272

The Different Aniline-Blacks.

CHEMICAL NEWS;
June 20, 1879.

acid) to 185° to 190° for such a length of time, till it forms, And that of nitro-benzene on a mixture of aniline and after cooling a dull yellowish, bronze-coloured, brittle toluydin— substance.

At that state most of the aniline is converted into

Aniline.

Toluydin.

Nitro-benzene.

violanilin, which is obtained pure by neutralisation of the (C6H5NH2) + (C6H4-CH3-NH2)+{ C6H5-NO2}

arsenious and arsenic acid in the melt with caustic soda, driving off the un-converted aniline by a current of steam, separation of the melted violanilin base from the water (formed by condensation of steam), powdering, and drying it. This base is converted with aniline and acetic acid into the spirit-soluble indulin or its base (as described above), which is made soluble with oil of vitriol, similarly as the indulin base from magenta refuse.

Violanilin is also produced by the action of arsenic acid on aniline hydrochloride, or other suitable salts of pure aniline; further, by the action of pure nitro-benzene on pure aniline alone, or mixed with aniline salt, and in general by the action of suitable oxidising or dehydrogenating substances on pure aniline or suitable aniline salts at a temperature of 185° to 190°. Also, for example, by a current of chlorine gas into aniline at 180° to 190°, and then, on the same principle, with a mixture of nitrate of aniline with aniline salt, or by a mixture of nitrate of soda with aniline salt in excess, and so on.

Of course in all these processes some other substances besides violanilin are coming forth, but the latter will be the principal one if the operation is conducted very carefully, and the temperature of forming violanilin does not rise higher than 190°. Above that temperature other decompositions take place, and by-products will be formed to a great extent-as, for example, triphenylen-diaminblue, &c.-but which to take into consideration would complicate this paper to an enormous extent. Therefore I will only treat on the principal substances formed in the largest proportions by these processes, under the supposi tion that they are carefully conducted.

As an explanation of the chemical reactions going on in the processes above described I give the following:Violanilin is the product of elimination of hydrogen from pure aniline, and simultaneous condensation.

Mauvanilin is the product of elimination of hydrogen and simultaneous condensation of a mixture of two molecules.of aniline and one molecule of toluydin. Both these reactions are represented in the following:3 aniline 6 hydrogen violanilin.

H

Mauvanilin + water.

H

CH2-C6H4-N-C6H4

=

= 3(H2O)

C6H4

N-N

H H

=

Even a

If there is no hydrochloride of aniline, or of the mixture of aniline and toluydin, and no free aniline or toluydin to be acted upon, then the process must be watched very carefully, and by all means be kept below 190°, else a large quantity of by-products is formed, much easier than in the same process without hydrochloric acid. sudden reaction (especially on a large scale) may take place, producing a rise of temperature by itself up to 140° at once, and forming a large quantity of several byproducts. Therefore, if the temperature should rise above 190° the mixture should be cooled down by a thin stream of water whilst agitated, and by these means the temperature should be kept within the limits given above.

The conversion of violanilin with or without mauvanilin

into spirit-soluble indulin is caused by the substitution of one, two, or three hydrogen atoms in the violanilin appendant by phenyl.

If acetate of violanilin with or without mauvanilin is heated with aniline for blue to 140° to 160°, then ammonia is formed, and the above-named substitution takes place, producing in the first instance the mono-phenyl-violanilin

In the second stage of the process diphenyl-violanilin is formed

2 aniline+violanilin = diphenyl-violanilin + 2 ammonia.

H

C6H4-N-C6H4

2 {C6H5NH2}+

If that process is carried on so far till the formation of ammonia ceases, then a complete substitution of the hydrogens in the appendants has taken place, and triphenyl-violanilin has been formed.

C6

C6H4-N-N-C6H5
C6H5 H

By the treatment of these bases and their salts with oil of vitriol, as described above, the four conjugated acids and their salts may be produced.

Sodium triphenyl-violanilin-mono-sulphonate

SO3NaC6H4

C6114-N-C6H4

C6H4-N-N-C6H5

C6H5

hydrochloric acid. After it is dissolved water is added slowly under agitation to five times the weight of glycerin, by which means a solution is obtained which can be used for dyeing. But all solutions of spirit-soluble indulin have the disadvantage that the indulin separates quickly in the bath, rendering the dyed shades uneven.

