figures drawn by prior harmonographs are all more or less imperfect, owing to loss of motion in the pendulums actuating the marking pen; and Mr. Wilson therefore designed a new harmonograph, which not only gives perfect figures, but admits of the phase of either of the two compounded motions being decreased by a known amount. In this instrument toothed wheels take the place of pendulums, the ratio of the teeth giving the ratio of the periods of the motions. By employing the device of an intermediate wheel gearing with two others, and arranging two or more wheels on he intermediate axle, a great variety of phase can be obtained for each motion. An ingenious adjustment by means of a movable nut allows the phase of either or both motions to be altered to a known extent, and thus an endless variety of figures can be obtained. As in other harmonographs, a writing table, on which the paper is placed, and an aniline glass pen, are used. Several of the figures done also on glass were thrown on the screen, the stereoscopic effect being very apparent. In reply to a query, Mr. Wilson said that he had adapted some of the figures to the stereoscope. Prof. HUGHES explained his new Induction Balance, and showed some of its principal effects. It is well known that on an electric current passing along a wire adjacent to another wire, an induced current is set up in the second wire in an opposite direction to the first or primary current. In the induction balance two primary circuits or coils are taken, with the same current (interrupted by a microphone acted upon by the ticking of a clock) running through both; and between these is placed a secondary circuit or coil in connection with a telephone. The primary coils are so wound as to oppose each others induction on the intermediate secondary. There is a point, moreover, between where these opposed inductive influences exactly neutralise each other. If the secondary coil be placed there, no induced ticking of the clock can be heard; but if the secondary be displaced to one or other side of this point, the ticking can be heard in the telephone, increasing in loudness as the secondary approaches one or other of the primaries. If the distance between the primaries be graduated into a scale, this contrivance becomes a sonometer, since it gives an absolute zero of sound and degrees of loudness. It is well adapted for measuring the hearing power of the ear, and when used for this purpose it is known as the audiometer. By splitting the secondary coil into two parts and placing each close to its proper primary, so that there are four coils in all arranged in two pairs, the extremes in one primary circuit and the means in one secondary, the two opposing parts of the balance can be separated from each other, so as not to disturb each others action, and the balance made very sensitive by the closeness of the primaries and secondaries. Prof. Hughes finds that there is a line or zone of maximum induction midway between each primary and its secondary. If a conductor, such as a piece of metal, be put in this position it has a maximum distributing effect on the balance, due probably to the electric currents generated in it by the induction. The effect is apparently proportional to the conductivity of the metal. It requires an exactly similar piece of metal put between the other pair of coils to restore the equilibrium of the balance. A very slight difference of alloy or of weight between two like coins is at once observed from the imperfect restitution of the balance; base coins are thus also at once detected. Again, it is possible for a person to tell what particular coin or coins are in one part of the balance by trial of the same coins in his part. When plates of non-magnetic metals are held vertical in the balance their distributing effect is nil; iron, on the other hand, gives its maximum effect at this position, because its maximum effect overbalances its electrical effect. Two pieces of iron may therefore neutralise each other as cores in an induction coil. Steel is easy to balance compared with soft iron. Zinc disturbs most when placed along the sides of each pair of coils; iron when in centre. A certain length of metal laid along the outsides of the coils produces silence. The maximum line of inductive force is midway between the coils, and there is a line of minimum force at half the thickness of each coil; a metal placed at these lines of minimum force has no disturbing effect on the balance. Pressure, torsion, heat, magnetism, strain, and in fact all imponderable forces, are indicated, and their effects may be measured. Prof. W. G. ADAMS believed that one result of Prof. Hughes experiments will be the determination of the way in which the law of electro-dynamic induction depends on density. He also imagined that the metal when in 248 Report on the Air of Glasgow. the maximum line between the coils gathered the lines of force to itself, whereas when on the minimum lines it could not thus divert them. Prof. AYRTON cited the early experiment of Faraday with a sheet of copper oscillating to rest between two opposite magnetic poles. The copper took a long time to stop; but a sheet of iron placed between two like poles was soon stopped, owing to its becoming imbued with an opposite polarity, and deflecting