disks and armature in the secondary. When a current passed through the magnet, the armature was attracted, compressed the carbon disk, diminished its resistance, and so increased the current strength in the secondary circuit. Since the diminution of the resistance is exactly as the pressure, the relay translated the varying current strength of the one circuit into a varying current strength in the other, of precisely similar character; thus for the first time making it possible to relay telephone currents. That the effects thus obtained by Edison are due simply to varying external contact, was first proved by C. B. Richards of Hartford in July, 1877. Placing a graphite cylinder between the jaws of a vise, platinum battery-contacts being provided at the ends, he found that the resistance of the cylinder to an electrical current diminished as the jaws of the vise were brought together, exactly as asserted. But if, in place of contacts at the ends, the connections were made by winding platinum wire round the cylinder just inside the ends, no variation of the galvanometer deflection was observed on increasing the pressure; thus proving conclusively that the phenomenon discovered and utilized by Edison depends upon the simple fact that a great variation in the resistance of a semi-conductor takes place on varying the surfaces of contact by pressure, the variation of resistance being directly as the pressure exerted. It would seem sufficiently evident that the phenomena, of Hughes and Edison alike, are due to the varying resistance of an electrical circuit at the point or points of contact. The correctness of this explanation is proved by the increase of the effect with multiple contacts. This is accomplished by Hughes with finely divided materials such as metallized carbon, or metallic filings or carbon fragments in a glass tube; and by Edison by layers of silk covered with graphite, by several cylinders of graphite placed in a row, or by increasing the surface of his carbon button. The extreme sensitiveness of the Hughes apparatus is fully equalled by that of Edison, all the phenomena described with it being readily repeated with Edison's carbon transmitter, especially if a carbon button be used which has been worked over several times so as to be in a state of minute division. The tick, the brush, the fly tramp can all be heard with it. For purposes of practical telephony, however, this sensitiveness is a serious objection, and was overcome by Edison only after long experimenting. It is mainly a matter of adjustment of the contact pressure, as well in the carbon telephone as the microphone, the apparatus being the more sensitive the less the pressure. Moreover, the fact that Hughes transmits speech without the use of a diaphragm does not affect the question. Edison months ago replaced the vibrating diaphragm of his telephone by a plate of metal rigidly attached to the carbon, and serving to increase the loudness by increasing the surface on which the sound acts. This, however, is not at all necessary. It is easy to talk with the carbon transmitter of Edison, by projecting the sound waves directly against the carbon itself as in the microphone. Finally, Edison has utilized the varying resist ance of carbon contacts by pressure, in the construction of an apparatus by which minute differences of pressure may be measured, and has applied it to the construction of a thermometer, barometer, and hygrometer of extraordinary delicacy, and to the production of a rheostat of great simplicity. G. F. B. 2. On the Boiling Point of Sulphuric acid of various strengths. -Though the boiling point of the most concentrated sulphuric acid-containing 98.5 per cent H,SO-was carefully fixed by Marignac at 338°, no determination of the boiling points of acid of less concentration has been made since Dalton. LUNGE has undertaken to redetermine accurately these boiling points by the following method: About 150 c.c. of the acid to be examined was placed in a flask having a long and wide neck and heated to boiling. In the flask the thermometer was so suspended by wires of platinum as to maintain a central position, the bulb being wholly immersed in the liquid. Since by loss of water the strength of the acid is increased, the boiling point must be determined at the beginning of ebullition. This the author takes to be the instant at which the stem of the thermometer is surrounded by transparent vapors, and a partial condensation takes place on the neck, the thermometer becoming at the same time stationary for from a quarter to half a minute. In this way, an accuracy of half a degree may be attained. The density of the acid was determined by direct weighing and reduced by Bineau's formula to 15°. The percentage of H,SO, was obtained from this by interpolation in Kolb's tables below sixty-three, and in Bineau's above this percentage. Plotting the observed boiling points as ordinates and the percentages of H,SO, as abscissas, a curve is obtained which is very nearly a parabola and by which the boiling points may be obtained for intermediate strengths.-Ber. Berl. Chem. Ges., xi, 370, March, 1878. G. F. B. 3. Substitution of Sulphur for Oxygen in the Fatty Series.