Obrazy na stronie

Presence of Arsenic in the Vapours of Bone Manure. {

Oct. 13, 1876. were only known in the anhydrous state. Now, I do | Athenæum in matters of fact, and I have resented the pretend to have discovered the facts, whatever their im- silly little insult which it has presumed to put upon the portance may be, (1) that all crystalloid bodies soluble in members of the British Association. I may add that I do water are capable, at temperatures below o° C., of uniting " seriously" think it is the “concern" of a critic who with water to form solids containing definite quantities of takes exception to an expression, not only to point out water; (2) that the temperatures of solidification of these how the expression is bad-if he can-but also to suggest bodies, which I call cryohydrates, determine the limiting a better one—if he can. The first of these duties the temperatures of freezing mixtures.

Athenæum has attempted and signally failed to perforni. “With regard to the second part of your reporter's re- The second it declines to attempt because, forsooth, it is mark, namely, the accusation of sensationalism, I am not its “ concern." constrained to say that it is as discourteous as it is un- From the assertion that the difference between the founded, and I shall be glad to learn that, on reflection, reporter or editor or whoever he is of the Athenæum and your reporter regrets having allowed an expression of myself is only one of taste I must beg to dissent ; or only such questionable taste to have escaped him.

agree to so far as I must admit that the misrepresenta“ FREDERICK GUTHRIE. tion of facts exhibits the worst possible taste. Prof. Guthrie admits that he does not pretend to

Although, of course, one has to be serious in remonbe the discoverer of water of crystallisation as it is ordi. strating with a journal devoted to “ English and Foreign narily understood. Well, but this water of crystallisa-Literature, Science, the Fine Arts, Music, and the tion as it is ordinarily understood' is solid water, and we

Drama,” there is something exquisitely ridiculous in the were therefore quite correct in maintaining there was

notion of “ Solid Water” being a " sensational ” expres. nothing new in this. We never said that Prof. Guthrie sion. "Hard Water" I presume is “ Indelicate;" “Cold had not discovered various salts which could, under cer

Water" is clearly “ Atheistic ;” and “Vapour of Water" tain circumstances, be got to crystallise with water, but should be avoided on high Æsthetic principles if we wish we only found fault with the designation, which includes

to avoid the imputation of “Cannibalism."-I am, &c., much more than Prof. Guthrie himself claims to have

Frederick GUTHRIE. achieved. Surely the giving of such a designation justifies the charge of sensationalism.”


“ September 30, 1876. “The remarks appended in the Atheneum of the 30th

To the Editor of the Chemical News. inst. to my note on your report of my communication to the British Association on Solid Water,' call for a word before writing to you, he would not, I am sure, have

Sir,--Had Mr. Wanklyn paused to make a few enquiries or two. You say :**** Well, but this 'water of crystallisation as it is have found that at the time the Analyst published the

dragged my name into this discussion, because he would ordinarily understood,' is solid water, and we were there article and report which originally gave him offence, I was fore quite correct in maintaining there was nothing new

enjoying a ramble in Switzerland, and I can safely say in this.' “ In what? That water of crystallisation as it is In fact Mr. Wanklyn and myself have precisely the same

never wasting a thought either on butter or Mr. Dittmar. ordinarily understood is solid? Of course it is. I never dreamt of denying it. What I asserted, and conceive to

amount of responsibility for the contents of the Analyst be new, is that water may be solid and associated in Committee of Publication, and that we each of us neglected

for September, viz., that we were both members of the definite proportions with salts, and yet not be water of crystallisation as it is ordinarily understood. It may and therefore we ought to be the last to throw stones at

our obligations as such, and stayed away from the meeting, either be such water or it may be the water of the cryohy; I those who did their duty by attending. drates. I used the term solid water' to include and because it includes both; and in my communication I the paper was simply taken to get the Society out of the

My position as one of the "registered proprietors" of spoke of both to discriminate between them. Can you difficulty that, not being corporate, they could not legally suggest a more appropriate or less sensational’expres- hold a copyright, and I will have much pleasure in handing sion?

over the position (involving, as it does, pecuniary respon“The charge of sensationalism, which I regret to see not only not withdrawn but reiterated, may sometimes

be sibility) to any other member who may be public spirited permissible when brought against a writer of fiction, but enough to accept it. I trust Mr. Wanklyn will withdraw to bring it on no better grounds than those adduced, against I am, &c.,

his remarks so far as I am personally concerned. a writer on a scientific subject is injurious and unjust. You owe me an apology.