The water-soluble indulins are dissolved in warm water, and the solution given in the luke-warm acidulated bath where the goods had been immersed before, and then the bath is heated nearly up to the boiling-point, and kept there till the desired shades are produced. The watersoluble indulins dye good shades of light and dark greys, even approaching black, which shade to reach fully offers some difficulties, so that they are scarcely used for blackdyeing on a large scale; besides, the black, when reached, is of a dull and inferior shade, and only slightly resists light, air, and soap. (To be continued.)

ELECTRIC LIGHTING.

THE Report of the Select Committee of the House of
Commons on Electric Lighting was issued June 18th.
It is as follows:-

The general nature of the electric light has been well explained in the evidence of Prof. Tyndall, Sir William Thomson, Dr. Siemens, Dr. Hopkinson, and others. It is an evolution of scientific discovery which has been in active progress during the whole of this century. Essentially the electric light is produced by the transformation of energy either through chemical or mechanical means. The energy may be derived from a natural force, as, for instance, a waterfall, or through combustion of a material in the cells of a voltaic battery, or of fuel in a furnace. The energy being converted into an electric current, may be used to manifest electric light by passing between carbon points, or by rendering incandescent solid bodies, such as iridium. A remarkable feature of the electric light is, that it produces a transformation of energy in a singularly complete manner. Thus the energy of onehorse power may be converted into gaslight, and yields a luminosity equal to 12-candle power. But the same amount of energy transformed into electric light produces 1600-candle power. It is not therefore surprising that while many practical witnesses see serious difficulties in the speedy adaptation of the electric light to useful purposes of illumination, the scientific witnesses see in this economy of force the means of great industrial development, and believe that in the future it is destined to take And also the tri- and tetra-sulphonates. And, of course, a leading part in public and private illumination. There besides these the corresponding sulphonates of the accom- is one point on which all witnesses concurred, that its use panying compounds are formed simultaneously. The would produce little of that vitiated air which is largely mono-sulphonic acids are insoluble in water, but their formed by the products of combustion of ordinary illualkali salts are easily soluble. The disulphonic acids are minants. only sparingly, but their alkali salts are easily, soluble.

Sodium triphenyl-violanilin-disulphonate

SO3NaC6H4

C6H4-N-C6H4

C6H4-N-N-C6H5

SO2NaC6N

The tri- and tetra-sulphonic acids, and their salts of the phenylated viol- and mauvanilins, are soluble in water, the last the most, and these form the principal constituents of the commercial water-soluble indulins, sometimes containing some of the nigrosin sulphonic acids or their salts.

The properties of the spirit- and water-soluble indulins are very nearly like those of the aniline-blues, and their constitutional formulæ are also much alike.

The spirit-soluble indulin dyes wool, silk, cotton, and other fibres grey in various shades, whilst it is difficult to dye black shades with. It is dissolved in acidulated alcohol (or methylated spirit) by boiling. The filtered solution is added to the acidulated cold bath, in which the goods to be dyed are immersed, and which is heated up slowly to the boiling-point, and kept there till the desired shade is reached.

The spirit-soluble indulin dissolves at about 115° in 2 to 3 parts of its weight of glycerin containing 5 per cen.

Scientific witnesses also considered that in the future the electric current might be extensively used to transmit power as well as light to considerable distances, so that the power applied to mechanical purposes during the day might be made available for light during the night. The Committee only mention these opinions as showing the importance of allowing full development to a practical application of electricity, which is believed by competent witnesses to have future important bearings on industry.

So far as the practical application of the electric light has already gone, there seems to be no reason to doubt that it has established itself for lighthouse illumination, and is fitted to illumine large symmetrical places, such as squares, publie halls, railway stations, and workshops. It is used in Paris for lighting shops which require a light by which different colours may be distinguished, and has recently been used in England for the same purpose with satisfactory results. Many trials have been made for street illumination with greater or less success.

274

Sensitiveness of Electric Discharges in Vacuum Tubes.

