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March 28, 1879.
after Professor Church had left, and as the College has THE CHEMICAL NEWS. frequently been deft in the charge of two, the argument
thai Professor Church's proposal for non-residence would
unduly disturb the present organisation of the College VOL. XXXIX. No, 1009
carries with it very little weight.
The consequences of the resignation of three senior Professors, the only University men, by the way, in the College, cannot be otherwise than disas.rous. AC
the end of this term the senior Professor will b: a young THE ROYAL AGRICULTURAL COLLEGE, man, who only two years ago was a student himself, and CIRENCESTER.
he will very possibly be called on to rule over students who are his seniors in years, an anomaly which cannot
fail to bring about unpleasant consequences sooner or Professor CHURCH's connection with the Royal Agricul. later. tural College will, we regret to say, shortly be severed, We hear that a new bye-law has just been promulgated the only reason being, as far as we can ascertain, that he for the well-being of the future Professors. They are not is about to marry, and therefore will be unable to reside to engage in any literary work without special leave from in the College. Seeing, however, that his immediate pre. the Principal; in other words, they must take no steps decessor was non-resident, we should have thought the to make a reputation outside the College walls without Council would have hesitated to adopt this as their reason the express permission of their ruler. Had this rule for depriving the College of the services of so able and obtained during Professor Church's Professorship how experienced a chemist as Professor Church, and we shall many valuable contributions to scientific literature would jook with some eagerness for their explanation of the have been lost. circumstances.
Such restriations will certainly prevent any man of It appears that at the beginning of February Prof. Church, worth from accepting a position in the College. The who has occupied the Chair of Chemistry at the College for Principal may, it is true, gather round him a knot of the last sixteen years, had an interview with the Principal, second or third rate men; but the interests of the College the Reverend John Constable, and informed him of and, indeed, of agriculture generally, must necessarily be his intention to marry during the coming vacation, and of injured thereby; indeed, we do not see how the College henceforth discontinuing to reside in the College. This can escape collapse and ultimate extinction is something intimation the Principal regarded as a resignation of the is not done either by the Government or the bondholders Professorship, and wrote to Professor Church accepting to prevent such a catastrophe. the resignation. In answer to this letter, Professsor Church On looking over the list of Professors that have formerly informed the Principal that if he decided that his Chair occupied Chairs in the College we find that Principal became vacant by the fact of non-residence it would there. Constable has made no less than twenty-two within the fore become vacant at the date previously mentioned, last fifteen years, more by many, we should imagine, than April 24th. He furthermore assumed that this decision any other man in a similar position has made in his whole was that of the Governing Body of the Colleze, as he was liłe. Professor Church has remained at the Coilege elected in 1863 under the bye-law then in force, which for sixteen long years, but most of the others have left placed the power of appointing and dismissing Professors but little trace behind them. Again and again have first in the hands of that body, and not under the twenty-fourth class men been engaged, but there has never been any bye-law of 1870 (vide Chemical News, vol. xxxix., p. 105), inducement held out to them to cast in their lot with the by which this power was vested in the Principal. The College. matter was then referred to the Committee of Management, A contemporary gives the Principal the credit of having and on the 5th of March the following resolution was made the College pay, the bondholders having of late passed :
received a four per cent dividend, and something has been " The Committee of Management are of opinion that done towards paying off the loan, but this has only been the discipline of the Agricultural College cannot be satis-accomplished by raising the fees from £90 to £ 126, by factorily maintained except by the residence of the Pro discontinuing the farm which some authorities consider fessors within the walls of the College in conformity with to be a breach of the provisions of the Charter, the sale the original bye-law No. 47. Being fully s:nsible of the of the steam plough, and the most pernicious economy services rendered by Professor Church during his sixteen in every direction. Nothing is spent on the Museum, and years' residence in the College, they the more regret that nothing in several departments for specimens and appaihey cannot accede to his recent proposal of non-residence; ratus. To have a good surplus every year is no doubt a compliance with it involving such alterations as would gratifying to the Council and bondholders, but even gold unduly disturb the present organisation of the College may be purchased at too high a rate. staff.”
