摘要:

PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE monthly meeting of the Society was held on Wednesday evening, December 4, 1895, at the Chemical Society’s Rooms, Burlington House, the President (Dr. Thos. Stevenson) occupying the chair. The minutes of the previous meeting were read and confirmed. On the proposal of Mr. A. E. Ekins, seconded by Dr. Voelcker, Dr. F. L. Teed and Mr. John Hughes were appointed to act as Auditors of the Society’s accounts for the year.2 THE ANALYST. The following gentlemen were proposed for election. As Member: A. C. Chapman, F.I.C., Analytical and Consulting Chemist. As Associates : Norman Leonard, B.Sc. (Lond.), F.I.C., and Harry M. Smith, assistants to Dr. Stevenson. The following gentlemen were elected Members of the Society : Thomas Hawkins ; Percy Heriot ; Frank H.Leeds, F.I.C. ; Alex. K. Niller, Ph.D., F.I.C. ; C. A. Mitchell, B.A. (Oxon.), F.I.C. ; C. H. R. Moore, F.I.C. ; Clarence Arthur Seyler, B Sc. (Lond.), F.I.C. ; and Benjamin Watmough. Dr. BERNARD DYER (Ron. Sec.) read the list of officers for 1896, as proposed by the existing council. The following paper was read by Mr. Dibdin : THE MICROSCOPICAL EXAMINATION OF WATER. BY W. J. DIBDIN, F.I.C., ETC. FOR some years past it has been the custom for public analysts to include a micro- scopical examination of the matters held in suspension in water when making an ordinary chemical analysis ; but this practice is not universally adopted, and the valuable information which niay be so obtained is not infrequently missing in many published results. With the view of placing this important point in its proper position, I venture to submit the following details of the method which I have found to yield unexpected results in my own practice, and which, it is to be hoped, will, after careful trial, be widely, if not universally, adopted.Hitherto the inode of collecting the suspended matters has been by simple sub- sidence, often in the bottle in which the sample is collected, but often by allowing the water to stand for some hours in the special settling tubes introduced by Mr. Wynter Blyth, and which I myself employed for a considerable period. These tubes are 2 i inches diameter, and 20 inches long, being contracted at the bottom to a diameter of half an inch. At the bottom of this narrow end, a cup is ground to fit so that the solid matters as they fall are deposited therein.When the subsidence is considered complete, a, ground-glass plug, with a glass handle equal to the length of the tube, is placed in position inside the settling-tube just above the cup, when the latter can be removed, and with it the suspended solids, which can then be examined in the usual way. In the course of a considerable experience with this method, I observed that no small portion of the sediment was collected on the sloping sides of the tube, and that all the free swimming organisms did not fall to the bottom, a considerable proportion thus escaping observation. After various trials to overcome these defects, I have adopted a method which removes these objections, and, while rapidly and conveniently enabling the whole of the suspended inatters to be placed under one cover-glass on the stage of the microscope, at the same time enables a determination of the volume of the suspended matters contained in a given quantity of water to be recorded.I use the expression ‘‘ volume ” in preference to ‘‘ weight,” as in many otherwise pure waters the total quantity is so small as to be practically unweighable when collected from such a quantity of water as is usually taken for the purpose of analysis ; andTHE ANALYST. 3 again, because the fact of drying so alters the character of the deposit that it no longer represents the condition in which it existed in the water. By the introduction of the specially-prepared samples of hard filter-paper now so generally employed in the laboratory a ready means is afforded of collecting the sediment by simple filtration, and then washing’lthe so collected sediment into a suitable tube, which I call the “ Micro-filter,” and in which all the excess quantity of water can be separated, until the whole of the solid matters are contained in one drop of water, thus collecting not only the dead matters, but also the living organisms.This drop of water is then carefully placed on the usual glass slip and examined, first in its natural condition under the microscope, and then, when desirable, after being dried, stained, and mounted in balsam, or water if preferred, for further examination under higher powers for the presence of the various bacteria, etc. One great advan- tage of this method is that, while the ordinary gelatine plate culture affords valuable information as to the presence of the free bacteria in the water, their presence, often in infinitely greater numbers, entangled with, and feeding upon, the solid matters, is demonstrated in a most striking manner.The details of the process are as follows : The neck of the bottle containing the sample is first carefully cleansed, to remove extraneous dust, and then one litre of the water, or proportionately less when the quantity of sediment is evidently large, is decanted into a litre-flask, which has been carefully cleansed and washed with pure filtered water. This flask should have a narrow neck, such as those used in the well- known Bischof’s bird-fountain, which I have found to be specially suited for the purpose.A clean filter-paper, 3 inches in diameter, is placed in position in a funnel resting in the neck of a flask of at least a litre in capacity, and then the flask con- taining the sample is inverted so that its mouth is just inside the filter. The water will at once fill the filter-paper, and so close the mouth of the flask, which then acts in the ordinary way of the bird-fountain, feeding the supply in the filter until the whole of the water has passed through. During this operation care must be taken to exclude dust by placing a perforated card, through which the neck of the flask passes, over the funnel. When the water is thus filtered, the deposit is washed from the filter-paper, to which it lightly adheres, into the micro-filter by means of an ordinary wash-bottle having a fine jet and charged with pure water.The micro-filter is prepared by selecting a length of combustion-tubing, from 8 to 10 inches long, which, after thorough cleansing, is plugged with clean cot ton-wool, and then heated to redness in the middle of its length and pulled out to a capillary tube, the narrowest part of which should be something less than 2 millimetres in diameter. I t is nicked with a file at the two points at which the tube is exactly 2 millimetres in diameter and neatly broken. By this means two micro-filter tubes will be prepared. They are then converted into filters by charging the small end with a suitable porous diaphragm, prepared by mixing about equal parts of powdered air- dried clay and Kieselghur.This mixture is moistened and worked into a smooth, stiff paste, which is spread out on a, slab to the depth of about 2 millimetres. The filter-tube is held perfectly upright and forced steadily down on the mass, and then worked round in small circles. By this method the capillary tube will be neatly charged with a plug of the clay and Kieselghur, which is at once warmed in the4 THE ANALYST. Bunsen flame and gradually heated to redness, so forming a perfect diaphragm admirably suited for its purpose. As the fine sediment from the water will often choke the pores of this small filtering plug, the surplus water niay be conveniently removed by putting the small end of the glass tube through an aperture perforated in an indiarubber stopper fitting into a convenient bottle, another tube from which leads to an exhaust pump, which, when worked, creates a vacuum in the bottle, and so pulls the water through the filter.When only about half an inch of water remains the micro-filter is removed, and the depth of deposit which will now be collected on the filter-plug is measured, and the results expressed in terms of millimetres of deposit in a 2-millimetre diameter tube per litre o€ water. Thus, a numerical factor is obtained to express the actual quantity of suspended matter present in the water ; of course, in the case of dirty water, when the deposit from a litre would be too great to be contained in that part of the micro-filter-tube having a diameter of about 2 mm., half or a quarter of a litre may be taken, or even less, and the dept,h of deposit actually found should be multiplied accordingly, so that the results in all cases, even the most foul waters, where only a few C.C.of the water can be used, may all be expressed in the same terms. So delicate is this method that I have repeatedly demonstrated the presence of most objectionable matters contained in a single tumblerful of so-called ordinary good drinking-water. When the depth of the deposit has been thus recorded, the filter-tube is scratched with a sharp file about half an inch from the filter-plug and broken off. To remove the deposit which will often be found closely adhering to the plug, a fine, clean platinum wire is pushed up the tube, and used to loosen the fibrous sediment and pull it away from the plug.Upon inverting the tube for a few moments, the sediment will fall to the open end. The tube is cut again with the file close to the plug and the plug end broken off, the tube being held horizontally the meanwhile. We now have the deposit contained in the minute quantity of water held by capillary attraction in the tube thus open at both ends. On holding the tube upright over the microscope glass slide, and giving it a gentle downward shake, the deposit will fall down with one drop of water, and may then be at once covered with a thin glass, and examined pre- ferably at first with a low power, and then with higher powers as may be found desirable. I venture to predict, from experience with various operators, that no little astonishment will be expressed by those who have employed the usual methods at the unusually large quantity and varied character of the deposit so obtained from waters which are constantly passed as containing no suspended matters.Notably the presence of decomposing organic substances swarming with various kinds of bacteria will probably be the most striking when once the observer has accustomed himselE to the method of finding them. Many observers are under the impression that these minute orgsnisgs cannot be readily seen with the quarter-inch objective usually employed. The only precautions necessary are to work with the critical image, and to focus carefully the minute gelatinous specks which will be often seen close to or along the edge of particles of d6bris. When such are observed, the employment of the D eye-piece will bring them out distinctly, provided the object-glass be properly corrected for the cover-glass, and no other power will be required to differentiate bacilli from micrococci or diplococci.If it is desired to This is an entire mistake.THE ANALYST. 