ISSN:0003-2654    

DOI:10.1039/AN87702FP037

出版商:RSC    

年代:1877

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN87702BP039

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

THE A N A L Y S T . ORGANIZATION AMOSGST CHEMISTS. WE are not surprised that the article which we published last month under the abore heading should have called forth remarks on the part of two of our contemporaries, namely the Chemical News, and the Pharmaceutical Journal. We took some pains to point out in that article certain defects, which appeared to us to be self-evident in the organization scheme as at present proposed, and our remarks naturally invited comment or assent.The C7hemical News of the 14th September, devotes a column to the consideration of the subject, and except that the article does not go far enough, we agree with nearly all that it says. The main point to which it draws attention is the fact that certain persons are--or a certain person is-offering by means of circular or letter to perform commercial analyses for ridiculously low sums ; we know this is so, and the circular referred to is before us, and we quite agree that if analytical chemistry is to be prac- tised upon such terms, (‘ stone-breaking is of the two the more respectable profession.” But on two points we differ from the Chemical News.We do not think it is one or two men only who are guilty of this kind of unprofessional and unhsiness-like conduct.On the contrary, v e fear that it is a much larger number of men, some of whom occupy a respectable position in chemical society, who in ordor to fill up their so-called spare time, or more likely to utilige according to their own views the services of some one or two of their pupils are working at these low rates; therefore we again differ from the Chemical News, in that we think that the Institute of Chemistry, as a t present proposed, will do nothing whatever to remedy this grievance, if indeed a grievance it be : because among the Committee of the Institute of Chemistry itself are, if our correspondents inform us correctly, some of the most notoriously under-bidding men in the profession. Besides the advertisements from other members of the Committee to which me have already from time to time referred, we have as we write one lying befor5 us, offering to nnalyse starches or arrowroots, for the modest sum of half-a-crown.The other charges are correspondingly moderate. It is hardly likely, that while the heads of the profession, as we suppose we must assume the members of the Committee consider themselves to be, do such things as these, the men whom they are going to organize will do much better.The article in the Plz~maceutiealJo.urnal is a singular one. We wish we could stop at singular, but it mis-quotes UB. The Phurmaceutical Journal says, “ THE ANALYST 11 grants that the Committee of fifty, which had the care of the child institute, was (6 an able body, the most clever, the most competent, and most successful chemists in ( 4 the country.” THE ANALYST granted nothing of the kind; on the contrary, the words which we used were, “nevertheless these ‘private’ ‘general’ meetings have been held, arid 4 ‘ the gentlemen attending them have appointed a Committee of some fifty of their “friends to carry the scheme through-mistake again. These fifty may be, and perhaps ( 6 are the fifty most clever, most competent, and most successful chemists in the country.” The sentence did not need to be looked at twice to be seen that our meaning has been perverted.However, t,o make it perfectly clear and unmistakeable, we do nut tlzinlc that these fifty are the most clever, the most competent, and most successful chemists in the “country;” on the contrary, we think that the selection was in many cases an unwise one.110 THE ANALYST.Now having referred to a mis-statement which we are sure our contemporary will regret, we will proceed to deal with the other points in the article, and also with some further points relating t o the Institute itself.The Pharmaceutical Journal calls the article which we wrote on the subject, a ‘‘ funny article.” It is hard to conceive of a worse description; we were writing seriously, and there was nothing which could possibly justify such a remark. It also objects to our definition of Professional Chemists, because it thinks that we are wrong in putting in the wordg, t b purelr by the practice of Professional Chemistry, as distinct (I from Pharmacy.’’ We put them in advisedly, and me adhere to them.I f this organization is to be, or is to do anything at all, it must appear at once in its proper light, and that light, call it what they may, is simply and solely that of a Trades Union. Ncw it would be absurd to taik of a Trades Union embracing both civil engineers and machine makers, and equally absurd of one embracing both professional chemists and pharmacists, and still worse to speak of one embracing professional chemists? phar- macists, and scientific amateurs; therefore we say that the members mnst be limited strictly to those who earn an income by Professional Chemistry, as distinct from Phar- macy, and i f the Pharmacezctical Journal would wish us to add it, from every other branch of scientific or semi-ecientific work.The remark that there is hardly a man in all England who earns an income purely by the practice of Professional Chemistry is feeble, and most probably there has been a printer’s mistake here, and the writer meant to