the lines of force. He also suggested that the divergence of the results for conductivity of metals got by the induction balance from those got by the Wheatstone balance might be due to that electric inertia suspected by Sir William Thomson. Prof. GUTHRIE thought that the induction balance pointed to the conclusion that the disturbing effect of a conducting mass applied in this way is proportional to the quantity of electricity generated in it under certain conditions of temperature, &c. The determination of the conductivity of liquids would be a useful application of the balance. {CHEMICAL NEWS, June 6, 1879. chemists, more remote. Besides this, the difficulty of hunting down a practical fact amongst a crowd of theories is avoided. In the present issue the author has adhered more or less closely to the lines followed in the first edition, which was published in 1874. As then, he divides the elements and pseudo-elements into monads, dyads, &c.—an arrangement which greatly helps the memory. The chapter on Chemical Theory has also undergone the process of subdivision, and the matter has been greatly extended. The chapters on the Organic Compounds have also received large additions, and have also been relegated to the concluding chapters of the book instead of being classified according to their chemical constitution as in the first edition. This arrangement, though perhaps not very philosophical, is at any rate a convenient one for the hard worked medical or pharmaceutical student. Two useful appendices have been added to the new edition: one showing the quantities of the various ingredients to be added in parts by weight to 100 parts of alcohol, to produce the different artificial fruit essences; the other, the relation between the density and flashing point of paraffin oils. These appendices will be of great use to the practical chemist, but why annex them to the theoretical division of the work? The second volume of the work has been in a great measure remodelled and re-written. The processes employed by chemists are first described, beginning with solution and lixiviation, and ending with electrolysis and pyrology. The next chapter treats of the detection and separation of the metals used in pharmacy, and Chapter 3 follows with the detection and separation of the acidulous radicals. Chapter 4 gives the method of quantitative analysis as applied to the examination of the official salts official, by the way, being the new and more correct epithet applied to what used to be called officinal preparations. The next chapter gives a course of quantitative analysis as applied to the detection of unknown salts, while Chapter 6 gives a complete course of alkaloidal analysis. The other chapters are devoted to toxicological analysis, volumetric and geometric quantitative analysis Mr. CHANDLER ROBERTS gave some results which he had obtained from an examination of certain alloys by means of the induction balance. He had been able to detect a difference of 1 part in 1000 in the amount of silver present in two shillings of equal weight. He also pointed out that Mathiessen divided alloys into three classes :-(1) Solidified solutions of one metal in another; (2) Solidified solutions of one metal in an allotropic modification of another metal; (3) Solidified solutions of allotropic modifications of both metals. For the first class the curve of electric conductivity is a straight line; for the second, a parabolic curve; for the third, a bent line. Mr. Roberts found that the balance gave the characteristic curve for the first class with an alloy of lead and tin, and for the second with an alloy of gold and silver. With a copper-tin alloy, which is a good example of the third class, he found the curve given by the balance to be intermediate between Alfred Rich's curve of density and Matthiessen's curve of conductivity, and considers that the balance is influenced by the density as well as by the conductivity of the metal interposed. Prof. HUGHES said that as the working of metals ap-in general, ultimate organic analysis, and, lastly, special peared to effect their conductivity, he was inclined to rely more on the conductivity measurements of the balance than on those of the Wheatstone bridge. By the balance plain pieces of metal were taken, whereas by the bridge wires were mostly taken. He would rather not give any theories yet as to the results obtained from the balance. Dr. ERCK then exhibited his novel Pump for lifting solutions out of batteries. NOTICES OF BOOKS. An Introduction to Pharmaceutical and Medical Chemistry An Introduction to Analytical Chemistry, &c. Second DR. MUTER has done well to divide the second edition of analytical processes, such as the analysis of potable water and cinchona bark, the valuation of opium, the estimation of emetine in ipecacuanha, the alcoholic strength of spirits, wines, and tinctures, and the analyses of urine and urinary calculi. Mr. Joseph Ince has again done good service to Dr. Muter by undertaking the tedious-but, as far as his stu dents go, certainly not the thankless-task of compiling copious indexes to both volumes, which will greatly add to the value of Dr. Muter's already valuable work. Report on the Air of Glasgow, chiefly relative to Enclosed Spaces and Smoke. By W. J. DUNNACHIE, in cooperation