5 proceed still further, the use of an oil-immersion lens of as wide a numerical aperture as is obtainable will be necessary, when, especially if the preparation is stained by one of the usual methods, the bacteria will stand out boldly. How far direct microscopic examination may enable a skilled observer to differentiate between pathogenic and non-pathogenic organisms remains for the future to show. Up to the present we can only say that such and such types are present in greater or less numbers, and this without the lengthy process of the gelatine-plate cultures, but which, nevertheless, afford a doubtless valuable aid to the diagnosis of the quality of a drinking-water.By the combined results of that method with the one which I have described, aided by the ordinary chemical examination, no careful analyst could possibly certify as pure water contaminated with objectionable matters, and it may be confidently asserted that, whatever elements of doubt may have more or less legitimately existed during the past as to the value of an ordinaryanalysis of water, the question has now entered upon a now phase, ana is becoming more nearly based upon the foundation of exact knowledge. Before any results are accepted, care should be taken to make a, series of blank experiments with the purest water obtainable, in order that the accidental errors due to dust, etc., may be known and allowed for.A certain minute quantity of fibre will be washed from the filter-paper, and I have found starch granules from the same source. The character of these accidental contaminations is so marked, and essentially different to the objectionable matters found in more or less foul waters, that the careful operator cannot fail to differentiate between them. I t will be evident that a few clean linen fibres, even with an odd leguminous starch grain, are entirely different to the decomposing matters so often met with. I n the table attached I give a series of typical results, with the full analyses in each case, in order that the effect of the method may be clearly seen.They are placed in order of the source of the water, viz., deep and shallow wells, rivers, and brooks, in drought and in flood, etc., and well show the variation in the quantity and quality of the suspended matters as determined by the extremely rapid and exact method I have ventured to submit to the criticisms of the society. I n connection with the microscopical work, I may call attention to the special stand constructed by Messrs. Powell and Lealand, at my request, for the purpose of facilitating the counting and examination of the colonies obtained on gelatine-plate cultures. The stage has mechanical movements to the extent of 4 inches, and is arranged to support the ordinary glass culture plate generally employed.When the colonies are viewed with dark ground illumination, by means of a 4-inch object-glass and binocular vision, the process of counting proceeds with comfort and exactness, as well as greater rapidity. DISCUSSION. Mr. WYNTEH. BLYTH referred to the method of Dr. Klein in searching for the typhoid bacillus, which consisted in filtering a litre of water through a Pasteur candle and then cultivating the sediment. He also described the method of filtration of organisms in use by the biologist of the Massachusetts Board of Health. He considered that it would be bstter to state the results in cubic millimetres, whichSOURCE OF WATER. Chalk well ... .. Chalk well ... .. Chalk well ... .. *Deep well ... .. *Deep well ... .. tDeep well, 60ft. dee] Deep well, in clay .."Spring, on side of hi1 t Spring, turbid afte heavy rains .. tSpring ... .. *Well . . . . . . . . *Well . . . . . . . . t Well . . . . . . . . *Well . . . . . . . . "Rivers ... .. "Rivers ... .. River in drought .. River in flood .. Filtered river water ir drought ... .. Filtered river water ir flood ... .. tBrook, above sewagt outfall ... .. t Brook, below sewag( outfall ... .. tUnknown ... tShallow well, 14 fi deep ... ... WATER Table of Analyses and Microscopical Examination All quantities are stated in grains per gallon, except organic EXAMINATION IN A %FOOT TUBE. Appearancc clear clear clear - - - clear - - - pale greenid yellowisl - yellowisl. - - slight 1 y very clear clear turbid turbid - - - _ _ Colour by Lovibond's Tin tometer Scale. colourless colourless colourless - - - colourless - - -.slightly turbid Phosphoric Acid. V. S. T. V. S. T. none abundant traces - V. S. T. consider- able tracc - - V. H. T. traces - V. H. T. heavy traces slight heavy traces trace trace - S. T. - - - - AarMoNI A. Free. 0~0001 0.0001 0~0000 0-0220 0.0030 traces 0-0000 0-0110 0-0020 0~0000 0.0030 0~0010 0-0000 0~0010 0-0060 0.1090 0~0010 0.0060 0.0001 0.0007 traces 0.3000 traces Om0020 Albumi- noid. 0.0014 0.0038 0-0021 OmO880 0~0010 0~0010 0-0030 0-0340 0~0010 o*oooo 0.0020 0*0020 0*0050 0.0031 Om0O70 0.0250 0.0130 0-0860 0-0056 0.0091 0.0030 0.1500 0~0010 0.0040 :hlorine. 1-55 1-70 1-75 2-50 1.60 5.65 2.10 1-80 1-25 0.50 6.00 7.60 2-70 9-20 3.80 332.50 1.30 1-50 1-25 1-50 2.50 3-75 1.35 11-75 OXYOEN ABSORBED IN FIg 5s 2 s 0.010 0-014 0.017 0.057 0.014 - 0.013 0-202 - - 0.012 0-012 - 0.197 0.084 0.160 0.057 0.114 0-035 0.057 - - - - 2 g z; 0.019 0.029 0.021 0.091 0.061 0.027 0-030 0.436 0.027 0.020 0.024 0.027 0-040 0-337 0-116 0-289 0.092 0.295 0.058 0.109 0.152 0-541 0.028 0.084 m i z R E + 2 :g & g 2 z 0.370 0-370 0.345 0.540 traces 1.010 0-140 trace 0.028 - 1-88 0-16 0-29 4-38 traces traces 0.160 0-080 0.188 0.144 0-150 0.010 1.290 1-150 In each case the examination of suspended matters was made by the author.The cherriical Dr. J . A. Voelcker and Mr. E. MT. Yoelcker.ANALYSES of' some Typical Waters from Various Sources. carbon and nitrogen, which are stated in parts per 100,000. ORGANIC ELEMENTS. 1 Total Solids. 88-00 31-40 26-20 - 34.16 42.28 35-20 21.84 8-60 2.24 43.9E 20.1E 17.X 62*1f 29-15 670m6( 19-0( 294( 17-4( 23.: 29.4t 37% 31.9( 73-1( hltiva.tion ests by elatine P1:r tes. 'umber of olonier er 1 C.C. rim. of leposit micro- filter from 1 litre. ?n trace trace 0.5 2.5 1.0 1.7 trace 4.0 24.0 1-5 12.0 15-2 10.c 10-4 16-( 27.( 3( 84-( 0. ,' 1 *( 17-( 18.( 11-! 10.4 s 1;s PENDED MATTERS. Microscopical Examination. Few infusoria, fibres, and ddbris. Various fibres (some dyed), diatoiiis, and little debris. Few fibres (some dyed), general organic dkbris, bacilli, and micrococci. Black flocculent, spiral 1-essels, infusoria (perameciuiii) , scale of lepidoptera, aniiiial feathery hair, brown veget- able cellular tissue, dyed cotton-fibres, etc., spongy parenchyma, ainebe, numerous particles of organic matter (some gelatinous in appearance, swarming with bacilli, niicrococci, and diplococci), fungoid inyceliuiii, (3) begget oa .Fine mineral d&bris, confervze, a l p , streptothrix, various sniall infnsoria. Cotton-fibre, dyed wool - fibre, infusoria, vegetable epi- dermis, quantity of iiiineral iiiatter. Dyed fibres, anguillulat3, fungoid mycelium, and yellow red stained tissues, organic (Gbris, with bacilli, micrococci, etc. Infusoria, diatoiiis, few fibres, algz, numerous bacilli and iiiicrococci, dkbris, ctc. Mineral and organic ddbris, rotifers and other infusoria, fungoid mycelium, diatoiiis, algz, angnillult?e, sphsroplea, spongy parenchyma, colonies of bacilli, iiiicrococci, and diplococci, cotton-wool and other fibres (soiiie dyed). Brown flocculent, blue-dyed wool and other fibres, gela- tinous inasses infested with bacilli, iiiicro- and diplococci, fat globules, fragment of insect.Pilanientnns cellnlar growth, aniiiial hair (? iiiouse), dxed wool-fibre, rotifer, diatoms, desriiids, potato starch. Ferruginous (mostly fine granular matter, with soiiie bacilli and ruicrococci). Quantity of finely- granulnt e d matter , cot t on-fib r e vegc t able epidermis, fungoid iiiyceliuin, few bacilli. Dyed a i d undyed wool, and cottoii fibres, nun1crous nioving organisms, confer vat , fungoid mycelium, nunicr- ous bacilli and iiiicrococci. 13rown mud, quantity fine mineral dt'lbris, numerous scales of insects, vegctalile cl&bris, etc. Brownish-gray iiiiid, conferw , diatouis, various infusorin, vegetable tissues, oscillaria, aiigiiillulat, ameba, etc.Usual riyer clkbris, larvte of insects, diatoius, coloured fibres, etc. liiver clcbris, with niiiiierous cliatoiiis, fragments of insects, fibres (cotton, wool, etc.). FiLres and orgttnic ildbris, with very nuiiierom bacteria, etc. Few fibres (sonic dyed), living aniuislcule, decaying matter, starch cells. Mineral dkbris, oxi;lc of iron with brown filaments, con- fervs, vegetable d&bris, diatoms. Quantity fine granular debris with few fibres, the whole swarming with various infusorie and bacteria, etc. Brown mud, parenchyma, and oth& vegetable tissues, fragments of insects, conferva, etc. Cotton and wool fibres (some dyed), few infusoria, quantity oxide of iron, woody fibre, few diatoms, mineral dhbris. analyses of samples marked * were made by Dr. Bernard Dyer, of those iiisrlied t by In the other cases by the author.THE ANALYST.would enable the size of the tubes to be varied. He was confident that such a method of filtration as described by Mr. Dibdin was of the highest value. I t was now a question whether it would not be advisable to perform analyses always on the filtered water. To translate potato starcb, diatoms, desmids, and so forth, into carbon and nitrogen was but of little utility in comparison to the identification of the organisms themselves, and of the nature of the deposit. Dr. VOELCKER observed that, while determining the quantity of deposit obtained, it was necessary to bear in mind also the natzwe of the deposit, and this to a certain extent influenced the interpretation of its quantity. I n dealing with an ordinary town supply, the condition of which was pretty constant, it was fair enough to regard the deposits obtained from different samples as quantitatively comparable ; but in many cases it was greatly a matter of chance what quantity and what kind of deposit was found in the samples.I n fact, a sample might be quite different, both as to chemical characteristics and as to suspended matter, from the supply whence it was taken. Dr. RIDEAL asked whether Mr. Dibdin could give any figures as to the free and albuminoid ammonia in water which had been subjected to his process of filtration, as compared with water that had not been so treated. It seemed to him that a few millimetres of this suspended matter (which would probably contain a good deal of matter, the nature of which was not nitrogenous) would not seriously affect the amount of ammonia present.Mr. D. A. SUTHEBLAND said that to facilitate the counting and separation of the colonies he considered it preferable to attenuate 1 C.C. of the water by mixing it with 10 C.C. of gelatin broth, and again attenuating 1 C.C. of this mixture with another 10 C.C. of broth, and so on. Dr. Woodhead had recommended this plan to him, and he had found it to answer very well. He considered that any examination from a bacteriological point of view of a sample of water received in the ordinary way could be of little or no value. It was essential, especially when the colonies were to be counted, that their cultivation should be conimenced at the moment when the sample was actually drawn.He noticed that the deep well water referred to in the table appeared, from its analytical results, to be much worse than the water from the shallow well. He would like to inquire the depth of the so-called deep well, as in his experience he had found wells only thirty or forty feet in depth termed deep wells. The lining of such a well was frequently defective, allowing of surface contamination from a wide area, and this class of well could not be too severely condemned. Mr. HEHNER thought that too much importance ought not to be attached to the mere number of organisms iu the sediment. Water from the purest of mountain streams contained multitudes of diatoms, which, in fact, were rather an indication of purity than otherwise.With regard to the question of uniformity in the statement of results, the Society had, as Mr. Dibdin had pointed out, made great and successful efforts in this direction. Up to the time when the Society’s Water Committee took the question up, every chemist determined what he pleased, and returned his results in any notation that was convenient to him; but the great majority of English analysts, and many on the Continent and in America, now worked upon one uniform plan. Now, however, that decimal systems of notation were being so widely intro- duced, it would, he thought, be a great improvement if the results of water analysis were stated in decimal notation.THE ANALYST. 