We feel sure, in conclusion, that our readers will join This decision has not only deprived the College us in expressing our sincere sympathy with Professor of the services of Professor Church, but of_those Church and his colleagues at thus having to sever them. of his two senior colleagucs, Professors Lloyd Tanner selves from an institution with which they were so long and Fream, who have respectively vacated the Chairs of connected, and to which they had rendered such valuable Mathematics and Physics and Natural History as a pro services, as well as in paying a just tribute of admiration test against Professor Church's unworthy treatment. at the man'y, straightforward, and honourable course
The bye-laws of the College which we published in the they have taken. Chemical News are perfealy unique in their way, and would seem to show that the Principal entirely supersedes the Committee of Management. He evidently considers that Progress Effected in the Preparation of Colours the Scudents of the College are a set of unruly schoolboys Derived from Coal.-Adolphe Kopp.—The attempts who are only to be kept in order by the striatest discipline, made to dispense with arsenic in the manufacture of and that the Professors must lead the life of monks. They magenta have only been partially successful. The proare not only to devote themselves day and night to the cess of Coupier, who causes nitro-benzol to react upon a service of the College, but they are to act the much- mixture of aniline and toluydin in presence of hydro. despised part of the “pion," or maitre d'étude of a French chloric acid, is adopted in some manusactories, but it Lycée, and see that their young charges do not tear their offers serious difficulties which interfere with its general clothes, tell fibs, or say naughty words. But as three employment. It is more costly and more difficult Professors would have still been left to reside in the College I manage.-Moniteur Scientifique.
March 23, 1879. FILTER-PRESSES FOR CHEMICAL WORKS. able is proved by the fact that in the manufac.
ture of china and faience the cakes of clay coming out By J. MÁRZELL.
of the presses never can be used on the chairs before
having passed cutting and kneading machinery, as in In this time of depression of trade it is natural that che. baking the air would form bubbles on the goods. In the mical manufacturers should pay more attention to those washing process the air prevents the wash liquor from kinds of apparatus which, by a surer and better working, a thorough penetrating of the cakes. The water coming enable them to increase the yield, and permit quicker pass- from above would not remove but only dislodge the air. ing through the intermediate stages of the processes, thus | The consequence of that was the conclusion to let the giving to a plant a higher working power and efficiency. wash liquor enter at the bottom and make its way Among that class of machinery the so-called “filter- upwards, driving thus the air before it, which is removed presses” undoubtedly hold one of the foremost places, by a system of air channels and escapes, with a whistand their being taken up so rapidly--especially in the last ling noise, out of a mouthpiece. year-surely speaks in their favour.
The other disadvantage of the old system was the fol. The principle of the filter-presses is generally known ; lowing :—The water entered on the upper edge of the it is a filtering under pressure, for the object of
cake in two streams of about 4 in. thick. By the pres(a) Filtering the largest possible quantity of Auid...con naturally tried to find the most direa way to the outlet,
sure the washing was applied and the two streams sequently solids in comparison-through the smallest possible filter
and that is the line drawn from their point of entrance to space. (6) Freeing the residue remaining in the filter as much the outlet cocks! Besides that, the way was regulated by as possible from the filtrate.
