Obrazy na stronie

Chemical Notices from Foreign Sources. { .

Sept. 29, 1876. alloys by means of electro-deposition, have been ex- in water. I consider this as an interesting discovery, and tended. A small room has been set aside for chemico- one that may enable us to explain the persistent suspenoptical work, and fitted with a large reflecting goniometer, sion of clay in what we take as pure water. For instance, a Landolt's optical circle, a Browning's spectrometer, a the purest water we would take for experiments of this large direct vision spectroscope by Zeiss, a large inverted sort contains ammonia, either free or as carbonates. Why microscope, a smaller microscope, and three dissecting not, therefore, suppose that this ammonia forms a commicroscopes by Zeiss and Toller, and a saccharimeter by pound with the silica of the suspended clay, resembling Soleil.

soap in type of constitution, silica of course corresponding It may be interesting to the heads of colleges and with the fatty portion of such substances. As is well scientific institutions in this country to note the list of known, all soaps deport themselves like clay with regard desiderata which Prof. Wing still considers needful before to the phenomena under consideration. the chemical department of the Institute can be pro- I would like to know the deportment of pure water with nounced satisfactorily provided for :

pure hydrous silicate of alumina in regard to the question “ The instruction in chemistry is much hampered by the under consideration. Clay seems permanently suspended want of a laboratory for qualitative analysis apart from in strong ammonia.-I am, &c., the laboratory used for instruction in general chemistry ;

WILLIAM SKEY. of a laboratory for organic chemistry ; of a laboratory for applied chemistry; of a suitable reading room where the books of the chemical library may be consulted and writing done ; of a number of small rooms for the use of CHEMICAL NOTICES FROM FOREIGN special apparatus.” We regret to learn from a foot-note that the balance

SOURCES. room with its contents and the collection of substances for analysis have been destroyed by fire, and the library Note.--All degrees of temperature are Centigrade, unless otherwise very much damaged. We have no doubt that many che- expressed. mists in this country who have on hand substances of known composition would be happy to assist in restoring Comptes Rendus Hebdomadaires des Seances, de l'Acadeni the lost collection if some channel were pointed out.

des Sciences. No. 9, August 28, 1876. Amongst the theses presented by graduates, we find Sixth Note on Electric Transmissions through the only one which can be pronounced strictly chemical, i.e., Soil.-M. Th. du Moncel.–From the experiments dea paper on “ Anthracen Pressings,” by L. P. Kinnicutt. scribed it appears that under the most favourable condiThe subject is highly interesting, but the abstract given is tions the resistance of the soil varies from 4 to 5 kilometres so exceedingly brief that no opinion can be formed as to the merits of the essay.

of telegraphic wire, and that it is consequently far from It must be remembered that in addition to the chemi- other stores of water do not intervene the resistance may

being nil, as has been commonly asserted. If wells or cal department, or as we would rather say, faculty, che- be sometimes enormous. mistry forms a feature more or less prominent in the courses of mining, engineering, metallurgy, physics,

Alcoholic and Acetic Fermentation of the Fruits, natural history, and general science. Five professors and Flowers, and Leaves of certain Plants.-S. de Luca. as many assistants are occupied with various phases of In close vessels fruits keep for a greater or less length of our science.

time, whether in hydrogen or carbonic acid, or in a As a noveliy we may point out the introduction of vacuum, or in a limited quantity of air. In such condi“ military science and tactics " as a regular feature in all

tions fruits undergo a slow fermentation, with developthe departments. Were any of our English colleges or

ment of carbonic acid, nitrogen, and, in some cases, scientific institutions to take a similar step it would be hydrogen, and with formation of alcohol and acetic acid incontinently stormed, sacked, and burnt to the ground without the intervention of any ferment. In closed vessels by our advanced humanitarians, who protest even against these phenomena are produced imperfectly on account of the introduction of military drill into elementary schools.

the strong pressure produced by the gases evolved. Leaves and flowers behave like fruits in a limited atmo.

sphere, either of carbonic acid, hydrogen, or air, in a The Constants of Nature. Compiled by] F. Wiggles- vacuum or in sealed vessels.