-In the formula CH2+,COOH, which represents the acids of the fatty series, the oxygen of the carboxyl group may be partly or wholly replaced by sulphur, giving rise to three series of bodies, CH2+CSOH, CH2+,COSH, and CH+,CSSH, the first two of which are isomers. The confusion in naming these bodies is avoided by adopting the suggestion of Wurtz in his Dictionnaire de Chimie, and prefixing sulpho to the name of the acid when the oxygen in the carboxyl is replaced by sulphur, as in the first formula above given, thio when the oxygen of the hydroxyl is thus replaced, and thio-sulpho when both suffer substitution. Only the second of these classes has been yet produced, thioacetic, thio-propionic and thio-valeric acids having been studied. DUPRE has succeeded in producing a member of the first series, sulpho-propionic acid, by the action of sodium sulphydrate and hydrogen sulphide upon ethyl cyanide, the materials being placed in a flask with an inverted condenser, and heated on the water bath for five or six days. The flask contained two layers of liquid, the upper one of which was a solution of sodium sulphydrate. On decanting this, an oily liquid remained, which on cooling became a crystalline mass; and this after purification gave on analysis the formula C,H,OSNa,H,O. To establish the constitution of this body, nothing more is necessary than to convert the hydrate into the chloride, and see if the chloride contains sulphur; as this, of course, could not be the case if it is the hydroxyl oxygen which is replaced. For this purpose the sodium salt was treated with phosphoric oxychloride, and a chloride of sulphopropionyl CHS. CI was obtained, though in minute quantities. Sodium sulphopropionate, C,HCSONa, is very soluble in water and gives with lead acetate a white precipitate permanent in the cold; which distinguishes the sulpho from the thio salt, its isomer, which blackens at once. The barium salt was also obtained.Bull. Soc. Ch., II, xxix, 303, April, 1878. G. F. B. 4. On the Synthesis of Oxindol.-The conception that isatic acid is orthoamidophenylglyoxalic acid and that isatin is its anhydride, was first enunciated by Kekulé in 1869, who announced his intention to prepare orthoamidophenylacetic acid, and from this by oxidation to produce isatin. BAEYER has now succeeded for the time in preparing orthoamidophenylacetic acid, and in showing its ready conversion into oxindol. That oxindol is really the anhydride of orthoamidophenylacetic acid was proved by Suida, who, at Baeyer's suggestion, examined the question whether, in the reduction of isatin to oxindol, one or two CO groups were attacked, and if only one whether it was that group which was attached to the benzene, or the other one. On analytical grounds, the formula CH.CO CH, was established for oxindol, thus answering the problem. The synthesis of oxindol is extremely simple. Phenylacetic acid is nitrated by means of fuming nitric acid, producing nitrophenylacetic acid. This is reduced with tin and hydrochloric acid to amidophenylacetic acid. The acid liquid is neutralized with marble and boiled with precipitated barium carbonate. The isomeric amido-acids form barium salts, with the exception of the ortho-acid, which decomposes into its anhydride, and remains in the solution, from which the pure oxindol is extracted by ether. It fuses at 120°, yields indol when reduced with zinc dust, and yields the well characterized color reaction of nitrosoxindol with nitrous acid.--Ber. Berl. Chem. Ges., xi, 582, April, 1878. G. F. B. NH 5. On Aldehydines, a new Class of Bases.-LADENBURG has given the name aldehydines to a class of basic bodies formed by the condensation of one molecule of an orthodiamine and two molecules of aldehyde, with the separation of two molecules of For the preparation of tolubenzaldehydine, a mixture of one molecule of ortho-toluyl-diamine and two molecules of benzaldehyde is heated to 140° in open vessels for eighteen hours. The resulting mass is dissolved in hot alcohol, and on cooling yellow crystals separate, which, dissolved in hot dilute hydrochloric acid, yield long colorless needles of the hydrochlorate of the new base. Decomposed by ammonia, the base itself is obtained, and is purified by recrystallization from alcohol. It fuses at 195.5°, crystallizes in clear colorless monoclinic prisms, sublimes in small quantities, is insoluble in water, but soluble in alcohol and acetone, and in dilute acids. Its formula is C,,H,,N,. Heated with ethyl iodide to 120°, yellow crystals of tolubenzaldehydine-ethyl iodide are obtained; and these treated with silver oxide, yield a strongly alkaline solution from which on evaporation an oil separated which could not be crystallized. Oxidized with permanganate, it gives dibenzenylamido-benzoic acid, CH,COOH(NC,H),. Hence, the author assigns to tolubenzaldehydine the probable rational formula NCC,H, C,H. X NCC H Tolufurfuraldehydine, and tolusalicylaldehydine -to which he gives the special name azurine because of its magnificent blue fluorescence--are also described.--Ber. Berl. Chem. Ges., xi, 590, April, 1878. G. F. B. 6. On the Preparation and Properties of Invertin.