with the Medical Officer of Health. Presented to the Committee of Health of the Magistrates and Council of Glasgow. May, 1879. IT is found that the proportion of atmospheric sulphur reaches its annual minimum in July, and, as might be expected, is highest in the central stations. Nitrogen, in the forms of actual and potential (albuminoid) ammonia, has two periods of excess, one in the summer and one in the winter. It appears, from Mr. Dunnachie's experi ments, that these two forms of ammonia are largely derived from the combustion of coal, &c., and are consequently no absolute indices of the sanitary condition of the air. This fact has scarcely received sufficient attention on the part of sanitary chemists. Even Dr. R. A. Smith, in his classical work on " Air and Rain," though fully admitting the presence of tarry distillates in the atmosphere, still "the ammonia is one measure of sewage of air not purified." Dr. J. B. Russell observes, that "the methods of Pasteur and Pouchet, of Cohn and Lister, are necessary to give precise meaning to the work of Angus Smith gays and other chemists in the region of air, and of Wanklyn and Frankland in the region of water." The guidance of chemical analysis is not absolute and all-sufficient; but as the most dangerous impurities, whether of air or of water, appear to be not merely organic, but organised, it must be controlled and supplemented by biological inquiry. This, however, neither Dr. Angus Smith nor Prof. Frankland will, we think, dispute. Proposed Legislation on the Adulteration of Food and THIS pamphlet comprises the draft of an anti-adulteration and one" business man." The author gives an abstract of English legislation on the adulteration question, and a history of their working. Here he speaks of analysts who "took the initiative, bought their own samples for analysis, and entered upon prosecution where necessary." This is a misapprehension. A public analyst who should act in this manner would be gravely overstepping his duty. CORRESPONdence. MANUFACTURE OF SULPHURIC ACID. To the Editor of the Chemical News. SIR, I was pleased to note in the CHEMICAL NEWS, EXPLOSIONS IN FLOUR-MILLS. To the Editor of the Chemical News. SIR, Will you allow me, in reply to Mr. Arthur M'Dougall's letter, briefly to state that my letter on the above subject appeared in the Glasgow Herald immediately after the explosion in the Tradeston Flour Mills; in fact, I believe, about a couple of days after the sad accident. It was noticed in a brief leading article on the subject as the most likely solution of the mystery, and after Dr. Stephenson Macadam's paper appeared (which was considerably afterwards), the Scottish Royal Society appointed a commission of inquiry into the subject, together with the question of priority, the upshot of which was that I received a private letter from the Secretary, Dr. Ferguson, of Edinburgh, which I still have, in England), in which my prior claims were fully acknowledged, and I was informed, too, that my report or letter to the Glasgow Herald was framed as the first. Dr. Macadam was men. tioned, too, as having been the first to invite a scientific investigation to the theory I brought forward, and so to support it further. Still, I must conscientiously acknowledge that the brain which to the best of my knowledge Austrian chemist, whose name I have forgotten, but whose deserves the fullest credit of the conception is that of the little notice in Dingler's Journal supplied me with the necessary light on the snbject, which I did but endeavour to spread and throw upon that fatal catastrophe at Glasgow. Mr. McDougall's letter will be welcomed as a very interesting contribution, and I feel no doubt he is right as to the abolition of the stive-room. With regard to the inconvenience of small electric lights disposed over a flourmills, I cannot judge, not having experience in the matter. It is for the mill-owner to decide which inconvenience is greater, that of ordinary lights, with the chance of explosions; or the electric lights, with safety. I fancy the filtration of the air, as Mr. M'Dougall suggests, may prove a difficult matter; but I wish it all success, as it would doubtless remove the danger. Still, it is always to be remembered that from abnormal causes and accidents, the air may sometimes even then become laden with flour dust in certain rooms or parts of the mill, and a vivid flash might communicate itself where an ordinary flame or light would fail to do so.—I am, &c., To the Editor of the Chemical News. SIR, It was only a few days ago that my attention was NEWS (vol. xxxix., p. 197) on the ammoniated cupric liquid drawn to the article by Mr. Otto Hehner in the CHEMICAL proposed by me for the quantitative determination of sugar. I am glad to find that so able a chemist as Mr. Hehner has conducted an inquiry into the merits of the test, and it is satisfactory to notice that with a proviso regarding the amount of alkali employed he is able to speak of the method as "capable of furnishing excellent results." At the outset of his investigations Mr. Hehner obtained results which stood at variance with mine, and considerately paid a visit to my laboratory at Guy's Hospital to see in what manner the discordancy was to be accounted which consisted in using 100 c.c. of