Compared with gas, the economy for equal illumination does not yet appear to be conclusively established. Although in some cases the relative economy for equal candle power is on the side of the electric light, yet in other cases gas illumination of equal intensity has the advantage. Unquestionably the electric light has not made that progress which would enable it in its present condition to enter into general competition with gas for the ordinary purposes of domestic supply. In large establishments the motors necessary to produce the electric light may be readily provided, but, so far as we have received evidence, no system of central origin and distribution suitable to houses of moderate size has hitherto been established.

In considering how far the Legislature should intervene in the present condition of electric lighting, the Committee would observe, generally, that in a system which is developing with remarkable rapidity it would be lamentable if there were any legislative restrictions calculated to interfere with that development. The Committee. however, are not in a position to make recommendations for conditions which may hereafter arise, but at present do not exist, as to the distribution of electric currents for lighting private houses from a central source of power. No legislative powers are required to enable large establishments, such as theatres, halls, or workshops, to generate electricity for their own use.

If corporations and other local authorities have not power under existing statutes to take up streets and lay wires for street lighting and other public uses of the electric light, your Committee think that ample power should be given them for this purpose. There seems to be some conflict of evidence as to whether the existing powers are sufficient or not. But even in regard to local authorities it would be necessary to impose restrictions upon placing the wires too near the telegraph wires used by the Post Office, as the transmitting power of the latter would be injuriously affected by the too close proximity of the powerful electric currents needed for producing light. Gas companies, in the opinion of the Committee, have no special claim to be considered as the future distributors of electric light. They possess no monopoly of lighting public streets or private houses beyond that which is given to them by their power of laying pipes in streets. Electric light committed to their care might have a slow development. Besides, though gas companies are likely to benefit by the supply of gas to gas-engines which are well suited as machines for producing electric light, the general processes of gas manufacture and supply are quite unlike those needed for the production of electricity as a motor or illuminant.

The Committee, however, do not consider that the time has yet arrived to give general powers to private electric companies to break up the streets, unless by consent of the local authorities. It is, however, desirable that local authorities should have power to give facilities to companies or private individuals to conduct experiments. When the progress of invention brings a demand for facilities to transmit electricity as a source of power and light from a common centre for manufacturing and domestic purposes, then, no doubt, the public must receive compensation advantages for a monoply of the use of the streets. As the time for this has not arrived, the Committee do not enter into this subject further in detail than to say that in such a case it might be expedient to give to the municipal authority a preference during a limited period to control the distribution and use of the electric light, and failing their acceptance of such a preference, that any monoply given to a private company should be restricted to the short period required to remunerate them for the undertaking, with a reversionary right in the municipal authority to purchase the plant and machinery on easy terms. But at the present time the Committee do not consider that any further specific recommendation is necessary than that the local authorities

CHEMICAL NEWS,
June 20, 1879.

should have full powers to use the electric light for purposes of public illumination, and that the Legislature should show its willingness, when the demand arises, to give all reasonable powers for the full development of electricity as a source of power and light.

PROCEEDINGS OF SOCIETIES.

PHYSICAL SOCIETY.
Ordinary Meeting, June 14, 1879.

Prof. W. G. ADAMS, President, in the Chair.

NEw members:-Mr. Donald Macalister, B.A., and Mr.
St. George Lane Fox.

Prof. MACLEOD described a plan for Suppressing the Induction Disturbances in a Telephone Circuit. It is known that a secondary battery, composed of metal plates and sulphuric acid, allows weak currents to pass while stopping those of high tension. Prof. Macleod therefore inserted a secondary battery of platinum plates between the line and the telephone, but this stopped both the induction and the vocal currents. When platinum wires were substituted for the plates, however, the induction currents were stopped, while the vocal currents could be feebly heard.

Dr. O. J. LODGE exhibited his New Reversing Key for Electrometer Work, which is preferable to the ordinary forms, as giving a high insulation, small capacity, and not requiring the hand to approach close to it to work it. It consists of four platinum wires, arranged in pairs crossing one another; one pair crossing between the other two. These are the terminals and contact pieces of the key. The middle pair are supported by an endless silk thread, which runs on two pulleys, one of which is fitted with a handle. On turning the handle to right or left the two middle wires are brought into contact with one or other of the two outer wires, and the current reversed at will. The whole is enclosed in a metal box.