9 Mr. JOHN WHITE said it seemed to him that the filtration of the water through paper was a weak point.Most of the papers of the class referred to by Mr. Dibdin would pass barium sulphate in suspension, so that it was pretty certain that micro- organisms would go through, especially if the papers happened to contain what were technically known as ‘( pin-holes.” For collecting the suspended matter, however, for subsequent microscopical examination, this method was certainly the best that had hitherto been proposed. He did not quite understand how Mr. Dibdin had arrived at the figure 84.5 mm. given in the table. If he had drawn out a tube 84 mni. long, and of a uniform diameter of 2 mm., it was a most remarkable feat of dexterity in glass manipulation. Dr. WASHBURNE said that he had known bacteria pass through even a Berkefeld filter, owing probably to some slight crack.As the morphology of bacteria varied very greatly under different conditions, it was not possible to identify them completely by microscopical examination alone. With regard to counting the number of colonies, he thought it best to so dilute the water that the colonies were sufficiently separated and of such a size as to be easily recognised, either by the naked eye or with the aid of a small hand lens. Mr. CASSAL said that some persons regarded the microscopical examination of water as a matter of very minor importance. His own opinion was that a micro- scopical examination carefully carried out afforded most useful evidence, and was, in fact, an adjunct of the utmost value to the chemical part of the analysis. From his somewhat extensive experience in the analysis of water, having been constantly engaged for a number of years in analysing waters, he felt sure that a water analysis for sanitary purposes could not be regarded as satisfactory if it did not include a proper microscopical examination, even in the case of waters the general characters of which were well known.Mr. Dibdin’s process was specially applicable, and was specially valuable in the case of a water containing small quantities of suspended matter ; and he thought that the results which had been detailed were of much interest and importance. Since Mr. Dibdin had been good enough to show him his method of working, he (Mr. Cassal) had applied it to a number of samples of water with very satisfactory results, and he had found that he was largely helped by it in forming his opinions on the samples. The process was not intended to separate out all the micro- organisms-meaning by this term the “ bacteria”-which might be contained in a, water, and he did not understand that Mr.Dibdin had intended it for any such purpose ; but the process nevertheless arrested what he might call a ‘‘ sufficiency ” of such organisms when they were present in the suspended matter. Of course, with waters which contained considerable quantities of suspended matter, a sufficient amount could be obtained for examination by allowing settlement in suitable apparatus, and for this purpose he had long been accustomed to use the ingenious settling-tube introduced by Mr. Wynter Blyth, with the slight modification of a glass-tapped cup or separator fitted to the end of the tube, which allows a drop to be taken out at will on to a slide.Although this method was suflicient when dealing with comparatively large amounts of suspended matter, which could easily be obtained by subsidence, Mr. Dibdin’s practice of measuring the volumes of sediment obtained obviously yielded useful indications, if those indications were considered intelligently ; and that this was10 THE ANALYST. so was testified to by the fact that, even some members who had spoken a little dis- paragingly of Mr. Dibdin’s experiments in this direction, mere nevertheless anxious to have further information on the point. Allusion had been made to certain so-called experiments carried out several years ago, and reported in the eleventh annual report of the Local Government Board for 1881-82.These “ experiments ” consisted inaiiily in the haphazard addition, without proper mixture, of small amounts of urine, excremental matter, and infected liquids, to samples of water, and in then submitting these to certain chemists for analysis. He (Mr. Cassal) had had occasion to look into these “ experiments,” and in a paper written by Dr. Whitelegge and himself most of the fallacies and absurdities in this report had, he believed, been called attention to and exposed. The report in question, except in one respect, was worthless, and the experiments it detailed mere ludicrous ; but it was still occasionally referred to as if it contained information of value. The point in regard to which the report was of interest was that some of the infected samples had been examined microscopically, and the microscopic results were amply sufficient to absolutely condemn them.With regard to the bacteriological examination of water, Mr. Cassal again felt it necessary to point out that far too much importance was being attached by some people to the present value of bacteriological processes in water analysis. The mere counting of colonies aflorded but an additional test of a rough and misleading character for the existence of pollution ; and as to the detection of specific pathogenic micro-organisms, in no single instance in which an outbreak of disease could be attributed to drinking polluted water had bacteriologists been able to assert that they had, with any certainty, identified those micro-organisms which would produce the disease in question.On the other hand, having regard to present bacteriological methods and knowledge, it would be foolish to pass a water as safe upon negative bacteriological results. Dr. PAKES observed that if Mr. Cassal had read the last Local Government Board report he would be aware that Dr. Klein had, in the case of one of the last two epidemics of typhoid, been able to identify the typhoid bacillus in the water. He (Dr. Pakes) had himself succeeded in absolutely determining the presence of the typhoid bacillus and the bacillus coli communis by bacteriological methods in samples of water that had been passed as pure by analytical chemists. Mr. CASSAL had not seen the particular report referred to by Dr.Pakes; but he presumed that that report was like others that he had seen, in which the investigator stated that he had found a micro-organism which he was unable to distinguish from the typhoid bacillus. This was very different from any statement to the effect that the typhoid bacillus had actually been identified, and that it was a bacillus which would produce typhoid. Dr. DYER desired to thank Mr. Dibdin for having kindly examined for him by this process a considerable number of water samples. He had himself tried this process of separation, and concurred in all the remarks that had been made as to its ingenuity, and as to its probable usefulness in enabling the ordinary microscopical examination of the grosser particles of suspended matter in water to be made with more exactness than had hitherto been possible.At the same time, he had compared Mr. Dibdin’s method with that of subsidence in the old-fashioned conical glass, and found that, although the new process was undoubtedly more delicate, the results,THE ANALYST. 11 qualitatively speaking, were substantially the same. With regard to the quite separate question that had been raised about the distinction between pathogenic and non- pathogenic organisms in bacteriological water examination, he t’hought that there were really very few cases in which there was any necessity, even if it could be done with facility, to look for or demonstrate the existence of special pathogenic organisme in water. Cases did occasionally aris5, no doubt, in which it was desirable not merely to know that water was contaminated, but to trace the introduction of a specific disease, and under some circumstances it might be possible to do it.As a general rule, however, the main point was to demonstrate the presence of sewagt;. If sewage was present, it mattered little whether pathogenic organisms were or were not present at a given moment, since the water niust in any case be condemned. With regard to bacteriological examination, he thought that those analysts who had not familiarized themselves, to a certain moderate extent, at any rate, with bacteriological work, were apt to somewhat under-estimate the value of simple bacteriological methods as aids to the formation of a correct deduction from the chemical results. Sometimes the chemical results were just a little doubtful or suspicious ; and it very often happened in cases of that kind that a bacteriological examination yielded results which were of very great assistance to the analyst.It was desirable to make not merely gelatine plate cultivations at the ordinary temperature, but also agar-agar cultivations, with and without the addition of phenol, at blood heat. The PRESIDENT said that this method had been brought under his notice by Mr. Dibdin some months previously, and he had found it very advantageous. Criticisms had been passed upon the mode of measuring the amount of the deposit, but seeing that the object was to measure merely the bulk of the suspended matter, and not its weight or absolute amount, he thought that Mr.Dibdin’s method would probably answer all ordinary purposes better than previous methods. Mr. DIRDIN said that there was no difficulty in cutting off the tube of the micro- filter at a point where its diameter was exactly 2 mrn. He had found that this was about the most convenient for practical work. I t was of course necessary to adhere to one fixed diameter in order to obtain comparable results. The measurement of the depth of the sediment was only relative, and not absolute, in consequence of its often flocculent character. Dr. Voelcker’s remarks pointed t o the desirability of the samples being collected by the analyst himself, or by a careful and specially-trained assistant. He (Mr. Dibdin) did not attach quite so much importance as Mr. Sutherland did to the bacteriological examination being started at the moment of taking the sample. The main point was that the sample should be a fair one, and free froin any extraneous matter. The fact of the deep well water showing more objectionable features than that from the shallow well niight easily be accounted for by the existence of a fissure in the chalk, which, if it extended into the neighbourhood of a cesspool, would offer a very probable explanation. Such points as this were of course liable to arise in individual cases; no universal rule could be laid down. The figure 84.5 mm., alluded to by Mr. White, had been obtained by calculation from the results of experiments upon a much smaller quantity than the one litre to which the figure referred. Dr. Washburne seemed to think that there was no need for microscopical examination if only the water was sufficiently diluted in making the12 THE ANALYST. gelatin-plate cultivations. He (Mr. Dibdin), however, had found from his own experience that in practice the microscopical examination was of the greatest value, as it not only indicated the presence of bacteria, but the character of the sediment. The microscope was one thing and plate-cultures another, and both should be employed. With regard to Dr. Dyer’s remarks as to comparison between the conical- glass method and the use of the micro-filter, he might mention that in the case of the latter a water could be prepared for microscopical examination in half an hour’s time, whereas, in the case of a sedimentary process, twenty-four hours elapsed before the examination could be made, which even then was only partial, and took no account of the quantity.

