Dec. 29, 1870**; Experimental Contributions to the Theory of the Radiometer. , . 277 radiometer, it follows that, other things being equal, the fly | spiral, then drawing it out corkscrew fashion, blacking the should revolve faster in a small bulb than in a large one. upper surface and suspending it on a point, a spiral This cannot well be tested with two different radiometers, radiometer is made, which rotates like a screw on expoas the weight of the fly and the amount of friction sure to light. Here also the black surface need never be would not be the same in each, but I have constructed in darkness, the pressure acting continuously between the a double radiometer which shows this fact in a very black side of the spiral and the cylindrical tube in which satisfactory manner. It consists of two bulbs, one large it is mounted. and the other small, blown together so as to have a wide The experiments with the double radiometer of different passage between them. In the centre of each bulb is a cup, sizes showed that the nearer the absorbing surface was to held in its place by a glass rod, and in the bulbs is a the glass, the greater was the pressure produced. To small four-armed fly with roasted mica disks blacked on test this point in a more accurate manner, a torsion one side. The fly can be balanced on either cup. In the balance was fitted up with a glass suspending fibre smaller bulb there is about a quarter of an inch between and reflecting mirror, as described in my previous the vanes and the glass, whilst in the larger cup there is a papers. At one end of the beam is a disk of roasted space of half an inch. The mean of several experiments mica blacked on one side. In front of this black shows that in the small bulb the fly rotates about 50 per surface, and parallel to it, is a plate of clear mica, so cent faster than in the large bulb, when exposed to the arranged that its distance from the black surface can be same source of light. altered as desired, at any degree of exhaustion, without inOne of the arms of another radiometer was furnished with terfering with the vacuum. This apparatus is very sensiroasted mica disks blacked on alternate sides. The other arm tive, and gives good quantitative results. It has proved was furnished with clear mica disks. The two arms were that when light falls on the black surface molecular prespivoted independently of each other, and one of them was sure is set up, whatever be the degree of exhaustion. At the furnished with a minute fragment of iron, so that by means atmospheric pressure this disturbance can only be detected of a magnet I could bring the arms in contact, the black sur- when the mica screen is brought close to the black sur. face of the mica then having a clear plate of mica in front of face, and it is inappreciable when the screen is moved it. On bringing a lighted candle near the instrument, and away. As the barometer gauge rises the thickness of the allowing it to shine through the clear plate, on the layer of disturbance increases. Thus, retaining the blackened mica, the clear plate is at once driven away, standard candle always the same distance off, when the till the arm sets at right angles to the other. gauge is at 660 millims., the molecular pressure is repreTwo currents of force, acting in opposite directions, can sented by 1, when the space separating the screen from exist in the same bulb. I have prepared a double radio. the black surface is 3 millims.; by 3 when the intervening meter in which two flys are pivoted one over the other, space is reduced to 2 millims.; and by 5 when the space is and having their blackened sides turned in opposite direc- i millim. With the gauge 722 millims. high, the values tions. On bringing a lighted candle near, the flys rapidly of the molecular pressure for the spaces of 3, 2, and i rotate in opposite directions. millims. are respectively 3, 7, and 12. When the gauge is Experiment shows that the force can be reflected from a at 740 millims. the corresponding values for spaces of 3, plane surface in such a manner as to change its direction. 2, and i millim. are II, 16, and 23. With the gauge at If an ordinary radiometer is exposed to light the black 745 millims. the molecular pressures are represented by surface is repelled, owing to the excess of pressure acting 30, 34, and 40, for spaces 3, 2, and i millims. When between it and the glass. If, however, a plate of mica ihe gauge and barometer are level, the action is so strong were to arrest this force and reflect it back again, the that the candle has to be moved double the distance ofi, motion should be reversed. Experiment shows that this and the pressures when the intervening spaces are 12, 6, is the case. A two disk radiometer was made, having Aat and 3 millims. are respectively 60, 86, and 107. A large opaque mica disks blacked on one side. In front of the series of observations have been taken with this apparatus, black surface of the mica and about a millimetre off, is fixed