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202

New Class of Colouring Matters.

solution are carefully measured into the 20-oz. beaker already used; the filter with its washed contents added. A certain quantity of the ferrous sulphate is oxidised by the MnO2; this quantity is estimated with the standard dichromate solution, when the quantity of MnO2 can easily be calculated. The iron present must be at least equal in weight to the manganese during the precipitation in order to ensure the absence of lower oxides. The author gives in detail the slight modifications necessary in the analysis of spiegeleisen, ferro-manganese steel, and manganese slags; also some analyses which prove the accuracy of the process.

Dr. WRIGHT was extremely interested in the paper, especially as to the action of the ferric chloride. He asked if Mr. Pattinson had found any substances which acted in the opposite way, i.e., decreased the yield of MnO2.

Mr. PATTINSON said that all his efforts had been directed to ensure the complete formation of MnO2.

The PRESIDENT then called on Mr. WARINGTON to read a paper "On the Determination of Nitric Acid as Nitric

CHEMICAL NEWS.
May 9, 1879.

The PRESIDENT called on Dr. O. N. WITT to read a paper "On a New Class of Colouring Matters." This is the first part of a series on the simultaneous gradual oxidation of amido and methyl groups. If a mixture of metatoluylen-diamin and dimethyl-para-phenylen-diamin be oxidised in aqueous solution, or if the formation of the latter of these bases from nitroso-dimethyl-aniline be combined with this oxidation process, by acting upon metatolulylen-diamin with nitroso-dimethyl-anilin, the reaction results in either case in the formation of a new compound of an intense blue colour, for which the author proposes the name of toluylen blue, C15H18N4HCI+H20. It is the neutral salt of a new triatomic base, the acid salts being reddish brown. If treated with reducing agents it absorbs 2 atoms of hydrogen, forming a new colourless base, having the constitutional formula

(NH2)-C6H3CH2-N-C6H4N(CH3)21
H

and the formula of the blue is—

(NH2)2-C6H3-CH=N-C6H4N(CH3)2.

This compound may be considered as the first representa-
tive of a new class of colouring matters, which have the
group-
-C-N

H

stitution, a connecting link between the rosanilin and the
as a chromophor, and form, from their properties and con-
azo series, the chromophor of the former being-
H

and of the latter

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One of the most remarkable properties of toluylen blue is its power of absorbing hydrogen from other amines, and being reduced to its leuko-compound, the amine undergoing condensation similar to that effected by oxidising agents and invariably resulting in the formation of new colours. Thus the blue, by acting on another molecule of itself produces toluylen pink, C15H16N4, a crystallised compound forming two series of salts, one pink the other blue. By acting with toluylen blue on meta-toluylendiamin for twelve hours at 35° toluylen violet is obtained, C14H14N4. This new compound dissolves sparingly in alcohol and ether with a pink colour, exhibiting a most brilliant fluorescence; it forms two series of salts, one violet the other green. The constitutional formula of toluylen pink is—

Oxide by means of its Action on Mercury." During the
last two years the author has used this method to a con-
siderable extent: it was first suggested by W. Crum, and
has been much improved by Frankland. The author has
in the main carried out the process as recommended by
Thorp in Sutton's "Volumetric Analysis." He did not,
however, expel any gas which might be liberated before
shaking. In the presence of some kinds of organic matter
a permanent froth was at some times produced. This
could be destroyed either by the introduction of a little hot
water through the stopcock, or by gently warming the
liquid in the inclined tube by a small flame. A consider-
able number of experiments are given as to the effect of
chlorides on the accuracy of the results obtained in esti-
mating nitrates, nitrites, and the nitric acid in soils. The
author finds that the results are quite as satisfactory, even
when chlorine is present in a quantity equal to eight times
the equivalent of the nitrogen, and concludes that chlorides,
except perhaps in extreme cases, are no hindrance to the
accurate determination of nitric and nitrous acid by this
method, and that it is unnecessary to remove them by
previous treatment with sulphate of silver. The author
then investigated the influence of organic matter, and finds
that organic matter in quantities likely to be met with
affect the results but little; cane-sugar, however, has a
remarkable action in preventing the complete evolution of
the nitric oxide. In some cases a considerable quantity of
gas was evolved, without shaking; this gas was found to
be nitric oxide, the action taking place between the
nitric acid and organic matter instead of between nitric
acid and mercury.
It is obvious that a considerable error
would be caused by expelling any gas liberated before
shaking in such cases. Commercial glucose has a con-
siderably less injurious effect than cane-sugar. It is inter-
esting to observe that chlorides, if present, seem to pre-
vent to a great extent the injurious effect of cane-sugar.
Thus, a solution containing 20.8 parts of nitrogen gave by and of the violet-
the process, after removing chlorides, 12.6 and 115, but
with chlorides not removed, 18.5. In some cases the
author has observed that the reaction is not completed in
the shaking-tube, but that bubbles of gas continue to be
evolved when the liquid was transferred to the measuring-
tube; the reason of this defective reaction was not dis-
covered. The author draws the following conclusions:-
That in the absence of organic matter, and with proper
manipulation, the method is one of great accuracy, and is
capable of determining extremely small quantities of ni-
trates and nitrites; the natural error of the process is a
small one of deficiency; the presence of chlorides in mo.
derate quantity is no hindrance; quantities of organic
matter, small in relation to the nitrates present, have little
or no effect on the results; larger quantities, especially of
cane-sugar, may cause a considerable deficiency; this
deficiency is reduced by the presence of chlorides, but is
not entirely removed.

