tabular form except with certain groups, such as the alcohols | CHEMICAL NOTICES FROM FOREIGN and the cyanogen compounds. In general, however, space does not allow him to do more than define such classes as the ketones, amines, phosphines, &c. The last portion of the work is a synopsis of poisons with their antidotes and general treatment. The work upon the whole may be pronounced useful, and we hope that a future edition may see it freed from the oversights which we have pointed out, from certain typographical errors, and from the repetition of matter in different places. Notes on Certain Explosive Agents. By WALTER N. HILL, S.B., Chemist at the U.S. Torpedo Station. Boston: J. Allyn. THIS work treats first of explosions and explosive bodies in general; then of nitro-glycerin and its commercial mixtures; and of gun-cotton, which, with Prof. Abel, the author regards as trinitro-cellulose, and which he distinguishes from the lower substitution products used for making collodion. Like most chemists he admits the impossibility of sulphuric acid remaining in gun-cotton after it has undergone the process of washing, directed under Abel's patent, and concurs in the conclusion arrived at in England that the Stowmarket explosion must have been caused by the intentional addition of sulphuric acid to the finished product. The picrates and fulminates used as explosives are next described. In considering the respective forces of the agents in question he pronounces nitro-glycerin eight times as powerful as gun-powder, dynamite six times, and gun-cotton from four to six times. He draws, however, a very imporant distinction. "The harder and firmer the material to be blasted the more effective, proportionally nitro-glycerin or gun-cotton will be. In soft materials the reverse is true." As regards comparative safety he considers both nitroglycerin and gun-cotton to have the advantage over gunpowder. Disease of the Sugar Cane, Queensland. By Professor LIVERSIDGE. Sydney: Gibbs, Shallard, and Co. EPIDEMIC disease among important crops seems to be on the increase. The potato and the vine have long been sufferers, and, according to a writer in the Comptes Rendus the latter is now attacked by a new malady, quite distinct from the effects of the phylloxera. The coffee plantations of Ceylon are said to be withering away from some unexplained cause, and now the sugar cane in Queensland is affected with a disease, which is locally known as "rust." Prof. Liversidge, of the University of Sydney, who has made an official examination of the diseased canes and the soils in which they grow, does not consider that the malady springs from some one specific cause, but is due to imperfect cultivation, of which he certainly points out some decided proofs. SOURCES. NOTE. All degrees of temperature are Centigrade, unless otherwise expressed. Comptes Rendus Hebdomadaires des Seances, de l'Acade.nie des Sciences. No. 21, November 20, 1876. Physical and Chemical Properties of Ruthenium. -MM. H. Sainte-Claire Deville and H. Debray.-(See page 265.) New Researches on the Chemical Phenomena Produced by Electricity of Tension.-M. Berthelot. -In this paper the author examines what relations may exist between the chemical actions of electricity and the sign or tension of the electricity. He finds that ozone is formed equally under the influence of positive and of negative electricity. It is formed abundantly only under the influence of strong discharges. In operating upon mixtures of nitrogen and oxygen (both moist and dry) with the Holtz machine not the least trace of nitrous compounds has been observed, although a quantity smaller than 1-50th m.grm. could have been detected. Traces have been produced with the "effluve" of a Ruhmkorff apparatus. Acetylen is formed in notable amount in the vapours of organic compounds sealed up with nitrogen in tubes containing a metallic armature, and acted on by the discharges of the Holtz machine. The absorption of nitrogen by organic compounds is effected equally under the influence of both electricities. Composition of Certain Phosphites.-A. Wurtz.The phosphites in question are those of calcium and of barium (acid and neutral). Modifications of Elæomargaric Acid Produced by Light and Heat.-M. S. Cloëz.-These observations on the modifications of elæomargaric acid explain in the most satisfactory manner the curious properties of the oil of Elæococca. This oil contains 75 per cent of elæomargarin, the remainder being ordinary olein. On saponification the elæomargaric acid yields solid elæomargaric acid and glycerin, whilst the olein furnishes oleic acid and gly. cerin. In the oil congealed under the influence of light, the liquid elæomargarin is changed into solid elæostearin, accompanied with a small quantity of liquid elæolin; the ordinary olein undergoes no change. Saponification yields elæostearic, elæolic, and oleic acids. Oil heated for a long time to 180° with the exclusion of air loses the power of becoming solidified under the action of light. This is because the elæomargarin is completely transformed into elaolin. Note on a Method of Titrating Alkaline Sulphates. -M. F. Jean.