« PoprzedniaDalej »
August 11, 1876. from the summit of which hung a thread ending with a In all cases I find a strong feeling prevailing amongst heavy point. The base of the pyramid thus arranged was chemists of character and position as to the necessity for applied to the plane which was to be levelled, and carried | vigorous steps being taken to raise the status of persons over this plane in all directions. Wherever the plane adopting chemistry as a profession; and now that what ceased to be horizontal the joint deviated from the centre has for a long time past seemed to be idle talk, or the of the base.
dreams of visionaries, is assuming a form, and showing “The balance-clock consisted of a long lever suspended the elements of vitality, a lively interest is displayed by similarly to the balance-level. To one of its arms was many who are desirous that as soon as practicable the attached a reservoir of water, which, by means of a small Institute should be established and its important work hole perforated on the bottom of it, empțied itself in commenced, twenty-four hours. This reservoir, being filled with water, Questions are, however, from time to time raised as to was poised by weights attached to the other arm of the the persons to be admitted to membership, and the manner lever, and in proportion as the water flowed from it the of their election. Your readers may rest assured that arm bearing it was lifted, the weights on the other arm these questions have already received full consideration slid down, and by their distance from the centre of sus- on the part of the active promoters of the scheme. pension indicated the time which had elapsed."
The qualifications of the several classes of persons, and Many points of interest, demanding at least a passing the conditions upon which they were to be received into notice, may be embodied in a summary of the principal | the membership, as stated in my letter to you (CHEMICAL propositions contained in this treatise :
News, vol. xxxiii., p. 240), were not agreed to before 1. The “ Book of the Balance of Wisdom shows the objections thereto had been anticipated, and in consulta
Arabian philosophers of the twelfth century to have tion between some of my clients and myself fully disentertained advanced views regarding attraction. cussed. It was felt that under all circumstances the They recognised gravity as a force, and attributed regulations upon this point recommended by my clients to it a direction towards the centre of the earth; would in actual working prove to be conducive to the they also knew that it diminishes with the distance, success of the Institute, and as valuable in promoting its but they erroneously supposed this diminution to objects as any that could be devised. It was not, how. be in the direct ratio of the distance, and not as its ever, expected that all chemists would at once accept this square.
part of my clients' scheme, but although alterations 2. They were acquainted with the connection between therein have been suggested to me I still consider that
the weight of the atmosphere and its increasing my clients' proposals are the best, and when fully underdensity, since mention is made of the loss of weight stood will prove the most acceptable. of a body weighed in a denser atmosphere.
It is objected that inasmuch as all persons who have 3. They understood the theory of centre of gravity, and "practised on their own account in the profession of a
applied it to the investigation and construction of consulting or analytical chemist for a period of five years" balance and steelyards.
are to be eligible for election without producing evidence 4. They made frequent use of the hydrometer, which of training and fitness or undergoing an examination to
they, inherited from antiquity, and possibly they prove such fitness, that “high” and “ low” aralysts and employed this instrument as a thermometer for dis- quacks will not be excluded from membership, and that tinguishing by variations of density the different the principal object of the Institute will thus be lost. To temperatures of liquids.
guard as far as practicable against the admission of incom5. They observed the action of capillary attraction.
petent or disreputable men it is intended that every 6. They compiled full and accurate tables of the specific person proposed for election should be nominated by five
gravities of most of the solids and liquids with persons having personal aquaintance with the candidate, which they were acquainted.
that his name and the names of his nominators (after 7. Their system of philosophy was founded on experi- being submitted to the Council), and the date of his elecment and observation.