the little air-bladders forming a regular kind of network
in the cake. The result was that the streams, instead of Both points are realised by the pressure applied in filling equally impregnating the material, only parted themselves the filter-presses, and generally amounting to 120 lbs. per in the cakes, so to say, forming a system of small rivers, square inch. At the same time the filter-press represents the islands of which never came under the influence of the most convenient arrangement of filter cloth, as a very the water. large surface is brought into a very small space. In the To do away with this irregularity M. Dehne covered largest size presses over 425 sq. feet effe&ive filtering the channelled surfaces of the press plates inside, the surface are arranged in a box, if I may call it so, of 43 sq. chambers with perforated sheets of metal, and now in st. to 9 sq. ft. General rules of yields cannot be laid down, washing brought the water into the space formed between as specific gravity and physical properties of the different the channelled surface and the perforated plate. Thus on stuffs are important points to deal with. The greatest both sides of the cakes in this way walls or plates of water difficulty for chemical works always was to find a press are produced, which by the hydraulic acting pressure are suiting the different stuffs and operations, as these in most driven diametrically into the cakes. With a cake of 1 in. cases cannot be altered or modified without losing on the thick the water has only to moved in. to join the liquor other side all advantages the filter-presses might have pro: coming from the other side. As the air has been removed mised. It was therefore only natural that the massive and beforehand, each molecule of the stuff in the presses is enormous wooden cubes brought out at first, with their now brought into contact with the water, which thereby elaborate handling, had soon to make room for lighter has full power to take up all soluble particles. The constructions, with a number of improvements in many arrangement allows at the same time to regulate the directions.
pressure under which the extraction takes place. An important improvement has recently been made by
So far the theory. The practice, by working on large M. A. L. G. Dehne. I refer to a new arrangement scales under different circumstances and with different for an absolute outwashing of the press cakes in the materials, has given the best results. press itself under the following conditions :
As example I give the returns of the K. K. Zucker. (a) To use as little wash water as possible.
fabrik Swolonowas (Austria), which were kindly placed at (b) To remove the last traces of soluble substance out my disposal. The material is the product of precipitating
of the cake, to wash absolutely or completely- saccharate of lime with carbonic acid, thus yielding car-
“ The presses are such with 18 chambers of M. Dehne's,
Filling of press 30 minutes; washing absolutely = concentration for crystallisation (as with sugar, 18 minutes ; emptying and starting = 6 minutes ; together
citric, tartaric acids, alum, sulpho-salts, &c.) 54 minutes. (c) To do all that in the shortest time possible.
The weight of the extracted cakes out of one press, In the old method of washing the water was introduced 315 lbs. (157 k.); the cakes are hard.
The extracted cakes were entirely free from sugar. on the top of the cakes, trickling through the same, taking up in its way the soluble substances it met with,
The quantity of wash-water used for one press = 39 and leaving the press by the cocks. Every manufacturer gals: (176 litres): Density of the entire wash-liquor acquainted with these presses will have found that it takes 5*23° balling and 4'11 per cent sugar. a long time, and is seldom possible, to remove the last
The filter cloth has not to be removed for a fortnight. parts of soluble stuff, and therefore it was preferred in (This for the season in the arrangement that the washmany cases to take out the cakes, boil them up with liquor takes the opposite way of the filtration, thus always water, and to re-filter-press them; in many cases even
cleaning the pores of the cloth.-J. M.) The firm receives repeating the operation several times.
daily 131 tons (13,627 k.) of the washed-out residues. The The reason of this improper acting of the washing ap. 2.46 per cent of sugar, which it was not economical to
corresponding residues of the old presses retained about paratus is the insufficient distribution of the wash liquor regain, and the firm reckon the net gain they have by in the cakes, caused
putting up Dehne's new presses with absolute extraction (a) By the construction.
with 471 tons (47,400 k.) of sugar in a campagne of 150 (b) And principally, by the air enclosed in the cakes. days, representing a value of £ 1422 (14,220 Austrian Especially is this last point of great importance. florins). That the amount of air in the cakes is consider. The quicker working and the advantage of getting pretty
March 28, 1879.
