CHEMICAL NEWS,} Nov.3, 1876. Repulsion Resulting from Radiation. 90. EXPERIMENT proves the above reasoning to be correct. A bulb-tube was prepared in the manner already described (84), but in it were suspended, by separate silk fibres, two glass stems, each having pith balls at its extremity. Fig. 3 shows the elevation and plan of the apparatus. The torsion of the silk fibres was so arranged that the pith balls ab hung freely about a millimetre from the balls c d. The glass stems were looped in the middle, and bent so that they did not touch each other. After complete exhaustion the following experiments were tried. FIG. 3. a b c A beam of radiant heat was concentrated on to the two balls a c. When applied momentarily and then removed A Paper communicated to the Royal Society, March 20, 1875. From the Philosophical Transactions of the Royal Society of London, vol. clxv., pt. 2. 187 the radiation simply drove the balls apart, and immediately allowed them to come together again. When, however, the beam was allowed to play upon the balls for about half a minute they became warm and widely separated; and upon now removing the beam of heat the balls did not fall together at once, but took several minutes to regain their original position. This experiment therefore proves Case I. The bulb and contents being of the ordinary temperature, a spirit-flame was rapidly passed round the bulb to warm it quickly on all sides. The balls were thus in the condition imagined in Case II., being in a space warmer than themselves. They immediately came together, a touching c, and d touching b. Many experiments were tried with the object of proving experimentally the propositions in Cases III. and IV.; but with this apparatus it was found impossible to warm one of the balls without at the same time producing repulsion of the ball by the beam of radiation concentrated upon it. There is, however, little doubt, from the experimental proof of Cases I. and II., that the reasoning is equally correct in the other cases. 91. With a highly exhausted bulb and light pith index, which was found to be exceedingly sensitive to radiation, numerous experiments were tried to see if there was any difference in action between the fingers and a tube of water of the same temperature. Many persons believe that there is a peculiar emanation or aura proceeding from the human hand, and Baron Von Reichenbach* considered that he had proved this to be the case. Were this true it was not impossible that the emanation would affect the pith index. I have been unable, however, to detect the slightest action exerted by my own or any other person's hand which I could not entirely explain by an action of heat. 93. Attempts were made to see if chemical action would attract or repel the index. I could not, however, produce chemical action close to the exhausted bulb, without at the same time liberating such an amount of heat as to mask any other action. 94. Although I most frequently speak of repulsion by heat, and in illustrating any of the results obtained I generally use either the fingers or the flame of a spirit-lamp as a convenient source of radiation, it must be clearly understood that these results are not confined to the heatingrays of the spectrum, but that any ray, from the ultra red to the ultra violet, will produce repulsion in a vacuum. I have already mentioned this fact in my first paper (58, 68). Experiments proving the similarity of action of all rays of the spectrum were shown before the Physical Society on June 20, 1874. They were, however, tried with a less perfect apparatus than the one I have since used for the same purpose, and need not be further alluded to till I describe the most ecent results obtained with the spectrum (110, 111). 95. Some experiments were tried with the object of ascertaining whether the attraction by heat, which, commencing at the neutral point (30 et seq.), increased with the density of the enclosed air, would be continued in the same ratio if the apparatus were filled with air above the atmospheric pressure. Two bulbs containing ivory needles suspended by silk fibres were accordingly adjusted to show the same sensitiveness to a hot body. One was * "Researches on Magnetism, &c.," translated by Dr. Gregory. London, 1850. + Phil. Mag., August, 1874. 188 Development of the Chemical Arts. kept for comparison, and the other was attached to an apparatus whereby the internal air-pressure could be artificially increased by a column of mercury. A little increase of pressure was enough to show that the sensitiveness to radiation was greater; and under a pressure of 1 atmosphere the superior delicacy of the ivory in the dense air was very marked. Attempts to carry the pressure to higher points failed, owing to the bursting of the thin glass bulbs. With a little different arrangement no difficulty would be experienced in carrying the experiments to a much higher point; but hitherto the greater interest attending the vacuum experiments has prevented me from working further in this direction. My friend and pupil, Mr. C. H. Gimingham, succeeded in the very difficult feat of sealing up some of these tubes under an internal pressure of 1 atmosphere. 