-BARTH has investigated exhaustively the substance which is the inverting constituent of yeast, and which Donath called invertin. To prepare it, compressed yeast, freshly prepared, is coarsely pulverized, spread out in a capsule, and dried at a temperature not exceeding 40°, until it can be rubbed to a fine powder between the fingers. It is then heated on an air bath to 100° to 105° for six hours, mixed with water to a thin magma, allowed to stand for twelve hours at 40°, strained, and then filtered. The clear yellowish filtrate is poured into five or six times its volume of 95 per cent alcohol, by which a white flocculent precipitate is produced, which by strong agitation becomes granular, and may be easily filtered off. To free the ferment from albuminates-which this treatment with alcohol renders insoluble in water-the precipitate is freed from alcohol by pressure, digested in just sufficient water for solution, and filtered; the albuminates remain on the filter as a gelatinous mass. On pouring the filtrate into alcohol, the ferment is precipitated in the pure form. It is filtered off, washed with absolute alcohol at least ten times, the excess of alcohol expressed, and the precipitate dried in vacuo. The yield is about two grams from five hundred of yeast. Invertin thus obtained is a white powder, giving a clear yellowish-brown neutral solution with water, which, boiled with acetic acid and salt, is not rendered turbid, showing that it is neither an albuminate itself nor contains one as an impurity. Boiled with dilute copper solution and sodium hydrate, no violet color appears, showing the absence of peptones. No leucin could be detected on long boiling with sulphuric acid. On analysis it yielded 22 per cent of ash, consisting of potassium, calcium and magnesium phosphates. Calculating this out, it contained carbon 43.9 per cent, hydrogen 8.4 per cent, nitrogen 60 per cent, sulphur 0.63 and oxygen (by loss) 41.17 per cent. Experiments on the activity of invertin, using cane sugar solution, showed that it is dependent on the concentration of the sugar solution, is proportional to the quantity of the ferment AM. JOUR. SCI.-THIRD SERIES, VOL. XVI, No. 91.-JULY, 1878. present, reaches its limit in about forty hours, and that one part of invertin produces 760 parts of inverted sugar as a maximum.Ber. Berl. Chem. Ges., xỉ, 474, March, 1878. G. F. B. 7. On the occurrence of Allantoin and Hippuric acid in the Urine of the Dog.-SALKOWSKI has confirmed fully the statement of Meissner that both allantoin and hippuric acid occur in the urine of the dog. In the attempts to dissolve the crystalline residue of the evaporation of the urine of a dog in cold water, he noticed that a not inconsiderable mass remained undissolved. By recrystallization from hot water, crystals of pure allantoin were obtained. The amount given was 0.8 gram from the urine of four days, the dog being fed on meat. The hippuric acid was detected in the urine of the four days' experimented with, when hungry, when fed on meat, and when the intestine was ligated. As a maximum it reached one one hundred and twenty-ninth of the urea. It was never entirely absent, even when no food or only purely animal food was given; and the ligation seemed to be without influence. -Ber. Berl. Chem. Ges., xi, 500, March, 1878. G. F. B. He 8. On the Coloring Matter of the Shells of Birds' Eggs.-The brilliant and remarkably permanent color of the eggs of many birds has led LIEBERMANN to the investigation of its cause. finds that however widely different these colors are from each other, they are due essentially to but two coloring matters, one a blue or green substance, probably a biliary coloring matter, the other characterized by a remarkable absorption spectrum. These coloring matters are contained in the superficial layer of the shell, often in several thicknesses. When the shell is treated with dilute hydrochloric acid, the coloring matter separates in flocks, and by treatment with alcohol a strong solution may be obtained. With the eggs of gulls and plovers, an unsuccessful attempt was made to obtain the coloring matter pure. The colored alcoholic solution shows two sharp absorption bands, one on each side of the D line, when strongly acid. When alkaline, four weaker bands appear, none of which are coincident with the first.-Ber. Berl. Chem. Ges., xi, 606, April, 1878. G. F. B. 9. Chemistry in Space. Speculations on the forms of molecules and the arrangement of the atoms in space are generally as useless to the scientific world as they are entertaining to their authors, and are therefore almost exclusively confined to fanciful chemists, like J. G. McVickers, D.D., LL.D., who draw from their imaginations most beautiful and symmetrical pictures of molecules, which resemble nothing earthly unless those many-angled ornaments made of straw or perforated card-board so common in the windows of farmhouses. The pamphlet on "Chemistry in Space" recently published by Van't Hoff must not be confounded with these amusing but unprofitable examples of the so-called chemistry of the future, as its sole object is to establish a theoretical explanation of those cases of isomerism, usually called physical, and not accounted for by our present plane chemical formulas. Its importance is shown by a most complimentary preface written by Wislizenus for the German edition, and perhaps quite as well |