After a few remarks by Dr. GILbert,

NH

CH3

NHẠC H C - N-CHỌN CH

NH

NH,CH3 |

=

1

CH3
C=N-C6H3NH2

The general conclusions which may be drawn are that under the above circumstances a gradual dehydrogenisation of the amido- and the methyl-groups takes place, the quantities of hydrogen removed from both sources being always the same; that in a great many cases the use of oxidising agents may be avoided by using the corresponding nitroso-compounds, or by utilising the tendency of some organic compounds for the absorption of hydrogen. The author promises further investigations in the same direction. Specimens of the above new and beautiful colouring-matters were exhibited by the author.

The Society then adjourned to May 15, when the following papers will be read :-"On Nitrification," Part II., by R. Warington; "On Alkaloids of the Veratrums,"

Part III., by Dr. Wright and Mr. Luff; "On Alkaloids of | tions of the substituted radicles in benzene-derivatives is the Veratrums," Part IV., by Dr. Wright; "Alkaloids of the Aconites (Part IV.), and on Japanese Aconite Roots," by Dr. Wright and Mr. Luff; "On the Action of Hydrochloric Acid on Manganese Dioxide," by Spencer Pickering; "The Composition of Milk in Health and Disease", by A. Wynter Blyth; "Notes on the Effect of Alcohol on the Chemistry of Digestion," by W. H. Watson.

NOTICES OF BOOKS.

A Dictionary of Chemistry, and the Allied Branches of other Sciences. By HENRY WATTS, F.R.S., F.C.S., Editor of the Journal of the Chemical Society; assisted by Eminent Contributors. Third Supplement, Part I. Longmans and Co., 1879.

fully discussed, the views of Körner, Graebe, and others being given. The constitution and structure of the various mono-, di-, tri-, and tetra-bromo-benzene, as well as of their nitro- and chloro-congeners, are also thoroughly investigated. This article likewise contains an account of the iodo-, bromo-, and chloro-derivatives of aniline, the amido-benzenes, and the azo-benzenes. A useful table is given of the abbreviated symbol, the physical properties and positions of the substituted radicles of more than 120 ortho-, meta-, and para-benzene derivatives. The next part of this article treats of benzene-sulphonic acid and its numerous derivatives, and gives a table of the physical properties of its principal ortho-, meta-, and parasalts. A number of other tables are also given of the chemical and physical properties of the derivatives of benzene-meta-disulphonic acid and of those of the bromamido-benzene-disulphonic acid. Benzoic acid and its numerous derivatives are next treated of, the newest methods of making ortho-oxy-benzoic acid or salicylic acid being fully described, Directions are added for the purification, detection, and estimation of this now important compound. The next important articles are those on the inorganic and organic compounds of boron. Under Casium we have Godeffroy's method of separating cæsium, rubidium, and potassium by preparing their alums and separating them by fractional crystallisation according to the process originally devised by Redtenbacher. The Cerite group of metals also receives ample treatment, a large number of their principal salts being fully described. The article on Chemical Action is an important one from a philosophical point of view, the velocity of chemical action, the retardation of chemical reactions by indifferent substances, the decomposition of certain salts by water, the mutual replacement of halogen elements, and other similar questions being discussed at great length. Chloral and its compounds have 8 pages devoted to them, while cinchona barks, bases, and compounds take up 26 pages. Cinnamic and citric derivatives also receive their full share of attention. Thomas's researches on the gases enclosed in the coal of the South Wales basin are given nearly in full under Coal. Cumulative Resolution is a highly philosophical article from the pen of Dr. Mills. The other important articles are on Flame, by Professor Thorpe; Forest Trees, by Professor Warington; on the Diphenyl Derivatives, which have nearly 30 pages given to them; Dye Stuffs, Electricity, Electro-capillarity, Ethyl Derivatives, Fermentation, Fulminates, and Fulminurates.