96. To carry this experiment a step further bulbs containing a suspended ivory or mica index were filled with carbonic acid gas, water, carbonic disulphide, ether, alcohol, and other liquids. The index in carbonic acid behaved as if it were in air of somewhat higher density than the atmosphere; movements were also obtained when the liquids were present, but they were so obviously due, in whole or in greater part, to currents, that they proved nothing of importance. (To be continued.) REPORT ON THE DEVELOPMENT OF THE CHEMICAL ARTS Chlorine, Bromine, Iodine, and Fluorine. By Dr. E. MYLIUS, of Ludwigshafen. THE bromine lyes are kept in a large reservoir situate above the stills, in which they can be preliminarily heated by means of a coil of steam pipe. The height of the liquid is indicated by a float to which is attached a cord passing over a pulley and supporting at its other extremity a weight suspended in front of a scale, so that the workman in charging the stills is guided by the movements of this weight. The stone lid is closed by its own weight, but may be further loaded with extra weights; the joints are made good with plastic clay. As we have already mentioned, the cover is raised by means of a counterpoise, but only when the apparatus is filled anew with manganese. The charge is about 4 cwts., which quantity serves for an entire series of operations. Not all qualities of manganese are fit for this purpose, that of medium hardness being the most suitable. The charges of bromine liquor and of sulphuric acid are introduced through one of the small apertures in the stone cover, which is immediately afterwards closed with balls of clay held down by iron weights. As soon as the apparatus is thus suitably secured steam is turned on and bromine vapours immediately escape in abundance through the leaden tube cemented into the second aperture in the cover. This leads to a worm surrounded with cold water in which the bromine is condensed. The original leaden worms have long ago been replaced by a stoneware apparatus. At first the excellent but very costly stoneware worms of the English establishment "Lambeth Potteries," were used, but latterly German apparatus have been employed, especially those furnished by the firm of Jannasch, in Bernburg. The lower end of the stoneware worm opens by means of a bent glass adaptor into the central tubulure of a large three-necked Woolff's bottle holding about * "Berichte über die Entwickelung der Chemischen Industr'e Während des Letzten Jahrzehends." CHEMICAL NEWS, Nov. 3, 1876. 8 litres, in which bromine and bromine-water collect. Into one of the lateral necks is fixed a movable glass syphon, by means of which the bromine-water can be drawn off into stoneware jugs. From the other neck a bent glass pipe passes down to the bottom of an iron vessel, which widens upwards in a conical shape and which is filled with water and iron turnings. Vapours of bromine which have not been condensed in the bottle are arrested by the iron. The impure chloriferous bromide of iron, as well as the bromine-water syphoned off are returned to the stills for the next operation. At the beginning of the process scarcely anything but bromine is evolved, afterwards chloride of bromine escapes, and ultimately, when there is no more bromine in the apparatus, pure chlorine is evolved. Dr. Frank, for the instruction of the author, kindly caused an operation to be carried to the very end so that the three stages of the process, which are easily distinguished by the colour of the gas in the glass adaptor, were fully exhibited. In the ordinary routine of the works the operation is stopped when the chloride of bromine begins to be given off. The workmen in these establishments receive in addition to their wages a premium on the quantity of bromine obtained. Hence it is their interest to get through the greatest possible number of operations, and as the bromine lye is on hand in abundance they break off the operation as soon as the distillation of the bromine slackens. The quantity of sulphuric acid also is so calculated that it only just suffices for the liberation of the bromine in a charge. Hence the bromine obtained ought to be free from chlorine. It is found, however, in practice that, on account, doubtless, of the imperfect mixture of the reagents chloride of bromine is evolved even in the earlier stages of the distillation. The quantity of acid (hydrochloric acid?) must also be noticed which is given off towards the end of the process and produces such an evolution of hydrogen in the iron vessel that its contents froth strongly. In order to prevent loss by running over a broad saucer-shaped rim is cast on the iron at the distance of some centimetres from its upper margin in which the overflow collects and is conducted away by a side tube into a stoneware jug. Each operation takes up about two hours and yields from to 25 kilos. of bromine. The two bromine works at Stassfurt are so arranged that they are capable of producing 500 kilos. in twenty-four hours, but this quantity has never been actually furnished. (To be continued). THALLENE: ITS SOURCE, AND THE HISTORY By HENRY MORTON, Ph.D., As the