John Murer. South London Central Public Laboratory, “ FREDERICK GUTHRIE. Kennington Cross, S.E., October 7, 1876. "..* We must decline to continue this controversy. There seems to be no difference as to facts between Prof. Guthrie and ourselves. We neither denied Prof. Guthrie | ON THE PRESENCE OF ARSENIC IN THE the merit, if there be any, of having discovered the forma

VAPOURS OF BONE MANURE. tion of solid water under particular circumstances, nor, as far as we are aware, have we imputed to him any desire

To the Editor of the Chemical News. of denying the existence of hydrates known before his researches. As to our suggesting a more appropriate Sır:- The pamphlet published by Dr. Adams on the above designation for the class of bodies discovered by him, subject has occasioned some discussion in the CHEMICAL does Prof. Guthrie seriously believe this to be our con

News, and in your number of September 22nd, there cern? With regard to the title chosen by Prof. Guthrie is a note which seems to suggest a doubt whether the for his paper at Glasgow, we have only to say that this is chemists who made experiments for Dr. Adams had prenot a question of fact but of taste, and that upon it we viously satisfied themselves of the purity of their reagents. shall continue to differ from Prof. Guthrie."

I may state that I was expected to give evidence in the

particular case referred to in the pamphlet, and that I not With a journal which, after transgressing in this only made "blank experiments” when originally consulted manner, refuses to apologise when invited to do so I can, by Dr. Adams, but made them again in his presence when of course, hold no further communication. But your he came to my laboratory to see the experiments repeated. readers may permit me to state that there is no contro- Considering the abundant evidence adduced by Dr. versy" in the case. I have endeavoured to inform the | Adams, I think it may reasonably be conceded that



CHEMICAL NEWS,} Chemical Notices from Foreign Sources. 1876.

163 arsenical vapours are given off during the action of CHEMICAL NOTICES FROM FOREIGN arsenical sulphuric acid on bones or coprolites. On the medical question involved I have no opinion to offer.

SOURCES. I am, &c.,

Alex. T. Machartie.

Note.-All degrees of temperature are Centigrade, unless otherwise 88, Hope Street, Glasgow.

expressed. [We have also received a long communication on this subject from Dr. Adams, and a further letter from Dr. Comptes Rendus Hebdomadaires des Seances, de l'Acadenie Milne stating that blank experimen were made. This

des Sciences. No. 12, September 18, 1876. fact should, in our opinion, have been stated more ex- Lighting by means of Products Extracted from plicitly in the book. We can devote no more space to Resinous Trees.-M. A. Guillemare.—The author rethe subject, it being contrary to our custom to insert marks that if an attempt is made to burn in a common letters referring to our reviews of books, unless, indeed, lamp, adapted for oil of colza or petroleum, either oil of they point out a manifest injustice to the author, and this turpentine, “essentia viva," or the oil known as pyrogene we do not admit to have been the case in the present the two latter being extracted from resin by fractional instance.-Ed. C.N.]

distillation over 4 per cent of quicklime), two difficulties

are met with which have hitherto proved insurmountable. IMPROVED FORM OF ASPIRATOR.

The resinous liquids of commerce only rise into the wick

for a few minutes, after which the capillary action slackens To the Editor of the Chemical News.

considerably and soon stops. In all the lamps of com. Sir,- In the CHEMICAL News (vol. xxxiv., p. 141) Mr.

merce these same liquids burn imperfectly and diffuse an Richards describes an “Improved Form of Aspirator."

intense smoke. It is therefore needful to purify them This is somewhat similar in principle to one I constructed perfectly, aud to contrive a special jet or burner for their about four months ago, the chief difference being that Mr.

The clogging of the wick is due to the presence of Richards's pump requires a water pressure of 20 pounds resin or of naphthalen in solution. These impurities are to the square inch to exhaust “ to within i m.m. of the removed by distillation over an equal volume of water tension of aqueous vapour,” while mine takes less than rendered slightly alkaline, a current of steam being passed 5 pounds only to produce a vacuum (less, of course, by the through the apparatus, and by exposing the oils to the tension of aqueous vapour.) I append a drawing of my alkaline carbonates. The oils may be regarded as per

direct and prolonged action of concentrated solutions of arrangement.

fectly pure when they are no longer rendered milky by supply.

the addition of ammonia. A new burner has been devised, the construction of which is not quite clear, but which is said to prevent the formation of smoke.