tion should be communicated by post to each member of In conclusion we quote the following appropriate re
the Institute fourteen days before the date of election, and
that at the ballot four-fifths of the members present must marks from M. Khanikoff's introduction:
vote in the candidate's favour to secure his election. If “The history of the sciences presents to us an incon- the members do their duty, and act in a spirit of high testable fact of deep significance—the re-discovery in honour in the observance of these regulations it is thought modern times of truths laboriously, established of old ; that improper persons will be kept out of the Institute and this fact is of itself enough to indicate the necessity but should any such person become a member, the power of searching carefully in the scientific heritage of the of expelling therefrom, upon proof of unworthy conduct, past after all that it may be able to furnish us for the increase of our actual knowledge; for a double discovery, ing the Institute, be sufficient to ensure that all persons
will, if the members are true to the principles governnecessarily requiring a double effort of human intellect, wearing the dignity of membership shall be honourable is an evident waste of that creative force which causes
and trustworthy men. the advance of humanity in the glorious path of civilisation."
It has been suggested that “works'” chemists should be entitled to become candidates for election on the same conditions as persons “who have practised as chemists
on their own account for at least five years," and conseCORRESPONDENCE.
quently without affording the evidence of training and
employment as proposed in my letter of the 6th of ORGANISATION AMONG CHEMISTS.
June last, under the heading, “ As to persons not
now employed as chemists." Works' chemists are in To the Editor of the Chemical News.
many cases highly trained, able, and conscientious men,
and 'in such cases difficulty will not be experienced in SIR, — My letter to you of the 6th June last, published in their establishing their qualifications and fitness for adthe CHEMICAL News (vol. xxxiii., p. 240), has led to mission into the Institute. But it is, I believe, an some persons, interested in the establishment of the acknowledged fact that many “works”” chemists are ill proposed Institute, addressing communications to me, in trained, and, except as to their own particular branch of some cases seeking for information as to the details of the chemical manufacture, are, in many cases, ignorant of the scheme and promising both moral and financial support, simplest principles of chemistry as a science, and beyond and in other cases making suggestions with a view to my the circle of their own employment are quite unknown, clients' scheme being made more perfect in its details. and certainly have no public (and, outside the scene of
Chemical Notices from Foreign Sources. August 11, 1876.
63 heir employment, any scientific) reputation. The Insti- , ferment. The ferment which determines this transforma ute would undoubtedly suffer if all “works”” chemists tion is of a diastasic nature. were indiscriminately admitted to membership without Difference of the Potential Presented, after Rupproducing evidence of training and subsequent employ-ture of the Inductor Current, by the Isolated ment. As in the varied walks in life the innocent are
Extremities of an Open Induction Coil.-A matherequired to suffer for the guilty, so in the case of the matical paper, not suitable for abstraction. Institute, the competent “works'” chemist will have to prove his distinction from the incompetent servant, but Porous Carbon.-M. Melsens.-With reference to the
Reactions of Chlorine under the Influence of having done this the honour of membership will be more clearly brought out, and be more thoroughly appreciated. paper of M. Damoiseau, read at the last meeting of the It is obvious that in practice it would be found impos: carbon upon gases is already well known to physicists and
Academy, the author urges that the influence of porous sible for the Council of the Institute to enforce any rule
chemists. requiring candidates “now practising as chemists on their own account” to bring evidence of their training A New Butylic Glycol.-M. Milan-Nevole.- The and fitness, and the Council could not make selections author describes in this paper the products obtained by the amongst that class of persons, requiring some to bring oxidation of his glycol. such evidence and permitting others to come without it. Explanation of the Impressionability of the They would place themselves in a most invidious position Blackened Discs of the Radiometer by the Aid of were they to attempt to do so.
the Emission Theory, according to J. B. Biot.As it is understood the Chemical Society is now advised M. W. de Fonvielle.-J. B. Biot, in the third volume of that it cannot alter, or add to, its name, or inction the is “Traité de Physique,” explains how the luminous creation of an Institute which shall be an adjunct to the molecules cannot communicate their vis viva to reflecting Society, and in fact form a part thereof, it is desirable surfaces. In fact, these latter exert a truly repulsive action that the question of the establishment and the government upon those molecules which, not touching them, cannot of the Institute should now be taken earnestly in hand, so produce upon them any percussion similar to that im. that an unnecessary delay may not occur after the recess pressed by electric forces. The considerations developed in making the organisation complete.
by this illustrious physicist not being applicable to I shall receive with much pleasure any suggestions blackened discs, we understand that the rotation of the from your readers upon this important and interesting radiometer should be produced in such a direction that subject.-I am, &c.,
they may fly from the ray. Is it not curious to find that
J. PetTENGILL. the emission theory has permitted us to some extent, as 32, Walbrook, London, E.C.
far back as 1816, to foresee the experiment of Mr. Crookes ? August 3, 1876.