THIS is the third supplementary volume of "Watts's
Dictionary" which has been issued since the completion
of the body of that work, and brings the record of che-
mical discovery down to the end of the year 1877, in-
cluding some of the more important discoveries which
have appeared in 1878. The volume, which begins with
"Absinthol" and ends with "Fustic," comprises only
one-quarter of the letters of the alphabet; we do not see,
therefore, how the other three-quarters can be compressed
into the single volume mentioned in the Preface. It is
true that the articles on those very fruitful bodies the
benzo-compounds take up no less than one-fifth of the
part, but, notwithstanding this, if the remainder of the
alphabet is to be squeezed into a single volume, it will
have to be a very bulky one, or else an injurious amount
of compression will have to be exercised. The first im-
portant article we meet with is on Aniline Colours, which
gives the best method of testing their tinctorial power by
an accurately titrated solution of sodic hyposulphite.
We also have accounts of the formation of aniline-black
by the action of vanadic salts and by electrolysis; also of
its composition and probable formula. The article also
treats of aniline-green, grey, and red. Anthracen very
naturally claims a large amount of attention, the newest
views as to its molecular constitution being given at
length. Its latest derivatives and its isomerides are then
described, as well as its fluorescent properties. Under
Anthraquinon we have a full account of the most recently
discovered derivatives of that prolific body, and of the
formation of artificial alizarin from pyrocatechin. Under
this heading are also described quinizarin, purpuroxanthin,
the anthroflavic acids, the anthroflavons, chrysazin,
purpurin, anthrapurpurin, flavo-purpurin, oxy-chrysazin,
and rufiopin. Under Arsenic the continuation of Nilsson's
classical researches on the compounds of that metal are
described, more especially those on its sulphur salts. In
the article Atmosphere we have the most recent deter-
minations of the amount of carbon dioxide, ammonia,
hydrogen peroxide, and dust in the air by various ob-
servers. A few pages further on we have an exhaustive
article on barley, from Mr. R. Warington, the most recent
results obtained by Messrs. Lawes and Gilbert being fully
described. Under Beer we have full directions for the
detection of foreign bitters in that beverage, from which
we learn that brewers use nearly thirty different "hop-
substitutes," more or less poisonous, from strychnine and
brucine to gentian and wormwood. Benzacetic acid in-
troduces us to the benzo-compounds, to which no less
than 167 pages are devoted. It is strikingly indicative of
the progress of research in this direction that in the
original work the account of these compounds from their
first discovery onwards only took up 40 pages, while in
the first and second supplements we have 82 and 57 pages
respectively given to these bodies. In these articles the
vexed question of the determination of the relative posi-a

For the second part, which we trust will shortly appear, we are promised contributions by Drs. Armstrong, Roscoe, Thorpe, Flight, and Professors G. C. Foster and R. Warington.

The Chemistry of Common Life. By the late JAMES F. W. JOHNSTON, Professor of Chemistry in the University of Durham, &c. A New Edition, revised and brought down to the present time, by ARTHUR HERBERT CHURCH, M.A. Öxon, &c. Blackwood and Sons, 1879. JUST twenty years have elapsed since that versatile writer the late Mr. G. H. Lewes took up the pen which, so to speak, had fallen from Prof. Johnston's hand some two or three years before, and brought a second edition of a book which, amongst popular scientific works, had already taken its stand by the side of "Liebig's Letters on Chemistry. Prof. Johnston had performed his task so thoroughly that Mr. Lewes's utmost diligence had not been able to glean much after him, although seven years had passed between the appearance of the original and the revised editions. The book had three great meritsit was written in a popular and entertaining style, it was comprehensive in the choice of subjects, and, above all, it was thoroughly exact. It seems, therefore, strange that couple of decades should have been allowed to pass

204

Precipitation of Metallic Copper by Poor Copper Matt.