Physical Properties of Gallium.-M. Lecoq de

baudran.-Inserted in full. A

Suction tube.

Justus Liebig's Annalen der Chemie,

Band 182, Heft 3. Investigations on Bodies of the Hydrobenzo and Stilben Series.-T. Zincke.--An introduâion to th

next paper. С

Various Hydrobenzoins, or Stilben Alcohols.-C Forst and T. Zincke.—A very bulky essay, extending 50 pages, and unfit for abstraction,

Apparatus for the more convenient Determination of Nitrogen.—Karl Zulkowsky.--Animproved instrument for the determination of nitrogen by the method of Dumas, calculated to be of great value in laboratories where such determinations are frequent. The apparatus cannot be described in an intelligible manner without the aid of the

accompanying illustration. B

On Ultramarine.—Dr. Carl Boettinger.-It has always been assumed that the formation of the blue colour of

ultramarine depends on the action of oxygen: but in cracked The tubes A B are of glass, and placed diametrically ducts are often observed, which, on washing with water,

crucibles and on the edges of the blue mass white proopposite each other, so that the water issuing from the lose almost all their sulphur in the form of sulphate. That jet A passes smoothly down through B.

c is a mercury ! this phenomenon is due to oxidation seems to require no governor, to regulate the pressure when the pump is used for filtering purposes. The rapidity with which this pump destroyed by oxidation. In the author's opinion ideal

further proof. Hence, then, it appears that the colour is exhausts is very great.

The principle involved was fully discussed and illus-ultramarine is a compound of silicate of alumina and soda trated in a paper to the Engineer of June 9, 1876, by Mr. with pentasulphide of sodium. James Brownlee.--I am, &c.

Communications from the Chemical Laboratory of

A. Percy SMITH. the University of Moscow.—These communications Rugby, October 2, 1876.

include a paper by W. Markownikoff on isomeric tartaric

acids, and one by the same author on the normal oxyAction of Nitrous Acid upon Acetanilide.-Otto pyro-tartaric acid (glutanic acid), and the isomerism of Fischer.-On passing a current of nitrous acid into a re. the pyrocitric acids : an account of the preparation of frigerated solution of acetanilide in acetic acid until the trimethylen-bromide, by J. Lermontoff; on aceton in the liquid becomes green there is obtained, on pouring the urine of diabetic patients, by W. Markownikoff; on cersolution into a large quantity of water, a yellowish pre- tain constitnents of Adonis vernalis, by F. Linderos; and cipitate which possesses the composition and character a preliminary communication on isomeric dibrom-anthraistics of nitroso-acetanilide.—Moniteur Scientifique. cen, by Oswald Miller.

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Chemical Notices from Foreign Sources.


{ C 02. 13, 1856 Contributions to the History of Betulin.-U. Haus- An Analytical Query.-In separating arsenic, &c., from copper

&c., by treating with an alkaline sulphide, I generally get the filtrate mann.— The composition of betulin is

rather dark, and it seems to contain not copper in solution, but finely Carbon ..


divided. I believe there is a way of preventing even a slight trace of Hydrogen

copper getting through. I have looked at many analytical works but

have failed to see anything about it, except the diluting, but that I Oxygen ..


have always done. I have taken in the CHEMICAL News for years bu: have never seen anything on the subject.-Robert MOYGER.






corresponding to the formula C12H200. In a state of

TO CORRESPONDENTS. purity it is colourless, and forms long slender prisms, which are readily converted by pressure into shining asbestos-like masses. I: melts at 258o. At a slightly

F. 3. Rowan.-Apply to Messrs. Johnson and Matthey, Hatton

Garden higher temperature it is volatilised with incipient decom- Ammonium.-You should advertise for the information you require. position, and sublimes in long delicate needles.

Now ready, Third Edition, enlarged and revised, with 74 eogravings

Svo., 155.
Les Mondes, Revue Hebdomadaire des Sciences,

No. 4, September 28, 1876.
Adulteration of Wines.—The author remarks that so
long as falsification consisted merely in heightening the

VOLUMETRIC ANALYSIS; colour of wines with logwood and other vegetable matters it was only a semi-evil, though still considerable enough, QUANTITATIVE ESTIMATION OF CHEMICAL SUBSTANCES since one of the dyes most commonly used w

a drastic BY MEASURE, APPLIED TO LIQUIDS, SOLIDS, AND Gases. purgative. But magenta has now come into use on a scale

Adapted to the requirements of Pure Chemical Research, Patholoscarcely to be imagined. A small commune in the gical Chemistry, Pharmacy, Metallurgy, Manufacturing Chenistry neighbourhood of Béziers, containing only 1800 inhabit. Photography, &c., and for the Valuation of Substances used in Comants, has consumed in one year 30,000 francs worth of

merce, Agriculture, and the Arts.