Mr. J. F. MOULTON then demonstrated the results of the experiments of Mr. Spottiswoode and himself on the Sensitiveness of Electric Discharges in Vacuum Tubes. These experiments were undertaken to find the cause of the luminous layers or strata in the discharge, a Holtz machine being employed. It was observed that when feeble currents were drawn from the machine, the discharge could be depressed by laying the finger on the tube, and this depression always occurs with intermittent currents; therefore the feeble currents from a continuous current Holtz discharge themselves like intermittent currents by reason of their feebleness. This sensitiveness. of the discharge to the approach of the finger was found to be due to the conductivity and electric capacity of the hand. Electricity, opposite in kind to the discharge, is induced on the finger, and streaming upon the tube neutralises part of the discharge therein. This effect was also shown by means of tinfoil rings round the tube. An intermittent current is of course capable of this static induction on neighbouring conductors. The luminous discharge in a vacuum tube consists of a bright sharp glow at the negative terminal, followed by a dark space, then a hazy bluish light at the positive pole. The striæ or layers in these sensitive tubes merely repeat this appearance. They can be artificially produced by placing the fingers, or rings of metal, at intervals along a tube conveying an amorphous discharge; for in this case the induced electricity discharging itself from the fingers breaks up the amorphous discharge into dark and bright layers. In these stratified discharges the electricity appears to travel per saltum, or by stepping stones, as one may say, and the glow seems to be a molecular structure, a view which is supported by Mr. Crookes's

experiments. A negative discharge from the finger pro- | duces a dark space in the tube discharge, and a positive one a bright line; therefore, one can tell the kind of discharge passing in a tube by laying a finger on it. If the same pole be brought to both ends of a tube a discharge will still take place from each end, and there will be a dark space in the middle; the electricity here seeming to turn back again the way it came. The discharge from a pole through a vacuum tube would therefore appear to be not akin to conduction but to a disruptive discharge. It is a leap in the dark, and the phenomena observed are due to the gaseous nature of the medium. These experiments point to the possibility of completing a circuit by positive electricity alone.

Prof. GUTHRIE suggested that by combining vacuum tubes with the induction balance of Prof. Hughes it might be possible to get an optical balance for measuring inductive capacity.

Dr. HENRY DRAPER, of New York, who is now on a visit to England, then addressed the meeting on his alleged discovery of oxygen in the sun by bright lines in the solar spectrum. He said that hitherto he had not been able to find these lines projecting from the limb of the sun like hydrogen, and his impression is that oxygen resides lower than the reversing layer. He had lately been extending the dispersion of the spectrum of terrestrial oxygen, and from a light of maximum intensity of one candle power had now got a dispersion of 80 inches from A to O. He exhibited two of the original negatives of the solar spectrum, showing the bright lines.

Mr. J. NORMAN LOCKYER Congratulated solar science on having so able a worker as Dr. Draper, and remarked that if Dr. Draper proved his case for even two or three O lines it would be sufficient, considering the variability of the spectrum of matter under different physical conditions. He also alluded to traces of carbon which he himself had found in the sun by the dark flutings in the spectrum.

Dr. DRAPER said he did not see why carbon should not give both bright and dark lines.

Mr. SCOTT exhibited a number of coloured photographs done after the method of Mr. Albert, of Münich.

NOTICES OF BOOKS.

A Manual of Organic Chemistry. By HUGH CLEMENTS, of H.M. Civil Service, President of the Amateur Mechanics' Workshops Association, London, and Lecturer on Various Sciences at St. Thomas', Charterhouse, &c. Blackie and Son: London, Glasgow, Edinburgh, and Dublin, 1879.

THE difficulties of an examiner in setting questions, which shall fairly test the real knowledge of a candidate, have of late years considerably increased owing to the large number of text-books "adapted " to examinations which have been published, and serve merely to "cram" the candidate for the time being, with little or no regard to sound instruction. This is especially the case in respect to the examinations of the Science and Art Department. In a great measure, it is true, this is the fault of the system which makes the teacher dependent for his remuneration on the passing capabilities of his students, and therefore necessitates the use of those text-books which are best adapted for getting his men "through." Such a book is the volume before us, forming one of a large class which has come into being with the rapid mushroom growth of the system of competitive examination.