CHEMICAL NEWS, May 9, 1879.

away between the publication of the second and third editions.

CORRESPONdence.

Mr. Church has executed his task as a pious duty, and has been most careful to respect the method, the style, PRECIPITATION OF METALLIC COPPER BY

and the matter of Prof. Johnston's original, only such corrections and alterations having been made as were rendered necessary by the recent advances made in scientific knowledge. Only very few additions have been made, one of them of notable value, in the form of a chapter on the Colours we Admire, which forms a fitting pendant to the well-known chapters on the Odours we Enjoy. A sketch is given of the origin and properties of hæmaglobin turacin, the cupreous pigment discovered by Mr. Church in the red colouring matter of the wing feathers of some eleven species of the Touraco, the black pigment found in black hair and feathers, chlorophyll, colein, alizarin, and, lastly, of the coal-tar dyes.

In bringing out the third edition of this work Mr. Church possessed an advantage over the late Mr. Lewes, for he had the opportunity of consulting Prof. Johnston's private and corrected copy of the "Chemistry of Common Life," so that he was not only enabled to incorporate in his revisions some valuable matter gathered by the late author, but to learn the kind of additions which he contemplated.

Although appearing in one volume instead of two, as in the case of the first two editions, the present issue contains more matter, the type being smaller and closer and the pages larger.

OBITUARY.

WILLIAM GEORGE VALENTIN, F.C.S. LAST week we stated that a committee had been formed for the purpose of presenting Mr. Valentin with a testimonial in recognition of his long services to chemical science. It is now our painful duty to announce that he died suddenly on the 1st instant from apoplexy. This well-known chemist was born at Neuenburg, in the Black Forest, on the 16th of May, 1829. He came to England in 1855, and in the early days of the College of Chemistry studied under Dr. Hofmann, who esteemed him greatly, and, recognising his ability, made him Senior Assistant in the Laboratory. He retained this position under Dr. Frankland, with whom he organised the new laboratories of the Science Schools, South Kensington. He was also Gas Examiner to the Great Western Gas Company, and Chemical Adviser to the Trinity House. We have in these pages frequently pointed to the merits of his various text-books of practical chemistry, and within the last few days he corrected the final proofs of a new work which will shortly be published. His success as a teacher and his skill as an analyst are so well known that they need not be alluded to further, and at present we can only take this, the earliest, opportunity of expressing the regret that will be so widely felt at his loss. Unfortunately, he leaves a widow and a family without provision, and the labours of the committee to which we referred last week will be continued for their benefit. The Hon. Treasurer is Mr. F. W. Bayley, Royal Mint, E., who will gladly acknowledge any contributions that may be sent to him.

New Reagent for Carbolic Acid.-One to two drops of the liquid should be placed in a porcelain capsule with the addition of 2 or 3 drops of a solution of molybdic acid in 10 parts of sulphuric acid. If carbolic acid is present there is produced immediately a light yellow or yellowish brown colour, which changes to a maroon, and finally to a purple. The solution should be very dilute.-Polyt. Notizblatt.

POOR COPPER MATT.