The explanation of the phenomenon, if we admit M. Biot's
starting-point, does not require any new reasoning. The CHEMICAL NOTICES FROM FOREIGN cules seems at first sight not to produce any effect, a result
effort lost in the change of direction of the luminous moleSOURCES.
which does not appear reconcilable with the law of the conservation of the quantity of movement. Nevertheless,
we may reply to this objection that according to the theory NotB.-All degrees of temperature arc Centigrade, unless otherwise of emission this quantity of motion is represented by an expressed.
internal ray performed upon the ray of light; for the
direction of the axis of the luminous molecules has been Comptes Rendus Hebdomadaires des Seances, de l'Acade nie changed since the reflection, for in place of being situated des Sciences. No. 2, July 10, 1876.
in the direction of the ray these axes have become perpenNote on a Communication by M. Sacc, entitled dicular to that direction after the reflection. In this hy. “On Panification in the United States, and on the pothesis the energy destroyed is represented by that which Hop as a Ferment.”—M. L. Pasteur.—The author main has been employed for the polarisation of the incident tains, in opposition to M. Sacc, that the hop does not con ray. The author has studied, along with M. Ruhmkorff, tain a soluble alcoholic ferment.
an apparatus known in Germany under the name of light. Objections to the Last Communication of M. Hirn mill—an appellation which seems to him scarcely justifi on the Maximum Possible Repulsive Pressure of the able, for the rotation of a wheel placed in the centre of a Solar Rays.-M. A. Ledieu.-The author, like M. Hirn, Geissler's tube seems exclusively produced by a dynamic admits the excellence of the application of the method of effect peculiar to electricity, and in which light does not successive elimination to the study of the cause of motion intervene in any manner. In fact, the vacuum is so im. in the radiometer of Mr. Crookes; but an erroneous em- perfect that a radiometer placed in Geissler's tube cannot ployment of this method only introduces a new element of turn without the action of a ray of light. Further, the complication into a question so delicate in itself. The state of the surfaces has no influence upon the direction numbers o'0004157 grm. and o'0008314 grm., proposed by of rotation in Geissler's "mill,” which is entirely bright, M. Hirn to represent the maximum possible repulsion of whilst the direction of this rotation is chang at will by light per square metre, whether for a blackened surface or altering the direction of the current. The preponderance for one perfectly polished, have no acceptable signification of the negative flame, much more direct than the positive, M. Hirn assumes that the speed of the impact of the mole. cannot exert, as the author at first believed, any influence cules striking the discs is no other than the speed of light
on this inversion, for a very sensitive radiometer, capable itself, whilst in the hypothetical collision in question we of being set, in motion by the light from a smouldering must evidently consider the vibratory speed of the said match just blown out, was not moved by the light of an molecules. But this latter velocity has nothing in common induction spark striking sufficiently near to the glass case with the rapidity of propagation of the light-waves.
to perforate it. Experimental Researches on Magnetic Rotatory
Crystallisation of Sugar.-M. G. Fleurens.- The Polarisation (Third Part : Dispersion of the Planes of value of this paper lies in tables which cannot be abridged. Polarisation of the Luminous Rays of Different
Remarkable Case of the Reduction of Nitric Acid Lengths of Waves;.-M. H. Becquerel.—Unsuitable for and the Oxidation of Acetic Acid with the Producabstraction.
tion of Alcohol under the Influence of certain Cellulosic Fermentation of Cane-Sugar.-M. E. Microzymas.-M. J. Béchamp.-The author controverts Durin.-Cane sugar is split up into equivalent weights of the view of M. Méhay that the decompositions in question cellulose and levulose under the influence of a special are exclusively due to chemical reactions.