By FRANCIS SUTTON, F.C.S. this colour entirely for sophisticating wines.

J. and A. CHURCHILL, New Burlington Street.

Now ready, New Edition, 8vo., 75. 6d.,

Birmingham and Midland Institute.-The following

OR, THE KEY TO MODERN CHEMISTRY. are the lecture arrangements for the session 1876-73

By A. H. KOLLMYER, A.M., M.D.,

Professor of Materia Medica and Therapeutice at Montreal. This day (Friday), October 13.- Lieut. Cameron, D.C.L., on

J. and A. CHURCHILL, New Burlington Stratt. " Recent Explorations in Africa." October 16.- Captain Davis, R.N., F.R.G.S., on

Early in October. “ Antarctic Discovery, and its Connection with the

AND Transit of Venus, 1882. October 23, 30.-Prof. W. C. Williamson, F.R.S., on

STUDENTS preparing for Matriculation (University of London, “ The Early Forms of Animal Life," and " The Early ) aminations. By THOMAS ELTOFT, F.C.S., Chemical Teacher to the

College of Surgeons, Science and Art Department, and other ExForms of Vegetable Life.”

Matriculation Classes, St. Bartholomew's Hospital; Chemical November 6, 13.-George Dawson, M.A., on " Horace Lecturer, City of London College, St. Thomas, Charterhoase, Science Walpole."

Schools, &c. Cloth, post 4to.

London : SIMPKIN, MARSHALL, and CO., Stationers' Hall Court November 20.-Wm. Huggins, D.C.L., LL.D., F.R.S.,

Manchester : JOHN HEYWOOD, Deansgate. on “Spectrum Analysis Applied to the Heavenly Bodies.”

November 27, December 4. - Arthur Arnold, on " Persia."

December 11.-Prof. Boyd Dawkins, M.A., F.R.S., THE "YOUNG" CHAIR OF TECHNICAL CHEMISTRY. F.S.A., on “The Ancient Inhabitants of the Caves of

Professor E. J. MILLS, Dr. Sc. (Lond.), F.R.S.. Derbyshire."

SESSION 1876-7.

LECTUTES.-A COURSE of FIFTY LEOTURES on T&C. January 22, 29.-E. Ray Lankester, M.A., F.R.S., on

NICAL CHEMISTRY will be Delivered during e Sesslochan Mo “ Rots and Ferments, our Unseen Enemies."

DAY, TUESDAY, and WEDNESDAY in each Jdk, 9 a.m, February 5, 12.-Edward Dannreuther, on “The Piano. beginning on WEDNESDAY, 1st NOVEMBER The Lectures forte Works of Liszt and Chopin."

will be Ilustrated by the actual Inspection of Manufactoring Pro

They will include this year, as special subjects, the February 19, 26.-Prof. Sidney Colvin, M.A., on ALCOHOL INDUSTRY, Potable Waters, Sewage, and General “Olympia and Greek Athletics ; a Study of Ancient TECHNICAL SANITATION. Fee for the Course Two Guincas ; Usages and Recent Discoveries."

Laboratory Students Free. March 5.-Prof. J. M. D. Meiklejohn, M.A., on

The attention of Young Men qualifying for the Professions of Civil

and Mining Engineers, Architects, &c., as well as those more im. Parody."

mediately interested in the Study of Chemistry, is called to this March 12.-Prof. Sir C. Wyville Thomson, LL.D.,

Course of Lecturcs. F.R.S., on “ The General Results of the Challenger Ex

A Course of Thirty Lectures on TECHNICAL ORGANIC CHE

MISTRY will be commenced on April ist. These Lectures are more pedition."

especially intended for Dyers, Colour Manufacturers, Brewers and March 19, 26.-Prof. W. Barrett, F.R.S.E., on " Radia- Distillers, Tar Rectifiers, and Drysalters. Fee for the Course Two tion and Radiometers."