with the result not only of supplying important data for a large disk of thin clear mica. On bringing a candle near, future consideration, but of clearing up many anomalies the molecular pressure streaming from the black surface which were noticed, and of correcting many errors into is caught by the clear plate and thrown back again, causing which I was led at earlier stages of this research. Among pressure behind instead of in front, and the result is rapid the latter may be mentioned the speculations in which I inrotation in the negative direction, the black side now dulged as to the pressure of sunlight on the earth. moving towards the light. Hitherto most of my experiments had been carried on To still further test this view of the action I made ano- with bad conductors of heat. To get the maximum action ther radiometer, similar to the above, but having a clear of a radiometer it appeared necessary that no heat should mica disk on each side of the ordinary mica vane. This pass through to the back suriace, but that all should be prevents the reflection of the pressure backwards, and kept as much as possible on the surface on which the light causes it to expend itself in a vertical plane, the result fell.* At first I used pith, but since learning the advanbeing an almost total loss of sensitiveness. tage of raising the whole apparatus to a high temperature The above actions can be explained on the " evapora. during exhaustion, I have used roasted mica lampblacked on tion and condensation" theory, as well as by that of one side for the vanes; for this purpose it is almost perfect; molecular movement, and I therefore devised the following being a good absorber on one face, a good reflector on the test to decide between these two theories :-A radiometer other, a bad conductor for heat, extremely light, and able has its four disks cut out of very clear and thin plates of mica, to stand high temperatures. Many experiments have been and these are mounted in a somewhat large bulb. At the tried with metal radiometers, some of the results being reside of the bulb, in a vertical plane, a plate of mica, blacked corded in previous papers which I have read before the on one side, is fastened in such a position that each clear Society, but being less sensitive than pith or mica instru. vane in rotating shall pass it, leaving a space between of ments, I had not hitherto worked much with them. I about a millimetre. If a candle is brought near, and by now tried similar experiments to the above, using the means of a shade the light is allowed to fall only on the best conductors of heat instead of the worst; and for:1 clear vanes, no motion is produced; but if the light shines purpose thick gold-leaf was selected for the surface on on the black plate the fly instantly rotates as if a wind which to try the action of radiation. were issuing from this surface, and keeps on moving as An apparatus was constructed resembling a radiometer long as the light is near. This could not happen on the evaporation and condensation theory, as this requires that * I have already shown that when a ray of light from any part the light should shine intermittenaly on the black surface the spectrum falls on a black surface the ray is absorbed and degraded in order to keep up continuous movement. in refrangibility, warming the black surface, and being emitted as radiant heat. In this sense only can the repulsion resulting from By cutting a thin plate of aluminium into the forın of a I radiation be called an effect of heat. 278 CHEMICAL NEWS, { Experimental Contributions to the Theory of the Radiometer. Dec. 29, 1876. with an opening at the top, capable of being closed with a quently more facing the side of the bulb, greatly increases plate of glass. Through this I could introduce disks of its sensitiveness. any substance I liked, mounted in pairs on an aluminium The above experiments show that shape has even a arm rotating on a needle point. The first disks were of gold-stronger influence than colour. A convex bright surface leaf, blacked on alternate sides. After exhaustion, a candle is strongly rere'led, whilst a concave black surface is not repelled the black surface of one of the disks, but to my only not repelled by radiation but is actually attracted. surprise it strongly attracted the black surface of the other I have also tried carefully shaped cups of gold, aluminium, disk. I noticed that the disk which moved the negative way and other metals, as well as cones of the same materials. was somewhat crumpled, and had the outer edge curved so I will briefly describe the behaviour of a few typical radioas to present a slightly concave black surface to the candle. meters made with metal cups, which I have the honour of I soon found that the curvature of the disk was the cause exhibiting to the Society: of the anomaly observed, and experiments were then tried No. 1035. A two-disk, cup-shaped radiometer, facing with disks of gold and aluminium; the latter being opposite