we cannot produce artificially, and without which we cannot exist. The quantity of madder grown in all the madder-growing countries of the world prior to 1868 was estimated to be 70,000 tons per annum; and at the present time the artificial colour is manufactured to an extent equivalent to 50,000 tons, or more than two thirds of the quantity grown when its cultivation had reached its highest point. I might have referred to other subjects besides the coal-tar colours which have resulted from scientific research; but I know of no other of such interest and magnitude. From the brief history I have given, we see that the origin of these colouring-matters is entirely the fruit of many researches made quite independently by different chemists, who worked at them without any knowledge of their future importance; and on looking at the researches which have thus culminated in this industry, it is interesting to notice that many, if not most of them, were conducted for the purpose of elucidating some theoretical point. These facts certainly ought to be a great encouragement to chemists, and stimulate them to greater activity. It would be very pleasing to see more work emanating from the chemical schools of the United Kingdom; and I think no student should consider his chemical curriculum finished until he has conducted an original research. The knowledge obtained by a general course of instruction is of course of very great value; but a good deal of it is carried on by rule. In research, however, we have to depend upon the exercise of our judgment, and, in fact, of all our faculties; and a student having conducted even one, under the guidance of an efficient director, will find that he has acquired an amount of experience and knowledge which will be of the greatest value to him afterwards. It is hoped these remarks will encourage young chemists to patiently and earnestly work at whatever subject they may undertake, knowing that their results, although sometimes apparently only of small interest, may contain the germ of something of great scientific or practical importance, or may, like a keystone in an arch, complete some subject which before was fragmentary and useless. On a Safe and Rapid Evaporating-pan. By F. H. T. ALLAN. In the course of various chemical manufactures there is sometimes met the difficulty of products and apparatus being injured or destroyed in the process of rapid evaporation by the salts settling to the bottom of the pan, and there becoming a solid mass. This pan is intended as an effort to overcome that difficulty. Besides attempting to compass the evaporation of the leys or other fluids safe from the danger of deposition upon the heating-surface, it also provides for the rapid evaporation of the fluids, with continuous action in the pan, and the ready removal of the solids when formed. To attain these several ends, the form to be described has been found necessary. The pan may be made of boiler-plate, and about 30 feet long, by 10 feet broad, and 9 feet high. The heating-surface is supplied by two flues of a V-shape carried through the fluid from one end of the pan to the other. The acutest angle of the V is downward, and within 2 feet of the bottom of the pan. This form of heat-source whilst raising the temperature to boilingpoint and effectually keeping it there, offers no resting-place for descending particles; and consequently the salts on separating fall to the bottom of the pan and there accumulate. Now the apparatus is so arranged that the bottom slopes in one or more directions; the salts gather in the deepest parts, and suitable outlets that may be closed at pleasure being provided in the sides, they gravitate outwards into proper receptacles. Care must be taken that sufficient solids are left in to occupy the outlets, and the passage of fluids thereby prevented. The upper part of the V-shaped flue is covered in its whole length and breadth by an air-chamber of iron fitted with pipes or other arrangement passing into the liquid, whereby the air heated from the waste heat of the flue is forced into the boiling liquid, and there materially increases the rapidity of the evaporation. For the purpose of utilizing any heat that may escape from the air-chamber a small pan occupies its upper surface. On this subsidiary pan the liquid may be boiled to nearly salting-point, and then allowed to flow into the salting-down pan, 1876. 6 the smaller one being replenished with weak liquor. A limited supply of air may be introduced into the second pan, and evaporation proceeds very rapidly. The liquor in the pans need never lose its level, because, as salts pass from below and steam from above continuously, it is continuously replaced by liquor flowing in; the air-pipes may therefore be only two or three inches below the surface of the fluid. The pressure thus being not great, an ordinary fan will be sufficient to force the air through for evaporation. On Sewage Purification and Utilization. By J. BANKS. On a new Voltaic Battery. By H. W. BIGGS. On the Action of Pentachloride of Phosphorus on Turpentine. In the earlier days of anthracene manufacture, when it was obtained solely from the last runnings of oil, and when the distillation was stopped comparatively early for the double reason of saving the bottoms of the stills and producing