129 concentrated liquors into the evaporating pans need not being at the edge of the cut or bruise. So, too, in the be mentioned.
living plant, when some injury accidentally occurs to a Another example. The quick extraâion of valuable leaf, the part injured will appear blue. Nothing can be cakes is given in the manufacture of the artificial alizarin more natural than to suppose that in these cases the blue material ; alizarin paste must be freed from the sulphate colouring-matter is formed by the action of the air, i.e. by of soda. With the old presses the washing was the oxidation of some substance which escapes from the going on twelve to fourteen hours before the charge of a cells in consequence of organic lesion, just as the surface press with 18 chambers was finished. The new presses of a freshly cut apple or pear becomes brown on exposure. with absolute extra&ion-according to the returns of an If a plant of Polygonum tinctorium be immersed in alizarin works using twelve of these new presses-only water, and the water be frozen by surrounding the vessel wanted 35 to 45 minutes for the absolute neutralisation of containing it with a freezing-mixture, it will be found, a properly precipitated paste. In this case a secondary after complete thawing, that the leaves or parts of leaves but important advantage of the new process can be seen. which have been throughly frozen appear of a dark colour In washing there is always some alizarin taken up into and are quite faccid; and if the plant be then immersed suspension and washed away, especially in the last hours, in boiling alcohol so as to dissolve the chlorophyll and when the water is running pretty clear. As with the new other matters, those very parts show afterwards an inpresses the time, as well as the quantity of water, are tense blue colour, while those portions which had remained decreased considerably, this loss is reduced to a minimum. unfrozen appear almost colourless. This experiment, Of great weight this point is in the treatment of such sub- which had already been made by Joly, was considered by stances, which themselves are slightly soluble in water. him to prove the pre-existence of indigo-blue in the I only mention tartrate of lime.
plant—though why, if this were the case, the colouringNotwithstanding their short life the new presses with matter should not make its appearance in the unfrozen absolute extraction have been taken up by a great many portions of the leaf, I am at a loss to understand. firms. Like most new things they have often to meet The fact that a fresh leaf of Polygonum tinctorium, if with mistrust and criticism in sometimes the most incom- immersed in alcohol or ether, appears blue after the chlo. prehensible form. From the representatives of progress, rophyll has been removed, has also been considered to however, “ the go ahead people,” the new apparatus prove the pre-existence of indigo-blue in the cells. This everywhere meets with the greatest interest and acknow. phenomenon is always observed when the leaves are imledgment of its practical advantages, and the large nummersed in cold alcohol, and more distinctly when ordinary ber of these presses already delivered to various branches spirits of wine are taken than with absolute alcohol. Á of different countries may be proof of their value. very simple experiment suffices, however, to prove that 41, Woburn Place, London, W.C.
in this, as in all the other cases, appearances are deceptive. If freshly gathered leaves of Polygonum tinctorium are plunged at once not into cold, bu: into boiling alcuhol, the
whole of the colour is soon removed, the leaves retaining ON INDIGO-BLUE
only a faint yellow tinge. On now simply evaporating
the green alcoholic liquid, not a trace of indigo-blue will FROM POLYGONUM TINCTORIUM AND OTHER
be found in the residue. It is therefore absolutely certain
that the leaves contain no ready-formed colouring-matter ; PLANTS.
for so stable a body as indigo-blue could not possibly be By EDWARD SCHUNCK, Ph.D., F.R.S.
decomposed or be made to disappear by the action of (Continued from p. 120).