the test-liquid, and for. Upon being informed of his mode of procedure, dropping the saccharine solution in slowly throughout the process, instead of employing only 20 or 40 c.c., and running the liquid in rapidly from the burette until near the point required, and then proceeding slowly-a difference which leads to the operation being much more pro.. longed in the one case than in the other, it immediately occurred to me that the discordancy arose from the testliquid failing to resist the influence of the prolonged boiling, and that this would probably be rectified by the employment of a larger amount of alkali. I have found with Fehling's solution that its stability under ebullition is impaired by dilution unless an additional quantity of alkali is put into it. I suggested to my assistant, Mr. Scard, who has ably worked under my direction in this matter, that more alkali should be used, and it was found that the true explanation of the discordancy had been hit upon. Without further concert than I have mentioned, the idea also occurred to Mr. Hehner to try the effect of a larger quantity of alkali, and when an interview took place a short time afterwards each learnt that an accord had been arrived at. In my communication to the Royal Society I stated that with the test proposed, I atom of sugar appropriated 250 Chemical Notices from Foreign Sources. CHEMICAL NEWS, June 6, 1879. to give this as the relation existing. I am not aware that 6 atoms of oxide of copper instead of 5 as is the case with Fehling's solution used in the ordinary way. I further mentioned that potash might be added to the extent of I grm. to 20 c.c. of the ammoniated test without altering the result, but that with the addition of 5 grms., or any thing beyond, 5 instead of 6 atoms of oxide of copper were appropriated by I atom of sugar, and with quantities of added potash between the 1 and 5 grms. the results stood between the 5 and 6 atoms of oxide of copper. Mr. Hehner, in commenting upon this, says that his observations, which he has verified over and over again, show that a much CHEMICAL NOTICES FROM FOREIGN smaller excess of soda influences the result than is stated by me. Mr. Hehner seems not to have noticed that the added alkali in my observations consisted of potash instead of soda, which he employed. The difference in the atomic weights of the two alkalies will nearly suffice to account for the difference existing in our recorded results. For many years past the liquid which has been used in my laboratory as a sugar-test has been made with potash instead of soda, and has contained nearly double the equivalent of the soda existing in Fehling's solution. I was led to introduce the larger amount of alkali because it appeared to me that the liquid possessed greater stability and precision of b haviour. I am now using this liquid not only as formerly, but also for the preparation of the ammoniated solution, and it contains a sufficient amount of alkali to serve for what is required. The quantity of copper is the same as in Fehling's solution. The two liquids therefore possess the same quantitative value. The composition is as follows: For the ammoniated test 120 c.c. of this solution are mixed with 300 c.c. of strong ammonia (sp. gr. o.880), and water is added so as to make up to a litre. The test, being in this form a 6-atom instead of a 5-atom oxidising liquid, it is of 1-10th the value in relation to sugar indication of the original solution, or 20 c.c. correspond with 0'010 grm. of glucose. On account of the liability of the cupric sulphate to impurity it is preferable, where great accuracy is required, to use electrotype copper. The quantity of copper to be taken is 8.808 grms. This is dissolved in nitric acid and evaporated to dryness after the addition of sufficient sulphuric acid to secure that a sulphate is left. The product is then dissolved in water and neutralised with potash. In this way the exact amount of cupric sulphate is supplied that is required to yield a solution of the standard strength. I originally recommended, for preventing the atmosphere from becoming charged with the evolved ammonia, that a U-shaped tube containing fragments of moistened pumice-stone should be used. I find that a much more simple and convenient contrivance for attaining the object is afforded by carrying a piece of vulcanised tubing from the flask into a beaker or other vessel containing water. The end of the vulcanised tubing intended to dip into the water is plugged at the extremity, and just above the plug provided with a transverse slit through three-fourths of its extent. This admits of the escape of air and ammoniacal vapour from the flask, but precludes by its valvular arrangement the sucking back of water from the occurrence of any sudden condensation in the interior of the flask. Uric acid exerts a reducing action upon oxide of copper equally as precise as glucose. The quantitative determination of it has hitherto constituted a lengthy and not very satisfactory process, but I find that with the ammoniated cupric liquid its determination may be easily and speedily effected. A large number of observations have been conducted in my laboratory with the view of asceraining its precise reducing capacity, and the results so closely conform with the expression that 3 atoms of oxide of copper are reduced by 1 atom of uric acid that I am led SOURCES. NOTE. All degrees of temperature are Centigrade, unless otherwise expressed. Comptes Rendus Hebdomadaires des Séances, l'Académie de des Sciences. No. 17, April 28, 1879. The Electric Light.