LABORATORIES.-The Laboratories will be Open Daily, on and April 9, 16.-George Dawson, M.A., on " Sir Walter

aster Wednesday, ist November, from 10 a.in. to 4 p.m. (Saturdays Raleigh.

10 a m. to i p.m.), under the Superintendence of the Professor and his Asitants. Instruction given in the Preparation oi Chemical Sub

stances and Original Research, especialiy as relating to Manutacturing NOTES AND QUERIES.

Processes. Fees-Whole Session of Nine Months, £18; Six Months, £13; Three Months, £7; or for One Mun:h, £ 2 10.3.

Students entering upon Laboratory Instruction are requir:d Our Notes and Queries column was opened for the purpose of have a fair knowledge of Elementary Chemistry. giving and obtaining information likely to be of use to our readers BURSARIES.- A Few Bursaries of £50 euch per Annum, Tenable generally. We cannot undertake to let this column be the for Three Years, are now at the disposal ci the Trustees, who will ineans of transmitting inercly private information, vr such trade receive Applications in writing up to the 13th October. notices as should legitimately come in the advertising columns.

ALEX. MOORE, Secretary. Fluoride of Potassium.-Can any of your readers give me a 166, St. Vincent Street, Glasgow, process for the ready production of Nuoride of potassium.-FLUORINE.

October, 11, 1976.


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Oct. 20, 1876.
Repulsion Resulting from Radiation.


fusion, and where this is impracticable mercury joints THE CHEMICAL NEW S. should be used. The best way to make these is to have

a well-made conical stopper, cut from plain india-rubber,

fitting into the wide funnel tube of the joint and perforated VOL. XXXIV. No. 882.

to carry the narrow tube. Before fitting the tubes in the india-rubber, the latter is to be heated in a spirit flame until its surface is decomposed and very sticky; it is then

fitted into its place, mercury is poured into the upper ON REPULSION RESULTING FROM part of the wide tube so as to completely cover the indiaRADIATION.-PART II.*

rubber, and oil of vitriol is poured on the surface of the

mercury. When well made this joint seems perfect; the By WILLIAM CROOKES, F.R.S., &c.

only attention which it subsequently requires is to renew

the oil of vitriol when it gets weakened by absorption of 81. The present paper is in continuation of one which I aqueous vapour. Cement has to be used when flat glass had the honour of reading before the Royal Society, or crystal windows are to be cemented on to pieces of December 11, 1873, and which was published in the apparatus, as subsequently described (99, 102). Philosophical Transactions, vol. clxiv., part 2, p. 501. In It would be of great service could I find a cement which that paper I described various pieces of apparatus, chiefly is easily applied and removed, and will allow the joint to in the form of delicate balances suspended in glass tubes, be subjected to the heat of boiling water for some hours by means of which I was enabled to show attraction or without leaking under the highest rarefactions. Hitherto repulsion when radiation acted on a mass at one end of I have failed to find one which answers these requirethe beam, according as the glass tube contained air at the ments. I mention this in the hope that some one who normal pressure, or was perfectly exhausted. At an inter- happens to read this may be in possession of the recipe mediate internal pressure the action of radiation appeared for such a cement, and will communicate it to me. nil. Towards the end of the paper I said (70), " I have 84. Before my first paper on this subject was read arranged apparatus for obtaining the movements of resul. before the Royal Society I had discarded the balance sion and attraction in a horizontal instead of a vertical form of apparatus there described, and commenced explane. Instead of supporting the beams on needle-points, perimenting with bulbs and tubes in which quantitative so that they could only move up and down, I suspend results could be obtained. On December 11, 1873, when them by the centre to a long fibre of cocoon silk in such illustrating my paper, I exhibited to the Society many of a manner that the movements would be in a horizontal these new forms of apparatus. For the purposes of plane. With apparatus of this kind, using very varied simple illustrations, and for experiments where quantitamaterials for the index, enclosing them in tubes and bulbs tive determinations are not required, I find a horizontal of different sizes, and experimenting in air and gases of index suspended in a glass bulb the most convenient. different densities up to Sprengel and chemical vacua, I The apparatus, with its mode

attachment to the pump, have carried out a large series of experiments, and have are shown in fig. 1. obtained results which, whilst they entirely corroborate those already described, carry the investigation some steps

ODDDDDDDDDDD further in other directions."