boiling alcohol only. It must necessarily appear either in the alcoholic extract of the leaves or in the residual portion
left by the alcohol. The preceding experiments lead to the conclusion that A very simple explanation offers itself, I think for all the leaves of Polygonum tinctorium contain a substance the phenomena hitherto observed. Indican, the mother not to be distinguished from the indican of Isatis tinctoria, substance of indigo-blue, is a body the molecules of which which by decomposition with acids, yields indigo-blue and are in a state of unstable equilibrium. As long as it is glucose, accompanied by some by-products, and that there contained within the cells of the plant the vitality of the is no proof of the existence of ready-formed colouring. | cells keeps it in its original unchanged condition. As matter in the plant while the latter is living and in a soon, however, as this vitality is destroyed (whether by healthy state. The pre-existence of indigo-blue, or of its organic lesion, by extreme cold, or by any other meansi, hydride, indigo-white, in these plants was taken for granted the indican begins to undergo decomposition, the mole. forty or fifty years ago when the class of bodies which we cules rearrange themselves in the order to which their che. now call glucosides and the peculiar kind of decomposition mical affinities predispose them, and the compound splits which they undergo were unknown. Even now a superfi- up into indigo-blue and indiglucine, this taking place so cial examination of some phenomena would almost cer- rapidly that in certain cases it would appear as if the tainly lead to the conclusion that the indigo-blue is formed colouring-matter pre-existed in the plant. (to take the by the action of air, i.e. in conseqence of the oxidation of simplest case) the leaves as soon as gathered are immersed some easily oxidisable substance in the plant, Bearing in cold spirits of wine or in cold ether, the vitality of the in mind, however, with what extreme facility indican is cells is thereby destroyed; and the indican contained in decomposed, its watery solution on standing some time, them is then in part decomposed, yielding indigo-blue, even at the ordinary temperature, depositing indigo. blue, I which remains undisolved, imparting a more or less dis. think it will nct b difficult to explain all the phenomena tinct blue tint to the leaves. When boiling spirit of wine hitherto observed by myself and others.
is taken, the indican is extracted before it can undergo de. On taking a plant of Polygonum tinctorium and making composition, and dissolves in the spirit. It may be deincisions with a penknise in the leaves between the main tected in the residue obtained on spontaneous evaporation vessels, or crushing the soft parts of the leaves here and of the alcoholic extract by its property of yielding indigothere with an agate pestle, then, after a short time plung- blue on decomposition with acids as above described. It ing the whole plant into boiling alcohol to remove the is posible that the leaves contain some ferment which chlorophyll, it will be found that those parts of the leaf hastens the decomposition of the indican as soon as which have not been injured, become white or retain only | vitality has ceased; but I have no positive evidence to a faint yellow tinge, while those parts that have been cut, offer in favour of this view. crushed, or otherwise injured, show a blue colour, the I may, in conclusion, describe another experiment, which, colouration extending for some distance inwards from the though it teaches nothing new, confirms what I have just place where the lesion occurred, the most intense colour stated, and is interesting in its way. Having cut some
March 28, 1897. sprigs of Polygonum tinctorium, about six inches long, I, this is found, however, not to be the case. The colouring. immersed the cut ends in dilute hydrochloric acid (con- matter is discovered within the cells of the parenchyma sisting of one part of acid of specific gravity 1'15 and ten in the shape of separate dots and parcels ot various sizes, parts of water), and left them to stand for several days and apparently in an amorphous state, the cell.wall being exposed to the sun and air. The acid was gradually quite colourless. These dots and parcels being very absorbed, ascending through the stems, first into the numerous, produce, when seen in the mass, a uniform lower leaves, then into the higher ones. The gradual blue colouration, more or less intense. The darker colour absorption of the acid was distinctly seen by the dis- of some leaves is simply the effect of a greater crowding colouration of the leaves, which commenced at the basis of the blue particles in each individual cell, the cells of of each leaf and extended towards the apex, the lively the paler leaves containing fewer of these little masses, green colour being changed into a dirty yellow. After some sometimes hardly any. time this colouration was followed by a dark blue one, Mr. Charles Bailey, to whom I gave some specimens of commencing at the base of each leaf and extending leaves of Polygonum tinctorium coloured blue, had the towards the apex, but never quite reaching the latter kindness, at my request, to submit them to microscopic except in the lower leaves. When the change in colour examination, and gave the following as his opinion had begun to show itself in the upper tenderer leaves, the thereon :whole showed symptoms of fading, all further power of “ The colouring-matter lest in these specimens would absorbing the acid liquid seemed to be lost, and the sprigs seem to be what Nägeli terms.crystalloids;' and, with one were then at once immersed in hot spirit of wine. After re- exception, these bodies are, as far as my examination has maining in the spirit until the chlorophyll was removed, gone, confined to the interior of the cells of the parenthe part of each leaf which had undergone a change chyma. I do not see the least trace of ny of this appeared blue, whilst the part into which the acid had not colouring-matter occurring in the intercellular spaces. penetrated appeared almost colourless. In this case it is the only part of the tissue where I find it, other than the probable that the indican was decomposed not so much in parenchyma, is in the cells of the stomata; but it occurs consequence of the loss of vitality in the cells as by the nowhere else in the cuticle." direct action of the acid. In some of the leaves there was
(To be continued.) another distinct blue colouration towards the apex, in the part to which the acid had not penetrated, separated from the blue part at the base by a white zone. This second colouration may be attributed to the loss of vitality in that part of the lear.
