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THE ANALYST. AUGUST, 1898. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. SUMMER MEETING. THE summer meeting of the Society this year took the form of a visit to the Duke of Bedford’s estate at Woburn, for the purpose of inspecting the Agricultural Experi- mental Station which has been conducted there for many years by Dr. Voelcker, under the auspices of the Royal Agricultural Society of England. On the morning of Tuesday, July 12, a party of about forty (including a large proportion of ladies) met at Euston and travelled to Bletchley, where, after changing trains, they were conveyed to Woburn Sands Station. Conveyances were in readiness, and after a drive of some three miles through very pretty country the main experimental field, called ‘‘ Stackyard Field,” was reached. Here the various plots of wheat and barley were inspected.Some of these had not received applications of any kind for twenty- two years, others had been treated every year with sulphate of ammonia or with nitrate of soda alone, others with mixtures of various chemical fertilizers, others, again, with farmyard manure. The members accordingly were able to estimate for themselves the influence exercised by the different methods of treatment. All the details were explained by Dr. Voelcker as the party moved on past the various plots, and attention was drawls to the most striking features. Each member of the party was, in addition, provided with a pamphlet, giving plans of the various experiments, the treatment to which each plot had been subjected, and the yield over a series of years.After viewing the fields, the company were conveyed to the experimental pot-culture station, where they inspected the laboratory and also a number of experiments, con- ducted in pots, designed with & view to discovering the effects on agricultural crops of compounds of some of the rarer elements, such as iodine, bromine, fluorine, lithium, manganese, titanium, etc. This department had only quite recently been established, but several results of an interesting and unexpected nature have already been obtained. After this the party sat down to an excellent luncheon, laid out in the large green- house belonging to the station, during which, on the proposition of the President (Dr. Bernard Dyer), a vote of thanks to Dr. Voelcker for his kindness was carried by acclamation, Dr.Voelcker saying, in reply, that the inception of the visit was really due to the fact that the Society had this year an ‘‘ agricultural president.” After luncheon the party were conveyed through the beautiful grounds of Woburn Park to Woburn Abbey, which is the principal seat of the Duke of Bedford. Here the198 THE ANALYST. picture and sculpture galleries and other interesting collections were visited. The weather was most propitious, and the general arrangements were well and carefully organized, the result being a most agreeable, entertaining, and instructive day. SEWAGE ANALYSIS AND STANIIARDS OF PURITY FOR EFFLUENTS. BY C. G. Mooii. (Read at the Meeting, Jwie 1, 1898.) CI~UDE sewage as brought to purification works necessarily varies from town to town.It varies in composition according to the presence or absence of abnormal institu- tions, such as factories, and according to the manner of its collection ; for example, as to whether this is from a high level by continuous gravitation, or from a low level by continuous pumping. The latter is a matter of considerable importance, because in the older precipitation processes it was very difficult to deal with sewage that waB stale, as it always is when collected froin a low-level system, which is pumped during a few hours only of the working day. Sewage varies in quantity and in concentration, primarily, according to the extent of the water supply in gallons per head of population, and, secondly, according to the rainfall, etc.I n a given town it varies in all respects from hour to hour, and, as a rule, to a less extent from day to day and from season to season. The extent of none of these variations can be stated in advance. In the estimation of the relative efficiency of the purifying processes used at different towns, it is therefore the ratios of the measurable factors of impurity in the effluent to those in the crude sewage from which it was derived, that must be compared so far as it is possible to obtain them. The sewage which is spread over a field will not all find its way into the effluent. Some will be absorbed in the ground, and there disintegrated by the action of micro-organisms and of higher plants. This is the purification process proper, and its extent will vary up to a limit with the extent of saturation of the soil with previous additions of sewage.Another part may, however, be temporarily arrested, and the interval which elapses before it is washed through may vary, not only with the nature of the ground and of the crop8, but with meteorological and other conditions. This is not neces- sarily a process of purification, and the comparison of the effluent with the crude sewage may be improperly favourable or unfavourable to the process, according to the time at which the effluent was taken. Evaporation from the surface of the sewage- field will in all cases tend to exhibit the degree of purification as less than it actually is, and less to an extent varying with the presence and nature of the drainage and with the temporary condition of the soil in respect to saturat'ion with sewage.Dilution by rain will affect both sewage and effluent, though possibly not to the same extent ; but a more serious variable is the height of the ground-water, which may dilute the I n thccase of sewage farms these are difficult to obtain.THE ANALYST. 