ISSN:0003-2654    

DOI:10.1039/AN896210001b

出版商:RSC    

年代:1896

数据来源: RSC

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12 THE ANALYST. NOTE ON THE ESTIMATION OF MINUTE QUANTITIES OF METALS IN LIQUIDS. BY E. RUSSELL BUDDEN AND H. HARDY. (Bend at the Meeting, Norember 6, 1895.) IN continuance of our experiments on the estimation of minute traces of metal in liquids, we tried the effect of various substances in common use in the preparation of beverages, to see if they produced any appreciable alteration of the tints in colorimetric testing. I n addition to sugar, which has much the same effect as glycerin in pre- venting precipitation and deepening colour in many cases, we tried the effect of essence of lemon, saccharin alone, and saccharin and sugar (as employed in the manufacture of lemonades), but the results obtained were of a negative character, and would certainly have little, if any, practical effect upon results hitherto recorded, since the alteration of tint is, in nearly every instance, too slight to be appreciable.We noted, however, that in the case of the estimation of iron the tint rapidly darkens if the solution be allowed to stand for any length of time-a further indication of the im- portance of making these tint-tests under precisely similar conditions in every way. Continuing our search for accurate methods of metal determination, we made a large number of experiments on the deposition of metals from solution by electro- lytic processes. I n the case of copper, the results obtained were fairly satisfactory, the necessary conditions apparently being that the current must be continued for a long time, and the film upon the platinum electrodes very carefully washed with alcohol and thoroughly dried.With all precautions, however, we found the tendency of the results was to be somewhat low. Theo- retically it would seem that the lead should be deposited upon the positive electrode. But, in varying degree, owing apparently to differing degree of acidity of solution, this metal deposits upon both electrodes. The metal is deposited in the form of oxide, and the proportion upon the opposite electrodes is not uniform. There is a great tendency for one or other of the deposits to redissolve, and we only obtained accurate results in about one-third of the determinations made; the results are usually too low. The process at present does not give very satisfactory results when With lead, however, the results obtained were extremely unsatisfactory.THE ANALYST.13 copper and lead are both present in a liquid, owing t o the irregularity of behaviour of the lead. With mercury, if the solution be moderately strong, the inetal is rapidly deposited upon the platinum plates and falls off in globules ; in weaker solutions the globules aggregate chiefly upon the plates, I n the case of weaker solutions a curious divisional line forms in the solution exactly at the level of the lower edge of the positive electrode. This line becomes violently agitated imniediat ely before the falling down of a globule. We have not yet been able to effect satisfactory separation of minute traces of metals when several are present in a liquid, and upon the whole find the colorimetric methods preferable for attaining this end in the testing of beverages for metallic contamination. DISCUSSION.The PHESIDENT said that in cases where the metals to be estimated existed in presence of organic compounds it was necessary to know the condition of the organic matter, in order to be certain of success and with coloriinetric methods. Otherwise the organic compounds must be destroyed and the metal redissolved-a process not always possible in cases where the inetal was present only in very small quantity. Mr. BEVAN said that in recently making some estimations of lead in mineral waters he had found comparison with a simple aqueous solution to be comparatively useless. Mr. ALLEN said that he had had occasion to examine inany thousands of samples of water for lead.Under favourable conditions, the depth of colouration produced by sulphuretted hydrogen was fairly proportionate to the amount of lead present, but where the water contained much mineral or organic matter he thought the results thus obtained were unreliable. Sugar and other forms of organic matter caused lead sulphide to assume a colloidal form, so that the liquid appeared of a brown colour, and no precipitate could be removed by a filter. A better plan was to work on a solution of the ash. I t was very important to avoid free acid, as the formation of minute traces of sulphide of lead was inuch impeded by acids, even acetic acid. When water was derived from recently-melted snow it caused an immediate decom- position of sulphuretted hydrogen, with precipitation of sulphur-a fact which Mr. Allen suggested was due to the presence of peroxide of hydrogen in the snow- water. Mr. Allen considered that for many purposes potassium bichromate was preferable to sulphuretted hydrogen as a test for lead. He allowed a drop or two of a saturated solution of bichromate to fall, without agitation, into the water contained in a tall glass cylinder. As the heavy liquid fell through the water the chromate of lead produced a yellow milkiness, which was very characteristic. The effect was instantaneous with one-twentieth grain per gallon, and with smaller quantities if more water was employed and time allowed. Some years ago all the water supplied to his house contained half a grain of lead per gallon, and he recovered the impurity from a quantity of the water in the form of an ingot of metallic lead by precipitating the metal as chromate and reducing the lead from the precipitate.

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DOI:10.1039/AN8962100012

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年代:1896

数据来源: RSC

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14 THE ANALYST. NOTE ON A CONVENIENT FORM Ol! POLARIMETER FOR EXAMINING ESSENTIAL OILS. BY E. RUSSELL BUDDEN. (Read at the Meeting, November 6, 1895.) IN the chemical and physical examination of many of the essential oils in use for flavouring purposes, the rapid determination of the specific gravity and optical rotation of the sample greatly facilitates the forming of an opinion as to purity, and not infrequently obviates the necessity of an elaborate chemical analysis. But the ordinary appliances of these determinations are cumbrous and costly. For the specific gravity, however, it is now possible to obtain a very inexpensive and sufficiently accurate plummet-balance, after the fashion of the Westphal, but much cheaper, and just as good. Until recently I have not found a' really satisfactory and inexpensive polarimetric instrument, however.After trying various polarimeters, I found that E. Leitz, of Wetzlar, had devised a very beautiful little instrument intended for pathogenic work in the testing of diabetic urine and similar matters. It seemed to me that this possessed so many advantages over the larger and more costly instruments that I made a number of experiments with it. It seemed, how- ever, that the original form of the apparatus was too restricted as to the scale for work of the class I required, since the rotation of some oils is very high. I therefore communicated with the maker (through his London agents, Messrs. C. Baker, of 244, High Holborn), and ultimately obtained an instrument with a complete divided circle.This is as perfectly constructed as any I have ever seen, and the arrangement for rotation and reading of the scale is very convenient indeed. One special advantage of the instrument is that it can be inclined at any angle and used with ordinary light. A polarimeter requiring monochromatic light is, in many small laboratories, a great inconvenience. The description of the optical and mechanical arrangements, given by the maker, is briefly as follows : The improved Mitscherlich consists of two Nicol prisms, between which the object-tube is fitted. The polarizer is fitted upright. Behind the polarizer is the bi-quartz plate, turning to right and left. The analyser, with a vernier attached on st radial arm, traverses the divisions on a circular plate by means of an endless screw. A small movable mirror illuminates the apparatus, and therefore the latter can be brought into any position for comfortable working.The vertical crossed position (viz., entire darkening of the visual field) corresponds to the zero-point. As this position cannot be again obtained after the introduction of an optically active substance, because of the rotation of the latter, the colour- violet-has been chosen as the end-point ; the transition of this colour into blue on the one side and into red on the other can be observed most exactly. The range of prismatic colours is seen to be repeated on turning. As long as blue is seen the vernier has not passed far enough ; but when red is seen it has passed too far. The eye-piece is movable, and can be focussed exactly on the bi-quartz plate. The particular fraction of a degree that can be read depends on the experience and colour- sensitiveness of the operator. There is a convenient arrangement for adjusting theTHE ANALYST. 15 zero-point, and although, of course, there is a personal factor in all these observa- tions, I have found it easy to read to one-tenth of a degree with this instrument. I strongly recommend it to those who have occasion to do work of this class.