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OR THE USE OF
65 August 18, 1876.
water, and an excess of stannous chloride run in from a THE CHEMICAL NEWS. burette. After the fluid had lost colour a little starch so
lution was added, and iodine solution run in from another
burette until the blue iodide of starch remained perma. Vol. XXXIV. No. 873.
It was found best to have the iron solution rather concentrated and warm. One c.c. of the stannous chloride solution was equivalent to about o'o 120 metallic
iron and 3 c.c. of iodine solution. The stannous chloride VOLUMETRIC ESTIMATION OF IRON. worked best when freshly prepared. Ten determinations
of iron in a limonite gave-
38.15 By far the best method of estimating iron volumetrically
Average, 38'235. encountered is how to perform this reduction in the best, quickest, and cheapest manner. The best and most com- Two determinations of the iron in the same sample, by plete method of redu&ion, according to my experience, is the preceding method of reduction by hydrogen, gavethat by hydrogen, in a porcelain tube, at a red-heat. To make the reduction complete it is necessary to pass the
38.00 and 38:16. gas over the heated ore for three hours. Not more than A gravimetric determination by Dr. Drown, in another 0-3000 grm. of the ore should be taken, otherwise at the sample of the same ore, gaveend of the time specified the reduction will be found to be
38:14. incomplete. The ore is weighed out in platinum boats, four of which may be placed in the tube and reduced at
These results for technical purposes are as good as is The tube is allowed to cool while the hydrogen is necessary. Four of the samples were weighed, dissolved, still passing the boats, removed, and carefully dropped reduced, and titrated in an hour and twenty minutes. In into flasks containing hot dilute sulphuric acid. The
a second trial, with four more samples, the same time was
taken. In both cases the solutions were standardised flasks are closed with doubly-perforated corks, and a current of hydrogen is passed into them while the iron is while the ore was dissolving. This gives an average of dissolving. When the solution is complete the flasks are twenty minutes as required for one determination, which plunged into cold water (hydrogen being still passed into is all that could be desired. I find it best to standardise them) and allowed to cool completely, and are then
the stannous chloride solution by means of metallic iron. titrated in the usual way. Coal-gas cannot be used in This is dissolved in hydrochloric acid and a few pieces of place of the hydrogen, as some of its constituents dis- potassium chlorate added; after which the solution is solve in the hot acid and exercise a reducing action on the evaporated nearly to dryness. By this means every trace permanganate. With a great many ores, especially li- of free chlorine seems to be expelled. A solution of monites, the reduced iron dissolves with great difficulty, ferric chloride, when freshly prepared, is reduced almost sometimes not at all. This difficulty has been overcome immediately upon addition of the stannous chloride. by Dr. T. N. Drown, who passes oxygen or air over the After standing some time, however, it is more slowly reheated ore for half an hour before reducing. The car. duced, and seems to require less tin solution. A solution bonaceous matter is in this way destroyed, and the reduced of ferric chloride which had been kept for some months, iron is found to dissolve with the greatest ease. In this
one volume of which by precipitation in a platinum dish modified form I know of no more elegant and accurate by ammonium hydrate gave o-1024 and o-1024 iron, when method of determining iron in its ores. Some results ob. estimated by means of the tin solution gavetained at different times, on different ores, show the pre
O'IOIO cision of the method. The numbers represent percentages
0*1007 of metallic iron.
results which are neither high enough nor closely agreeing. No. 1. No. 2.
Lafayette College, June, 1876. 62'19) 66.69
47'97 62.25 | Average, 66.64 | Average, 47.86 Average, 62'11 62-195 66.64 66.63.