CLARKE. Washington : Published by the
Smithsonian Institution.
We have here a continuation of this valuable series of Moniteur Scientifique, du Dr. Quesneville,
tables. The first supplement to Part I. is devoted to

August, 1876. specific gravities, boiling-points, and melting-points. Salicylic Acid in the Milk Trade.-Drs. L. Manetti Part II. is occupied with the specific heats of solids and and G. Muso.—The authors recommend the use of liquids; whilst No. III. comprises tables of the expansion salicylic acid for the preservation of cream in small farms of solids and liquids by heat. We need not say more where butter is made only a few times in the week, and than that the undertaking is equally laborious and praise for the preservation of butter where there is no conveniworthy.

ence for storing it in places at a temperature not higher than 6° to 8° C., as well as to keep it from rancidity when forwarded during the summer season to distant markets.

Researches on Viscous Fermentation.-A. ComCORRESPONDENCE.

maille.—Not suitable for abstraction. ,

Study on Coffee.-A. Commaille.—The author has SUSPENSION OF CLAY IN WATER. endeavoured to ascertain if it is possible to class coffees

by analysis, as the brokers, merchants, and experts do by To the Editor of the Chemical News.

certain outward characteristics or by taste. In this Sir,— Numerous contributions on this subject to the attempt he does not consider that he has been successful. CHEMICAL News have appeared since mine in 1866, but

History of the Manufacture of Turkey-Reds.I do not find anything new in them, with the exception of Theodore Chateau.-A continuation; unsuitable for that by Mr. W. Durham, F.R.S.E., who discovers the fact

abstraction. that alkalies and their carbonates in small quantity pre- Constitution of the Derivatives of Benzin.-M. E. vent the coagulation and precipitation of clay suspended Nolting.–A lengthy treatise, containing a large amount


,} Chemical Notices from Foreign Sources.

143 Sept. 29, 1876. of hypothetical matter, somewhat naïvely ushered in with destroy it rapidly. The new colour, like most of its conthe confession that " not merely the practical man, but geners, is capable of yielding other colouring matters by even the theoretical chemist, has difficulty in finding his substitution; if heated with aniline it yields a blue soluble way across the labyrinth of memoirs and dissertations, and in alcohol, but insoluble in water; if submitted to the in extricating himself from the chaos of contradictory action of aldehyd, iodide of methyl, &c., under ordinary hypotheses !"

conditions it is transformed into blues of a more and more New Class of Colouring Matters.-M. Ch. Lauth.- green tone, but of great purity, and which present the reThe raw materials employed for obtaining these new pro inarkable feature that they are soluble in water, and may ducts are the aromatic diamines obtained on reducing the be fixed in dyeing, by merely immersing the fibre. The nitro-derivative from the acetylisation of organic bases. colouring matter just described has been obtained with Thus, taking aniline for an instance, acetanilide is first B-phenylen-diamine; if we set out from pseudo-toluydin prepared, then nitracetanilide and nitraniline ; then the we obtain a violet much redder, and crystalline toluydin nitraniline is reduced either by iron and acetic acid, or by yields a violet-red. It is very probable that in the same tin and hydrochloric acid. In the first case it is necessary, circumstances other organic bases will likewise produce when the reaction is completed, to add to the mixture an colouring matters. Sulphur, then, may play a part in the excess of lime and to distil, obtaining thus B-phenylen- formation of colouring matters, and as it is permissible to diamine, which a single rectification yields perfectly pure ; suppose that other simple bodies possess analogous proin the second case we obtain a liquid, from which perties, the field of research is indefinitely extended. the tin is removed by zinc, and this mixture may serve at Ferments and Fermentations.-M. Charles Blononce for the production of the colouring matter, as will be deau.--Unsuitable for abstraction. at once explained. The various isomeric diamines have been studied for a long time with the object of turning them to account in the production of colouring matters : the aniline-brown obtained by the action of nitrous acid

Les Mondes, Revue Hebdomadaire des Sciences, upon a-phenylen-diamire is the only interesting product