ISSN:0003-2654    

DOI:10.1039/AN8962100014

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年代:1896

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THE ANALYST. 15 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOOD ANALYSIS. The Detection of Ergot in Heal and Bread. M. Gruber. (Arch. Hyg., 1895, xxiv., 228; through Chenz. Zeit. Rep,, 1895, 329.)-Contrary to the experience of most observers, the present author finds microscopic examination of bread, etc., better adapted for the detection of ergot than the chemical methods. I n the case of meal, Vogel’s and Hoffmann’s colour reactions, nevertheless, succeed perfectly, and they are also available for bread, provided the ergot is present in considerable quantity. For detection by means of the microscope, a little of the flour, or a few crumbs of the bread, are moistened with water, placed on a slide, the cover applied, and the mass heated to the boiling-point. I n this manner the starch granules are sufficiently swollen to permit the broken-down portions of the ergot to be infallibly recognised.The slide is first examined under a power of 100 to 120, when the powerful refracting power, the colour-deep violet on the edge, and greenish-yellow within-and the furrowed outlines of the ergot are all characteristic. A second examination with a power of 300 to 400 enables any doubtful particles to be identified. F. H. L. The Iodine Number of Lard at Different Times of the Year. L. van Itallic. (14poth. Zcit., 1895, x., 694 ; through Chenz. Zeit. Izep., 1895, 329.)-After experiments lasting a twelvemonth, the author is unable to trace any variation in the iodine number of lard dependent on the different seasons of the year. F. H. L.Detection of Fluorine in Beer. J. Brand. (Ztschr. p s . Brauzo.., 1895, xviii., 317 ; through Chem. ‘Zeit. Rep,, 1895, 327.)-One hundred C.C. of the beer are made slightly alkaline with ammonium carbonate, then heated, and 2 or 3 C.C. of a 10 per cent. solution of calcium chIoride added. After boiling for a few minutes, the liquid is filtered through it plain (not folded) filter, and the precipitate washed slightly and dried. It is introduced into a 25 C.C. platinum crucible, moistened with 1 C.C. of strong sulphuric acid, and kept for an hour at the boiling-point. The crucible is covered with a watch-glass, the convex side of which is protected from the hydro- fluoric acid by-a coating of wax, in which a pattern is scratched, while the concavity contains a lump of ice to keep the cover cool, with a wick syphon to remove the melting water.In this manner 1 milligramme of ammonium fluoride may be detected in 100 C.C. of beer ; and by preparing a number of watch-glasses etched by16 THE ANALYST, the action of increasing amounts of the fluoride (0-5 to 5 milligrammes per 100 c.c.), the process may be rendered approximately quantitative. F. H. L. Zinc Sulphate as a Precipitant for Albumoses. A. Bomer. (Zeit. anal. Chem., 1895 ; Fiinftes Heft., pp. 562-567.)-The precipitation of albuinoses by saturated salt solutions and by alcohol depends on the attraction of these reagents for water. Hence, ammonium sulphate, which is soluble in cold water in the pro- portion of 76.8 parts per cent., is especially suitable for this purpose.The great disadvantage attending its use is the introduction of ammonia,, which inust be removed before the nitrogen in the precipitate can be determined. Of other readily soluble salts, zinc sulphate appeared most promising to the author, its solubility being 135 parts in 100 of cold water, and experiments were accordingly made to determine whether it could take the place of ammonium sulphate. The precipitations were carried out in exactly the same way as in the case of the ammonium sulphate method, the precipitate being washed with a cold saturated solution of zinc sulphate. The filter and its contents were then placed in a Kjeldahl flask, and the nitrogen determined in the usual way. I n each case, before adding the zinc sulphate, 1 C.C. of dilute sulphuric acid (1.4) was added to prevent the precipita- tion of zinc phosphate.The results obtained with different meat extracts were as follows : Albuniose Nitrogen determined by precipitation with Ammonium mlphate. Zinc sulphate. Liebig’s meat extract ... ... ... 1-17 per cent. 1.19 per cent. Kemmerich’s meat extract . . . . . . 1.55 ,, 1-52 ,, I , meat peptone ... ... 5-51 ,, 5-44 ,, Cibil’s meat extract ... ... ... 0-96 ,, 0.92 ,, In no case could the biuret reaction be obtained in the filtrates. In the case of the zinc sulphate filtrate the test was made in two ways : 1. The saturated zinc sulphate solution was freed from zinc by adding saturated sodium carbonate solution. The filtrate was concentrated on the water-bath, made strongly alkaline with sodium hydrate, after which several drops of a 2 per cent.solution of copper sulphate were gradually added. 2. Since zinc hydrate is soluble in excess of sodium hydrate, the test was also made directly with the somewhat diluted zinc sulphate solution. A further advantage in the use of zinc sulphate is that the peptones, flesh base8, etc., in the filtrate may be at once precipitated with phospho-tungstic acid, which is not possible in the ammonium sulphate method, since ammonia itself is precipitated by the reagent. An equal volume of dilute sulphuric acid (1.4) should be added, and then the phospho-tungstic acid. I n the four meat preparations examined the amount of nitrogen found in phospho- tungstic precipitate was : Nitrogen. Liebig’s meat extract . . . ... ... 5.31 per cent.Kemmerich’s meat extract ... ... 4.05 ,, 9 , meat peptone ... ... 3-16 ,, Cibil’s meat extract ... ... ... 1.11 ,,THE ANALYST. 17 The author concludes, from these experiments, that the albumoses are com- pletely precipitated by zinc sulphate in the case of Cibil’s extract and Kemmerich’s peptone. I n the case of the other two, the negative results of the biuret reaction cannot be accepted as complete proof, on account of the dark colour of the solution. With regard to the behaviour of the zinc sulphate towards the ammonium salts, it would be reasonable to expect the difficultly soluble double salt-(NH,),SO,.ZnSO,, 6H,O-to be formed; but the author found that the nitrogen usually assigned to the ammonium salts was invariably contained in the filtrate from the zinc sulphate pre- cipitate.In the case of Kemmerich’s meat extract the ammoniacal nitrogen deter- mined directly in the original extract by distillation with an excess of magnesium oxide was 0.413 per cent., while in the filtrate from the zinc sulphate precipitate the amount found was 0.415 per cent. Hence, it is possible that the ammonia obtained by distillation with magnesia ia not derived from ammonium salts, but from some other nitrogenous compounds. C. A . M. On the Composition of Meat Extract. J. Konig and A. Bomer. (Zezt. anal. Clzem., 1895; 5th Heft, pp. 548-562.)-While there can be no doubt that nearly all the constituents of the muscular fibre which are soluble in cold water will be found in the nieat extract, the presence of gelatin or other decomposition products of the nitrogenous matter is by no means a certainty.Since the extract is prepared at low temperatures, and is only at the end concentrated to the required consistency after filtration, the amount of gelatin can only be excessively small. This view receives confirmation from the experiments of E. Beckmann (Hilger’s Fonch iib. Lebensm.itteZ, 1894, p. 423), who could only find 0.5 per cent, of albuiiiin and gelatin in Liebig’s extract by precipitation with formalin. On the other hand, Kernmerich ( 2 e i t . f . Physiol. Chew, 1894, xviii., p. 409) endeavoured to prove that in South American meat extract there was about 6 per cent. of gelatin, and about 30 per cent. of albuminoids, in the form of albumoses, peptones, and other soluble compounds.I n his analyses he employed fractional precipitation with alcohol of different strengths, as well as precipitation with ammonium sulphate and sodium phosphotungstate. By these means he found, in addition to flesh bases, the following amounts of albuniinoids in this meat extract : Per cent. 1. Gelatin precipitated by 50 to GO % alcohol ... ... ... 6-19 2. Albumoses precipitated by 80 2 alcohol . . . ... ... 14-76 Of these there were precpitated by (NH4)$0, ... ... 9-89 Other albuminoids soluble in (NH,),SO, . . . ... ... 4-87} 3. Peptones soluble in 80 % alcohol, precipitated by sodiuiii phospho- tungstate ... ... ... ... ... ... 12-31 33.26 Since the meat extract contained 8.13 per cent. of total nitrogen, these figures gave 6-5 per cent. of this to the albuminoids, which, in the authors’ opinion, was extremely improbable.They therefore critically examined the work of Kernmerich and of Stutzer (ANALYST, xx., 246), and by precipitation of the meat extracts with alcohol18 THE ANALYST. of different strengths and determination of the nitrogen in btained results considerably lower than those of Icemnierich. For South American meat extract Gelatin (?) precipitated by 50 to 60 per cent. alcohol. Kernmerich found ... ... 6.19 2 ... Konig and Bomer ... ... 1.83 ... the precipitates they Albumoses precipitated by 80 per cent. dcohol. 14-16 X 4.50 ' " These differences were too great to be accounted for by variation in the meat extracts, and must have been due to difference in method, Kemrnerich having determined the amount of his precipitates gravimetrically, and not by direct estima- tion of the nitrogen.The authors then made coniparative determinations by precipitation with 80 per cent. alcohol end precipitation with ammonium sulphate, with the following results : Liebig's Kernmerich's Kernmerich's Cibil's Per cent. Per cent. Per cent. Per cent. extract. extract. peptone. extract. Total nitrogdn ... ... 9-32 6.94 9.88 2.77 Precipitated by 80 per cent. alcohol ... ... ... 0.69 1-05 4.05 0-61 Corresponding to albumoses 4.31 6.56 25-31 3-81 -- Albumoses obtained by satur- ation with ammonium sul- phate ... ... ... 7-32 9.71 34.44 5-97 These results, and the fact that in the filtrate from the 80 per cent. alcohol pre- cipitation the biuret reaction was always obtained, showed that albuminoids were still present, and it was extremely doubtful whether these were to any extent peptones.The usual method of determining the peptones is to precipitate with sodium phosphotungstate, determine the nitrogen in the precipitate, and deduct from this the albumose nitrogen previously determined. In this determination the figures obtained were : Liebig's Kernmerich's Kernmerich's Cibil's extract . extract. peptone. extract. Pcr ceiit. Per cent. Per cent. Per cent. Nitrogen in phosphotung- Albumose nitrogen . . . ... 1-17 1-55 5-51 0 -96 Peptone (3) nitrogen.. . ... 5.10 4.04 2-78 1-04 I t is obvious that so large a quantity of peptone nitrogen cannot be present-at any rate in the meat extracts, and that the flesh bases must claim a considerable amount of it.All flesh bases, together with the rest of the nitrogenous constituents, are precipitated by sodium phosphotungstate if they are allowed to stand for sufficient time, and therefore this reagent cannot give any idea of the amount of peptone present. Basing their conclusions largely on the absence of the biuret reaction in the filtrate of a meat extract, the authors believe that the extractls state precipitate . . . ... 6-27 5.59 8.29 2.00 __ ..- -TEE ANALYST. 19 examined contained either no peptone at all, or, at most. very slight quantities (2 to 3 per cent.). They assigned the nitrogen found as follows : Liebig'e extract. Kernmerich's extract. Ken s peptone. Cibil's meat extract. Per cent. Per cent. mt. Per cent. Substance. Sitrogen. Substance. Sitrogen.Subwince. Sitrogen. Substance. Xitrogen. Total nitrogen ... 9.28 100 9-14 100 10.08 100 2.77 100 1. 2. 3. -1. 5. 6 . 7. - - - - _ _ - - -- Soluble albumin . , . trace trace 0'08 0.87 0.06 0.59 trace trace Nitrogenous com- pounds insoluble in 60-64 per cent. alcohol ... ... 0.21 2.26 (1.33 3-61 1-36 13-49 0.25 9.02 Albumoses ... 0.96 10.34 1.21 13'23 3-15 41-17 0.70 25.27 Peptones ... ._. 0 t o trace 0 to trace 0 0 0 0 0 0 3.97 39-38 1-56 56'31 Flesh bases ... 6.81 i3.38 5-97 ti5 -3.2 Ammonia ... 0.4i 5.06 0'41 4.49 0.29 2.88 0.09 3-25 Other Nitrogenons compounds ... 0.83 8.96 1.14 12-47 0.25 2-49 0.1; 6-15 As regards the chemical examination of meat extracts, the authors remark : 1. Precipitation with 80 per cent. alcohol is of no value in determining the kind of nitrogen.2. Albumoses should be determined by salting out with ammonium sulphate or zinc sulphate. 3. The filtrate from the ammonium or zinc sulphate precipitates should be decolorized with animal charcoal, and tested for peptones by the biuret reaction. 4. A determination of the ammonia by distilling an aqueous solution of the extract with ignited magnesia, is valuable. 5 . When peptone has been proved to be absent, the nitrogen in the phospho- tungstate precipitate, after deducting the nitrogen derived from gelatin, albunioses, and ammonia may be ascribed to the flesh bases. The precipitate should stand at least one day. 6. The difference between the total nitrogen and the nitrogen in the form of gelatin + albumoses + flesh bases + ammonia gives the amount of nitrogen present in compounds not precipitated by phosphotungstic acid.C. A. M. The Estimation of Gelatin in Meat Extracts and Commercial Peptones. .A. Stutzer. (Zeit. aiial. Clzem., 1895 ; 5th Heft., pp. 568-570).-The chief difficulty in the examination of these articles is the determination of the nitrogen present in the form of gelatin. Since his last communication (see ANALYST, xx. 248), the author has found that the best process for estimating this constituent is as follows : From 5 to 7 grammes of dry, and from 20 to 25 grammes of fluid preparations are weighed into a tinfoil basin, and sufficient hot water added to dissolve the extract, Ignited sand, which has been freed from fine dust by a sieve, is then added in suficient quantity to absorb the whole of the fluid, and the basin is placed in the water-oven until the weight becomes constant.The sand and extract are then ground in a mortar, the tinfoil cut into small strips, and the whole placed in a beaker, where it is extracted four times with 100 C.C. of absolute alcohol, the supernatant fluid being each time removed by filtration through an asbestos filter.20 THE ANALYST. The residue is now treated with a mixture of alcohol and ice-water, prepared by mixing in a large flask 100 grammes of alcohol with about 300 grammes of ice, and adding sufficient distilled water to bring the total weight up to one kilogramme. This flask and four beakers ( b , c, d, and e) are placed in a bath filled with broken ice. Into the beaker a, containing the sand, peptone, etc.(which is also placed in the ice bath), about 100 C.C. of the alcoholic ice-water are poured, care being taken that the temperature of the mixture does not exceed +5" C. After stirring with a glass rod for about two minutes, the supernatant liquid is poured into beaker b, a piece of ice being added at the same time. The extraction in beaker a is then repeated with a fresh portion of alcoholic ice-water, the liquid being decanted into beaker c ; and this process is continued until the liquid above the sand is completely colourless. Upon each repetition the fluid is poured into a fresh beaker, and the extraction is generally complete after this has been done four times, These consist of funnel about 7 centimetres in diameter at the top, in which a perforated porcelain disc about 4 centimetres in diameter is placed, this being covered with long-fibred asbestos. The first filter receives the liquid in beaker n and the insoluble residue, with the exception of the sand. The contents of beaker b are poured upon the second filter, while the third filter is used €or c, d, and e. After being well washed with the alcoholic ice-water, the whole of the asbestos filters (including the one used in the treatment with absolute alcohol) and the sand in beaker n are repeatedly boiled with water in a porcelain dish, the filtrate concentrated by evaporation, and the residue used for the determination of the gelatin nitrogen. When carried out in exact accordance with these details the estimation presents no difficulties. A Bunsen's water-puiiip may be used to accelerate the filtration through the asbestos, but should be very gramdually applied. I n order to filter the extracts, three asbestos filters are used. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8962100015