48.or 47.98. 62:22)
NEW FORM OF COMPENSATING PENDULUM.
By J. LAWRENCE SMITH, Louisville, Ky 48.88
In the construction of this new form of compensating
pendulum I have taken advantage of the very great ex48.78)
pansibility of that combination of sulphur and caoutchouc
known as vulcanite or ebonite. Its coefficient of expanAlmost all the magnetites when dissolved in acid leave sion is known to approach that of mercury in the ranges a residue containing iron. The iron in this residue is not of temperature from oo to 70° C. reduced by the hydrogen when the iron is determined as The mechanical arrangement adopted is a very simple above. In this respect, however, the process is neither The rod of the pendulum is of round steel, with an better nor worse than those ordinarily used. There are adjusting screw at the lower end; a round rod of vulcanite only two valid objections against this method. The first with a hole in the centre is passed on to the steel rod, is the gas consumed, which makes it costly. The second fitting it loosely, and being held in place by the adjusting the time required-from four to six hours. In order to screw. The bob of the pendulum consists of a heavy find a means of determining iron very rapidly, with a mass of brass, with a hole through the centre large reasonable degree of accuracy, various processes have enough to admit the vulcanite over which it passes, and, been tried, but thus far none have given better results by a properly arranged stop, rests on the end of the vulthan that by reduction of the hydrochloric solution of the canite farthest from the lower end of the pendulum, so ore by stannous chloride. The ore was dissolved in that any expansion of the vulcanite elevates the brass hydrochloric acid in a beaker, and evaporated nearly to bob, thus compensating for the downward expansion of dryness. The solution was then diluted with a little | the steel rod and brass bob.
August 18, 1876. There is a simple mechanical arrangement for adjusting, till 425° does the formation and volatilisation of chloride the proper difference between the length of the vulcanite of copper begin. The permanence and the efficacy of the and the other parts of the pendulum.
sulphate of copper can be increased by the presence of For a second pendulum to an astronomical clock I have certain salts inactive in themselves, such as the sulphates used the following dimensions :-Diameter of the steel of potash and soda. rod, 6 m.m.; diameter of vulcanite, 25 m.m.; length of A number of experiments conducted by Deacon in same, 165 m.m.; diameter of brass bob, 63 m.m.; length concert with Hurter and Carey, since the year 1867, have of the same, 156 m.m. These dimensions are in no way led to a knowledge of the conditions of the reaction of air insisted on as being the best. For a half-second pendulum and hydrochloric acid in presence of salts of copper, * I have used a steel rod, 3 m.m. in diameter; vulcanite, 1. The quantity of the hydrochloric acid decomposed In m.m. in diameter and 63 m.m. long ; brass bob, 38 m.m. by a molecule of copper sulphate in gaseous mixtures of in diameter and 57 m.m. long.
similar composition at the same temperature depends on I have had one of these pendulums attached to an how often the gaseous molecules pass through the sphere astronomical clock, and after adjustment it has been of action of the copper salt. running four months with very satisfactory results.
2. At all speeds of the gaseous current in long tubes of Should this form of pendulum prove itself constant and the same section, the opportunity for action in one and correct, it would certainly be a convenient one for trans- the same time is invariable. portation, and very much less costly than the ordinary 3. In long tubes of different sections the opportunity of form. And as for the half-second pendulum, in such action is equal when the velocities of the currents are constant use in mantle clocks, it will be of the greatest inversely as the squares of the diameters of the tubes. service, and not add more than 20 cents cost to the com
4. In porous masses the efficacy increases directly as monest form of pendulum that can be used.
the speed. As regards the unisormity of the coefficient of expan. 5. Other conditions being equal the quantity of hydro. sion of all vulcanites, of course it is not to be supposed chloric acid decomposed varies as the square root of the that it can be relied upon; but a very simple method is number expressing the proportion of the hydrochloric acid used to ascertain it for any single specimen, or for a num- and oxygen. ber made of the same lot of material.