No. 16, August 17, 1876. hitherto obtained. We arrive at different results if we Soap obtained directly from Salt.-If tallow, oil, and begin by introducing into the B-phenylen-diamine a new resin, the matters commonly employed in soap-making, element, sulphur. This B-phenylen-diamine may be are heated with an excess of common salt, ammonia, and obtained by heating the diamine with its own weight of water, a soda-soap separates, leaving in the liquid chloride sulphur to 150° to 180°, when an abundant escape of sul- of ammonium along with the excess of free ammonia and phuretted hydrogen occurs. When the reaction is at an salt. This reaction is due to the greater solubility of end, the mass is treated with hot dilute hydrochloric acid, ammoniacal soap in ammoniacal water, and the and filtered to remove excess of sulphur. The liquid thus insolubility of soda-soap in water containing per obtained gives splendid violet-blue colours with oxidising cent of salt. At first the ammonia combines with the agents. It is, perhaps, more advantageous, and certainly fatty acids, then the sodium contained in the salt takes more expeditious, to produce the sulphuration and oxida- the place of the ammonia in the soap. An excess of amtion in a single operation. For this purpose the hydro- monia and soap is essential. 100 parts of tallow require chloric solution of the phenylen-diamine is saturated with 15 or 20 parts of ammonia, 20 to 30 of salt, and 200 to 300 sulphuretted hydrogen (and we may, in this case, utilise parts of water (Whitelaw in Chemischen Centralblatt). directly the liquid containing zinc mentioned above), and we add perchloride of iron; the sulphur liberated com

No. 17, August 24, 1876. bines in the nascent state with the base, and if the addition of the oxidiser is continued little by little the Sweden, June 28, between 11 and 12 a.m.

A fall of meteoric stones took place near Ställdalen, in

Twelve fragcolouring matter is developed and precipitated. It is filtered, washed with slightly saline water to eliminate

ments have been found, one of which weighs 43 lbs. A certain impurities, dissolved in boiling water, and let cool, spectator affirms that a very intense whistling was heard, when it is obtained pure in splendid crystals. The fol- 1 accompanied by a light which was very distinct, though lowing are the proportions employed :-To 20 grms. of the day was clear and cloudless. Two very loud explosions hydrochlorate of phenylen-diamine-Water saturated with

were heard, succeeded by one less violent, after which sulphuretted hydrogen, 4000 c.c.; hydrochloric acid, eight or ten persons saw the meteorites fall. 20 grms.; perchloride of iron in solution at one-tenth,

The Radiometer of Mr. Crookes.-A memoir read 500 c.c. The new violet is a beautiful dye, giving very before the Academy of Padua by Prof. F. Rosetti.—The pure shades, much more blue than can be obtained with author concludes his paper as follows :-“ After the ex. Paris violet of the bluest quality, and it preserves its hibition which I have performed you will be convinced special tone by artificial light. It is very soluble in

that the radiometer is not an instrument destined merely boiling water, but the smallest trace of foreign matter

to attract general attention by reason of its novelty and modifies its solubility. The alcoholic solution is redder the curious phenomena which it presents, but that it may than that in water, and is dichroic. The solution in serve as a prompt and sensitive thermoscope, and, if used alcoholic soda is of a splendid magenta-red. Soda added with proper precautions, also as a photometer. It is a novel to the solution of the violet gives a brown precipitate, the acquisition for science, both from a theoretical and a pracbase of the new colouring matter; ammonia and acidstical point of view, and as such it is is capable of many give a violet precipitate, soluble in an excess of acid. The applications." The author then describes a modification acetic solution is-violet ; that in mineral acids a fine pure of the instrument for the purpose of registering the intenblue; on dilution with water it is re-precipitated. Metallic sity of the solar radiations. salts give precipitates which re-dissolve when the salt Movements Produced by Light and Heat, and on has been eliminated by washing; chloride of zinc gives a the Radiometer of Mr. Crookes.-Dr. A. G. Bartbi.very bulky amaranth-red precipitate ; chloride of sodium A luminous or thermic pencil which falls upon any body separates the violet from its solutions, but converts it produces a movement due to four causes-(1) Action of partially into a new violet substance insoluble in water. the heated sides. (2) Currents of air produced around the If this precipitation is several times repeated the trans- heated body itself. (3) Reaction of gases or vapours formation is complete, and the soluble colouring matter liberated by heat. (4) Reaction of air heated by contact disappears entirely. Boiling with salt water gives rise to with the surface upon which the rays fall. On suppressing the same reaction. Tannin