new hydrocarbon, thallene, which I succeeded in isolating and investigating in 1872-3, is now being produced on something approaching a commercial scale, though in a very impure state, some points in reference to its source, and the actual history of its discovery, may be of interest at this time. Petroleum is ordinarily distilled from first to last in two stages. In the first place, it is heated in large stills until all the lighter oils, consisting chiefly of benzin and the burning oils, are driven off, and there is then left a residuum or petroleum tar, of a density of about 20° B. This residue or tar is then transferred to other stills, in many cases run by other parties, and is again distilled for the production of lubricating oils and paraffin. At the end of this operation, when the bottom of the still is already red-hot and some coke has been formed, there runs very slowly from the condensor a thick yellow-brown tar, which is almost solid in cold weather, and in summer 9,} CHEMICAL NEWS, On Thallene. 189 only semi-fluid. Much of it seems to lodge permanently of this new substance, which indicated that it was proin the heads of the stills, and my friend Prof. S. P. Lang-bably isomeric with anthracen. ley, of Pittsburgh, once secured me a barrel of it by having the still-heads blown out with steam. A specimen of the same material was kindly conveyed by my friend Dr. H. C. Bolton, to Dr. Tiemann, of Berlin, who made two combustions of it with the following result: This thick tar, prior to 1873, was only used as a lubricant for the necks of rolls in rolling-mills, its great tenacity securing its adherence under the very unfavourable I. 0.2821 grm. thallene gave o'1430 H2O conditions to which it was there exposed. II. 0'2750 About March, 1873, however, Mr. John Truax, of Pitts- I. 0.2821 burgh, wrote me as follows, referring to this tar, a conII. O'2750 siderable quantity of which he had before sent me from his own works : "Within a few months we have found a new use for it in the manufacture of a lubricating oil, and we are trying in every direction to obtain it. When we shall have our new works in order-in the course of a couple of months -we can let you have as many specimens as you want." It is this substance which contains thallene, and from which I extracted it. My attention was first drawn to it in the following way : In the early part of 1872 I was engaged in the systematic examination of various fluorescent bodies, and one day in February Prof. E. N. Horsford calling upon me, I showed him some of these, and he then mentioned that he had brought from Pittsburgh a highly fluorescent tar, which he would send to me. Shortly afterwards about half an ounce of the yellow tar, enclosed in a bottle, was sent to me by Prof. Horsford from Cambridge. The bottle was broken in transit, and I presume that part of the contents escaped. There was, however, enough for me to examine so far as to show that a solid crystallisable hydrocarbon could be extracted from the yellow tar. For convenience of reference I called this "viridine," from its green colour and fluorescence, and made a preliminary note of it in a paper which I read before the American Institute in New York on March 29. Wishing to carry my investigations further, I wrote to Prof. Horsford for a further supply, and in answer received the following note : "MY DEAR SIR, "New York, March 2, 1872. On receipt of the above letter I wrote at once to Dr. Tweddle, describing the tar sent me by Prof. Horsford, and he then and subsequenly promised to send me a quantity, but never did so. In the meantime, my friend Dr. G. F. Barker, then of New Haven, who had also brought some of the same tar from the works of Mr. John Truax, of Pittsburgh, hearing of my destitution, sent me part of his specimen to see if my new body was in it, and on my finding that it was he wrote to Mr. Truax to send me a large quantity. This Mr. Truax did promptly, and on my further advising him how to purify it he sent me some pounds of the new material, extracted from the tar as a dark olive-green solid mass. It was with the material so received by me from Mr. Truax that I made my investigations, already published, which ended in establishing the individuality of a new hydrocarbon, resembling in many points anthracen, but fusing at 460° F., and forming compounds with chlorine, bromine, oxygen, picric acid, &c., entirely unlike the corresponding derivatives of anthracen.