A feature in this Manual which cannot be too strongly condemned is the publication at the end of the book of a series of short answers to all the questions set in Organic Chemistry by the Examiners in the Science and Art Department during the last ten years. This

occupies no less than one-third of the whole volume. A student, therefore, who learns by rote a good selection of these answers runs a fair chance of passing, though his real knowledge may be of the most fragmentary and imperfect kind. As practical examinations are to a certain extent free from the objection which applies to written examinations, it is to be hoped that in the future much greater stress will be laid on practical work than has hitherto been the case. In the meantime it is highly satisfactory to know that the Department is alive to this necessity, and to find that a large percentage of the candidates in practical chemistry at these examinations send up very creditable results, showing that at many science schools a really sound knowledge of chemical analysis is being imparted.

As regards the book itself it is difficult to imagine how anyone who professes to be a teacher and to have experience enough to write a text-book on the subject could employ the arrangement adopted by the author. In many cases compounds are classed together which have little or no connection with one another; thus, under the heading of hydrides of organic radicals we have in the following order: Hydrocarbons, cyanogen, oxalic acid, oxamic acid, oxamide, hydrocyanic acid, formic acid, and Prussian blue; whilst among organic bases we have cyanic acid. Nor is his plan of describing the apparatus employed in organic analysis, &c., to be recommended. This he does in a final chapter quite apart from the description of the processes themselves. Space also is here wasted unnecessarily in giving a figure of an ordinary "specimen tube" for weighing out the substance for analysis, as well as by drawings of two retorts, the difference between which it is impossible to see, except that in the one the neck is turned to the left and in the other to the right. The notation is exceedingly loose and defective, different symbols for the same or an analogous radical being frequently used indiscriminately, even in the same compound or equation, thus

C2H OMeOHO+KHO=CH2Ho+C2H2OKOHO. But one of the greatest defects in the book is the almost total neglect of the use of structural formulæ, without which a sound knowledge of organic chemistry can never be obtained by the ordinary student. In many even fundamental points the book is also very imperfect. General reactions are not made sufficiently prominent, and no explanation is given of isomerism and polymerism, nor of the difference between empirical and rational formulæ. To the glycols and their derivatives five lines only are devoted, whilst no special reference is made to identification of glycerin. The relations of the various glycerin, erythrite, mannite, &c., except as regards the organic acids to one another and to other compounds are by no means sufficiently insisted on, nor is any evident distinction made between primary, secondary, and tertiary alcohols, nor between the different behaviour of aldehyds and ketones on oxidation. The important series of aromatic compounds are passed over far too cursorily, no reference at all being made to the ortho-, para-, and metapositions of the side chains in the derivatives of benzol, &c. Anthracen, naphthalen, and all the other important hydrocarbons and their derivatives, containing more than one benzol nucleus, are omitted altogether, except the identification of naphthalen.

But it is in the series of exercises given at the end of the book that the author shows his want of proper chemical training, or he would not set such childish questions as the following, in which and in many others he has evidently tried in how many different ways he could vary the same question:- -"What organic substances are soluble in water?" "What insoluble in water?" "Which are soluble in alcohol?" "Which insoluble

in alcohol?" "Which partly soluble in alcohol?" "Which insoluble in water but soluble in hot alcohol?" and so on, through quite a long string of such questions on solubilities. Then follows a long series of similar questions on the taste of organic substances, including

میرا

Chemical Notices from Foreign Sources.

To the Editor of the Chemical News.
SIR, In the last number of the Chemical Society's Journal
there is the description of a process for determining chro-
mium, based on the oxidation of chromium oxide by potas-—I
sium permanganate in presence of sulphuric acid, also
described in the CHEMICAL NEWS, vol. xxxix., p. 131. May
I refer the author (Mr. Sell) to the CHEMICAL NEWS,
vol. xxv., p. 151, in which I have described the same
process for the determination of chromium in chrome iron
and steel? The process as described there is in daily use,
and gives thoroughly reliable results.-I am, &c.,