forms with the violet a com- these causes in the best possible manner, incident light pound insoluble in water. Reducing agents completely was no longer found to produce attraction or repulsion. decolourise the solutions of this dye, but the colour These results, however, do not prove that a very feeble returns on exposure to the air. Oxidising agents also impulsive action is not exerted by heat or light.

The Carriage of Explosives.

Sept. 29, 1876

, Bulletin de la Société d'Encouragement pour l'Industrie

MISCELLANEOUS. Nationale. No. 33, Sepcember, 1876. Report Presented by M. F. Le Blanc on behalf of Trade Report for September, 1876, of Gehe and the Committee of Chemical Arts on a New Apparatus Co., of Dresden.— This price current of chemicals and for the Condensation of Liquefiable Matters Held in pharmaceutical products is preceded by some very sound Suspension in Gases or Vapours.-MM. E. Pelouze and and judicious remarks on modern trade and its customs. P. Audoin.— This apparatus cannot be described in an in- The authors consider that England has set a good example telligible manner without the aid of illustrations. (See in its recent legislation on the adulteration of food and Comptes Rendus, lxxvii., pp. 819 and 928.)

drugs, and hopes that there will be a return to genuineReport Presented by M, F. Le Blanc on behalf of ness and solidity now the whole civilised world has seen, the Committee of Chemical Arts on a New Spectro- to its horror, the results of unfettered sophistication. Electric Tube or“ Fulgurator.”—MM. B. Delachanal The Carriage of Explosives.—The British Dynamite and A. Mermet - This interesting paper also cannot be Company, Limited, Glasgow, have written letters to the made intelligible without the two accompanying illustra. Board of Trade on the above subject. These letters are tions.

written as a protest against the conduct of certain railway Extraction of Vanillin from the Sap of the Pine.- companies and harbour authorities in refusing to convey M. Bouquet de la Grye, on presenting to the Agricultural or receive for storage any explosive which they may Society of France two samples of vanillin derived from the notify that they will not receive. The writer points out sap of the pine, made the following remarks :-One of the that most of the leading railway companies refuse to samples is vanillin in a pure state, whilst the other is carry dynamite, and hence its manufacture and use in the prepared for the uses of the confectioner. Vanillin exists United Kingdom is virtually prohibited. He maintains in the sap of the pine (Pinus sylvestris) and of the larch. that dynamite, according to the evidence of Major The first attempts at its extraction were made by Hofmann, Majendie, “is, on the whole, safer to transport than but on a small scale. The price of vanillin, though high, gunpowder packed in barrels.” This refusal to convey in consequence of the operations necessary for its extrace dynamite he considers a serious injury to the mining in. tion and purification, is still lower than that of natural dustries of the country, and an obstacle in the way of vanilla. The difficulty lies in procuring the sap.

For harbour improvements and other engineering works of this purpose the trees are felled during the period when public utility. A still greater evil is that there are good vegetation is most active-in May and June—and stripped grounds for suspecting that dynamite and other explosives of their bark. They are then immediately scraped. The are surreptitiously conveyed in passenger trains to a product of this operation, collected in vessels of tinned serious extent. It has often struck us as a serious incon. iron, is immediately heated on the spot to prevent fermen-sistency that while the sale of poisons is placed under very tation, filtered, concentrated, and allowed to cool and stringent regulations, that of explosives is practically settle. A substance is thus obtained which resembles open. Yet explosives may either by accident or by malice powdered sugar, and which is known as coniferin. This give rise to far more serious calamities than the most is a stable compound, and is sent in barrels to Paris, malignant poison. We think that the sale of explosives where the vanillin is extracted.