say that there are but few men on the Institute Committee who earn an income by Professional Chemistry, because we could point without difficulty to a dozen men who have not beeri invited to, or admitted to any of the conclaves of this body, who are not only earning an income, but a comfortable living, by Professional Chemistry only.The (‘ Public Analysts-well, only Public Analysts,” of whom the Pharmaceutical Journal talks, are an almost extinct race. There is no doubt that at first when the Adulteration of Food Act came into operation, a large number of men possessing no higher qualifications for the position than the fact that they mere medical officers, or chemists and druggists in the town where they lived, did happen to be elected as Public Analysts, but experience in the working of the Sale of Food and Drugs’ Act has amended all this, and no further appointments of this kind can now be made, and even those few who had accepted the office and its responsibilities under the old Act are beginning to find out that the best thing they can do is to resign their appoint- ments, and leave Professional Chemists to carry ou the work which properly belongs to them. But those who remain are certainly entitled t o claim admission to any organization. Now learing the question of the article in the Pharmaceutical Journal itself alone, we come to the views which it puts forward, evidently as the views of the promoters of the Institute of Chemistry.I t says that we arc apparently unacquainted with the just and proper means which will be adopted in order to cause a just appreciation of mcrits and qualifications.We certainly admit that we are so ; but while admitting our ignorance on the point, we must say emphatically that there are no means which can infallibly be ueed to ensure this “just appreciation.” We know, for instance, of one man in good and successful practice who only analyses one single commercial product, and on that product he is probably the best and most reliable authority in England ; at any rate he has had the credit of carrying on a practice solely in connection with this etaple article of manufacture fur years, and supporting himself by his a o r k ; in fact,THE ANALYST.111 earning a living by Professional Chemistry as distinct from Pharmacy. How would it be possible for any of the promoters of the Institute to judge as to his merits and qualifica- tions, when his attention has been directed solely t o an article in reference to which they are themselves profoundly ignorant ! We know at least three other men, all of them mith practices of the largest character, whose business is simply and solely Consulting Chemistry in its reference to chemical manufacture; men who in fact spend the entire of their time in visiting chemical worlis, and consulting with different manufacturers, and advising them as t o the most desirable mode of working, so as to achieve the greatest economy in their fwtories.These men stand alone in the profession, and we believe that not one of them is included in the Institute. Who then is to judge as to their capacity? And again we may have one more class, and we think this class should certainly be included, the class of chemists and assistants in iron works, chemical factories, and manure factories, each of whom, in his own line, acquires an amount of knowledge and ability quite sufficient to justify the claim to admission t o the Institute; but ability of such a kiud, that no Committee could fairly or fully comprehend it, unless some of the class were included.The whole thing virtually sums itself up into this. There is only one way in which the Institute can be formed to become a success, aud that is, as we and our correspondents have repeatedly urged, to call a public meeting of every professional chemist in England, and let them elect their own Committee, and without any hesitation, we say that the Committee who would be elected would be different from those who form the present body.Apparently at present, the object of the promoters has been t o include the names of a host of their personal friends, the (( nobodies ” whom the Pl~nmaacezcticaJ Journal refers to, in order to gain all the power that they possibly could in the balloting for or election of “the gentlemen who pursue science as a profession,” and earn a Ziz$n..by it, but who ha\Te not yet been invited t o come among them. We somehow think it will be a long time before they will have to exercise their balloting powers. I n conclusion, we repeat what we hare said all along, that an organization founded on the private meetings of a clique sitting with closed doors, will never be acceptable t o the mass of Professional Chemists throughout England. Let therefore the present Committee fairly and openly call a public meeting of the analytical chemists of the country by public advertisement, and laying the proposed scheme before them, invite them all to join and assist in forming the Institute, and in electing a council, and all will go well. I f the Committee really has the interests of the whole profession at heart, as distinct from private aggrandisement, and an endeavour to injure some of their present successful competitors, they will at once accede to our proposition. If not, then the latent spirit of the promters of the present scheme will shine forth in all its true colours, as intended simply for the benefit and glorification of the few, a t the expense of the many.