To the Editor of the Chemical News. SIR,-Having lately read the very interesting paper by Mr. Dixon, on the "Method of Extracting Gold, Silver, and other Metals from Pyrites," which appeared in the CHEMICAL NEWS, I should like to correct one statement made there in reference to the precipitation of metallic copper, from solution of its sulphate, by poor copper matt. In the above paper Mr. Dixon says (CHEMICAL NEWS, vol. xxxviii., p. 303) that:-"Whilst experimenting on the removal of copper from solution I found that this could be conveniently done by filtering the slightly acid solution by ground matt obtained from the same ore by simple melting. This method of separating copper from solution may be of advantage in treating poor copper ores or pyrites containing small quantities of copper:The matt obtained by simply melting poor cupreous pyrites, with the addition of sufficient 1oasted ore to form a flux for the silica present, consists of sulphide of iron containing more or less sulphide of copper; and by filtering through a bed of this matt, the solution of sul. phate of copper obtained by calcining and extracting a large portion of the ore, the copper is deposited, and the iron goes into solution. I expected to find that the whole of the iron could be thus removed from the matt which would be converted into sulphide of copper, but found that in all cases the action stopped short of this. The percentage of copper in the treated matt varied from 30 to 33 per cent, approximating, therefore, to copper pyrites, which contains 346 per cent of copper. From this residue refined copper could be made in three operations." Now, before having read that paper, I had already been making experiments on the same subject to see if it were possible to raise the percentage of copper in poor matt by some simply wet process, in which the use of acids could be avoided, as by calcining poor cupreous pyrites in heaps, by which means large quantities of sulphates of copper and iron would be produced. I found by filtering a solution of sulphate of copper through a bed of matt containing from 13 to 16 per cent copper, smelted in cupola furnaces, that the percentage of copper was nearly doubled, but on examination I found that this was accounted for by the presence of a large quantity of metallic iron which had been reduced in the furnaces, and had been tapped out with the matt. This iron was disseminated through the mass in very minute globules, and was easily extracted from the ground matt by means of a magnet. To make sure that it was only owing to the presence of this metallic iron that precipitation of copper took place I took some. samples of poor matt produced in reverberatory furnaces, and found that no precipitation of copper whatever took place, except in one instance, where o'83 per cent of copper was thrown down by a sample of matt containing 22 per cent copper, and in this case a small quantity of metallic iron was detected by the magnet, which may possibly have been derived from pounding the sample, which was very hard, in a rather soft iron mortar. The following is the result obtained by treating various samples of poor matt containing metallic iron with a sulphate of copper solution.

A saturated solution of cupric sulphate, slightly acidified (as recommended by Mr. Dixon), was filtered through a layer of 1000 grains finely ground matt, placed in a funnel, the neck of which was plugged with asbestos, till no further precipitation of copper took place. The matt was then washed, dried, and the copper estimated.

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No. I. was a mixture of samples from about 250 taps, | the Alkali Makers' Association, asserts that the exit gases and No. II. from above 1200 taps. contain sufficient oxygen to convert the N2O2 into N203'

The analysis of the two samples of matt is as follows:- and therefore that N2O2 is never to be found in exit

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I.

II.

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Sulphides of copper and iron 89'06
Metallic iron

88.69 10'94 11.31

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This proportion is far higher than the results generally obtained by precipitating copper from solution by means of scrap iron, the quantity used in practice ranging from 2 to 4 times the amount required by theory.

The precipitation of copper by the matt was very rapid, owing to the very fine state of division of the metallic

iron. This reduction of iron to the metallic state is one

great drawback to the smelting of poor cupreous pyrites in cupola furnaces, as unless a very strong and hot blast is kept up (in order to run the ore down as rapidly as possible) the iron soon forms and sets below the tuyeres commencing at the back of the furnace and gradually extending till the tap holes are quite choked up with it; the furnace has then to be cooled down and the mass of

iron cut out.

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To the Editor of the Chemical News. SIR, My name occurring so many times in Dr. Hurter's letter (CHEM. NEWS, vol. xxxix., p. 170) calls for remark; but first I would mention that Dr. Hurter spells my name incorrectly in every instance.

gases.

It would be very interesting if those chemists who have observed N2O2 passing in company with oxygen would come forward and state what they have found.

I have a set of experiments going on which may tend to throw some light on the subject of the oxidation of the arsenic. I still maintain that N202 does go away in the exit gases when from 4 to 8 per cent of oxygen is present. This may be only under certain conditions of working, but still I have found it, and so have others.

I never considered that the samples from absorber exits E, F, and G (CHEM. NEWS, vol. xxxvii., p. 157) were satisfactory solutions of the question. E gives more nitre escaping than used; of F I gave no exit tests; and G stated that the chambers were old, much air was drawn in at the last ones, and the amount of nitre unaccounted for was 20 per cent.

Dr. Hurter states that my figures prove that the chemical losses in the chambers are from 10 to 15 per cent. Now I stated distinctly that in samples A, B, C, and D the total unaccounted for was 5 to 9 per cent. This steam is present, but I have no proof of it, neither do I quantity might be decomposed in the chambers where

know any one who has.