ought to be regulated with great stringency, and that no one ought to be allowed to purchase them without giving

proof of his identity, residence, of the purpose for which Gazzetta Chimica Italiana.

the substance is required, all these points being registered Anno vi., 1876, Fasc. v. and vi.

by the dealer. The custom of miners buying their own Inactive Amylic Alcohol of Fermentation.-Luigi gunpowder, guncotton, &c., and storing it in their cottages Balbiano.—The author describes sulphamylic acid, and is most reprehensible, and has given rise to many acthe sulphamylate of baryta, inactive amylic alcohol, in- cidents. Explosives needed in mining should be bought active amylic chloride, bromide, acetate, and valerate, and by the employer only, who should be responsible for their inactive valerianic acid.

sale custody and legitimate employment, and should be Alkaloid found in Damaged Indian Corn and in served out to the workmen as wanted. In the meantime Mouldy Maize Bread.-Prof. T. Brugnatelli and Dr. E. we are very far from approving of the arbitrary manner in Zenoni.—The authors consider that the alkaloid in ques. which railway companies refuse to carry certain substances, tion is the cause of the disease known in Lombardy as whilst they convey without scruple goods equally dan"pellagra.”

gerous. Series of Compounds derived from Ammonaldehyd. KING'S COLLEGE.-EVENING CLASSES. -R. Schiff.—The author describes the action of ammonIdehyd on phenylic essence of mustard, the formation of

WINTER SESSION, 1876-77. acetyl-phenyl-thiosinnamin, the action of ammonaldehyd on the allylic and ethylic, essences of mustard. The for- | The Evening Lectures commence on Monday, mulæ given are remarkably sensational.

October 9th, and terminate in March. On Gelatin, considered especially in reference to

CHEMISTRY--Mr. W. N. Hartley, at 7 o'clock. Mondays and its Reducing Agency.-Prof. G. Bizio.-- This paper is

Thursdays. Fee, £ius. 6d.

ANALYTICAL CHEMISTRY—Tuesday from 7 to 9. Fee, £2 28. chiefly devoted to an examination of the precipitate produced when gelatin dissolved in water is treated with a St. Mary's Hospital Medical School, solution of mercuric chloride in excess.


NATURAL SCIENCE. Emission of Nascent Hydrogen from Vegetables. The Examination for 1876 will be held on Tuesday, the 3rd of -Prof. E. Pollacci, -Not adapted for abstraction.

October, and following days. Candidates are requested io call upon

the Dean, at 49, Seymour Street, Portman Square, on the morning of Action of Certain Reagents on the Principal Or- Monday, October 2nd, between the hours of 10 and!, and to bring with ganic Colouring Matters.--G. Scurati-Manzoni.—An

them the necessary certificates.

For further particulars apply to the Registrar, at the Hospital, or to interesting paper, giving the reactions of colouring matters

A. B. SHEPHERD, M.B., Dean of the School, with certain reagents in a series of tables, too lengthy for insertion.

St. Mary's Hospital Medical School. Natural Poisonous Nature of the Human Corpse.

Paddington, W.

OPENING of WINTER SESS-ON, October 2nd, 1876.-Intro-A. Moriggia.-The cadaveric poison may be extracted ductory Address by Dr. Wiltshire. from the viscera of a body under toxicological examina- SCHOLARSHIPS in Natural Science, Classics, and Mathematics, tion by methods used for the alkaloids, and may complicate varying in value from £120 to £20. For further particulars apply to the result.

A. B. SHEPHERD, M.B., Dean of the School.

the Dean

Oct. 6, 1876.
Some New Derivatives of Anthracen.


it is difficult to obtain in a pure condition, as it is usually THE CHEMICAL NEWS. mixed with anthracen and dibrom-anthracen.