出版商:RSC    

年代:1896

数据来源: RSC

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20 THE ANALYST. TOXICOLOGICAL ANALYSIS. The Presence of Solanine in Potatom. N. S . Klepzow. ( J . ocluan. narod. s~7i*aiu., 1895, v., 659 ; through Chem. Zeit. Rep., 1895, 338.)-Otto’s method for the extraction of solanine is very convenient where the alkaloid exists in the crystalline condition, as in the buds of germinating potatoes, but less suitable for the treatment of the rind and of the body of the tubers, where it is found in an amorphous state. In November no solanine could be detected in new potatoes after peeling; but in December, after an artificial germination, the rind contained 0.11 per cent., and the buds 0.19 per cent,, while the potato itself yielded only a slight reaction. I n March, potatoes which had sprouted in the ordinary manner contained in the peel 0.07, in the buds 0.2, and in the tubers 0.024 per cent.of solanine. The author does not consider that potatoes that have germinated can be harmful as food, so long as they are properly peeled and prepared, since Clarus has found, experimenting on himself, that 0.4 gramme of solanine (corresponding to 8 kilo- grammes of potatoes freed from buds) was required to produce symptoms of poisoning. F. H. L.THE ANALYST. 21 Th9 Toxicological Detection of Aqua Regia. P. Ildola. (Boll. chiin. farm., 1895, xxxiv., 513 ; through Chem. Zeit. Rep., 1895, 327.)- Mixtures of flesh (100 grammes), water (500 c.c.), and aqua regia (2 c.c.) do not give off, at ordinary temperatures, the smallest traces either of chlorine or of hydrochloric acid; only a little nitrous acid can be detected. Even on fractional distillation the distillates remain neutral till the temperature reaches 190" C., when nitrous acid comes over, but neither nitric nor hydrochloric acid is to be found. The best method for the examination of organic substances is that already described by Vitali for the detection of hydrochloric acid. The article to be tested is warmed in a, porcelain baain to 50" or 60" C., and finely-powdered quinidine stirred in until the acid reaction dis- appears. The liquid is filtered, concentrated, and mixed with two-thirds of its volume of chloroform. Enough alcohol is then added to dissolve the chloroform, and finally, water to reprecipitate it. The quinidine salts thus remain in the chloroform, and on evaporation of the solvent, the acids may be detected in the ordinarymanner. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8962100020