ways; both sides bright. The disks are 14'5 chiefly used as being lighter and stiffer, whilst it acted in millims. diameter, and their radius of curvature is 14 other respects as gold. millims. A radiometer, the fly of which is made of perfectly fiatalu- Exposed to a standard candle 3.5 inches off, the fiy minium plates lampblacked on one side, is much less sensi- rotates continuously at the rate of one revolution in tive to light than one of mica or pith, but as I proved in my 3-37 seconds. A screen placed in front of the concave side earlier papers, it is more sensitive to dark heat. Exposed to so as to let the light shine only on the convex suriace, repels light, the black face of a metal radiome ter moves away as if the latter, causing continuous rotation at the rate of one it were black pith. When, however, it is exposed to dark heat, revolution in 7'5 seconds. When the convex side is citner by grasping the bulb with the warm hand, dipping it screened oft, so as to let the light shine only on the con. into hot water, or covering it with a hot g'a s shade, it rapidly cave side, continuous rotation is produced at the rate of rotates in a negative direction, the black advancing, and con- one revolution in 6'95 seconds, the concave side being tinuing to do so until the temperature has become uniform attracted. throughout. On now removing the source of heat, the fly These experiments show that the repulsive action of commences to revolve with rapidity the positive way, radiation on the convex side is about equal to the attracthe black this time retreating as it would if light shone on tive action of radiation on the concave side, and that the it. Pith or mica radiometers act differently to this, dark double speed with which the fly moves when no screen is heat causing them to revolve in the same direction as light interposed is the sum of the attractive and repulsive does. actions. The outer corners of the aluminium plates, which were No. 1037. A two-disk, cup.shaped aluminium radio. mounted diamond.wise, were now turned up at an angle meter as above, lampblacked on the concave surfaces. of 45°, the lampblacked sursace being concave and the In this instrument the action of light is reversed, rota. bright convex. 'On being exposed to a candle, scarcely tion taking place, the bright convex side being repelled, any movement was produced; when one vane was shaded and the black concave attracted. off the other was repelled slightly, but the turned up That this attraction is not apparent only, is proved corner seemed to have almost entirely neutralised the by shading off the sides one after the other. When the adion of the black surface. A greater amount of the light shines only on the bright convex side, no movement same corner was now turned up, the fold going through is produced, but when it shines on the black concave the centres of adjacent sides. Decided rotation was now side, this is attracted, producing rotation. produced by a candle, but the black surface was attracted No. 1038. A cup-shaped radiometer similar to the instead of repelled. Dark heat still caused the opposite above, but having the convex surfaces black and the conrotation to light, repelling the black surface. cave bright. The plates were now folded across the vertical diagonal, Light shining on this instrument causes it to rotate the black surface being still inside, and the bright metal rapidly, the convex black being repelled. No movement outside. The actions with a candle and hot glass shade is produced on letting the light shine on the bright conwere similar to the last, but more decided. cave surface, but good rotation is produced when only The plates were now flattened, and put on the arms at the black convex suriace is illuminated. an angle, still being in the vertical plane. When the No. 1039. A cup-shaped radiometer like the above, but bright surface was outside, scarcely any action was pro- blacked on both sides. duced by a candle, but when the lampblacked surface was With this a candle causes rapid rotation, the convex outside strong repulsion of the black was produced, both side being repelled. On shading off the light from the with a candle ard with a hot shade. concave side the rotation continues, but much more Two square aluminium plates were mounted in the ex-slowly; on shading off the convex side the concave is perimental apparatus, one being attached to the arm by strongly attracted, causing rotation. the centre of one of the sides, and the other by an angle. When either of these four radiometers is heated by a The opposite corner of the one mounted diamond-wise hot shade or plunged into hot water, rotation is always prowas turned up at an angle. The outer convex surface of duced in the opposite direction to that caused by the light. the diamond plate was blacked, and the side of the square On removing the source of heat, the motion rapidly stops, plate facing the same way was also blacked, so that either and then commences in the opposite direction (i.e., as it two black or two bright surfaces were always exposed to would rotate under the influence of light), the rotation the light, instead of a black and a white surface, as is usual continuing as long as the fly is cooling. Chilling one of in radiometers. As might have been expeded both these these radiometers with ether has the opposite aäion to black surfaces were repelled, but the turned up corner of exposing it to dark heat. the diamond-mounted plate proved so powerful an aux- The vanes of radiometers have also been formed of iliary to its black surface, that strong rotation was kept up, metal cones, and of cups and cones of plain mica, the square plate being dragged round against the action roasted mica, pith, paper, &c.; and they have been of light. used either plain or blacked on one or both surfaces. Folding the plates with the angle horizontal has not These have also been balanced against each other, and so decided an action as when the fold is vertical. against metal plates and cones. The results are of con. Sloping the plates and disks of a lampblacked mica siderable interest, but too complicated to explain without radiometer so as to have the black outside, and conse- great expenditure of time and numerous diagrams. The * I use the word attraction in these cases for convenience of ex broad facts are contained in the above selections from pression. I have no doubt that what looks like attraction in these and my experiments. Other cases is really due to a vis a tergo. The action of light on the cup-shaped vanes of a radio ,} Dec. 29, 1876. New Tests for Anthracen. 279 А meter probably requires more experimental investigation before it can be properly understood. Some of the phenomena may be explained on the assumption that the molecular pressure acts chiefly in a direction normal to the surface of the vanes. A convex surface would therefore cause greater pressure to be exerted between itself and the bounding surface of glass than would a concave surface. In this way the behaviour of the cup-shaped radiometer with both bright surfaces, No. 1035, can be understood, and perhaps also that of Nos. 1038 and 1039. It would not be difficult to test this view experimentally, by placing a small mica screen in te focus of a concave cup where the molecular force should be concentrated. But it is not easy to see how such an hypothesis can explain the behaviour of No. 1037, where the action of the bright coavex surface more than overcomes the superior absorptive and radiating power of the concave black surface ; and the explanation entirely fails to account for the pow. erfui attraction which a lighted candle is seen to exert on the concave surfaces in Nos. 1035, 1037, and 1039. NEW TESTS FOR ANTHRACEN. By JOSEPH BENNETT BROS. : test. The following is a new test for the determination of pure anthracen, and also a more detailed account of the process by which the tar distillers may get a fair idea of the quality of their anthracen before it is sampled and tested by the analyst. This will save them the trouble at times of having the goods disputed on the point of quality. In the rough sketch herewith, a is the tap-funnel containing the oxidising mixture, which drops through the half-inch pipe c, pass condenser (containing cold water, to e) into flask H. F is india-rubber joint to prevent the water in condenser escaping: B is wire and support to apparatus; G, cork; J, wire gauze; k, stand; and l is Bunsen burner. Apparatus without stand, about 4 feet high; condenser about 2 inches diameter. No. 1.—The oxidising solution is made by dissolving 100 grms. of chromic acid in 50 c.c. of glacial acetic acid and 50 c.c. of water. The whole is kept standing G to allow the impurities to precipitate. I grm. of anthracen is placed in a flask fitted with a condenser, 45 c.e. of glacial acid is added, the whole is heated C to gentle boil; 21 c.c. of the oxtaising mixture (about 15 grms. chromic acid) is now added by degrees, and the boiling continued until finished, as in the anthraquinon The quinon is then precipitated and washed in the usual way. It is now washed into a dish, and dried on a water-bath. The dry residue is treated with ten times its weight of concentrated sulphuric acid (about 1.84 sp. gr.), heated on a water-bath for one hour, or until it becomes a J crystalline mass by absorbing water. It is then diluted with 100 C.C. of water, thrown on a counterpoised filter, and washed, first with water, then with a I per cent boiling solution of caustic potash, fir ally with water, dried, and weighed. From the weight of quinon thus obtained sub. tract the ash remaining after incineration, and calculate, with the allowance, into pure anthracen by the ordinary method. It must be well understood that this test should only be used when the chosen analyst's decision is final for percentage for value. tervals into the flask h, occupying about two hours in No. 2.