ISSN:0003-2654    

DOI:10.1039/AN8770200109

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

THE ANALYST. 111 NOTE ON THE DETECTION OF STRYCHNINE. BY ALFRED H. ALLEN, F.C.S. Bead at the Meeting of the Society of Public Analysts, PZymouth, on the 17th August, 1877. IN my practice I have had a great variety of animals submitted to me t o be tested for poison. The number of cases in which strychnine has been found is probably greater than that all other cases pat together, and as I find some chemists profess a difficulty in112 THE ANALYST.applying the tests for strychnine, I believe I may do a service by publishing my method of procedure, though it has no claim to novelty, except, perhaps, in one or two details. The matter to be tested is, first of all, digested on the water-bath with water and Borne acetic acid. Alcohol is next added in sufficient amount to facilitate the filtration of the liquid.The filtered liquid is evaporated nearly to dryness, water again added, and the solution filtered. The clear liquid is again evaporated to a syrup, strong alcohol added, and the liquid once more passed through a filter, The alcoholic solution is evaporated, the residue taken up with a small quantity of water, the solution filtered, if necessary, and treated with soda in moderate excess.The alkaline liquid is next shaken wit8h ether, the etherial layer removed with a pipette and allowed t o fall-one drop at a time-into a porcelain basin, heated by hot water. I n this manner the strychnine is concentrated in a comparatively small space, instead of being spread out over a large surface. When the ether has all evaporated and the basin become cool, the residue is treated with concentrated sulphuric acid.* Bichromate of potassium is decidedly the worst, in ruy opinion, of all those commonly used.Dioxide of lead is not very satisfactory. Powdered ferricyanide of potassium gives a very good result, but requires to be used carefiilly. Finely powdered dioxide of manganese gives the best results in my hands.It should be added to the sulphuric acid in moderate amount, so as not to obscure the violet coloration, and the mixture should be well stirred. The changes of color occur much less rapidly with the manganese dioxide than with ferricganide. I have sometimes used dialysis for the original extraction of the strychnine, but a9 ths aqueous liquid requires t o be subsequently treated in much the same manner as already described, the loss of time involved is seldom accompanied by any compensating advantage. Dr. Muter said he had found that the agitation of the acid solution of the strychnine with ether, to remove indifferent matters, greatly facilitated the subsequent purification of the strychnine. bilr. Thomson had obtained good results bv preparing chromate of strychnine, and subsequently treating that salt with sulphuric acid. There is considerable choice in the oxidising agent employed. This is in some cases an advantage.

ISSN:0003-2654    

DOI:10.1039/AN8770200111

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

112 THE ANALYST. AN EASY AND RAPID METHOD OF I!JANIPULATING “FATTY ACIDS.” By A. WYNTER BLYTH, F.C.S. Read bgore the Society of P&ic Analysts, at Plymouth, 17th August, 1877. I USE an apparatus, the principle of which has long been known t o chemists, and indeed a small flask similar to the one I am about to describe is Agured in ( I Mohr’s Toxicologie,” being there recommended as convenient for the separation of the alkaloids by solvents.My flask is between 300 and 400 C.C. capacity, its neck is rather long and narrow, and is furnished with an accurately fitting stopper, through which two tubes pass, one provided with a stop cock to let out the liquid, and therefore, of course, terminating on a level with the inferior surface of the stopper, the other to let in the air, prolonged to nearly the bottom of the fiask, and externally bent syphon-like. * If any serious discoloration ensues, the basin should be heated on the water-bath for an hour or two to destroy foreign matters.The sohition is then treated with water, filtered, again rendered alkaline, shaken with ether, the etherial layer evaporated to dryness and the residue reheated with acid,THE ANALYST.113 The fat is saponified in the flask, and the soap decomposed in the usual way, when this is effected, the stopper is inserted, and the flask is turned upside down and kept in that position during the entire washing process. Directly the whole of the fat has risen t o the surfage, the lower liquid is run off, whilst hot or cold water is introduced by opening the stopper under the water, and simultaneously sucking at the syphon. Thus a11 waiting for the fat to cool is discarded, any reasonable quantity of water can be rapidly used to thoroughly wash the fatty acids, and a filter is not required.