Pure monobrom-anthracen fuses at 100° C. It is easily

soluble in benzol and carbon disulphide, and moderately VOL. XXXIV. No. 880.

soluble in alcohol, more so than dichlor-anthracen. It also dissolves in glacial acetic acid. It crystallises in long yellow needles. In fuming sulphuric acid it dissolves

with a dirty yellowish green colour, addition of water NOTE ON SOME NEW DERIVATIVES OF causing a brown precipitate to separate. When its ben. ANTHRACEN.*

zolic solution is mixed with a similar solution of picric

acid it becomes red, and on evaporation deposits orange. By W. H. PERKIN, F.R.S.

red crystals of the new compound not unlike sublimed

alizarin. ANTHRACEN when treated with chlorine or bromine, under Dichloride of Anthracen.-When about the theoretical ordinary circumstances, yields dichlor- or dibrom-anthra- quantity of chlorine is gradually passed into a one per cent cen, even if the hydrocarbon be used in excess.

This was

solution of anthracen, cooled to about o° C., a white shown by Graebe and Liebermann, who found that by crystalline product separates out. This is the dichloride : treating anthracen under carbon disulphide with only one

it is even more unstable than the dibromide, giving off molecule of bromine, dibrom-anthracen resulted. Dr. hydrochloric acid rapidly at ordinary temperatures, and Anderson has described, however, a dichloride of anthra. still more quickly when heated. It was therefore impos. cen, and also a monochlor-anthracen. There can be no sible to analyse it, but from its decomposition into doubt, from the way he produced these bodies, that the monochlor-anthracen there can be no doubt about its first was only ordinary dichlor-anthracen, and the latter formula beingI am inclined to believe was a mixture of anthracen and

C14H10Cl2. dichlor-anthracen.

This substance is difficultly soluble in alcohol, ether I thought under these circumstances it would be of benzol, acetic acid, and carbon disulphide. interest to make further experiments on this subject, Monochlor-anthracen.—This is best obtained by fusing and see if it were possible to obtain some definite mono- the dichloride, the reaction beingderivatives containing chlorine or bromine. Dibromide of Anthracen.-A one per cent solution of pure

CH10Cl2 =HCI+CHAH,CI anthracen in carbon disulphide cooled to within a degree

Dichloride of anthracen. Monochlor-anthracen. or two of 0° C. when mixed with the theoretical quantity of bromine dissolved in carbon disulphide, and also cooled The product is purified by crystallisation from alcohol, with ice, gives a reddish brown fluid, which gradually be from which it is deposited in golden yellow flat needles, comes nearly colourless, and at the same time small white often of considerable length. It may also be obtained brilliant crystals are deposited: these, when collected, were

from the mother-liquors of the dichloride, which, however, washed with anhydrous ether, and allowed to dry sponta- usually contain a good deal of dichlor-anthracen. It neously or under the air-pump. They decompose, how- gave the following numbers on analysis :ever, rapidly, and hence good numbers could not be ob

Theory for Experiment. tained on analysis; but the following combustion, taken

CH,Cl. in connection with the other facts relating to this sub

Carbon stance, shows that it is a dibromide of anthracen.

79'05 78.62


4'23 4*22 4'52
Theory for

Monochlor-anthracen fuses at 103° C. It is very easily


48.85 soluble in ether, benzol, and carbon disulphide. It is also Hydrogen..



easily soluble in alcohol, and moderately so in glacial

acetic acid. It dissolves in fuming sulphuric acid with a Dibromide of anthracen crystallises in flat oblique green colour : addition of water to this solution gives a prisms, which quickly become yellow and opaque at the brown precipitate, but if the sulphuric solution be heated ordinary temperature with evolution of hydrobromic acid. it turns brown, and is then not precipitated on addition of This decomposition takes place very rapidly if heat be water, and seems to consist of disulpho-anthraquinonic applied. It is difficultly soluble in alcohol, ether, and acid. Like monobrom-anthracen, it produces a compound carbon disulphide. It yields anthraquinon on oxidation. with picric acid, which crystallises in most beautiful tufts

Monobrom-anthracen.—This substance is formed when of scarlet needles. the dibromide is kept at the ordinary temperature, or better when it is heated ; thusC14H10Bra=HBr +CH,Br

ON THE PROXIMATE COMPOSITION OF Dibrom-anthracen. Monobrom-anthracen.