6. At very high temperatures a certain quantity of I have made experiments on several different specimens, chloride of copper is formed, but its amount stands in no and the results vary little from each other. The range of proportion to the chlorine liberated. temperature with which the experiments were made was 7. The efficacy of the copper salt extends to gas mole. from zero to 43° C., on a bar 25 m.m. in diameter, and cules not in contact with the salts; the decomposition of 304 m.m. long, this expanding in length 9 to 10 m.m.; the hydrochloric acid takes place, therefore, under condimaking the entire expansion equal to 1-126th of the entire tions in which a material exchange between the copper length of the rod for a temperature ranging from freezing- salt on the one hand and the hydrochloric acid and air on to boiling-point, giving as coefficient for linear expansion the other cannot take place. for 1° C. O'000079365. This coefficient is seen to be lower Without entering upon the experiments made to explain that that of mercury: but from the fact that mercury cor: the efficacy of the copper salt we turn to the method of rects the pendulum by only one-half its expansion, and the practical execution of Deacon's process as hitherto the vulcanite is made to correct it by its entire expansion, carried out. the length of vulcanite required is even less than the
The hydrochloric acid is either prepared from salt and column of mercury used in the mercurial pendulum. This sulphuric acid in a common salt-cake furnace or from instrument is one whose use depends on its accuracy of previously prepared aqueous hydrochloric acid. On a operation after careful trial for some time.-American small scale the latter is preferable, as in this manner it is Fournal of Science and Arts.
easy to produce a current of hydrochloric acid of always equal strength, whilst the evolution of hydrochloric acid in the preparation of salt cake is very rapid at first, and
subsequently becomes slow. On the large scale this REPORT
difficulty is met by allowing several salt-cake furnaces to work in a series, so that when the evolution slackens in
one, the activity of the next commences. The gas obDEVELOPMENT OF THE CHEMICAL ARTS
tained in one or other manner is at once mixed with a DURING THE LAST TEN YEARS.* quantity of air containing more oxygen than suffices to
convert all the hydrochloric acid into chlorine. It is then By Dr. A. W. HOFMANN.
conducted through heated U-tubes of cast-iron, which (Continued from p. 55.)
communicate to it the temperature required for the pro.
cess. The composition of the gaseous mixture can be Chlorine, Bromine, Iodine, and Fluorine. regulated at any moment by a small air-pump which, at By Dr. E. Mylius, of Ludwigshafen.
every piston stroke, drives a certain volume of gas through
a standard solution of soda coloured with litmus. DEACON observed that the decomposition between hydro- From the heated tubes the gaseous mixture passes chloric acid and oxygen takes place at a far lower tempe- downwards into an almost cubical tower whose interior rature if the gaseous mixture, instead of passing simply is filled with wall-stones arranged like a grating, and through ignited tubes or over porous substances, is con- whose sides are traversed by flues, which keep up the ducted over heated salts of copper, lead (except the temperature favourable for the process. The heai here, as sulphate), or compounds of manganese. The copper in all other parts of the apparatus, is regulated by metallic salts were found most effectual, so that when a mixture of pyrometers. The tower fitted up with stone blocks (the hydrochloric acid with an excess of atmospheric air was | Regulator) serves to take up the excess of heat from the passed over porous bodies saturated with sulphate of gaseous mixture, if the temperature has been carried too copper and heated to 370° to 400°, all the hydrochloric high, or to impart heat to it if the proper degree has not acid was burnt to chlorine and water. In this reaction, I been reached. Recently, however, Deacon considers the which begins at 260°, the sulphate of copper remains i regulator as unnecessary. unchanged if the temperature is not raised too high. Not
(To be continued)
Henry Deacon. " On Deacon's Method of Obtaining Chlorine * "Berichte über die Entwickelung der Chemischen Industrie Illustrating some Principles of Chemical Dynamics." Chem. Soc. Während des Letzten Jahrzcaends."
Journ., 1872, 725.