-The quantitative determination of sul phuric acid combined with potassa and soda may be effected very rapidly and exactly by means of a simple alkalimetric titration. The aqueous solution of the substance in which the sulphuric acid combined with the fixed alkalies is mixed with a slight excess of baryta water, and then with Seltz water. The excess of baryta is precipitated in the state of baric carbonate, but as the carbonic acid would be able to dissolve this salt the liquid is decanted from the precipitate, which settles rapidly; it is raised to a boil and the whole is filtered. On account of the carbonate which envelopes the sulphate and acts like starch the filtration is effected very easily. The mixed precipitate having been washed with boiling-water until the washing waters no longer present an alkaline reaction, the filtrate is mixed with tincture of litmus, raised to a boil, and titrated with a standard solution of sulphuric acid. The quantity of sulphuric acid necessary to saturate the alkalies set at liberty by the baryta water is exactly the same as what was combined with the alkalies, potassa and soda, in the original matter. The titration of the alkaline sulphates may be effected by his process as rapidly as NEWS the alkalimetry of a sample of carbonate of soda. On operating with dilute solutions, and under the conditions indicated above, the alkaline carbonates do not decompose the sulphates of baryta. This process may be ad ESTABLISHED 1798. ROBERT DAGLISH & CO., BOILER MAKERS, ENGINEERS, AND MILL-WRIGHTS, BRASS AND IRONFOUNDERS, vantageously applied to the titration of the salts of Stassfurt and of Bene, so much employed in agriculture. These salts, besides the alkaline sulphates, contain sulphates of lime, magnesia, &c., which render the determination of the alkaline sulphates by ordinary methods very ST. HELEN'S FOUNDRY, LANcashire. tedious, and necessitate a complete analysis of these salts. By the method of titration which I point out these sulphates of lime, magnesia, &c., do not interfere, since these bases are precipitated by carbonic acid, whilst only the sulphates of potassa and soda enter into solution. This process is equally suitable for the assay of alkaline carbonates, but in this case care must be taken before treating the substance with baryta water to saturate the alkali with hydrochloric acid. On the Saccharine Matter Contained in the Petals of Flowers.-M. J. Boussingault.-The author gives a list of flowers from the petals of which reductive sugar has been obtained. Others yield invertible sugar which has no action upon the cupric liquid until after the intervention of an acid. Makers of every description of Chemical, Colliery, Copper Ore, Gold Makers of the latest Improved Revolving Black Ash Furnace with Siemens's Patent Gas Arrangement, and as used in the Manufacture of Soda. Improved Valveless Air Engines, and Pumps or Acid Forcing, Air Agitators, Compressors for Collieries, and Weldon's Patent Chlorine Process. Caustic, Chlorate, Decomposing, and Oxalic Pans. Gas Producers for Heating Furnaces. Pyrites Burners for Irish, Norwegian, and Spanish Ores. Photographs, and other information, supplied on receipt of Orders. Suit uitable for Manufacturers, Professors, and Experimenters, such as Large Glass, Earthenware, Copper and Iron Retorts, Stands, Receivers, Stills, Condensers, Purifiers, Pepys' and other Gas-holders, Crucibles, Mortars, Crushing Mills, Pumps, Furnaces, Bellows, Oxy-hydrogen Blowpipes, Batteries, &c., at a fourth to half usual prices, may be had of On a Process for the Detection of Magenta in Wines.-M. Fordos.-The author takes 10 c.c. of the SECOND-HAND wine and agitates it briskly for some seconds with I c.c. of pure ammonia in a test-tube. He adds to the mixture 5 to to c.c. of chloroform and agitates again, closing the end of the tube with the thumb and inverting several times, and finally pours the whole into a glass funnel fitted with a tap. When the chloroform has collected at the bottom of the funnel he opens the tap and receives the chloroform in a capsule of porcelain, which is then placed on the sand-bath. A small piece of white silk is then steeped in the liquid and heat is applied. As the chloroform escapes, the magenta, if present, is fixed on the A. CAPLATZI, AT THE SCIENCE DEPOT AND EXCHANGE, CHENIES STREET, TOTTENHAM COURT ROAD. silk and dyes it a rose colour. Pure wine does not dye MORRIS TANNENBAUM, 37, FITZROY silk a rose colour. To prove that the colouration is due to magenta it is sufficient to put the swatch of silk into a little ammonia, when the rose colour at once disappears and returns if the ammonia is driven off by heat. Note on the Detection of Rosolic Acid in Presence of Magenta (in Wines).-MM. P. Guyot and R. Bidaux. -Reserved for insertion in full. On Crystals of Ferrous Oxide Presenting a Singular Deformation.-M. C. Friedel.-Not adapted for abstraction. 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Vol. I., Parts 1 and 2, price 36s., with more than 400 Illustrations. Nature and Properties of Fuel: Secondary Products obtained from Fuel: Production of Light: Secondary Products of the Gas Manufacture. Vol. I., Part 3, price 33s., with more than 300 Illustrations. Vol. I., Part 4, price 21s., 300 Illustrations. BAILLIERE AND CO., 20, King William Street, Strand. Apparatus and Chemicals for Scientific Pursuits. Laboratory Fitter and Furnisher. Photographic Apparatus and Materials 8, KINGSLAND GREEN WEST SIDE), LONDON. BECKER & SONS, Rotterdam, MANUFACTURERS OF ASSAY, ANALYTICAL, PHARMACEUTICAL, AND OTHER BALANCES AND WEIGHTS. Sole Agents for England, Ireland, and Wales :— 89, BISHOPSGATE ST. WITHIN, LONDON. Balances are exhibited at the South Kensington Museum, Samples kept in stock by their Agents. : 1 T. & M. will forward complete Illustrated Catalogue on receipt of postage stamp id. PATENTS. 