199 effluent to an extent which would altogether vitiate any figures that did not take account of it. These are only some of the factors affecting sewage-farms, which are liable to vary beyond control and to some extent beyond measurement. They are indeed in- evitable in any system in which provision is not made for the uniform treatment of all parts of the crude sewage. I n the artificial processes, whether chemical, electrical, bacterial, or bacterio- mechanical, the difficulties in the way of obtaining comparable figures are consider- ably less.I n all of them the whole of the sewage is subjected to a uniform treatment, the interval between the inlet and outlet is known, and the factors of variation between town and town, hour and hour, day and day, may be expected to affect the ctonstitu- tion of the effluent no less than that of the sewage, or at least to affect it to an extent so small as not to seriously invalidate the comparison it is desired to make. The following scheme of observations would be applicable in most cases where the question to be set,tled is the efficiency of a particular process at a particular place : Town Variables. 1. Note nature and extent of factories or other abnormal sources of pollution.2. Chart the water-supply for previous week and for period of experiments, and 3. Chart rainfall during the experiments and for the previous week. 4. Note the temperature of the air and sewage during experiments. ascertain that it is normal. Works Variables. 1. Ascertain dimensions of works, the length and fall of sewers, and the general structural details of works and sewerage, and whether pumping is required- z.e., are there low-level sewers ? 2. Chart the volume of sewage at intervals during the experiments. 3. Where screens are in use, estimate the solids they retain. Sewage Variables. 1. Take samples at intervals during the first twenty-four hours of sewage and effluent, determine the chlorine and loss on ignition for each, and compare the result with that of an average sample taken in quantities proportional to the flow for the time being during the working day, measured so as to include the time of maximum impurity.If these factors give sensibly the same results as average samples, the remainder of the investigation can be conducted on average samples. All samples, average or otherwise, must be kept in ice from the time at which they were taken up to the time of examination, and the interval should be as short as possible, 2. The following estimations and observations should be made : PHYSICAL EXAMINATION. Smell. Co1our.-Whether any in one inch in white dish. TTLrhidity and determination of suspended matter, if present.200 THE ANALYST. CHEMICAL EXAMINATION. Total Solids. Mineral Solids. Loss on Ignition.-I attach considerable importance to this, and shall refer to it later on.ClzZori?ze.-This figure is of high value in enabling us to identify the effluent with a sample of sewage with which it is desired to compare it.. If one goes to a sewage works at 11 or 12 o'clock, when the sewage is foulest, and takes samples of the raw sewage and of the effluent, they will almost invariably not correspond. An example of this is shown in the case of some analyses made for the Manchester Corporation, the figures of which appeared in the Sanitary Record for May 27. A sample of raw sewage contained 14.9 grains of chlorine per gallon, whereas the effluent contained only 6.3 grains per gallon, showing that the sewage corresponded to a period of con- siderable impurity, while the effluent was probably derived from sewage that was not nearly 80 foul.Hardness.-Considerable hardness is produced on adding the large quantities of h e sometimes employed, as in Hansen's process, in which lime and sulphurous powder are used, or in other processes where lime and alumina salts are used, Nitrites.--I regard the presence of these as showing a want of free access of oxygen. They are not often found in effluents unless the latter have been bottled up and kept in the laboratory for some days, in which case nitrites are always present in large quantities. Nitrates.-If we determine that nitrates ought to be present in definite quantities, it will probably compel those works at which precipitation is practised to add filter-beds to their plant.The presence of nitrates in the effluent is highly desirable, as showing that oxidation has proceeded to some extent, and that true purification has therefore begun, and some figure should be provisionally fixed so that at least a certain quantity of oxidized nitrogen should be present. SaZine Ammo7zia.-This cannot be objected to as a natural step in the breaking down of nitrogenous matter. Albwminoid Ammonia.-The lower the quantity of this, the better. Oqygen Absorbed. -Four hours at 80" F., Tidy's modification of Forschammer's process. 3. Chart the temperature of sewage and effluent. In some bacteriological pro- cesses there is reason for supposing that the temperature rises during the operation. The following supplementary estimations from a bacteriological point of view would add greatly to the interest of the determinations above mentioned : 1. The number of bacteria, in both sewage and effluent, that grow on gelatin, and the number that liquefy that medium, These determinations will be of com- paratively little value unless the following estimations are also undertaken, namely, an estimation of those organisms that live at blood-heat, and of the anaerobic bacteria present, which must, of course, be cultured in a neutral gas under special conditions.In addition, the investigation of the bacterial contents of the eflluent in particular would not be complete without a special estimation of the, nitrifying bacteria, whichTHE ANALYST. 