COAL-GAS. The fused product is crystallised from alcohol once or

By W. DITTMAR, twice, and is then pure. I: gave the following numbers

Professor of Chemistry in the Andersonian University, Glasgow. on analysis :

Theory for Experiment.

In a memoir, “Sur le Gaz d'Eclairage," which he pub-

65'37 65.66

lished some months ago in the Comptes Rendus, M. Ber-

thelot reports on a most elaborate proximate analysis of 3:54 3'56

the Paris gas, which brought out the startling result that It is also produced by gradually adding the theoretical that gas contained only 3•7 per cent of heavy carburetted quantity of bromine to a solution of anthracen in carbon hydrogens, and that these 3-7 per cent included of disulphide at the ordinary temperature, and may also be


3'0 to 3'5 per cent. obtained from the mother-liquors from the dibromide of

Acetylen anthracen by distilling off the carbon disulphide and crys.


o'r to 0'2 tallising the residue fractionally; but in both these cases

Propylen and other hydrocarbons Read before the British Association, Glasgow Meeting (Section B.). * Read before the British Association, Glasgow Meeting (Section B.)





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0:13 vol.

0:62 ,

Proximate Composition of Coal-Gas.


Oct. 6, 1876. In other words, the gas was found to contain only about | It is true there is room for a little benzol. To find a 34 per cent of things not diluents, and that these 33 per maximum limit for this potential benzol, let us assume cent consisted substantially of benzol only. Regarding the observational errors had made the carbon too high and the experimental evidence adduced, it may suffice here to the hydrogen too low, and take x=I'I and y=1.8, instead state that the sum total of heavy carbides was determined of 1'05 and 2*00 respectively. If we do so we findby absorption with bromine, and that the volume of the

Benzol benzol vapour was identified with the contraction suffered by the gas when shaken with fuming nitric acid.

containing c**'or C26Hą.s2 in 2 vols. Comt'ha Cz26H4.52

. From the numbers just quoted it would appear that the Paris gas, as analysed by Berthelot, has quite an excep- We see that what was put down by Bunsen as so much of tional composition, owing perhaps to an exceptional mode a mixture of C2H4 and C4H8 could not well be assumed to of manufaäure. This, however, is not the view which have contained much above 17 per cent of benzol. Berthelot takes of the matter. He does not hesitate to No doubt if we went to the trouble of re-calculating, in extend his results as applying substantially to illuminating a similar manner, the coal-gas analyses executed after gas in general, these results, he says, being in perfect ac- Bunsen's method by Frankland, Landolt, &c., we should cordance with what he had found out long ago regarding arrive at similar results. I prefer passing now to a series the pyrogenic relations of carburetted hydrogens.

of experiments which I made for ascertaining to what Now it so happened that at the time when Berthelot's extent Berthelot's views hold with regard to Glasgow memoir reached me I was just engaged in collecting ma

coal-gas. terials and apparatus for investigating, by synthetical The first experiment I made was to pass a current of methods, into the extent to which the several constituents the gas through a long column of nitric acid, of 1.5 sp.gr., of a coal-gas contribute to its illuminating power: I ac- into a glass gas-holder, and then to compare the illumi. cordingly read Berthelot's paper with the greatest possible nating power of the product with that of the original gas, interest, and at once decided upon looking into the a " fish-tail" burner being used in both cases. The flame matter.