PROCEEDINGS OF SOCIETIES. All these experperiments must be made with plants whilst in a state vigorous growth. If made when the season is advanced (ihat is, oster the flowers have begun
CHEMICAL SOCIETY. to appear), the leaves, though apparently unchanged, show only iraces of blue colour after treatment and subsequent
Thursday, March 20, 1879. immersion in hot alcohol. This shows either that the indi. can has disappeared, being applied to other purposes in Dr. J. H. Gladstone, F.R.S., President, in the Chair. the economy of the plant, or that it has undergone the peculiar molecular change before referred to, into a sub. After the announcement of visitors the minutes of the stance which no longer yields indigo.blue by decomposi- previous meeting were read and confirmed. The following tion, but indirubine and other products. The latter is the certificates were read for the first time :-W. Johnstone, more probable way of accounting for the difference; lor | W. B. Turner, C. Slater, T. Palmer, A. H. Black, W. A. the parts of the leaf which have been accidentally injured | Bradbury. by the bites of insects or from other causes at the later
The President then called on Dr. FRANKLAND to read stage of the plant's development become red, not blue, as at the earlier stages. This red colour disappears on im
a paper on “ Plumbic Tetrethide," by E. FRANKLAND and mersion of the leaves in hot alcohol, the indirubine, to
A. LAWRANCE. This substance was discovered by Buckton which it is probably due, being more soluble in that
in 1859. The authors prepared the compound as follows:menstruum than indigo-blue.
Plumbic chloride is added to zinc ethyl contained in a The leaves of Polygonum tinctorium in which the blue
stout glass bottle as long as any reaction takes place. colour has been developed by any of the means described; and distilled (from an oil bath) in a current of steam.
The product is mixed slowly with a large volume of water, exhibit even to the naked eye, and still more distinály | The distillate separates into water and a heavy layer of when examined under the microscope, certain appearances plumbic tetrethide. During the preparation no gas was which are not without some interest.
1. The colouring.matter seems to be confined to the evolved, and the authors infer that the decomposition parenchyma of the leaf. The stem and its fibrous raini has two stages, PoCl2 +2ZnEt2=PbEt2+2ZECI and fications in the leaf are free from it, so that in the 2PbEt?= Pb+ PbEt4. The following gases have no action coloured leaf the vessels may be distinály traced as white monia, carbonic anhydride, carbonic oxide, cyanogen,
at ordinary temperatures on plumbic tetrethide :-Am. veins on a blue ground. Even the cells of the parenchyma nitric oxide, oxygen, sulphuretted hydrogen. Sulphurous adjacent to the vessels are much less coloured than those a little further off, which produces the effect of a gradual anhydride is rapidly absorbed and the liquid plumbic shading of colour from the white of the vessels to the tetrethide converted into a white amorphous solid. dark blue of ihe remoter cells. The cells of the leaf- This product was placed in a beaker, over which was in. cuticle are also free from colouring-matter.
verted a second beaker, the two being luted with gummed 2. The younger leaves at the summit of each branch paper. On heating the lower beaker with steam, crystals generally show a more intense colour than the older ones sublimed, which, after purification from a volatile lead near the base. Each leaf probably contains the same compound by treatment with strong nitric acid, evaporaamount of colouring-matter ; but in the lower leaves it is in chemical composition and physical properties to be
tion to dryness, and re-crystallisation from alcohol, proved more widely distributed.