201 only grow on special media, such as silica jelly. From these considerations it will be conceded that a bacteriological investigation (even if we had the power of duly inter- preting the results when obtained) would be no light matter ; and in the present state of our knowledge it could not yield results of anything like the practical value that we can derive from a chemical examination.I n regard to the relative importance of the chemical processes, I will not go over ground which is obviously familiar to all of us ; but I would draw special attention to the determination of the ‘‘ loss on ignition ’’ as being one of the most important factors for characterizing a sewage in respect of its richness in organic matters. Personally, I think that for this purpose it is to be preferred as a, characteristic estimation to the results of the popular ‘ I oxygen-absorbed ’’ process.For instance, cellulose in various forms occurs in considerable quantities in sewage, and this, while it would probably not be attacked by the perrnanganate used in the “oxygen- absorbed ” process at blood-heat, would certainly be liable to undergo bacterial decomposition and to produce offence. No doubt this would come out in the determinations of organic carbon and nitrogen which have been recommended by a high authority for the examination of sewage. It must be remembered, however, that life is short, and these processes are long; and it is in the belief that their adoption would tend to the limitation of the number of determinations, and, through this, cause a far greater loss in useful information than would be gained by their practice, that I have intentionally omitted them from my list.By proceeding as I have described, the principal factors affecting the efficiency of sewage purification processes can be obtained, and while the selection of observa- tions which I have made is subject to criticism, there will be probably little funda- mental differences between us as to the necessity and sufficiency of such observations or their equivalents. The interpretation of these results is, however, a matter of inore complexity, and more likely to excite differences of opinion. On that ground, and rather with the object of drawing discussion than of formulating any final state- ment, I submit certain considerations which appear to me to be fundamental. I n the first place I am convinced that the purification of sewage, so far as it is con- templated by any existing scheme, can only be regarded as a chemical process, and that it is in terms of chemical determinations alone that the results of any process for effecting it can be expressed.I do not lose sight of the fact that the processes (which through the industrious genius of one of our members, and of others who have worked on similar lines, have now been shown to be the most promising) are bacterial; but it must be clearly remembered that the bacteria so involved are merely means for applying biological energy in place of the chemical energy previously employed, and are used for the precisely identical purpose of altering the sewage in its chemical composition, from a substance highly favourable to the growth of putre- factive and some other organisms, into a substance not specially favourable, and perhaps ultimately inimical to their growth.The only terms, therefore, in which a standard of purification for a process or a staizdard of permissible impurity in an effluent can be expressed are necessarily and soZeZy chemicail. The function of bacteriological examination is in no way depreciated by this circumstance. If the202 THE ANALYST. bacteria of sewage were constant in the sewage of all towns and at all epochs, and if the circumstances affecting their survival and metabolic activity were the same in all sewage or, if variant, they equally affected all the organisms essential to bacterial purification, the place for bacteriology in the matter would be confined to the deter- mination of the extent to which effluents favoured or impeded the growth of un- desirable organisms, in particular those which directly cause disease, and those which produce offensive organic substances.This function it must have in any event, and in the present state of knowledge no general statement can be made in regard to the substantial constancy-that is, as to the constancy in particulars material to the purification processes-of the bacterial conditions to which I have referred. I t remains, therefore, for bacteriology to determine the relation between the various organisms and the various chemical factors and physical conditions which occur in practice. The problem is one of extreme complexity, and its investigation is the more tantalizing by reason of the probability that many of the organisms norinally found inay be individually indifferent in the purification process.I t is on this ground that I think the present object of such investigation should be rather the examination of these organisms in groups collected under such characters as those which I have selected than the individual identifica- tion of particular organisms. Such inquiry in any case has far more than academic interest. I t may well turn out that in some cases artificial addition of bacteria may form a part of that process which in the particular circumstances is the most efficient. There remain, again, questions which experience at present bas not gone far enough to settle; such, for instance, as the extent, if any, to which the first products of the bacterial energy are in stable or unstable equilibrium, and their liability, or freedom from liability, to become the subjects of secondary disintegrations, and to result in secondary degradation of the effluent.But whatever result such investigations may have, and essential as I regard them to placing the problem of sewage purification on a satisfactory basis, it is in q?inntitative teyms of the chemical products which varying bacteria and varying conditions produce that the results of bacteriological investiga- tion must be expressed before they pass over from the domain of experimental science into that of practical application. In the absence of such data; it is impossible to define any standard either of percentage purification or of maximum permissible impurity which can be regarded as final or constant for all places, Several standards of permissible composition have been proposed; and perhaps it may be convenient if I re-state some of them.There is, first, that of the Rivers Pollution Commissioners : I n Parts per 100,000. 