of the de-benzolated gas was only very feebly luminous, I will begin by offering some remarks on the manner in which, at the time, I felt inclined to accept as strong eviwhich Berthelot tries to account for the fact that all pre- dence of the absence in the gas of any considerable quanvious coal-gas analysts, instead of his few per milles, tity of olefines; but not feeling quite sure on this point I invariably found large percentages-sometimes as much tried some experiments on the luminosity of synthetically as 10 per cent, and even more-of olefines. Berthelot's prepared mixtures of hydrogen and ethylen. To my surexplanation is this :-Until now analysts (in attempting to prise I found that the addition (to 1 vol. of C2H4) of only determine the composition of their olefines) have entirely 3 vols. of hydrogen sufficed to bring down the luminosity relied on the eudiometric method of combustion, and "la to about the level of marsh-gas, while a 10 per cent traduction de leurs resultats par les noms de est ethylen flame was no more luminous than that of a absolument erronée comme repasant sur un simple jeu Bunsen's lamp! On the other hand, a mixture of benzol. d'equations algèbriques, calculées dans l'hypothèse de zapour and hydrogen, which (by combustion of a measured certaines inconnues qui ne sont pas conformes à la realité." volume with oxide of copper) had been proved to contain Now this, I think, is putting it rather strongly. It is quite | 3 per cent of benzol-vapour (equal in carbon to only 9 per true that gas analysts hitherto have not always kept quite cent of C2H4), was found to give a brilliantly luninous alive to the obvious proposition that the combustion of a flame. gas cannot by any means give us more than the quantita- These results render it highly probable that the lighttive elementary composition of the unit volume, and that value of a coal-gas depends far more on the proportion of consequently the reporting of so-and-so many per cents of benzol than on the proportion of olefines contained in it. ethylen, butylen, &c., is nothing more than a rather This, however, has nothing to do with the question on clumsy modus of stating the volumes of carbon-vapour hand. More nearly related to it is an observation which and hydrogen in the part condensable by bromine or by I made incidentally in preparations of benzolated hydrofuming oil of vitriol. But is it possible to assume that gen. The 3 per cent gas above referred to had been made in the many coal-gas analyses which have been published by passing hydrogen slowly through a bulb apparatus by Bunsen, Landolt, Frankland, and others, the numbers charged with benzol, and kept at about 18° C. From the which to these chemists served as a basis for their calcu- bulb apparatus the gas was made to bubble up through lations should have been so entirely wrong as to enable water into a gas-holder. Now, according to Regnault's them to turn into CnH2n what in reality consisted mainly tension determinations, the gas should have contained of C6H6 ?

about 10 per cent of benzol-vapour, and yet it contained Let us look at an example. Bunsen, in his “Gasome-only 3 per cent. I could not explain this otherwise than tric Methods,” gives all the details of a complete analysis by supposing that the greater part of the vapour originally of a sample of Manchester coal-gas, in which his "ethy- present had been dissolved out by the water in the gasolen” and “ ditetryl" (C4H8) were calculated from the meter. To test this hypothesis a quantity of benzolated following data:—(After removal of H2S and CO2) 11'i vols. hydrogen, kept over mercury, and proved by combustion of tho gas gave up to suming oil of vitriol 0'747 vol. To to contain 6 per cent of C6H6, was shaken with water determine the carbon and hydrogen in this 0.747 vol. and again analysed. The percentage of benzol-vapour two combustions were made, viz., one of the original gas, was reduced to less than 2. and, secondly, one of the part not condensable by Sozi After these experiences I felt convinced that, although and from the result it appeared that the “olefines,” is coal-gas as it comes out of the retort cannot help conburned by themselves, would have given

taining a considerable proportion of benzol, only very

little of this vapour will survive the subsequent processes A contraction of 10747 vols.

of purification. And having previously found that Glasgow CO2 2.089

gas when shaken with bromine contracts about 10 per Now these numbers show that, whatever may have been cent, I had no doubt in my mind that the greater part of its proximate composition, the elementary composition of this contraction must be owing to olefines. the “ olefine was CrosH2 = say o‘75 vol. (which is

Wishing to determine the exact ratio in the gas between

the benzol and the olefines, I tried very hard to find out a near enough), and, neglecting the small excess in the carbon, we see that these numbers agree with the hypothesis but I did not succeed. That nitric acid of 1'5 is not the

quantitative method for their separation from each other; that the absorbed gas consisted of

proper reagent for the purpose a few experiments were CzH6=2 vols of propylen, and

sufficient to show-some made with pure ethylen, others C2H4= 1 vol. of ethylen.

with synthetically prepared mixtures of this gas with ben.

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