---Place i grm. of anthracen in the glass flask, H, adding all: the liquid must then be boiled fully two hours which will hold about 500 c.c. (through the cork of which longer; the heat is then shut off, and the flask with its a glass pipe with a glass condenser is fitted), add 45 c.c. contents allowed to stand about twelve hours in the cold. glacial acetic acid, now fix in the cork with pipe and The cork with pipe and condenser is then removed, and condenser, and gently boil; place in the other end of the about 400 c.c. of cold water are mixed with the contents pipe above the condenser a glass tap-funnel. Pour into of the Hask; it is then allowed to stand for about three the funnel 21 c.c. of the chromic acid mixture (which hours longer. The liquid is now filtered, the precipitated should contain about 15 grms. chromic acid), keep #ask at anthraquinon collected on the filter, washed with cold gentle boiling heat, and by turning on the tap of the fun water, then with i per cent boiling solution of caustic nel let a few drops of the chromic acid mixture fall at in. I potash, finally with pure hot water. The quinon is now 280 New Gas-Bottle. { CHEMICAL News, Dec. 29, 1876. washed from the filter into a dish, and evaporated to dry. , downwards, and be hermetically sealed by the layer of ness on a water-bath. The dry residue is now dissolved liquid above it. in ten times its weight of concentrated sulphuric acid When reversing the bottle it is necessary to avoid (about 1.84 sp. gr.), and heated on a water-bath for one allowing the acid to run into the glass tap connected with hour until it becomes a crystalline mass by absorbing the centre bulb. The production of gas can be stopped by water. It is now diluted with 100 c.c. of water, thrown restoring the bottle to its original position, which will on a counterpoised filter, washed, first with water, then cause the acid to flow away from the sulphide of iron. with a I per cent boiling solution of caustic potash, finally It will be found convenient to fix the bottle by a piece with pure hot water, then dried, and weighed." The anthra- | of copper wire twisted round its necks, and fastened in a quinon is now volatilised from a platinum crucible, and cork to some stand or support, upon which it may be easily the weight of ash remaining deducted. reversed. As a check two tests should be made at the same time, The gas-bottle is connected by rubber tubing with a requiring, of course, another apparatus. cork, preferably a rubber one, containing two glass tubes, The anthraquinon is calculated into pure anthracen by and fitting into the mouth of a very stout test-tube, about multiplying the net weight of anthraquinon by o:856; as, 7 inches in length and 1 in diameter. It is necessary that for example, the test-tube should be stout, or it will be liable to break Anthraquinon .. 36'050 grm. upon corking and uncorking, and it is advisable to procure Multiplied by several which will fit the cork bearing the gas delivery-tubes, 0.856 one of which, connected by the india-rubber tube with the Gives pure anthracen, about 30.860 , gas-bottle, passes to the bottom of the test-tube, and serves to convey the sulphuretted hydrogen through the liquid to The allowances for ash, &c., should be left to the analyst, be tested, and the other just penetrates the cork, and is but this is only a small matter. also attached to a rubber tube, which conveys the excess 22 and 23, Great Tower Street, London, of gas to the receiver in which it is to be absorbed. The December 11, 1876. test-tube is loosely fitted by means of a bung into a jar which contains hot water, as the precipitates formed by sulphuretted hydrogen are produced most favourably when the liquid assayed is kept warm. This jar also serves as DESCRIPTION OF A NEW GAS-BOTTLE AND a stand for the test-tube, and prevents its being upset by ARRANGEMENTS OF APPARATUS FOR the twist of the india-rubber tubes. Small flasks can be APPLYING SULPHURETTED HYDROGEN used instead of the test-tubes, but, on the whole, the latter are preferable, riot being so liable to upset. WITHOUT SMELL, AND AVOIDING ITS ESCAPE. The absorber consists of an upright cylinder on a foot, By WILLIAM GRIFFIN, F.C.S. with a neck near the base, usually called upright chloride of calcium jar, and is connected with the second glass tube in the cork of the test-tube. This cylinder is It often occurs that the study of chemistry has been pre-filled with sawdust mixed with coarsely powdered sugar vented in consequence of the disagreeable and noxious of lead, and it is as well if before being used it is moistened vapours of sulphuretted hydrogen, which is one of the with a saturated solution of sugar of lead. The top of chief reagents employed in the ordinary course of analysis. the cylinder is loosely closed with a cork. When not in Few private houses contain rooms which can be furnished use it may be corked up at top and at the neck at the foot. with the regular fittings of the laboratory, including the A small brush, such as is ordinarily used for cleaning expensive chamber for