6rgnnic Organic Albuminoid Ox&en Carbon. Xitrogen. Ammonia. Absorbed. I ... - Rivers Pollution Comn~issioners . ., 2.0 . , . 0.3 . . . ... 0.1 ... 1.0 - ... - Derbyshire County Council . . . ... In addition, the Rivers Pollution Commissioners’ standard requires that a certain degree of alkalinity or acidity is not to be exceeded, that the matter in suspension is not to exceed 3 parts per 100,000 of dry mineral matter, nor 1 part of dry organic matter, that there shall be no visible colour in a stratum 1 inch deep when viewedTHE ANALYST.203 in a white dish, nor any metals except calcium, magnesium, potassium, or sodium present to a greater extent than 2 parts per 100,000, and a limit is also set for free chlorine, for arsenic, and for sulphur as sulphuretted hydrogen or free sulphuric acid. The other standard, suggested by Dr. Barwise, is of a much more practical nature, though it appears to me to be somewhat too severe, and is, in my opinion, rarely attained by any of the processes in common use. The Thames Conservancy, in the upper reaches of the river, recognises, as a “good effluent,” any efflucnt which gives less than 0.2 part per million of.alburninoid ammonia. I should be inclined to suggest the following standard as satisfactory for general use : Parts per 100,000.Total suspended matter (not to exceed) ... ... ... 2.0 Albuminoid ammonia ... ... ... ... ... ... 0.2 Oxygen absorbed.. ... ... ... ... ... 0.75 Total hardness ... ... ... ... ... ... ... 25.0 Nitrogen as nitrates (not to be less than) ... ... ... 0-75 . ... The amount of nitrates should be insisted on, as showing that true purification has begun, and that there is a store of oxygen that could be drawn on, as a guarantee against possible putrefaction. I base this standard on the fact that, on the examination of a large number of samples of effluents, I have found no sample which, falling within this standard, became putrefied on keeping either in closed OY open vessels. For my own part, therefore, I should at present prefer this standard ; but I put it forward with the reservation that any standard must at the present time be regarded as tentative, and be subject to, and likely to undergo, revision in, I hope, no distant future, when more exact data correlating the bacterial, physical, and chemical circumstances are avail- able.In the meantime, however, I think that in this, as in so many other matters in which our profession is concerned, it would add to the authority of all of us, and conduce to the advantage of the public, if we could arrive at some agreement as to the standard which should, for the time being, be adopted in common. DISCUSSION. Dr. DursB said that he totally objected to any universally applicable standard being laid down in the case of sewage effluents.What was or was not permissible depended entirely upon where each effluent was to go to--whether, for instance, it was to be discharged into a comparatively large stream of water, or into a dry, or nearly dry, ditch. The Thames Conservancy had, he believed, several different standards. They would allow to be discharged below the intake of the waterworks an effluent which they would not allow to go into the river above the intakes. A very fair measure of the impurity present in a water or effluent might be obtained by determining the quantity of dissolved oxygen absorbed from the effluent. Pure water remained aerated when bottled up, but water containing sewage de-aerated itself. An effluent which did not appreciably de-aerate itself might be admitted anywhere without fear of putrefaction taking place.A s a chemist, he always preferred to rely upon chemical tests, and to do without bacteriology if possible; and this measurement of the oxygen absorbed by the water itself was a fairly good substitute204 THE ANALYST. for a bacteriological examination. Unfortunately, although the actual work could be carried out in it few minutes, the sample had to be allowed to stand for from five to ten days. He thought it of far more importance to agree to some methods of analysis than to lay down standards ; he would particularly refer to the determination of the oxygen absorbed by permanganate. This was one of the most useful factors in a water analysis; but, unfortunately, chemists differed very greatly in their methods of arriving at it.Some followed the late Dr. Tidy, and used open flasks kept at the temperature of the laboratory, and hoped that an equal amount of dirt might fall into the flask containing the standard used for comparison, and into the experimental flask; others, like Dr. Rideal, placed their bottles on the top of the water-oven, others actually boiled their acidified solutions. I t was, however, very desirable that all should agree to make the determination upon a definite plan. He believed that he had himself been the first to suggest the carrying out of the process in a closed bottle, and at a fixed temperature. I n doing so, he had not had in view the question of chlorides being present ; but it was found that the use of a closed vessel did away entirely with the difficulties