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CONTRIBUTIONS TO THE INSTEAD of bringing another preliminary notice before the Society, I should have preferred reserving the announcement of my new results on the Repulsion resulting from Radiation until they were fit to be offered in a more complete form; but the radiometer is now so much occupying the attention of scientific men, and results of experiments with this and allied instruments are appearing so frequently in the scientific journals at home and abroad, that were I not to adopt this method of bringing the results of my more recent experiments before men of science, I might find myself anticipated in some or all of the conclusions at which I have arrived. I have not only measured the force of repulsion, but also the viscosity of the residual gas, and from the results plotted I have the observations in curves which accompany this paper, and which show how the viscosity of the residual gas is related to the force of repulsion exerted by radiation. These curves must not, however, be considered as representing more than the broad facts, for I have not included in them my final observations, which in all probability will introduce modifications in them. In plotting these curves I have supposed my scale to le 1000 metres long, and to represent one atmosphere. Halfway up the scale therefore, or 500 metres, represents half an atmosphere; 999 metres up the scale represents an exhaustion of 1-1000th of an atmosphere; each millimetre, therefore, stands for the millionth of an atmosphere. My results have principally been obtained at the top of the scale, and it is the last quarter of a metre which supplies the diagrams accompanying this paper. When the residual gas is air, the viscosity (measured by the logarithmic decrement of the arc of oscillation) is practically constant up to an exhaustion of 250 millionths of an atmosphere, or o'19 millim. of mercury, having only diminished from o'126 at the normal pressure of the atmosphere, to o 112. It now begins to fall cff: at 200 millionths On June 15th last I mentioned to the Society that the repulsion resulting from radiation increases up to a certain point as I exhaust the air from the torsion apparatus. After long-continued exhaustion the force of radiation approaches a maximum, and then begins to fall off. I have since succeeded in experimenting at still higher exhaustions, and with different gases in the apparatus; and by means of a McLeod gauge attached to * A Paper read before the Royal Society, November 16, 1876. it is o110; at 100 millionths it is oo5; at 50 millionths it is o078; at 20 millionths it is o'o ; at 10 millionths it is 0035; and at o'1 of a millionth o. an atmosphere, the log. dec. has fallen to about o'01. Simultaneously with this decrease in the viscosity, the force of repulsion exerted on a black surface by a standard light varies. It increases very slowly till the exhaustion has risen to about 70 millionths of an atmosphere; at about 40 millionths the force is at its maximum; and it then sinks very rapidly, till at o'r millionth of an atmosphere it is less than one-tenth of NEWS its maximum. On continuing the curves of the log. | Hydrogen gives a remarkable diagram. The viscosity at the normal pressure is measured by a log. dec. of 0.063; at 250 millionths of an atmosphere it is o057; at 100 millionths it is o'052; at 50 millionths it is o'046, whence it rapidly sinks. The force of repulsion increases slowly up to an exhaustion of 250 millionths, then quickly until it attains its maximum at about 50 millionths, and it then rapidly sinks. The force of repulsion is very great in a hydrogen vacuum, being in comparison with the maximum in an air vacuum as 70 to 41. Neither is it necessary to get so high an exhaustion with hydrogen as with other gases to obtain considerable repulsion. This shows that in the construction of radiometers it is advantageous to fill them with hydrogen before exhausting. Carbonic acid has a viscosity of about o'or at the normal pressure, being between air and hydrogen, but nearer the former. On approaching a vacuum the force of repulsion does not rise very high, and soon falls off. Before working with this apparatus I thought that monohydrated sulphuric acid evolved no vapour, and I therefore freely used it for cleaning out the pump and for drying the gases. I can even now detect no vapour tension, but a comparison of the curves, with and without sulphuric acid, shows that the presence of this body modifies the results. One of my curves represents the action of the residual sulphuric anhydride gas. The experience thus gained has led me to adopt phosphoric anhydride for drying the gases. I can detect no ill effects from the presence of this agent, and I have been able in consequence to push the rarefaction to higher points than before. The McLeod gauge will not show the presence of mercury vapour. It is therefore possible that I have a greater pressure in the apparatus than is here stated. I have, however, entirely failed to detect the presence of mercury vapour at any great distance from the mercury in the pump; and the tube packed with gold-leaf, which I frequently interpose between the pump and the apparatus, shows no trace of bleaching, and exerts no appreciable effect one way or the other on the results. With this pump, assisted sometimes by chemical absorption, it is not difficult to