* 0'1412 H2O 5'70 p.c. H. o'9622 CO2 = 93'02 p.c. C. 0'9384 CO2 €93.06 p.c. C. Anthracen requires-H, 5.62; C, 94'38. = However, I by no means consider that I have exhausted this subject, and hope to be able to give a rational formula for thallene before long. Among the articles constituting the exhibit of the Stevens Institute of Technology in the Centennial Exhibition at Philadelphia are the following preparations and compounds of thallene : I. Crude thallene washed with benzin. II. Crude thallene washed with benzin and hot alcohol. III. Thallene purified by repeated crystallisations IV. Thallene as above re-crystallised from hot alcohol. VI. Thallene chloride. IX. Sublimed thallene. X. Solarised thallene. Within the last few weeks I have received from Dr. H. W. C. Tweddle (the same gentleman from whom I was not able to procure any material with which to carry out my investigations four years ago) a series of solid bodies, to which he has given a variety of names, but which seem to consist simply of thallene in a greater or less state of purity. In the first place, under the name of petrozcene, he sends me a quantity of the product obtained by washing thallene-tar with benzin or petroleum naphtha. This was the first step of my process, published in 1872 (see CHEM. NEWS, vol. xxvi., p. 272), and, as might be expected, yields a product containing, it is true, some thallene, but contaminated with a large amount of uncrystallisable tarry matter and other impurities, which can be separated by washing with hot alcohol and repeated crystallisation from solution in hot benzol (coal-tar naphtha) in the ` manner described by me at first. Together with the above, Dr. Tweddle sends me a series of products which he has obtained by distilling the same, and separating from time to time what passed over, as the temperature of the still rose. The last but one of these products, which Dr. Tweddle finds to have a melting-point of 460° F., which was the melting-point found by me for thallene in 1872 (see CHEM. NEWS, vol. xxvi., p. 274), appears to be a tolerably pure specimen of thallene, yielding by two crystallisations from benzol a clear yellow substance characterised by the peculiar fluorescent spectrum and other physical properties by which this substance was first recognised. The other materials obtained at lower temperatures, prove to consist of thallene mixed with greater and greater amounts of the tarry substances and other matters which are removed by the process of crystallisation from hot benzol. Tweddle's last or highest product seems to be a mixture of thallene with carbon and other matters, the result of a partial decomposition caused by exposure to too high a temperature. Dr. While it is interesting to find that by working on large quantities of a material a partial separation of thallene from other substances accompanying it may be effected, my observation of these products would not lead me to recommend it as a desirable method of obtaining pure thallene. xlvi., p. 89; Poggen. The best of the products sent me by Dr. Tweddle yielded Not having facilities in my own laboratory at that time for such work, I was indebted to the kindness of my friend Dr. G. F. Barker, then of New Haven, for a combustion * See CHEM, NEWS, vol. xxvi., p. 272; Monit Scient,, vol. xv., p. 356; mer. Chem., vol. iii., p. 162; Phil. Mag Annalen, vol. clv., p. 551. Practical Chemistry in the University of Virginia. in benzol a dirtier and less pure solution than I obtained from the material supplied me by Mr. Truax when that had been well washed with benzin. Dr. Tweddle's material, according to his own description, was also washed with benzin before it was distilled, so that nothing was saved here, and evidently a considerable amount of the thallene must have been decomposed in the process of distillation. To obtain anything like a pure product crystallisation from hot benzol must, moreover, be resorted to at last. I have now on hand a large quantity of purified thallene extracted from a barrel of the tar which was secured for me by the kind exertions of my friend Prof. S. P. Langley, of the Allegheny Observatory, and with this I am conducting a thorough investigation of its chemical properties and derivatives. NOTES OF WORK BY STUDENTS OF IN THE LABORATORY OF THE UNIVERSITY OF Communicated by J. W. MALLET, (5.) Analysis of a Stove-Pipe Deposit. By S. D. CRENSHAW, of Orange Co., Virginia. In one of the working rooms of the Laboratory a "base burning" stone, burning Pennsylvania anthracite and fed by gravity from a central hopper, is kept alight during the whole winter both by day and night. The stove-pipe, of common Russia sheet iron, rises about 12 feet vertically, nd then runs horizontally about 24 feet before entering the chimney. When, in cold weather, the fire is burning slowly and draughts of cold air are allowed to enter the room from the doors, some of the products of combustion are condensed and come to the outside of the pipe at the joints, running slowly down the outside as a thick, orangeyellow, liquid mass in little streams of to inch wide. In the course of three or four days such a deposit hardens into an opaque mass of light brownish yellow colour. Qualitative examination proved that this consisted essentially of ammonium sulphate and free sulphur, with small quantities of ferrous sulphate, free sulphuric acid, and a hydrocarbon apparently of one of the higher series. A portion of the material was completely oxidised and the total sulphur determined as barium sulphate; the amount of barium sulphate yielded by another (unoxidised) portion treated merely with water was also ascertained, and the difference gave the means of calculating the free sulphur. Ammonia was determined in the cold by Schlösing's method. It was ascertained that the iron was present altogether as a ferrous salt; it was then fully oxidised and determined as Fe2O3. The carbon and total