82. I have introduced two important improvements into the Sprengel pumpt which enable me to work with more convenience and accuracy. Instead of trusting to the comparison between the barometric gauge and the barometer to give the internal rarefaction of my apparatus, I have joined a mercurial siphon-gauge to one arm of the pump. This is useful for measuring very high rarefactions in experiments where a difference of pressure equal to a tenth of a millimetre of mercury is important. By its side is an indicator for still higher rarefactions; it is simply a small tube having platinum wires sealed in, and intended to be attached to an induction coil. This is more convenient than the plan formerly adopted (51) of having a separate vacuum tube forming an integral part of each apparatus. At exhaustions beyond the indications of the siphon-gauge I can still get valuable indications of the nearness to a perfect vacuum by the electrical resistance of this tube. I have frequently carried exhaustions to such a point that an induction spark will prefer to strike its full distance in air rather than pass across the † inch separating the points of the wires in the vacuum tube. A pump having these pieces of apparatus attached to it

d was exhibited in action by the writer before the Physical Society, June 20, 1874.

83. The cement which I have found best for keeping a vacuum is made by fusing together 8 parts by weight of resin and 3 parts of bees'-wax. For a few hours this seems perfect, but at the highest exhaustions it leaks in the course of a day or two. Ordinary or vulcanised

a, b, c, d is originally a straight piece of soft lead-glass india-rubber joints are of no use in these experiments, as tubing 18 inches long, of an inch external and internal when the vacuum is high they allow oxygenised air to diameter. At one end is blown a bulb, d e, about 3 inches pass through as quickly as the pump will take it out. diameter. The part a b of the tube is drawn out to about Whenever possible the glass tubes should be united by half its original diameter, and bent at right angles. The * From the Philosophical Transactions of the Royal Society of and thickened at b. At a it is also contracted and

tube is slightly contracted at c, and very much contracted London, vol. clxv., pt. 2.

1 Philosophical Transactions, 1873, vol. clxiii., p. 295 ; 1874, vol. cemented by fusion to a narrower piece of tube bent in clxiv., pp. 509, 516. Phil. Mag., August, 1874.

the form of a spiral, and fitting by a mercury joint into the




Development of the Chemical Arts.


oa. 20, 1876. sulphuric acid chamber of the pump. The object of the form was devised which will be described further on (102), spiral is to secure ample flexibility for the purpose of together with the experiments tried with it. levelling the apparatus, and at the same time having a

(To be continued.) fused joint. f g is a very fine stem of glass, drawn from glass tubing, and having a small loop (h) in the middle. At each end of the stem is a ball or disk, made of pith, cork, ivory, metal, or other substance. h i is a fine silk

REPORT fibre made from split cocoon-silk; it is cemented by shellac at the upper end to a piece of glass rod a little

DEVELOPMENT OF THE CHEMICAL ARTS smaller in diameter than the bore of the

tube, and drawn out to a point, as shown. The contraction (c) in the tube

DURING THE LAST TEN YEARS.* is for the purpose of keeping this glass rod in its place ;

By Dr. A. W. HOFMANN. when properly adjusted it is secured in its place by a small piece of hot shellac, care being taken not to

(Continued from p. 149.) cement the rod all round, and so cut off the connection between the air in the bulb and that in the upper part of Chlorine, Bromine, Iodine, and Fluorine. the tube. The silk fibre is tied on to the loop of the glass

By Dr. E. MYLIUS, of Ludwigshafen. stem at h. The length of the fibre is so adjusted that the stem and disks will hang about 5 of an inch below the As leaden worms are very rapidly destroyed by liquid centre of the bulb; that much having to be allowed for bromine, though very slightly attacked by bromine the contraction of the silk when the air is exhausted.

vapours, Frankt employs condensing tubes of earthen. 85. The bulb-tube is firmly clamped in a vertical posi; bromine simultaneously evolved he avoids a too perfect

To separate the bromine from the chloride of tion, so that the index hangs freely, and the pump is set to work, the bulb being surrounded with a vessel of water refrigeration, and conducts the more volatile products, which is kept boiling all the time exhaustion goes on.

including the chlorine, into a receiver charged with ironThe gauge soon rises to the barometric height; but the turnings or with potash-lye. The crude bromine in the operation must be continued for several hours beyond this first receiver is then completely freed from chlorine and point in order to get the best effects. If the bulb is not

from sparingly volatile organic bromides which are usually heated during the exhaustion, the index loses sensitive preseni by fractionated distillation. ness after it has been sealed up for a few days, probably alkalies and alkaline earths deserve notice. Henner and