exhaust a radiometer to such a point that it will not move to a candle placed a few inches off; but I have not yet succeeded in stopping the movement of the beam in the torsion apparatus. A long series of observations have been taken, at different degrees of exhaustion, on the conductivity of the residual gas, to the sperk from an induction coil. Working with air, I find that at a pressure of about 40 millionths of an atmosphere, when the repulsive force is near its maximum, a spark, whose striking distance at the normal pressure is half an inch, will illuminate a tube having aluminium terminals 3 millimetres apart. When push the exhaustion further, the 1-inch spark ceases to pass; but a 1 inch spark will still illuminate the tube. As I get nearer to a vacuum more power is required to drive the spark through the tube, but at the highest exhaustions I can still get indications of conductivity when an induction coil, actuated with five Grove's cells, and capable of giving a 6-inch spark, is used. When so powerful a spark is employed there is great danger of perforating the glass, thus causing a very slight leakage of air into the apparatus. The log. dec. now slowly rises, the repulsive force of the candle increases to its maximum, and then slowly diminishes to zero, the log. dec. continuing to rise till it shows that the internal and external pressure are identical. With a fine perforation several days are occupied in going through these phases, and they take place with such slowness and regularity as to afford opportunities for getting valuable observations. The improvements now added by Mr. Gimingham to the pump render it so easy to obtain high exhaustions that, in preparing experimental radiometers, I prefer to exhaust direct to one or two millionths of an atmosphere. By keeping the apparatus during this exhaustion in a hot air-bath heated to about 300° C. for some hours, the occluded gases are driven off from the interior surface of the glass and the fly of the radiometer. The whole is then allowed to cool, and attenuated air from the air trap is put in in small quantities at a time, until the McLeod gauge shows that the best exhaustion for sensitiveness is reached; if necessary this point is also ascertained by testing with a candle. Working in this way I can now do in a few hours what formerly required as many days. In this manner, employing hydrogen instead of air for the gaseous residue, and using roasted mica vanes set at an angle with the axis, as described further on, I can get very considerably increased sensitiveness in radiometers. I am still unable, however, to get them to move in moonlight. The statements made by an observer nearly a year ago, that he obtained strong rotation by moonlight, must therefore be considered as erroneous. My most sensitive torsion balance will, however, move easily to moonlight. The above-mentioned facts, in addition to what has already been published, leave no reasonable doubt that the presence of residual gas* is the cause of the movement of the radiometer. But few theories are sufficiently strong not to require reinforcement, and in the present case very much remains to be ascertained as regards the mode of action of the residual gas. The explanation, as given by Mr. Johnstone Stoney, appears to me the most probable, and having stood almost every experimental test to which I have submitted it, I may assume for the present that it expresses the truth. According to this the repul sion is due to the internal movements of the molecules of the residual gas. When the mean length of path between successive collisions of the molecules is small compared with the dimensions of the vessel, the molecules, rebounding from the heated surface, and therefore moving with an extra velocity, help to keep back the more slowly moving molecules which are advancing towards the heated surface; it thus happens that though the individual kicks against the heated surface are increased in strength in consequence of the heating, yet the number of molecules struck is diminished in the same proportion, so that there is equilibrium on the two sides of the disk, even though the temperatures of the faces are unequal. But when the exhaustion is carried to so high a point that the molecules are sufficiently few, and the mean length of path between their successive collisions is comparable with the dimensions of the vessel, the swiftly moving, rebounding molecules spend their force, in part or in whole, on the sides of the vessel; and the onward crowding, more slowly moving molecules are not kept back as before, so that the number which strike the warmer face approaches to, and in the limit equals, the number which strike the back, cooler face; and as the individual impacts are stronger on the warmer than on the cooler face, pressure is produced, causing the warmer face to retreat. I have tried many experiments with the view of putting this theory to a decisive test. The repulsive force being due to a reaction between the fly and the glass case of a It is a question whether the residual gas in the apparatus, when so highly attenuated as to have lost the greater part of its viscosity, and to be capable of acquiring molecular movement palpable enough to overcome the inertia of a plate of metal, should not be considered to have got beyond the gaseous state, and to have assumed a fourth state of matter, in which its properties are as far removed from those of a gas as this is from a liquid. |