ISSN:0003-2654    

DOI:10.1039/AN8770200112

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

THE ANALYST. 113 NOTES ON AN IMPURITY IN OXIDE OF ZINC. BY W. W. STODDART, F.C.S., &c. Read before the British Pharmaczutical Conferelzoo at Plymouth. A FEW weeks ago I had a sample of oxide of zinc sent to me for analysis. It was bought for mixing with white lead as a paint, but on being ground was found to be nearly useless. It monld not readily combine and form a homogeneous mass, as ueual, nor would it give the I n fact it was so unsatisfactory an article that i t was laid aside and another used in its stead, Some objection was raised to its being returned which caused the firm to have it examined, and the cause of failure ascertained.I have brought the subject before your notice, not on account of the peculiar impurity, but because it has a pharmaceutical interest, for it answers well to all the pharmacopaial tests for pure oxide of zinc, and yet it is impure to the extent of nearly ten per cent.The sample was nearly white with a very slight buff tint. Like the pure oxide it became a strong yellow when heated, regaining its former whiteness when cold. It was perfectly and easily dissolved in an excess of carbonate of ammonia, and the alkaline hydrates.From the alkaline solution a white precipitate was produced by a sulphide of ammonium. It dissolved without effervescence in dilute nitric acid, and was so little affected by chloride of barium that after standing for several minutes, the milkiness was so slight as to require a close scrutiny for its recognition. If, however, the solution in nitric or hydrochloric acid be made in a flask, a strong odour and copious evolution of sulphurous acid gas becomes very evident.A few grains were placed in dilute hydrochloric acid with a small piece of pure zinc when sulphuretted hydrogen was evolved, and speedily became evident with the help of a bit of lead paper. The addition of chlorine water produced a distinct precipitate of sulphate with chloride of barium.The use of nitroprusside gave a red colour with a little of the solution to which a little soda and acetic acid had been added. An analysis showed that the sample was composed of oxide and sulphite of zinc in the following proportions :- body ” required, Oxide of zinc . . . . . . . . . . . . . . . 90.87 Sulphite of zinc . . . . . . . . . . . . . . . 9.13 Sulphate of zinc, a very slight trace. 100*00 The trace of‘ sulphate was so small that it was probably due to oxidation of the sulphite. The cause of the presence of sulphite of zinc is not quite apparent, but the sample came from a continental house, and was very likely manufactured from a sulphide of zinc in some rapid and imperfect manner, which had partially oxidized some of the sdphide, and produced the impure product of which complaint had been made. The appearance of the sample suggested a process by hcat rather than by precipitation.

ISSN:0003-2654    

DOI:10.1039/AN8770200113

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

114 THE -4NALYST. ABSTRACT OF A SUPPLEMENTARY NOTE ON THE ASSAY OF OPIUK By S. B. PROCTOR. Read before thr Br isto Z Pharmaoeuticnl Conference at PZymouth. SINCE the publication of my former note on this subject, I have recorded two or three small matters which I now offer for your consideration. The process as described at our last meeting was devised with the object of being at once accurate and speedy.With the view of further expediting the extraction, I have modified the mode of operating thus :- Rub the lump opium with its own weight of water, to as smooth a pulp as possible, if necessary with the aid of a gentle heat; add spirit equal to about three times its weight and transfer t o a percolator tube which is furnished with a looselz fitting inner tube closed at both esds for increasing the hydrostatic pressure.A phial filled with water and corked answers well for the inner tube, a string being tied round the neck, by which it may be let down gently till the bottom of the phial just touches the surface of the opiam liquor. I t s position may then be