出版商:RSC    

年代:1896

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THE ANALYST. 21 ORGANIC ANALYSIS. The Determination of the Heating Effects of Coals. W. Noyes, J. McTaggart, and H. Craver. ( J O Z L I ~ . Anzc~. Chenz. SOC., 1895, xvii., pp. 843-849.)-The work here described was undertaken in order to compare the results obtained with Hempel’s calorimeter with those calculated from analyses and those obtained by Berthier’s test, Six specimens of representative Indiana coal were used, the first two being non-coking, and the others coking and bituminous. The methods of obtaining the results tabulated below were as follows : 1. Moisture. -One gramme of coal was dried for an hour in a toluene bath { 105” C.). 2. Ash.-The residue froin the above was ignited over a Bunsen burner. 3. Fixed Carbon.-One gramme of coal was heated for 7 minutes in a covered The residue, less the ash, 4.Volatile Combustible Matter.-The loss of weight in 3 less the amount of 5. Carbon and Hydroyeii.-About two-tenths of a gramme of coal was burned in 6. Nitrogen. -D e t ermined with soda-lim e. 7. Su@JZZLr.-Determined by Eschka’s method, using potassium carbonate and magnesium oxide, by the method of Carius, and also by the use of sodium peroxide as follows : Half a gramme of coal was weighed into a platinum dish, 3 grammes of sodium peroxide, and a, little water added, and the whole evaporated to dryness and ignited. This was repeated after adding another 2 grammes of sodium peroxide and gome more water. The mass was then boiled with water, filtered, acidified, and the sulphate determinedjn the usual manner. The results agreed well with those obtained by Eschka’s method, but were somewhat lower than those given by Carius’s method.8. Oxygen.-This is usually calculated by subtracting the other constituents platinum crucible with the full flame of a Bunsen burner. gave the ‘6 fixed carbon.” moisture. a current of oxygen in a hard glass tube containing copper oxide and lead chromate.22 THE ANALYST. from 100. But where much sulphur is present an appreciable error is introduced. Assuming that the sulphur is usually present as iron pyrites, a correction was applied to the ash by adding to it five-eighths of the weight of sulphur present. The heating effect was calculated for the coal by the formula : 8080 C + 28800 (H-&O) + 1582 Fe + 2162 S. Calorimetric Determinations.-Hempel’s calorimeter was used (see Zeit.angew. Chem., 1892, p. 393). At least three determinations were made with each coal, and a correction of 610 calories per gramme of water was made for the water condensing in the calorimeter, the average temperature of which was taken as 26” C. Berthier’s Test.-One gramme of coal was intimately mixed with 40 grammes of litharge, the mixture being placed in a Battersea C crucible, and covered with a layer of salt. The covered crucible was then placed in a hot gas .furnace for 15 or 20 minutes, after which the button of lead was obtained, cleaned, and weighed. Theo- retically 1 gramme of lead should equal 234 calories, but this gives results about 12 per cent. too low. I n the following table an empirical factor of 268.3 calories per gramme of lead was employed, this being the average of the results obtained.The average difference of the results from the mean for a given coal was 0.11 gramme, which corresponded to 29 calories, or about 0.45 per cent. The differences between the results of calorimetric determinations and those obtained by other methods are given in percentages : Moisture . . . ... ... Volatile conibustible matter Fixed carbon ... ... Ash ... ... ... ... Carbon ... ... ... Hydrogen ... ... ... Nitrogen ... ... ... Oxygen ... ... Sulphur . . . ... ... Iron (calculated) . . . ... Ash (corrected) ... ... Calories (per gramme), C ... (calculated), H ... s . . . 9 , ,, Fe ... Total ... ... ... Difference per cent. ... ... Calories per gramme (Ber- thier’a test, factor 268.3).. . Difference per cent. . . . Calories per gramnie (calori- 3 9 J l ... meter) ... ... ... New New Yittsburg, Pittsburg, Lawaster. R A. 6.83 39.92 39.93 13-31 132.88 5-07 1.01 13-06 17.98 7 -46 6-53 5081 99 1 161 103 6356 + 2.6 6307 + 2-1 6175 5.89 42-23 40.40 11-48 65-26 5-17 1.17 13-25 15.15 5-88 5-14 5272 1011 137 81 6491 + 1-52 6471 + 0.9 6415 12.66 37.44 47 -22 2-68 71.41 5-56 1.54 18.42 3.07 0-62 0.54 5770 939 13 9 6731 + 0.4 6831 + 1-9 6703 Brazil. 8.98 34 -49 50.30 6.23 70.50 4-76 1.36 16-29 7-09 1.39 1.22 5696 784 30 19 6529 - 4% 6689 - 2.3 6846 Shelburn. 8.63 38.82 43.45 9-05 66-86 5-30 1-50 15.69 10.65 2.57 2.25 5402 962 55 36 6455 - 1.2 6461 - 1-1 6532 Shop. 2-36 31.11 42-44 24-09 57-32 4-56 1 -44 9.93 26-75 4.25 3.73 4632 956 92 59 5739 - 1.2 5726 - 1-4 5806 The results obtained from the analyses and by Berthier’s test agreed better with each other thaii either did with the calorimet.ric results, and on the average Berthier’s test, using the empirical factor, appeared to be more reliable than the results Calculated from the analyses. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8962100021

出版商:RSC    

年代:1896

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THE ANALYST. a3 INORGANIC ANALYSIS. (REV. h t . des Fals., viii., 98 ; through Bull. de Z’Assoc. belge Chirn. , 1895, iv. , 132.)-This is based on the property possessed by a solution of brucine in nitric acid of becoming reddish violet in the presence of stannous salts. The brucine solution is prepared by dissolving 0.5 gramme in 5 C.C. of nitric acid in the cold, adding 250 C.C. of water, boiling for ten or fifteen minutes, and making up the volume to 250 C.C. A trace of the substance under examination is acidified with a little hydro- chloric acid, evaporated to dryness, and the residue dissolved in several drops of water, and 1 C.C. at most of the cold solution of brucine added. By this reaction, as little as 0.05 mg. of tin can be detected, even in the presence of salts of copper and iron.In order to detect tin in metastannic acid, 1 C.C. of water, 0.5 C.C. of hydrochloric acid, and a fragment of pure zinc, are added to the sample. The tin is deposited on the zinc, and may then be detected as above. Rapid Detection of Tin. C. Deniges. C. A. M. The Estimation of Graphite in Iron. P. W. Shimer. (!Z‘rans. Ante?.. Inst. Min. Engin., 1895 ; through Chem. Zezt. Rep., 1895, 273.)-The processes for the estimation of graphite in iron, which depend on the solution of the metal in hydro- chloric acid, always yield higher results than those where nitric acid is the solvent. It is, however, not to the oxidizing action of the latter on the finely-divided carbon that this difference is due, but to the fact that the titanium carbide is broken up by nitric acid, while it is undissolved either by hydrochloric, hydrofluoric, or sulphuric acid, or by caustic potash.The author states that all crude irons contain titanium, the amounts varying from 0.05 to 0.40 per cent., while other carbides are usually present in minute traces. One sample of iron, containing 3-334 per cent. of total carbon (by combustion), proved to have 3.206 per cent. of graphite, 0.128 per cent. of combined carbon, and 0.399 per cent. of titanium. By solution in hydrochloric acid, the yield of graphite was 3-327 per cent.-O.121 per cent. too much. The amount of carbon corresponding to the titanium found was 0.100 per cent. (? 0-096), and this, subtracted from the above surplus of ‘‘ graphite,” left 0,021 per cent. unaccounted for.Moreover, the carbon soluble in hydrochloric acid (probably combined with iron and manganese) was 0.007 per cent.; this deducted froni the total combined carbon again left a difference of 0.021 per cent. , which must be made up of the carbides of metals other than titanium. It is therefore advisable, in analysing crude irons, to make determinations of the total carbon, of the carbon insoluble in hydrochloric acid, and of the graphite by means of nitric acid. F. H. L. The Separation of Iron from Beryllium. Elizabeth Atkinson and E. F. (Jozmz. Arner. Chenz. Soc., xvii., 1895, pp. 688, 689.)-The usual method of Smith.24 THE ANALYST. separation by means of the solubility of beryllium hydroxide in ammonium carbonate does not always give satisfactory results. As a substitute for this, the authors have made use of nitroso-P-naphthol.The solutions used were : (1) A 50 per cent. acetic solution of nitroso-P-naphthol. (2) A ferric solution of which 10 C.C. contained iron, corresponding to 0.1278 gramme ferric oxide. (3) A solution of beryllium chloride of which 10 C.C. contained 0.1248 gramme. To test the completeness of the precipitation of the iron by the reagent, 10 C.C. of the ferric solution were diluted with 200 C.C. of water, and 25 C.C. of the nitroso- P-naphthol solution added to the liquid, which was allowed to stand for twenty-€our hours. The iron precipitate was then filtered, washed first with 50 per cent. acetic acid and then thoroughly with water. After drying, the iron nitroso-P-naphthol was mixed with an equal quantity of pure oxalic acid, and ignited in a weighed porcelain crucible until all the carbon had been burned off.The results obtained were : (1) 0.1277 gramme of ferric oxide. (2) 0.1283 ,, 9 , (3) 0.1277 ,, J , The amount taken was 0.1278 gramme. cipitate even after standing for twenty-four hours. manner, the ferric oxide found was : Ten C.C. of the beryllium solution being treated in the same way, gave no pre- When 10 C.C. each of the iron and beryllium solutions were treated in this (1) 0,1277 gramme, (2j 0.1275 - ,, (3) 0.1277 ,, instead of 0.1278 gramme. It was found that uranium salts could not be precipitated by this reagent. Nor did it precipitate solutions of cerous salts, of lanthanum ammonium nitrate, of praseodymium nitrate, of neodymium nitrate, of terbium, of erbium, or of sodium rnol y bdate or tungs tat e.With zirconium chloride there was an orange precipitate, and with ceric ammonium nitrate a bright scarlet flocculent deposit, the precipitation being, how- ever, incomplete. C. A. M. The Estimation of the Halogens in the Mixtures of their Silver Salts. F. A. Gooch and C. Fairbanks. (Zeits. anorgan. Chem., 1895, ix., 349; through Chenz. Zeit. Rep., 1895, 257.)-The mixtures of chloride and bromide or chloride and iodide of silver are filtered through a Gooch crucible, whose layer of asbestos is covered with a, piece of platinum gauze to ensure electrical contact. The precipitate is dried at 150" C. and weighed; then melted by the direct application to it of a gas- burner, the crucible being placed on an anvil to keep it cool and prevent the melted salts soaking into the asbestos.For the separation of the chloride and bromide, the crucible is filled up with a 10 per cent. solution of oxalic acid in 25 per cent. alcohol, and treated with a current of 0.25 to 0.5 amphe for six to seven hours. This electrolyte is chosen to prevent the platinum being attacked by the nascent halogen,THE ANALYST. 25 but in the case of mixtures of chloride and iodide it is replaced by the following: Two volumes of 40 per cent. acetic acid are neutralized with ammonia, one volume of ammonia, one volume of 75 per cent. aldehyde, and one volume of alcohol, mixed with them. If ammonium iodate separates out on the anode, it can be dissolved by immersion in hot water ; and if iodine is set free, it is a sign that the electrolyte is exhausted and needs replacing.The silver is finally washed, dried, and ignited gently in the usual manner. The latter liquid will do for the bromine separation equally well, but the former is simpler to prepare. F. H. L. The Detection of Cyanate in Potassium Cyanide. E. A. Schneider. (Berm, 1895, xxviii., 154O.)-By the employment of the azure-blue colour of cobalt cyanate, it is possible to detect from 0-35 to 1 per cent. of potassium cyanate in the cyanide. The solution to be examined must be as concentrated as possible, for on this depends the delicacy of the test. It is decomposed by a rapid current of carbon dioxide passed for about forty-five minutes, the carbonate precipitated with alcohol, and after the addition of a few drops of acetic acid, testled with cobalt acetate.In testing large amounts of the cyanide (e.y., 20 grammes), they should be dissolved in the minimum of water, the bulk of the salt thrown down by alcohol, filtered, treated as before, again filtered, and a second current of oarbon dioxide employed to remove the hydrocyanic acid. F. H. L. The Estimation of Molybdenum, and the Volumetric Separation of Molybdenum and Vanadium. (Bey., 1895, xxviii., 2061 and 2067.)--1. Gmvinzetric Process. -- The molybdenum is precipitated as sulphide, either by dilute acid from a solution in ammonium sulphide, or by sulphuretted hydrogen from an acid liquid. When it has thoroughly settled, it is filtered of, washed first with very dilute sulphuric acid, then with dilute alcohol, till the washings are neutral, and placed in a tared porcelain crucible, and dried at about 100" C.The crucible, with its cover on, is heated cautiously till all hydrocarbons are driven off, then uncovered, and the sulpur burnt off' at as low a tempera- ture as possible. The heat is finally raised till no more sulphurous acid is formed, the crucible allowed to become cold, the oxide dissolved in ammonia, filtered from the particles of unburnt carbon, the solution evaporated to dryness, and ignited till of a uniform yellow colour, when it is weighed as molybdenum trioxide. 11. Volzmetric Proccss.-0-2 to 0.3 gramme of the molybdate and 0.5 to 0.75 gramme of potassium iodide are placed in the decomposing flask of Bunsen's apparatus, together with enough 1 to 12 hydrochloric acid to fill it two-thirds full.The heat is raised very slowly, and the liquid is only brought to the boil when the leading tube has become full of iodine vapour, and there is danger of the iodide in the condensing tubes being drawn back. The free iodine in the latter is then titrated with thiosulphate, the action taking place as follows : C. Friedheim and H. Euler. MOO,, + 2HI = MOO$ + I + H,O, or 2Mo0, + 2HI = Mo,Oj + I, + H,O.26 TEE ANALYST. This process is available far the analysis of all molybdates, except those whose bases decompose hydriodic acid with production of free iodine, while it simplifies the examination of many complicated substances, such as the silicomolybdates and the phosphomolybdates. 111. Separation of Molybdenzm from Vanadium.-The substance to be analysed, containing the pentoxide of vanadium and the trioxide of molybdenum, is introduced into the flask of Bunsen’s apparatus as before, together with potassium bromide and fuming hydrochloric acid.The molybdic oxide is uot attacked, but the vanadic oxide is decompclsed according to the following equation : (a) V,O, + 2HBr = V,O, + H,O + Br,. The iodine liberated by the action of the bromine on the iodide in the tubes is deter- mined as usual, and when the blue solution in the flask has cooled, 1 gramrne of solid potassium iodide and 1 or 2 C.C. of syrupy phosphoric acid are added, and the distillation, etc., repeated. Both oxides are now attacked as follows : (b) V,O, + 2HI = V,O, + H,O + I,. (c) 2M00, + 2HI = Mo,O, + H,O + I,.The iodine liberatedin ( b ) being the same in quantity as that in (a), if the amount of thiosulphate used in the first titration is subtracted from that required in the second, the remainder expresses that corresponding to the iodine in (c), or to the molybdenum present. A number of analyses are quoted in the paper, showing satisfactory results. F. H. ri Estimation of Uranium i n Ores which contain Phosphoric or Arsenic Acids. R. Fresenius and E. Hintz. (Zeit. angezo. Chem., 1895, pp. 502, 503.)-In the ordinary methods for estimating uranium in its ores, the presence of phosphoric and arsenic acids, as well as of copper and iron, causes considerable difficulty. I t is only after repeated precipitation with sulphuretted hydrogen from acid solution that it is possible to obtain the precipitate of metallic sulphides free from uranium.Moreover, the presence of phosphoric acid considerably increases the difficulty of separating iron from uranium, Potassium ferrocyanide appeared a likely reagent to precipitate uranium in acid solution, and thus to effect a separation from phosphoric and arsenic acids; but it was found that the precipitate of uranium ferrocyanide could not be filtered off. When, however, the liquid was saturated with sodium chloride, after the addition of the potassium ferrocyanide, the precipitate rapidly settled, and could then be easily filtered off, and washed with a solution of sodium chloride. On this fact the authors have based their method of determining uranium in the special cases mentioned above.After silica has been removed from the nitric acid, hydrochloric acid, or aqua regia solution in the ordinary way, an excess of potassium ferrocyanide is added to the dilute hydrochloric acid solution, and the liquid then saturated with sodium chloride. The precipitate containing uranium, copper, and iron ferrocyanides rapidlyTHE ANALYST. 27 settles, and is washed first by decantation and then on the filter with water con- taining sodium chloride, after which it is treated in the cold with dilute caustic potash. The hydrates are filtered off and washed with water containing ammonia and ammonium chloride until ferrocyanide can no longer be detected in the acidified filtrate. On treating the hydrates with hydrochloric acid they should dissolve com- pletely.The solution of metallic chlorides is then concentrated, most of the free acid neutralized with ammonia, and an excess of ammonium carbonate added. After some time the insoluble ferric hydrate is removed by filtration, and washed with water containing ammonium carbonate. The filtrate is heated to remove ammonium carbonate, hydrochloric acid added, and the copper precipitated with sulphuretted hydrogen, the liquid being heated at the same time. After filtration the liquid is concentrated, the uranium is precipitated with ammonia, and the uranium hydrate converted into uranic oxide by ignition in an uucovered crucible, and weighed as such. As a control this is converted into uranous oxide by ignition in a current of hydrogen, and the amount of this also determined. To test the method, an aqueous solution of pure uranium nitrate was used, and the following results were obtained : The amount of uranium in 25 C.C. of the solution was determined by the ordinary methods, and found to be (1) 0.2437, and (2) 0.2438 gramme. The uranium in the solution was then precipitated with ferrocyanide, and the precipitate treated as described above : 25.250 gramrnes of the uranium solution yielded 0.2889 gramme of uranic oxide, corresponding to 0.2453 gramme of uranium. The amount of uranous oxide obtained was 0.2782 gramme, which corresponded to 0.2454 grainme of uranium. These figures corresponded to 0.2430 gramme of uranium in 25 C.C. of the original solution. Control experiments with solutions containing copper, sodium phosphate, iron, and arsenic, gave equally satisfactory results. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8962100023