Dr. Hurter draws his conclusions on the exit escape of convinced that as long as this is done we shall never nitre from the averages of seven different works. I am arrive at the true cause of all the nitre losses. These losses must be studied in each individual works, and One

where the conditions always remain the same.

works may have an equal number of chambers of a simiwith denitrators and absorbers equal; one may be using lar size with another works, doing the same work, and 1.8 per cent of nitre, and the other 3 per cent; and again, in the same works an even number of chambers may be divided into two sets, and yet one may always consume more nitre than the other, in order to prevent an escape of SO2.

ferred from Mr. E. Jackson's letter (CHEM. NEWS, vol. The difficulties which surround this subject may be inxxxviii., p. 147), in which he states "Thus during the past week the average quantity of nitre found in the exit gases does not exceed 4 lbs. per ton of stone, while about a month ago the quantity found during one week exceeded the quantity used for that week." Since then Mr. Jackson has informed me that during one whole period of six months he could account for all the nitre used, within a small percentage, without reference to any theory of reduction to nitrogen or nitrous oxide. Perhaps the following experiments may be of use to investigators :

1. The acid was issuing from a Glover tower at 150° Tw. cold, and at a temperature of 290° F. containing 0'02 per cent of nitrogen compounds, calculated at N2O3 by the mercury method. A damper was now inserted in the iron pipe (leading the SO2 gas into the tower) having in its centre a 4-inch circular opening, a direct (extra) way being opened for the gases to go direct into the chambers. The small quantity of SO2 which now went up the tower effected no concentration, the acid was perfectly denitrated, the issuing acid was from 90° to 100° F., and no saving of nitre was effected.

At the conclusion of his letter he writes-" It is not, in my opinion, of any service to the manufacturer to put him off his guard, and prevent further search by such statements." Now I wish to point out that at the time of reading my three papers before the members of the Faraday Club, I distinctly stated that the instances E, F, and G (working with towers) were not satisfactory, and I urged the members of the Club to work in this direction. With regard to the oxidation of the arsenious acid by the nitrous anhydride, this reaction was repeatedly tried in the Labor-placed in a very cool part of the flue leading from the atory without success; still, finding nitric oxide in the outlet, and also finding that the arsenious acid was oxidised to arsenic acid in running down the tower, I supposed that as the physical conditions were different the supposed reaction might take place in the tower. When I perceived I might have been mistaken, and that N2O4 might have been the oxidiser, and not N2O3, I wrote the letter (CHEM. NEWS, vol. xxxvii., p. 195).

Dr. Hurter, in his letter already quoted, and also in a statement made to the Noxious Vapours Committee of

2. The nitrous vapours were being boiled off in pots kilns to the chambers (working without towers). The consumption of nitre was 4'2 per cent upon 47 per cent of sulphur. The potting place was changed to a bright redhot portion of the flue; this change caused no more nitre to be used, nor was the colour of the chambers or escape in any way affected. The potting place was again changed to where the active combustion was going on, and this spot was nearly at a white-heat: within a few hours from this change the chambers began to grow pale, hard potting was necessary, more nitre was used for some time-to try

206

Chemical Notices from Foreign Sources.

CHEMICAL NEWS, May 9, 1879.

and bring the colour of their chambers to their normal | CHEMICAL NOTICES FROM FOREIGN conditions-without success, and when the first and original potting place was resumed the nitre went down to its original amount.

3. It is thought by some that the last chambers reduce the N2O4 to NO2 by means of the excess of water present (i. e., the low density of the acid). It was tried to work the last chambers stronger than usual, viz., 136° Tw., to 140° Tw.; the result was a greater use of nitre than before, even taking into consideration the amount absorbed by the acid. This experiment was going on for many months, and during the whole of the time the total acidity of the exit was more regular and lower than when the last chambers were worked weaker.

4. Tests of inlet and outlet of absorbing towers :a=Na2CO3 neutralised by S compounds, grains per

cubic feet.

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Before leaving this subject I wish to point out that Dr. Hurter has applied the most refined methods to the ascertaining of the mechanical losses; he should therefore be able to give us them within 1 or 2 per cent.