conveying away noxious fumes. In tobacco pipes, will be found useful for cleaning the glass order to obviate this difficulty I have devised the following tube which leads the sulphuretted hydrogen into the test. apparatus : tube, and it is convenient to have several pieces of such A gas bottle, consisting of three glass bulbs, one some tubing of equal length and diameter. what larger than the other two; these bulbs are connected When sufficient gas has been passed through an assay by necks of about a quarter of an inch internal diameter. the gas-bottle is reversed, the tap turned off, and the rubThe larger bulb is furnished with a neck, tightly closed ber tube disconnected from the glass tap. A piece of the with an india-rubber plug, and the centre bulb is fitted glass tubes mentioned above can then be slipped into the with a stopcock. end of the rubber tubing, and the remnant of the gas above the assay in the test-tube blown into the absorptioncylinder. Digestions with sulphide of ammonium can be made with the test-tube and the absorption cylinder alone. The gas-bottle, for cheapness, can be made without the glass stopcock; in which case the rubber tube between it and the test-tube should be of two portions connected over a piece of glass tubing. When an operation is over, and the gas-bot:le reversed, the piece attached to the bottle is slipped off the connecting glass tubing, and its orifice is closed with a piece of solid glass rod or a pinchtap. To charge this gas-bottle it is necessary to fill the small German Chemical Society.-At the annual meeting of bulb with diluted sulphuric acid ; about one part of acid to the German Chemical Society, held at Berlin Dec. 22, five parts of water will be found a convenient strength. the following officers were elected for the year 1877 :If the acid be either too strong or too weak the evolution President, Prof. F. Wöhler; Vice Presidents, Profs. of the gas is hindered. A piece or so of sound sulphide of Kekulé, Baeyer, Hofmann, and Liebermann. The retiring iion, previously washed io remove powder and small President (Prof. Hofmann) stated in his annual report that pieces which might fall through the necks, is then placed the present number of members was 1598, showing an inin the large bulb, and to produce the gas the bottle is re- crease of 225, during the past year, and that 423 original versed, so as to cause the acid to flow from the smal scientific communications had been presented before the bulb into the large one containing the sulphide of iron Society during this time twelve months. The Berichte which will then have the neck containing the rubber plu for 1876 form a volume of about 1900 pages. CroHs Nu NH2 water Dec. 29, 1876. 281 PROCEEDINGS OF SOCIETIES. noticed cavities, but they contained nothing ; cavities containing liquefied carbon dioxide had been observed, however, in trap. He had not considered the question as CHEMICAL SOCIETY. to whether such cavities contained hydrogen, his attention Thursday, December 21st, 1876. having been chiefly confined to quartz, granites, porphyries, &c., as most likely to have cavities containing liquefied carbon dioxide, the special object of his search. Professor ABEL, F.R.S., President, in the Chair. Dr. H. E. ARMSTRONG then gave a paper “On Thymo quinon." In a recent communication to the Berlin After the minutes of the preceeding meeting had been Chemical Society, Liebermann pointed out that the read and confirmed the names of Messrs. A. Gaved “oximido.naphthol,” Phillips and F. Kopser were read for the first time. The 1он President read a letter from the Secretary of the Royal C10H3 NHL Society as to the nature and conditions under which (NH grants would be made from the £4000 given by Govern- of Graebe and Ludwig, prepared by the oxidation of ment in aid of original research. The first paper, entitled “A further Study of Fluid formula diamido-naphthol, is more probably a compound of the Cavities,” was read by Mr. W. N. HARTLEY, and the results of his examination of a large number of topazes NH/ selected from the magnificent collection in the British Museum showed that the cavities scarcely ever contained anything but water. If the view be accepted that topaz and that when it is oxidised to naphtha-quinon, the NH, has been formed by the action of alkaline fluorides or group is displaced by OH ; in other words, the OH group cryolite on kaolin no carbon dioxide would be liberated, and one of the NH2 groups in diamido.naphthol are conso that it might not necessarily be found in the fluid cerned in the formation of the quinon, and not both the cavities. This is corroborated by the fact that in one and NH2 groups as Graebe and Ludwig supposed. It is to be the same topaz cavities may exist side by side, one of which presumed, therefore, that in the formation of oxythymois nearly filled with liquid carbon dioxide, the other one. quinon from diamido-thymol (recently effected by third with water, one-third with liquid, and one-third with Carstanjen) by