fixed by pressing the string between the side of the tube and a cork wedge. When thus arranged, morespirit may be added, till a column of 6 01’ 8 inches is obtained without disturbing the marc or mixing t o any apgreciable degree with the opium liquor, and without using more spirit than is required for the exhaustion of the opium. I n one experiment with 200 grains of a soft sample of Turkey opium treated thus, a head of 8 inches pressure was obtained.I n four hours, four ounces of percolate had passed through, which contained 98 per cent.of the morphia present ; another ounce was considered to have effected practically a perfect exhaustion. Other trials gave similar results. I have occasionally met with specimens, which deposited along with the morphia, a white amorphous substance which could be mashed out only by long continued washing with spirit, strong or dilute.These specimens I have assayed by the lime process, and by the acetate of lead process (in conjunction with the above mode of extracting), but without quite satisfactory results . Upon the whole, 1 find it most advantageous to cut the washing short when I find such impurity present, dry the precipitate, wash out the narcotine with benzine as usual, and then re-dissolve with hydrochloric acid and spirit, and reprecipitate with ammonia, which treatment I have never found fail to give me well-crystallized, and nearly white morphia of almost absolute purity.If the quantity of spirit and wdter used for solution be limited to two drachms of each, (the quantity I find desirable for an operation upon 100 grains of opium), and the washing be not unnecessarily prolonged, one-quarter-grain may be allowed for the loss in purification.I find the solution by spirit and acid followed by reprecipitation is both more convenient and less wasteful than crystallization from boiling alcohol, which has been recommended by some analysts; and I find the loss of time is not necessarily great, for the morphia goes down with more promptness and certainty from this approxirnately pure solution than when deposited from a liquor containing the soluble extractive matters of the opium.Three to four hours are sufficient i n the former ease, while eighteen to twenty are desirable in the latter,THE AXALYBT. 115 ~ -~ I have found in sundry cases that the precipitation of the morphia from solution in strong spirit and acid is advantageous, inasmuch as the crystals are whiter, larger, and sooner washed clean, but my experience is too limited yet, to say whether the strong spirit is generally preferable.When rectified spirit is used without water, for the solution from which the morphia is to be precipitated, a larger correction must be made for the quantity of morphia retained in the mother liquor.Mr. Cleaver, regarded the washing water as a saturated solution of morphia, and quoted evidence in support of the supposition. I think it is safe after sundry experiments to assume that the loss of morphia in the mother liquor and washings when the process is performed as I have described, amounts to 0-2 to 0-25 grain. Some analysts recommend the washing of the precipitated morphia with a small quantity of chloroform as well as with ether, benzine, or spirit.1- have found the loss involved by its use to be very trifling, but I have limited its quantity to a fluid drachm or two, and in those cases where the washing with spirit and benzine did not readily remove the impurities, the chloroform also failed t o do so unless used freely, and as its solvent action upon morphia is much greater that of ether or benzine, the estimation of morphia washed away by its use becomes more important, at the same time that it is more troublesome. 11.2 is the highest percentage of morphia I have found in Turkey opium in its fresh moist condition. The percentage of water in moist opium I have found to vary from 19 per cent, to 27 per cent. Mr. Dott’s table agrees closely with my observations in this particular, if we omit one anomalours sample which he found to contain 31.2 per cent. of water and yield only 20.1 per cent. of aqueous extract.