Several methods for obtaining the bromides of the owing to the evolution of vapour from the pith ; when, however, the precaution is taken of heating the pith the von Hohenhausen; prepare the bromides of calcium, apparatus preserves its sensitiveness. On this account it barium, and strontium by diffusing the respective hydrates is necessary to tie the silk on to the loop in the centre of in water, decomposing with bromine, evaporating till the the glass stem, instead of adopting the easier plan of formation of crystals begins, and mixing the liquid with cementing it with shellac. During the latter stages of the alcohol, which precipitates the last portion of the bromate exhaustion, oil of vitriol (which has been boiled and cooled formed. The bromide is then obtained from the liquid, in vacuo) should gently leak into the pump through the and a further portion is procured by heating the bromate funnel-stopper at the top of the fall-tube (44). This with charcoal. c. Wendler|| proposes to prepare the bro. covers each globule of mercury as it falls with sulphuric , mides of the alkaline earths according to Rud. Wagner's acid, and stops mercury vapour from getting into the approved method for the manufacture of the corresponding apparatus. I cannot find that any vapour is evolved iodides, i.e., by the action of bromine upon the sulphites. from oil of vitriol.

According to A. Faust Bædeker obtains the bromides When the exhaustion is carried to the desired degree as follows:-Bromide of sulphur is prepared from 20 parts a spirit flame is applied to the contracted part of the tube flowers of sulphur and 240 parts of bromine, and gradually at a (fig. 1), and it is sealed off. The apparatus is then poured into the milk of lime made from 140 parts of quickunclamped" and the tube is again sealed off at b. This lime, or into a corresponding solution of baryta. The double operation is necessary to secure strength at the bromide of sulphur in contact with the hydrate of the final sealing, which can only be got by holding the tube alkaline earth is decomposed into a metallic bromide and horizontally and rotating it in the flame, watching the

a sulphate. The latter is removed by the addition of glass to prevent it softening too suddenly.

alcohol and subsequently of lime. The solution of calcic 86. The best material of which to form the index in or baric bromide can either be used for obtaining those these bulb-tubes is pith, either in the form of a needle salts, or for preparing the sodic, potassic, or ammonic or bar, or as disks at the end of a glass stem. On De- / bromide by decomposition with the corresponding carcember 11, 1873, and again on April 22, 1874, I exhibited bonate or sulphate. before the Royal Society a glass bulb 4 inches in diameter,

Casthelazsi prepares bromide of sodium by forming, in having suspended in ií a bar of pith 34 * inches. It the first place, bromide of ammonium by dropping brohad been exhausted in the manner above described; and mine into liquid ammonia, and decomposes this by the so sensitive was it to heat, that a touch with the finger addition of an equivalent quantity of caustic or carbonated on a part of the globe near one extremity of the pith

soda. would drive the bar round 90°, whilst it followed a piece potassium may be removed by agitation with free bromine.

Falières points out** that iodine present in bromide of of ice as a needle follows a magnet. To get the greatest delicacy in these apparatus there is

of all these methods of preparing bromides, especially required large surface with a minimum of weight (75, 76). bromide of potassium, which is most in use, none is prac. Thin disks of pith answer these requirements very satis: tised on the large scale. Either the ferroso-ferric bromide factorily; but I have also used disks cut from the wings is decomposed by the addition of carbonate of potassa, or of butterflies and dragonflies, dried and pressed rose

vapours of bromine are conducted into potash-lye, and leaves, very thin split mica and selenite, iridescent films he potassic bromate formed along with potassic bromide of blown glass, as well as the substances mentioned in

"Berichte über die Entwickelung der Chemischen Industrie my former paper (25). Quantitative experiments to prove Während des Letzten Jahrzehends." this law were attempted ; but the bulb apparatus was Private communication. found too imperfect for accurate measurements, so another

Henner and Hohenhausen, Dingl. Pol. Journ., clxxiii., 1864, 221. !! C. Wendler, Wagner Jahresber., 1863, 291.

Ş A. Faust, Archiv. d. Pharm., clxxxi., 216. Wagner Jahresber., * By adopting this precaution it is not difficult to raise the mercury 1867, 196. in the gauge higher than that in the very perfect barometer by its a Casthelaz, Monit. Scient., 1870, 65. Chemical News, 1870, side, the latter being somewhat depressed by the tension of mercury No. 532,58; and 547, 238, Wagner Jahresber., 1870, 195.

** Falières, Wagner, Jahresber., 1872, 274.


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