The residue 3. The intense and apparently uniform colouration of identical with diethyl-sulphone, so2Etz. some of the leaves might lead to the conclusion that the after the sublimation of the diethyl-sulphone consisted cellular tissue is itself dyed blue-which would not seem
principally of plumbic ethyl-sulphinate, improbable considering the affinity which indigo-blue shows for cellulose, as seen in the blue-dyeing of cotton
SOET fabrics. On examining the leaf-cells under the microscope, ! Ethyl-sulphinic acid may be considered as sulphurous
March 28, 1879.
131 acid, SOHO2, in which a semimolecule of ethyl has re- , were also made with sealed tubes. The authors conplaced one of hydroxyl, SOE:HO, or as propionic acid in clude that sulphur decomposes water, uniting both with which one atom of tetrad-sulphur has been substituted its oxygen and hydrogen, the decomposition being indefor one of carbon
pendent of atmospheric oxygen. The authors repeated C2H5 (C2H5
iheir experiments with sulphur purified by treatment with 1 соно sono
potassium permanganate, and find that the reactions above
described remain unaltered. Selenium and tellurium have No volatile organo-metallic base was detected in the pro. an appreciable action on water at 160°. Amorphous duct of the action of SO2 on PbEta similar to that produced phosphorus does not decompose water at 100o. At 160° a in the corresponding reaction with stannic ethide. small quantity went into solution. When lead acetate In answer to a question of the President,
solution was substituted for water, metallic lead, phosphate, Dr. FRANKLAND said that plumbic tetrethide could be and phosphide were formed. With copper sulphate prepared directly without the intervention of zinc ethyl, metallic copper was deposited with phosphide and sulbut the product was small in quantity and impure. phide, phosphoric and sulphuric acids being also formed;
Prof. W. Foster then gave a verbal communication cupric chloride at 160° is first reduced to cuprous chloride, " On the Production of the Higher Oxides of Iron; phorus does not decompose boiling water except in the
and finally converted into a phosphide. Vitreous phosChromium, Manganese, and Bismuth.” Prof. Foster said that the observations he had to make were a continuation Solutions even when oxygen is excluded. \Bromine and
presence of oxygen; it reduces metallic (lead acetate) of a paper which he had recently communicated to the iodine, when heated with excess of water, dissolve in Society. When a strongly alkaline solution of sodic small quantity as alkaline bromides, bromates, &c. If hypobromite is heated with a solution of potassic ferro- bromine be treated with lead acetate, lead bromide and cyanide the solution rapidly becomes deep red from the dioxide are formed. formation of a ferrate. Almost any iron compound, and even freshly precipitated ferric hydrate can be substituted observed that gypsum was formed by the action of calcium
Mr. WARINGTON remarked that an Italian chemist had for the ferro-cyanide in the above reaction. The author carbonate on sulphur in the presence of moisture. has not attempted to isolate the potassium or sodium ferrate formed under these circumstances. Similar reac. The next paper was read by the Secretary, "On the tions occur if manganese, chromium, or bismuth com. Volumetric Determination of Chromium,” by W. J. Sell. pounds be boiled with alkaline hypobromite, perman. The author having discovered that chromium in ordinary ganate, chromate, &c., being formed. Oxygen is evolved chromic salts can be completely converted into chromic during the reaction. Cobalt
, nickel, and copper salts also acid by means of potassic permanganate, endeavoured to evolve oxygen. The author demonstrated this fact in the apply this reaction directly for the estimation of chromium. case of cupric sulphate, a considerable quantity of oxygen He was, however, unsuccessful, owing to the separation being collected when the sulphate was mixed with alkaline of manganese dioxide. He has devised the following hypobromite, and the mixture heated to about 20°C. method, which yields rapid and accurate results. The