a good marketable pitch, the principal solid impurities were naphthalene, phenanthrene, and paraffin. With samples of this description the method of testing by agitation, after washing with petroleum spirit, with a limited quantity of bisulphide of carbon gives approximate and practically useful results. When, however, the demand for anthracene increased, the tar-distillers found it more advantageous to carry on the distillation as far as possible, only stopping just before the point at which coking commenced. This method of working gives an entirely different variety of crude anthracene, viz. one in which the principal solid impurities have higher boilingpoints than anthracene. These bisulphide of carbon fails to remove; that test therefore, with these samples, ceases to give true indications of their commercial value. To correct this the anthrakinone test was introduced, and was, judging from the terms in which it was proposed, looked upon as applicable to all commercial anthracenes. The appendix to the paper soon followed, and showed that experience had not confirmed those anticipations; and now the kinone produced requires to be tested as to its purity, as the result is by no means definite. In applying the kinone test to commercial samples various minor difficulties occur, one of which is that damp samples of anthracene are apt to lose moisture during the time that is occupied in reducing them to a sufficient degree of fineness to allow the small quantity of 1 gramme to be a correct sample of the bulk; and another and more serious one is the uncertainty caused by the occasional occurrence of accidental impurities in the quantity weighed out. To remedy these defects and facilitate the testing, the author proposes the following modification: - Weigh out 50 grammes of the crude anthracene, and measure out 250 cubic centims. of petroleum spirit; triturate the anthracene in a mortar with a sufficient quantity of the spirit to form a thin cream, and pour it on a weighed filter (taking care at the same time to leave in the mortar any grit or sand which may be present); rinse on to the filter any anthracene which may be round the sides of the mortar, and employ the remainder of the spirit in washing the filter and its contents. Allow it to drain, then fold it carefully, press between bibulous paper, dry at about 60°-80° C., and weigh. Crush to a fine powder the contents of the filter, and from that quantity weigh out the gramme required for the kinone test; then proceed in the usual manner. In calculating the result allowance must of course be made for the diminution in weight caused by washing the crude sample with petroleum spirit. The method proposed in the foregoing short note does not claim for itself theoretica accuracy, but it claims the following advantages: 1st. It affords a ready method of detecting and separating extraneous matter, such as grit, sand, shreds of canvas, or splinters of wood, all of which are liable to occur even in good anthracene. 2nd. The preliminary washing produces a dry powder of perfect uniformity, from which it is easy to weigh out a small quantity. 3rd. The preliminary washing removes, beside others, the greater part of two important impurities, one of which, viz. paraffin, defies the kinone test, and the other, viz. phenanthrene, is not, if present in large quantities, completely oxidized under a considerable time. 4th. By removing a large proportion of the impurity beforehand the oxidation proceeds more quietly, and the kinone obtained is more crystalline and freer from chromium compounds. On some Instruments used in the Challenger. By J. Y. BUCHANAN. On Ammonic Seleniocyanide. By Dr. CAMERON. On a Gas-condensing Machine for the Liquefaction of Gases by combined cold and pressure, recently employed in the manufacture of Volatile Liquid Hydrocarbons. By J. S. COLEMAN, F.C.S. This paper gives a résumé of the author's paper on the effects of pressure and cold upon the gaseous products of the distillation of shales, read to the Chemical Society, September 1875. It then enters into certain thermodynamical questions relating to the best method of obtaining cold from a compressed gas, so as to utilize the cold produced in expansion, to supplement the effect produced by simple pressure. It then describes the engineering arrangements finally adopted for dealing with 250,000 feet of gas daily at the works of Messrs. Young & Co., on the principle of the drawing exhibited. The diagrams used were enlargements of the actual drawings of the machine as erected, and showed all the precautions found necessary in actual construction. The working of the machine, which gives, as a maximum, 2000 gallons per week, during the last three months was described, and samples of the product exhibited burning in Laidlaw's air-gas apparatus. Experimental Researches on the Chemical Treatment of Town Excretion, By J. S. COLEMAN, F.C.S. On the Transformation of Chinoline into Aniline. By Prof. DEWAR, F.R.S.E, On the Proximate Analysis of Coal-Gas.