-J. Jamin.-The burner submitted to the Academy with its points downwards has considerable advantages; such as simplicity, since it requires no mechanism and requires no preliminary preparation, beyond a support and the coke points; mechanical economy, since the number of flames is almost doubled; augmentation of light, since each of the new foci is almost twice as powerful as those of the old construction; quality of the light, which is whiter; more advantageous arrangement of the foci, which direct their greatest quantity of light downwards, where it is wanted, instead of up into the air, where it is useless; and, lastly, economy of combustible material. Electric Inscription of Words.-M. Boudet de Paris. -The transmitting apparatus is a microphonic speaker, the carbons of which, instead of being pressed by a spring, are simply maintained in contact by the pressure of a small piece of paper folded in form of a V. The vibrations of the diaphragm of the receiving apparatus cannot be written, since the movements of the style, however delicate the apparatus, can scarcely be distinguished upon the lamp-black. To enlarge the magnetic vibrations of the receiver the cover and the diaphragm of a Bell's telephone are taken away, and on the wood of the instrument there is fixed the end of a small stiff steel spring. The other end of the spring abuts on the surface of the magnetic nucleus surrounded by its coil; to this extremity is soldered a small mass of soft iron, weighing about 10 grms., and upon this mass and in the produced line of the axis of the spring is fixed a light style of bamboo, 10 centimetres in length and terminating in a slender whale-bone pen. Theoretic and Experimental Demonstration of the following Definition of Temperature; the Temperature is Represented by the Length of the Calorific A mathematical paper, not capable of useful abstraction. Oscillation of the Molecules of a Body.-R. Pictet. A Siren with an Electro-magnetic Regulator.-M. Bourbouze.-By means of this instrument sound can be made to pass from 8162 vibrations per second, through all the intermediary notes to 128 vibrations. The Laws of Dissociation. MM. Moitessier and R. Engel.-The dissociation of a body both whose components are volatile takes place even when the body is placed in presence of one of the products of dissociation, so long as the tension of this product does not surpass the dissociation-tension of the body at the temperature of the operation. When the tension of one of the components is greater than the dissociation-tension of the compound the dissociation no longer takes place. Two cases may then arise; either the dissociable compound is volatile, and in that case the true vapour density may be determined, or else the dissociable body is not volatile, as is the case with chloral hydrate at 60°. When two gaseous products on combining form a dissociable com NEWS pound the combination only takes place when the sum of the tensions of the components exceeds the dissociation-tension of the compound. Determination of Glucose in Blood.-P. Cazeneuve. -A reply to the criticisms of MM. d'Arsonval and Picard (Comptes Rendus, 1879, pp. 753 and 755). Contributions towards the History of Beer-yeast and of Alcoholic Fermentation: Physical and Physiological Action of Certain Substances, Saline or otherwise, upon Normal Yeast.-A. Béchamp.Yeast which has undergone the influence of sodic acetate, and which has been well washed and drained, can no longer be as completely fluidified by a new addition of acetate. Yeast, after a first treatment with the acetate, and whilst still impregnated with this salt, is still capable of undergoing fermentation. Yeast which has been, after two or three treatments with acetate, deprived of the greater part of its soluble matters is nevertheless capable of setting up energetic fermentation in cane-sugar. No. 18, May 5, 1879. The author has obtained iso-angelic acid along with ethyl-oxy-valeric acid on causing the bromo-iso-valerate of ethyl to act upon the ethylate of sodium in an alcoholic solution. Transformation of Camphic Acid into Camphor.J. de Montgolfier.-On heating calcic camphate and formiates together the author obtained camphor, well characterised by its composition and properties, and accompanied by camphren, an isomer of phoron. No. 19, May 12, 1879. The Vision of Colours, especially the Influence exercised upon the Vision of Coloured Objects in Rotatory Motion when Observed Comparatively with Identical Bodies in a state of Rest.-E. Chevreul.This is a somewhat diffuse extract from a recent work by the author, and does not admit of useful abstraction. Bases Derived from Aldol-ammonia.-A. Wurtz.Ammonia, when reacting upon aldol, gives rise to various bases, whose nature varies according to the conditions of the experiment. At 100° there are formed certain oxy. Certain Derivatives of Durol (a-Tetra-methyl-genous bases soluble in water, the study of which is benzol).