I have heard it remarked that Lunge has stated that my process for the estimation of nitrous compounds in nitrous vitriol, by shaking up with mercury and measurement of the nitric oxide, is liable to an error of as much as 10 per cent, on account of my not taking the temperature and pressure into consideration. I have heard that this has been abstracted into the Journal of the Chemical Society, though I have not seen it, therefore it is necessary for me to quote from my paper (CHEM. NEWS, vol. xxxvii., p. 45):-" For technical purposes this volume will be found accurate enough, but in cases where extreme accuracy is required the tube must be left to itself for several hours, the temperature and pressure noted, and the necessary corrections made." -I am, &c.,

Heaton Chapel, Stockport, April 28, 1879.

GEORGE E. DAVIS.

Determination of Nitric Acid Contained in Commercial Lime-Juice.-F. Dotto-Scribani.-The author takes 100 c.c., boils the liquid, and neutralises exactly with baryta water. Citrate of barium is formed and precipitated, whilst barium nitrate remains in solution. The liquid is let cool, the citrate is separated from the nitrate by filtration, and the latter salt is decomposed with sulphuric acid. The barium sulphate obtained is filtered, washed, &c., and weighed with the usual precautions, and on multiplying its weight, less the ash of the filter, by 04635 the quantity of nitric acid present in 100 c.c. of the juice is obtained.-Gazzetta Chemica Italiana.

SOURCES.

NOTE.-All degrees of temperature are Centigrade, unless otherwise expressed.

Bulletin de la Société d'Encouragement pour l'Industrie Nationale.

No. 62, February, 1879.

Report Presented by M. le Compte du Moncel on Behalf of the Committee of Economical Arts on M. E. Reynier's Electric Light Regulator.-The committee decide that M. Reynier has solved the problem in question. His arrangement has been successfully tried at the station of the Northern railway and in M. Breguet's work-shop, where it has acted for some hours with regularity under the influence of the current of a small Gramme machine. The arrangement is figured on the accompanying plate.

Report Presented by M. Aimé Girard on M. Kuhl. mann's (junior) Methods for Recognising the Com. position and Measuring the Volume of the Gases and Acid Vapours given off by the Chimneys of Chemical Works.-By means of this arrangement a manufacturer can at any hour inform himself concerning the nature of the gases traversing his chimney. To establish the composition of the chimney-gases and to detect, e.g., the presence of hydrochloric acid therein, M. Kuhlmann introduces into the shaft a glass tube, which communicates with a series of test-tubes, at the end of which is a cistern of water, which acts as a respirator. The flow of water compels the gas to traverse the series of test-tubes, the first of which contains caustic soda coloured with litmus. Then follow solutions of barium chloride and silver nitrate. The dimensions of the cistern are such that five or six hours are required for the total efflux of the water which it contains, and the strength of the alkaline liquid coloured blue is such that in the regular course of work five or six hours are required to turn them red. An earlier colouration gives immediate warning. M. Kuhlmann's method of measuring the total volume of gases escaping is as follows:-When he wishes to know the speed of the gases he introduces at the bottom of the chimney a certain volume of a strong-coloured gas, such as hyponitric acid, which accompanies the colourless gases up the chimney and presents itself along with them at the top. Knowing, then, the volume of the chimney and the mean temperature it is possible to calculate from the time which has elapsed the quantity of gas emitted.

Bulletin de la Société Chimique de Paris,
No. 6, March 20, 1879.

Action of Mono-chlor-acetic Acid upon Sulpho. cyanic Acid and its Salts.-M. Nencki.-On heating a mixture of 1 mol. chlor-acetic acid dissolved in double its weight of water with 3 mols. ammonic sulpho-cyanate, the liquid obtained deposits crystals of a new compound, rhodanic acid, C3H2NS2O, which crystallises in tables and six-sided prisms of a fine yellow, scarcely soluble in cold water, but readily in alcohol, ether, and alkalies. It melts about 168° to 170° with partial decomposition, yielding a brown-red liquid. Under the influence of feeble oxidising agents it produces colouring matters. A red and a violet matter have thus been obtained which in acid solutions dye silk and wool, and in alkaline solutions produce a blue shade upon cotton.-Journal f. Praktische Chemie, xvi., I.

Action of Cyanogen upon Albumen.-O. Loew.-By treating albumen with cyanogen gas the author obtains three new compounds, cyalbidin, oxamoidin, and a third body not named.-Fourn. f. Prakt. Chemie, xvi., 60.

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