oxidation, a similar reaction takes place, gaseous carbon dioxide, the space occupied by the gaseous namely, that only one of the NH2 groups and the OH CO2 having been produced by the contraction of the group are concerned in the production of this quinon, the on cooling. He inferred, moveover, that the other NH2, group being merely replaced by hydroxyl. critical temperature of water had not been reached, other- / Carstanjen has also obtained the saine oxythymo-quinon wise the contents of the adjacent cavities would have by treating the monobromo derivative of thymo-quinon been uniform. with potassic hydrate. Ladenburg has employed these The author has also examined a very large number of results as the basis of a speculative theory as to the value rock sections, principally granites and porphyries, almost of the several hydrogen atoms in benzene, in which he all of which contained water cavities, but in none of them makes the perfectly gratuitous and unsupported assumpwas the presence of carbon dioxide distinály proved. A tion that in the first instance the thymol OH group curious phenomenon in connection with the bubbles in remains unaffected, only the two amido groups taking part the water cavities of rock crystal was sometimes observed, in the formation of the quinon ; whilst in the second namely, that when heated the bubble became more dense | instance the thymol OH_group does take part in the than the liquid, and sank; so that in large deep cavities formation of the quinon. This, Liebermann points out, is they went entirely out of focus when observed with a not only unproved but is improbable. Dr. Armstrong hall-inch objective. In one specimen of quartz it was stated that for a long time he had been engaged in an found that the bubble began to sink at 150° C., but not investigation of thymol and its derivatives, and had already before it had reached this temperature. The cause of this obtained results which show that Ladenburg's assumpmotion appears to be that the bubble consists of a gas so tion was incorrect, even if it had not been contrary to our highly compressed that it is nearly of the same density as knowledge of the law governing substitution in the water at the ordinary temperature. On heating, the water phenol derivatives that para and ortho compounds are expands, thus still further condensing the gas in the first formed. The author had found that monamido. cavity, which then becomes heavier than the liquid and thymol from nitroso-thymol, in which the NH2 group consequently sinks in it. It is very remarkable that the occupies the para-position relatively to the OH group, cavities are not only frequently arranged symmetrically yielded thymo-quinon when distilled with ferric chloride around the axis of the crystal, but in some cases they equal in weight to more than half the weight of the thymol take the form of the crystals in which they are enclosed, employed in the preparation of the nitroso-derivative. He each side of the cavity being parallel to a face of the also stated that the formula suggested by Liebermann for crystal. Drawings of sections of crystals were exhibited "oximido-naphthol," &c., had already been suggested by in which this was very clearly shown. This is probably Mr. C. E. Groves and himself in a foot-note in the new caused by the water exerting a resistance to compression edition of Miller's "Organic Chemistry” they are now comparable to a solid body at the high temperature at preparing, the proof sheet containing the note being which the crystal was formed, but being mobile the shape handed in to the President. of the enclosed water was altered so as to conform to the The President having thanked the author for his planes of crystallisation of the mineral as the silica mole communication, cules grouped themselves around it. A paper “On High Melting-Points with Special ReferThe President, in thanking the author, remarked that ence io those of Metallic Salts (Part II.),” by Dr.T.Carnelley, this investigation in his hands had been prolific in in was read. The method to be employed depends on the teresting results. He hoped that his ingenious specula. principle that if three salts, A, B, and C, whose fusion tions, bearing on the formation of these crystalline sub points are in the order A, B, C, be arranged on a cold stances and the cavities contained in them, would give block of iron, and then introduced into a muffle kept at a rise to a valuable discussion. yi constant high temperature the ratio is approximately In reply to a question put by Dr. ARMSTRONG with reference to the occlusion of hydrogen by trap rocks, constant for the same three salts, whatever the temperarecently investigated by an American chemist, Mr. ture of the muffle ; x being the number of seconds which Hartley said that in samples of trap from the neighbour. elapse between the melting of A and B, and y that between hood of Edinburgh, which he had examined, he had | the melting of B and C. The arrangement of the muffle x |