ISSN:0003-2654    

DOI:10.1039/AN8770200114

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

THE AXALYBT. 115 REVIEW. A TREATISE ON CHEMISTRY. By H. E. ROSCOE, F.R.S., and C. SCHORLEUNEB, F.R.S., YoZ. 1 .-The Non-metallic Elements. h ITANDSONE 8vo. volume of 771 pages, well-printed, and beautifully illustrated, a book more for the drawing room, than for the study and the laboratory. It is a work of some pretensions, and coming as it does from two chemists, long and favourably known both as workers and teachers at one of our highest science schools, will probably have no inconsiderable influence on the teaching of chemistry i n England. This influence we fear will not be a favourable one ; among much that is commendable, its completeness, its full description of many fundamental experiments, the frequent employment of equations to express re-actions, &c., there is much that has to be condemned.The book abounds in loose and illogical writing, conclusions are drawn, which, though frequently correct in themselves, have no logical connexion with the premises from which they are supposed to be drawn, and thus the chief value, as an ediicational instrument, which can be claimed for science teaching, the training of the mind to exact logical reasoning, is lost.The book opens with a short historical sketch based chiefly on the writings of Kopp. Next follow some chapters on general principles, well illustrating our above remarks. On page 43 we are told that a science may be called experimental as opposed to observational, ‘+hen we are able so to control and modify the conditions under which the phenomena occur as to produce results which are different from those which are116 TEE ANALYST.othervise met with.” Surely experiments are not merely, or even chiefly, for the purpose of producing results, not otherwise met with, but rather for the purpose of showing that certain phenomena are produced under such and such conditions, proving the correctness, or otherwise, of our observations or conclusions.On page 70, after a table giving the combination by volume of various elements, when in the gaseous condition we are told : (( It is thus clear that the number of atoms which is contained in a given golunze of any gaseous body, must stand in a sitn9le reZation to that contained in the same volume of any other gas,” whereas all that is really clear, is that combination by volume usually takes place in very simple ratios, and this might well be, nay probably is, the case without the existence of atoms.Again, on page 71 we are told, “From this train of reasoning, it follows, that an atom is the smallest portion of matter which can enter into a chemical compound, whilst a molecule, on the other hand, is the smallest quantity of an element, or of a compound, which can exist in the free state.” This is simply a definition of what chemists at present understand under the term atom and molecule, but does not by any means necessarily follow from this train of reasoning.’’ On the same page we find the following strange logic.After defining the use of symbols and explaining that by placing symbols of elements side by side, a combination of these elements is signified, we are informed, ‘‘ hence it is clear that the atomic weight of a compound is the sum of the atomic weights of its component parts,” this again is simply a statement of observed fact, although it would have been better to have put it, that the molecular weight of a compound, &c., &c., but no more follows from what precedes it than-well the idcas of the authors as to what is clear, clearly differ from ours.The whole of these chapters seem to be written by men who have not clearly grasped the subject, and are therefore unable to place it clearly and logically before the student. On the whole, this part is far better done than the first, but even here we find many instances of what we have called loose writing.On page 177 the preparation of oxygen from barium peroxide is described, and we are then informed that L 1 this simple method has not unfortunately come into general use, as the baryta looses its power of absorbing oxygen,” $c., $c., the unfortunate thing being, not that the method has not come into the general use, but that the baryta looses its power of absorbing oxygen.On the same page it is stated that the mixture of caustic potash and lower oxides of manganese, produced by the action of steam on heated manganate, ‘( when again heated absorbs oxygen,” where from ? On page 178, we find (‘ certain metals also absorb oxygen when in a molten state, and give it off again on cooling,” they give it off, like water, on 8022Z~ying. But we must hurry on, on page 713 we have, I ‘ This crystal,” Bcc., &c., “ must now be placed in such a position, that the edge whose angle of inclination has to be measured, is placed exactly in a line with the axis of the instrument.” It should of course be, the intersection of the two planes, whose angle of inclination to each other is to be measured, must now be placed, &c., &c.It is also unnecessary to place the intersection or edge, exactly in a line with the axis of the instrument, which would be almost impossible t o accomplish, but it is necessary to place it parallel with the axis, and nearly conincident with it, and this can readily be accomplished, although we are not told in this book how to do it.The work is, as before observed, very complete, nevertheless some things are omitted which Beem to us would have been worth mentioning.The preparation of The descriptive part begins on page 95, commencing with hydrogen. To give a few examples msrely.THE ANALYST. 117 hydrogen by the action of sodium is described, but no hint is given that there is danger of explosion, and of course no directions are given for avoiding it. Among the properties of oxygen, no mention is made that it combines, at ordinary temperature, with binoxide of nitrogen, or that it is readily absorbed by alkaline pyrogallatcs, and various other substances.I n some cases we come also across bad chemistry, as for example on page 410, where the action of nitric acid on metah is incorrectly given, it is the hydrogen and not the metal that reduces the acid.On psge 650, very erroneous ideas respecting urea are put forward ; urea is the predominating nitrogen compound in the urine of man, not in that of animals generally. The printing is on the whole well done, though there are misprints in the book not mentioned in the table of errata. On page 128 the tension of hydrochloric and vapour at-10 is given incorrectly; page 146, line 9 from the bottom, hydroiodic is printed for hydrobromic; pago 177, line 8 from bottom, we have manganese for manganate, &c. In conclusion, we must express our sorrow that we have felt obliged thus to write of a work on which both authors and publisher have evidently expended much laboiir and capital, and we sincerely hope that future editions may be free from the blemishes we have thought it our duty to censure in this.