Dr. Wright said that some samples of bleaching solution, containing chromium acidified with sulphuric powder when closely stoppered were apt to explode: (he acid, is boiled, and a dilute solution of permanganate had always found manganese in these samples). Possibly added to the boiling liquid until a purplish tint remains this might be accounted for by the evolution of oxygen by after boiling for three minutes. The solution is then a reaction similar to that described by the author. rendered slightly alkaline with sodic carbonate, alcohol is
Mr. Neison asked if Prof. Foster had noticed any for- added, and the manganese filtered off. The chromic mation of a green manganate in the oxidation of man- acid in the filtrate is estimated by titration with iodine ganese compounds. Some time since he was working and sodic thio-sulphate. The author has successfully with ferrates, and obtained once a green iron acid which applied the method to the estimation of chromium in he had never seen since. Perhaps by these reactions it chrome iron ore. He recommends the following plan of might be obtained.
effeciing its decomposition. The chrome iron ore is Mr. Hartley had noticed that when the copper sulphate placed on the top of about ten times its weight of a mix. and alkaline hypobromite were first mixed the solution ture composed of one molecule of well-fused and powdered turned yellow, but when the evolution of oxygen ceased sodium bisulphate to two molecules of sodium fluoride, the liquid was quite dark. This yellow substance was and the whole is ignited for fifteen minutes. An amount probably Brodie's cupric peroxide.
of sodium bisulphate is now added equal to that of the Mr. Kingzett had made some experiments on the mixture taken, and when thoroughly fused a further addiaction of oxide of manganese on bleaching powder; oxy- tion of an equal quantity of bisulphate is made, the mass gen was evolved, but the gas was not pure.
fused, and then rapidly cooled. The fused mass so obProf. Foster, in answer to a question of the President, tained dissolves completely in boiling water acidified with said that he had not tested the oxygen evolved quantita- sulphuric acid. In this way a determination can be made tively as to its purity.
in an hour and a quarter. The author's attention has The next paper was read by the Secretary, “On the been directed to a notice by Mr. Wanklyn in the Phil. Decomposition of Water by certain Metalloids," by C. F. Mag., February, as to the conversion of chromic oxide Cross and A. Higgins. The statements of Chemists into chromate by alkaline permanganate. This result the with respect to the action of sulphur on water are con
author arrived at some months ago, but has not yet Aliding., Mulder affirms that the vapour of water reacts succeeded in applying it quantitatively. on sulphur at a high temperature to form penta-thionic
During the reading of the last paper Dr. RUSSELL acid: Myers asserts that hydrogen sulphide and thio occupied the Chair. sulphuric acid are formed. Girard also found that hydro- The anniversary meeting will take place on Monday, gen sulphide was evolved by boiling sulphur with water. March 31. The next ordinary meeting will be on April 3, Geis ascribes this evolution to impurities in the sulphur. when the following papers will be read :-"On Terpin and The authors therefore investigated the reaction of sulphur Terpinol,” by Dr. Tilden ; "On the Transformation of with water. Water containing “flowers of sulphur” in Aurin into Trimethyl-para-rosanilin,” by R. S. Dale and suspension was boiled, and the vapour conducted into C. Schorlemmer; “On a Gold Nugget from South lead acetate. The latter was continuously decomposed | America, by Mr. Attwood; “On the Solution of Aluwith the formation of sulphide. The quantity formed minium Hydrate by Ammonia, and a Physical Isomeride under various conditions was estimated. The reaction of Alumina,” by C. F. Cross. which occurs is probably 2H2O+Sz=2H2S+SO2. If air be present sulphuric acid is also formed. Some experiments