hydrogen (there being also nitrogen and sulphur present) were determined by combustion with cupric oxide aided by a small amount of potassium chlorate, and the gases were passed over heated lead chromate and reduced copper turnings respectively. The oxygen of the water was obtained by difference. The results were :(NH4)2SO4 FeSO4 H2SO4 80.48 3'73 S 7'35 C 134 H comb. with O'II CHEMICAL NEWS, The deposition of free sulphur, doubtless as a result of the reducing action at a low temperature of the stove-pipe iron upon sulphur dioxide, is interesting; probably the reaction instead of Fe2+2SO2 = FeSO4 + FeS, which occurs when the materials are more strongly heated, is Fe+2SO2=FeSO4+S. The hard and heavy mass of carbon which encrusts the inside of a gas retort for some time in use, and which results from the decomposition of volatile hydrocarbons produced during the distillation, forms an admirable fuel for laboratory furnaces, in which a very high temperature is to be attained, this use having been first suggested by Violette (Comptes Rendus, October 28, 1872, p. 1028). Its value depends partly upon its high density, but chiefly upon the small quantity of ash which it leaves when burned, so that the intervals between the fragments of fuel do not become choked nor the draught of air obstructed. Mr. van Slooten undertook to determine the amount of ash in specimens of this carbon taken from a lot of several tons obtained from the gas works of Richmond, Virginia. Small fragments of the material were burned in a stream of oxygen gas, supporting them on platinum foil in a hard glass tube. The combustion was not very easy to manage, since too slow a supply of oxygen readily led to the dense carbon ceasing to glow, while a little faster stream swept away the light particles of ash. It soon appeared that different layers of the deposit varied considerably in the amount of ash. Thus three specimens The trace of lithium was detected by the spectroscope in the flame of the furnace. the furnace is seen to be due not always to the existence The immunity from clinker or accumulation of ash in of a very small proportion of mineral matter in the fuel, but also to the very light condition in which this separates and is swept up the chimney with the draught. The occurrence in some cases of so considerable an amount of the not readily volatilisable elements silicon and iron in this retort carbon is not very easy to explain, and rather suggests the mechanical carrying forward of solid particles with even the comparatively gentle rush of combustible gas escaping from the coal. (7.) Production of Metallic Zinc free from Iron and Carbon, for Analytical Use. By R. D. BOHANNON, of Mathews Co., Virginia. On the whole, metallic zing is the most convenient material for reducing ferric to ferrous sulphate in the often recurring volumetric determination of iron by potassium permanganate. For this purpose we must have the metal perfectly free from iron and carbon, a condition in which it is almost impossible to procure it in commerce, even from the professed dealers in pure chemicals, while the purification by distilling out of contact of anything which can yield either of the elements to be removed is not an easy or convenient laboratory process. It is true that zinc containing iron might be used if the amount of the latter were certainly known, and known to be uniform, but this can scarcely be depended on. Mr. Bohannon has tried the production of the pure metal from the chloride (free from iron) by means of sodium, and with fairly factory results. not to give a blue reaction with the molybdic test, owing to the minute quantities of volatile oils and other impurities they contain." I think I shall be able to show that this blue reaction is due simply to the presence of alcohol, and not to volatile oils or similar impurities. In the first place, I examined a sample of the ordinary unreduced chloroform prepared from ethylic alcohol by Messrs. J. F. Macfarlan and Co., and found that it gave no trace of blue coloration with the molybdic test, while the reduced chloroform (sp. gr. 1'496) gave the characteristic alcohol satis-reaction at once. I next procured some of the volatile oil obtained in the purification of chloroform, and treated it repeatedly with solution of calcic chloride, to remove the alcohol. When a drop of this oil was added to the molybdic solution a pinkish tint was developed, but no blue coloration. I then mixed a drop of the purified oil with I drachm of pure chloroform, and submitted the badlysmelling mixture to the molybdic test, with the result that no colour whatever was produced. Commercial zinc was dissolved in crude hydrochloric acid, the solution diluted, and sulphuretted hydrogen passed through to saturation. The clear liquid was filtered off from the precipitate of lead sulphide, &c., after standing for twenty-four hours, heated to the boilingpoint, and treated with nitric acid enough to peroxidise all the iron present, which was then precipitated by the addition of ammonia until a portion of the zinc had been thrown down. After again standing for twenty-four hours, the solution was filtered off, evaporated to dryness, and