ISSN:0003-2654    

DOI:10.1039/AN8770200115

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

THE ANALYST. 117 TREATMENT OF ORES OF LEAD AND ZINC. ALL metallurgists are familiar with the difficulties which have always been encountered in the attempt to treat these ores profitably, and immense masses of them have either been left altogether unworked or the waste portions have been thrown into heaps, encum- bering the mines with useless deposits. The specific gravity of the different ores are too similar, and their union frequently too intimate, to admit of merely mechanical separation, and apparently up to the present time no efficient chemical means of separa- tion seem to have been found, unless by processes involving so much expense as to make them unprofitable.In reference t o the extraction of the zinc, there is not, of course much difficulty theoretically in separating it by distillation ; but practically, the concen- tration of the lead remaining in the guangue has presented almost insuperable obstacles ; while if it be attempted to separate the lead and reject the zinc, the zinc has a tendency11s THE ANSLYST, to form a hard scoria, not only retaining much lead, but also holding back much of the silver which ought to be taken up by the lead, so that the consequence is a greatly diminished yield of lead, and that which is obtained is less argentiferous.Mr. Maxwell-Lyte, of Paris, has just published some processes which appear likely to remove a considerable amount; of the dffieulty which has been experienced with these ores. It is impossible in the space a t our disposal t o enter into a detailed account of the methods which hc proposes, but we may say that in the main they consist of a combina- tion of the wet and dry methods.Thus, in one of the cases to which he refers the mixed ore is treated in the first instance with dilute hydrochloric acid hot, by which means the zinc and lead are both chloridized, the lcad being more or less dissolved, the zinc entirely so; while on cooling the solution the chloride of lead is deposited, because of its relatively slight solubility in the cold liquid.The clear solution is poured back on t o the residuary guangue from which it was decanted, and again heated and rede- canted, when it carries over a fresh portion of lead. Thus the guangue, deprived of its lead as well as its zinc, may be thrown away. The silver also all passes over with the lead.The deposit of chloride of lead and silver is now reduced to a spongy metallic state by placing in the solution bars or lumps of metallic zinc, while all the zinc remairs in solution, whether that contained in the ore or that which had dissolved in the process of reduction of the lead and silver. This spongy lead may be easily fused in a rerer- batory furnace, and subsequently desilverized. The zinc from the decanted liquors ia precipitated by lime, washed and pressed into bricks, forming a kind of artificial calamine, containing from 60 to 70 per cent. of metallic zinc, and is ready for treatment by distil- lation. I n this way Mr. Naxmell-Lyte considers that he can extract from ores all the lead and silver, while the zinc is also recovered in an available form free from lead, Several alternative processes are also described, but the one of which we have sketched an outline shows his ideas.

ISSN:0003-2654    

DOI:10.1039/AN877020117b

出版商:RSC    

年代:1877

数据来源: RSC

摘要:

11s THE ANSLYST, SULPHUR I N GAS. THE vexed question of the amount of sulphur impurities to be allowed in gas, which for twelve months at least has been practically settled in London by the defeat of the two bills brought in by the Crystal Palace Gas Company and the Gas Light and Coke Company, has been raised at Naidstone, where the gas on two or three occasions appears t o have contained from 35 to 45 grains of sulphur per 100 cubic feet; or, in other words, t o have been in this respect as bad as absolutely unpurified gas.Complaints were naturally made on the subject, and the enginecr of the Naidstone Gas Works presented a report to the directors of the company, containing some statements which, to those who are familiar with the evidence recently given before the select committees of the House of Commons, must appear to be of a most remarkable character.Thus, this gentleman says ‘( the evidence given on that occasion by the chemists, who are alike the most eminent of the day and the most experienced in respect to coal gas, has gone to prove that a quantity of these compounds, up to about 35 or even 40 grains per 100 cubic feet, is not injurious to health; and that a partial removal is not worth the trouble and expense incurred.” It is certainly somewhat singular that, if the evidence of these chemists did prove this fact, the select committee should neverthelesg, as reported in our number for July, page 67, have thrown out both the bills, aod there-THE ANALYST.119 fore kept the companies still under restrictions in regard to sulphur compounds, There is no doubt that some evidence was given of the character alluded to in the engineer’s report, but this evidence was so emphatically contradicted by chemical evidence on the other side that the committee had no other course before them but to reject the gas companies’ proposals.We purpose in our next number, if space alIows, making further reference to this subject, with a special view to pointing out the character of the products which are produced during thc combustion of ordinary coal gas containing sulphur. It is quite evident that such a paper is needed, not perhaps so much for thc enlightenment of analysts RS for the information of those quasi chemists who put themselves forward to advise public bodies cin such points.Thus we find in this case an argument extending orer some half column of letterpress t o prove that 40 or 50 grains per 100 cubic feet cannot be injurious, because it only forms about 0.18 per cent. by weight of the gas which is burned, ignoring entirely the fact that this gas in its combustion produces a t least three separate ingredients in considerable quantity, namely-water, carbonic acid, and sulphuric acid. What can slnx percentage composition possibly have to do with a case of this kind, where the injury is done solely by the sulphuric acid which is formed? Impure gas has nearly as much influence on the death rate as impure water.

ISSN:0003-2654    

DOI:10.1039/AN8770200118

出版商:RSC    

年代:1877

数据来源: RSC