—MM. Friedel, Crafts, and Ador. -The authors still incomplete. At 140° to 180°, and in presence of an have obtained a compound, which may be named phenyl- excess of ammonia, dark-coloured oily bodies are formed, duryl-carbonyl, if we give the name duryl to the mon- soluble in ether. A mixture of liquid and volatile bases atomic residue of durol, from which I atom of the is obtained on submitting aldol-ammonia to dry distillahydrogen of the benzenic nucleus has been removed. tion in a current of ammoniacal gas. At the same time there is formed another compound, almost insoluble in boiling alcohol, duren-dicarbonyldiphenyl or duren-dibenzoyl, which, if treated at a boiling heat with melting potassa, is resolved into benzoic acid and durol. Crystals extracted from Cast-iron by means of Ether or Petroleum.-J. Lawrence Smith.-On treating comminuted cast-iron with these solvents, on the spontaneous evaporation of the liquid, the author obtained acicular crystals consisting principally of sulphur, and absolutely similar to those extracted by the same process from meteoric iron. M. Berthelot, to whom the author had forwarded specimens of the crystals, stated that he had obtained similar bodies by the action of pure ether upon octahedral sulphur and upon anhydrous iron sulphides. It thus appears that even neutral solvents do not in all cases act by simple solution upon the bodies with which they come in contact, but effect also a chemical alteration. Effects of Carbonic Sulphide upon the Radicular System of the Vine.-M. Boiteau.-The author concludes that this agent in doses of 6 to 10 grms. destroys by poisoning all the parts of the root system which are within a radius of about 10 centimetres of the point where it is applied. This action is produced in the parts situate from 20 to 35 centims. below the surface. He still recommends the use of this sulphide, applied at a distance of more than 10 centims. from the main root. Thermic Formation of Hydrogen Silicide.-J. Ogier. The heat disengaged in the combustion of 1 equiv. of this compound is 3243 cals., and the mean heat of its formation is 24.8 cals. Limit of the Separation of Alcohol and Water by Distillation.-J. A. Le Bel.-The greatest degree of concentration obtained by repeated rectifications was 96.5 per cent. On rectification over quick-lime an alcohol of 98.5 was produced. When this spirit was submitted to fractional distillation the water passed over first, and the residue was the most highly alcoholic. After three rectifications the first portions marked 974 and the residue 993. The author finds that amylic alcohol from wines has not the repulsive odour of fusel oil or of the crude amylated alcohols of (beet-root) treacle. This odour, and possibly the injurious physiological action of the higher alcohols, may possibly, he considers, be due to the presence of certain empyreumatic compounds. A New Isomer of Angelic Acid.-E. Duvillier. caré.-The author has examined 282 workmen who use Effects of Inhaling Oil of Turpentine.-M. Pointhis oil in their trades, and has kept animals for several months in a medium strongly charged with its vapour. Among the workmen the symptoms were headache, dizziness, watery eyes, weakness of sight, especially in artificial light, cough, and troubled digestion. In most cases the constitution became habituated to this agent, but sometimes a change of employment was necessary. The animals experimented upon remained in a normal condition if good ventilation was maintained. In confined air death ensued in consequence of congestion of the brain, lungs, &c. Two Applications of the Method of MM. Fizeau and Foucault.-M. Mouton.-A mathematical paper not suitable for abstraction. Thermic Researches upon Silicic Ether.-J. Ogier. -The mean heat of formation of silicic ether is 115 cals. Action of Ammoniacal Salts upon Certain Metallic Sulphides, and Application of the Facts Observed to Mineral Analysis.-Ph. de Clermont.-Bismuth, cadmium, and copper sulphides are not affected if boiled with a solution of sal-ammoniac, as is also the case with mercurous and mercuric sulphides. Antimony trisulphide is completely decomposed by sal-ammoniac, yielding ammonium sulphide, which escapes, and antimony chloride, which remains in solution. Stannic sulphide yields stannic acid and no tin dissolves. Stannous sulphide is similarly decomposed, leaving stannous oxide. Metals not thrown down by hydric sulphide from their acid solutions, but converted by ammonic hydrosulphate either into sulphides or insoluble oxides, after the action of this reagent, behave in a peculiar manner with sal-ammoniac. It is already known that manganese sulphide dissolves as chloride. Iron sulphide in the same manner gives iron chloride. Nickel and cobalt sulphides dissolve likewise, though more slowly. Zinc sulphide resists longer, but ultimately dissolves also. Alumina and chromic oxide precipitated by ammonic hydrosulphate are known to be insoluble in sal-ammoniac. On these reactions the author founds a method for the separation of certain metals. If a solution contains cobalt, nickel, manganese, iron, alumina, chrome, and zinc, it is precipitated with ammonic hydrosulphate, the mixture added to a boiling solution of sal-ammoniac, and kept in ebullition for a sufficient time. On filtering, which is effected rapidly, the filtrate contains all the iron and manganese, part of |