the fused zinc chloride broken into small fragments. These were mixed with bits of metallic sodium and thrown into a previously heated and clean earthen crucible. The reaction was so violent that most of the zinc was volatilised and lost, but it was found that this could be prevented by previously diluting the fused zinc chloride either with sodium chloride or zinc oxide to a moderate extent. The metal obtained was quite free from iron (and of course from lead, copper, &c.) but afforded a trace of carbon derived from a little naphtha still adherent to the fragments of sodium used. This is easily prevented by careful drying of the larger pieces with a cloth, and then cutting off the outside crust. As regards the yield, 19 ozs. of pure zinc was obtained with an expenditure of 2.0 ozs. of sodium, but it was found necessary to have much more zinc chloride present (as a protective covering from the air) than the sodium was capable of reducing. University of Virginia, August 28, 1876. I trust that I have said sufficient to prove that Dr. Davy's strictures on the character of commercial chloroform are unwarranted, and that the impurity he has discovered is simply alcohol, which is not an impurity in the correct sense of the word. 93, Abbey Hill, Edinburgh. ON ANTHRACENE TESTING.. By DR. FREDERICK VERSMANN. (Continued from page 179). I AM fully aware of the objections likely to be raised to my test. It will be said some confusion will arise in consequence, because the standard of valuation will be changed, inasmuch as my test will always indicate a lower percentage than the one now in use. My answer is-My test is more correct and more trustworthy; and at all events the buyers of anthracene are fully aware that the present quinone test does not give them the true value of the article, but only an indication, which they supplement themselves by further analysis. The history of anthracene testing has been gradually NOTE ON DR. DAVY'S TEST FOR THE PURITY progressive, from the alcohol to the bisulphide of carbon, OF CHLOROFORM. By DAVID B. DOTT. IN the CHEMICAL NEWS (vol. xxxiv., p. 137) appears an interesting and valuable paper on a "6 New Chemical Test for Alcohol," by Dr. E. W. Davy. In that contribution, however, there are some remarks of a misleading nature. which I think ought not to be allowed to pass without correction. The first statement to which I would take exception is the following: :-" As regards chloroform, one of its common impurities is ethylic alcohol, which it may contain either from imperfect preparation or from fraudu lent addition, the very high price of chloroform offering a great temptation to the unscrupulous vendor to increase its bulk or weight by the addition of alcohol." Now, it is manifest that as the specific gravity of pure chloroform is at least 1500, while the British Pharmacopoeia gives 1490 as its standard specific gravity, the official chloroform must of necessity contain alcohol. It is therefore altogether erroneous to assert that the alcohol is present either "through imperfect preparation or fraudulent addition," the real reason for its addition being the prevention of decomposition in the chloroform. It appears that this new test can detect the presence of 1 part of spirit in 1000 parts of chloroform; but as the addition of 1 part of spirit to 2000 parts of chloroform reduces the gravity by about o'oor, the specific gravity would seem to be a more delicate test of the presence of alcohol than is molybdic acid. Dr. Davy informs us that "he was unable to obtain any sample of chloroform in commerce sufficiently pure and thence to the quinone test. Each of these modifications reduced the percentage, and was accompanied by an increase in the price of per cent, and if my test should be adopted the enhanced value of per cent will soon be regulated and find its level. In looking at the first table it will be noticed that although the results found by the usual test range from 114 to 68.5 per cent, and that of the crystals from 6.6 to 632 per cent, the percentage of the powder fluctuates within very narrow limits. Omitting Nos. 2, 12, 28 on the one hand, and Nos. 9, 12, 26 on the other hand, the remaining 24 samples yield between 4 and 6 per cent of powder. I have been very particular, as far as possible, to learn the history of all these samples, and I can fully account for the exceptionally low and high percentage in powder of the six samples; hence I am justified in neglecting them in the following considerations: The observation that a sample of the lowest quality yields nearly as much powder as another of the best quality, which last shows six times the amount of quinone by the usual test, is a strong confirmation of the wellknown practical experience that the low per cent article is always of less comparative value than a better quality article. Although this fact is well understood, it is but little acted upon, or the many low-quality lots would long have disappeared from the market. I think if the manufacturer can be clearly shown that a better quality article is more profitable he will after all improve his make, and as the buyers will take it all the more readily, I shall be |