出版商:RSC    

年代:1896

数据来源: RSC

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THE ANALYST. 27 APPARATUS. Koch's Sterilizing Cylinder as a Water-bath. A . Bau. ( Chem. Zeit., 1895, xix., 2003.)-The author advocatles the employment of Koch's sterilizing apparatus as a water oven, especially where a number of flasks or similar vessels have to be heated exactly to 100" under precisely similar conditions. Other temperatures may be obtained by the use of liquids, having no action on metal, with different boiling points. One great advantage of the device lies in the fact that the evaporation of the heated substance is reduced to a minimum, while, as the disturbing influence of the atmospheric oxygen is in great measure obviated, the apparatus is particularly suitable for the estimation of sugar by means of Pehling's solution. F. H. L.28 THE ANALYST. An Asbestos Air-bath. S. Cerhez. ( S e i t . augezr. Chenz., 1895, p. 561.)-This consists of an asbestos basin, with a suitable cover provided with rings of different sizes, also of asbestos. The author claims that by means of it the temperature may he easily kept constant, and an evaporation completed in one-third of the time required on a water or saiid-bath. The apparatus may be obtained from F. Huger- shoff, Leipzig. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8962100027

出版商:RSC    

年代:1896

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28 THE ANALYST. R E V I E W S . By W. LLOYD WISE, J.P., F.R.G.S. (London : Cassell and Co.) Price 2s. This is a little book written by a well-known patent agent of thirty years’ experience, and one which will probably be of service to chemists who may be con- sulted in connection with patent matters. It is practically a collection of articles, which have already been published serially, affording systematic information as to the mode of application and procedure for the grant of patent rights abroad, and for their assignment and transfer, and also as to various cognate matters. Useful statistical information is given as to the principal industries, products, imports and exports, of the countries dealt with. The series of articles is not yet concluded, so that the present volume is but the first instalment of the whole, the second part of which will be issued later.So far there are included twenty-two countries, ranging in alphabetical order froin the Argentine Republic to the German Empire. GLEANINGS FBOM PATENT LAWS OF ALL COUNTRIES. B. D. QUANTITATIVE CHEMICAL AXALYSKS, adapted for use in the Laboratories of Colleges PRACTICAL CHEMISTRY AND QL-ALITATIVK ANALYSIS. FRANK CLOWES. (J. and A. The rapidity with which the two books require new editions is the best proof of their excellence. I t is evident that practical teaching in colleges and schools is at last departing from the Messrs. Clowes and Coleman’s ‘‘ Quantitative Analysis ” contains an immense amount of information ; and not only learners in colleges, but many who have long left college, may with profit turn to it. We note with pleasure that not only the commonly occurring elements are considered, but also the rarer ones, and that the characters of a, good many organic substances are described. We shall be glad t o see the list of organic substances still further extended in futare editions. Since the appearance of the classical works of Fresenius, nothing nearly so good as Messrs. Clowes and Coleman’s books has been placed in the hands of students. 0. H. and Schools. (E’NAIUK CLOWE:~ and J. BKRXARD COLEMAN.) Third edition. Churchill. ) Sixth edit ion. test-tubing ” stage, under which it has laboured so long. The instructions for qualitative analysis are clear and complete. APPOINTMENT. Mr. W. LINCOLNE SUTTON has been appointed Public Analyst to Norwich, vice W. G. Crook, deceased.

ISSN:0003-2654    

DOI:10.1039/AN8962100028

出版商:RSC    

年代:1896

数据来源: RSC