-Remarks on Reboul's Paper on Pyro-Tartaric Acid. By W. DITTMAR. On an Apparatus for the Analysis of Impurities in the Atmosphere. On Fire-Brick. By J. DUNNACHIE. On White-Lead. By A. FERGUSSON. On the Physiological Action of Pyro-, Meta-, and Ortho-phosphoric Acids. By Prof. GAMGEE, F.R.S. On the Influence of the Condition and Quantity of the Negative Element on the Action of the Copper-Zinc Couple. By Professor GLADSTONE, F.R.S. On Solid Water. By Prof. GUTHRIE, F.R.S. On the Critical Point of Liquid Carbonic Acid in Minerals. The History of Copper-extraction by the Wet Way. In this paper the author related the history of the introduction of these processes and their establishment in this country and abroad; he described the various stages of the manufacture of Spanish cupreous pyrites by his processes; he also described and illustrated by specimens the recent modifications introduced for improving the quality of the copper, and at the same time separating the small quantity of lead, silver, and gold always present in Spanish pyrites. On the Purification of the Clyde. By Col. HorE, V.C. On the Limited Oxidation of Terpenes.-Part IV.* In this part of his researches the author has more particularly inquired into the phenomena attendant upon the atmospheric oxidation of turpentine in the presence of water. These phenomena may be stated as: (a) Increase of the specific gravity of the oil as the oxidation proceeds. (b) Gradual increase in the amount of peroxide of hydrogen produced, or the rate at which it forms. (c) Gradual heightening of the boiling-point of the oil as it oxidizes. The oxidation, which takes place slowly at first, proceeds very actively afterwards, and the oil thus under treatment is capable of inducing fresh turpentine, which may be added to undergo oxidation at the same rate from the moment of contact. The oxidized oil evolves large quantities of oxygen on heating to near 160° C., and this oxygen is doubtless derived from camphoric peroxide. To the same substance the author assumes to be due the camphoric acid and peroxide of hydrogen found in the aqueous solution that results from its decomposition with water. There are contained also in the watery solution obtained when turpentine is atmospherically oxidized in the presence of water, acetic acid, camphor, &c. Thus a solution obtained in one experiment upon several gallons of turpentine contained 323 grains of peroxide of hydrogen and 367 grains of camphoric and acetic acids. The amount of peroxide of hydrogen produced is simply limited by the amount of turpentine oxidized, and can be regulated at will. This aqueous solution the author has proved to possess most powerful characters as an antiseptic and disinfectant, and continued investigations have shown these characters to be possessed by the individual constituents of the solution, viz. cam * Printed in extenso in Chem. News, vol. xxxiv. pp. 127 & 135, and in Pharm. Journ. Sept. 23, 1876. phoric acid, peroxide of hydrogen, &c. In the last part of his research the author has resumed the thread of his researches previously published, and found that menthene (CH), whether derived from solid or liquid Japan camphor (by the action of Zn Cl2), produces, on atmospheric oxidation, among other bodies peroxide of hydrogen, acetic and formic acids, &c. Now Wright (Journ. Chem. Soc. ser. 2, vol. xiv. p. 2) has obtained from menthene, by the action of bromine, cymene; and so the conclusion stated in the author's previous papers that all hydrocarbons containing cymene as a proximate nucleus give peroxide of hydrogen on oxidation is confirmed. 10 Wright has also failed to obtain cymene (C1o H,,) from clove terpene (C15 H24), a result in accordance with the author's observations previously made to the same effect. The author has submitted the ethers also to atmospheric oxidation, and in this way results have been obtained which are of the greatest interest and importance. Ethylic ether CO absorbs oxygen even in the cold, but more readily in sunshine, and gives rise in the presence of water to peroxide of hydrogen, which may result from reactions represented by the following equations : That is to say, the ether may, in the first place, become acetic ether and eliminate water; secondly, the acetic ether may become anhydride, and the latter may be finally converted into peroxide. This peroxide, being unstable in the presence of water, splits up into acetic acid and peroxide of hydrogen. These results are confirmed by the fact that Brodie discovered acetic peroxide by acting on acetic anhydride with baric dioxide. These equations are, moreover, exactly parallel with those indicated by the author as representing the production of hydric peroxide from turpentine, and it is to their substantiation that his efforts in the future will be directed. Meanwhile he claims that they experimentally demonstrate clearly for the first time the existence of the radical hydroxyl in combination; and, in short, the production of peroxide of hydrogen in the way described amounts to the isolation of hydroxyl in combination with itself. On two new Hydrocarbons from Turpentine. By A. C. LETTS. On Soda Manufacture. By J. MACTEAR. On the possible Genesis of the Chemical Elements out of a Homogeneous Cosmic Gas or Common Vapour of Matter. By Dr. MACVICAR, F.R.S.E. On Essential Oil of Sage.-Part I.* By M. M. PATTISON MUIR, F.R.S.E. This oil has a yellow-brown colour, without any shade of green, a strong sage-like odour, and a hot burning taste. Its reaction is neutral. Sage-oil does not deposit * Published in the Year-book of Pharmacy, 1876, p. 560. |