arising from the presence of chlorine when an open flask was used.The determination, in fact, could be made in sea- water as easily as in ordinary drinking-water. Dr. VOELCKER said that the importance of considering any particular effluent in relation to the water from which it was originally derived extended to other con- stituents besides the chlorine. For instance, in dealing with effluents from districts where the water was known to be unusually hard, the total hardness would have to be regarded in relation to that of the original water. I t was important, also, to know the nature of the suspended matter, and whether it consisted of organic matter or merely of mineral matter. He had not noticed in the paper any reference to a question which he thought was a very important one, and which Dr.Dupr6 had alluded to, namely, the ratio of the volume of the efluent to that of the stream into which it flowed. Dr. RIDEAL quoted, as an instance of the unreliability of standards, a case which had been referred to in a paper read by him before the Society of Arts, of a solution of putrid meat extract, diluted with water in the proportion of 1 to 6,000. The liquid was very putrid, smelling strongly of sewage, and was no doubt also a toxic solution oontaining ptomaines ; but it would nevertheless have passed any ordinary standard in regard to free and albuminoid ammonia, oxygen absorbed, etc. What, he thought, was to be aimed at was not so much a fixed standard as a ratio, showing what had become of the nitrogen, and how it had been altered. I n the original sewage the nitrogen would be entirely in the organic state. The action of bacteria resulted in the breaking down of this organic nitrogen with the production of free ammonia, followed by the formation of nitrites and nitrates, until finally the nitrogen became entirely oxidized.The total nitrogen in a sewage effluent, therefore, was to be looked upon as existing in four distinct forms, namely, organic nitrogen, free ammonia, nitrous nitrogen, and nitric nitrogen; and it was the ratio of these four different kinds of nitrogen to one another which indicated whether an effluent was satisfactory or not. If the ratio between the first two and the second two was such that the balance of oxygen in the nitrites and nitrates was more than sufficient to oxidize the nitrogenTHE ANBLYST.205 not yet oxidized, the liquid could not undergo any putrefactive change likely to cause a nuisance. R e therefore agreed with Mr. Moor in the importance of ascertaining that the nitric nitrogen was not below a certain amount, but contended that the amount was determined by the amount of the unaltered nitrogen present. He had found the loss on ignition to be a very unsatisfactory figure, yielding no information as to the quantity of organic matter present in sewage after treatment. I n some cases it would even increase, instead of diminish, after the sewage had undergone a process supposed to destroy organic matter. Mr. CHAPMAN said that in his experience it was usually iiripossible to derive any satisfactory information from the loss on ignition.In very many cases (more especially in impure waters) the loss due to decomposition experienced by the mineral matter, and to the expulsion of combined water, far overbalanced any loss that might be due to the combustion of organic matter. Dr. Rideal had apparently assumed that a, reaction would occur between the nitric and nitrous acid, and the ammonia present in a sewage effluent ; but he (Rlr. Chapman) did not think there was sufficient evidence to show that such a reaction would take place in the dilute solutions in which these substances were found in effluents. It was not always safe to assume that changes which took place in concentrated solutions also took place in very weak solutions.Mr. CASSAL said it was not possible to lay down rigid standards in matters of this kind. The question was really one that involved the getting of some figures by which the expert might be guided, and he thought that Mr. Moor’s object was rather to put before the Society Bome figures which, upon broad lines, would be of assistance in arriving at conclusions, than to suggest the laying down of any rigid standards. I t was quite plain that such matters must be governed by the special circumstances of each particular case. It was dangerous to speak of good, bad, and medium effluents. The object of the Local Government Board in insisting upon the treatment of sewage by passing it through land had ohviously been, or ought to have heen, the absolute purification of the sewage from objectionable organic matter by filtration through the soil; a purification carried to such an extent that the resulting efiluent should be no fouler than the stream into which it was to flow.Theoretically, at any rate, it ought to be assumed that there should not be introduced into any stream or river a liquid which contained in a notable degree a larger quantity of putrescible organic matter than was present in the stream itself. If the stream itself was polluted, the question of special circumstances came in very strongly, and the con- clusions of the engineer, as well as those of the chemist, had to be applied in order to determine whether there was any possibility of an increase in the pollution of the stream by the introduction of any given eauent. Apart from this, the aim of the sanitarian should be the introduction into any stream or river of perfectly purified or demonstrably innocuous eflluents. He, too, was of opinion that the ignition of water, or sewage “ residues,” while it was a valuable qualitative test, was not a reliable quantitative one, except when employed irl connection with the same set of water, sewages or effluents, as a means of comparison merely among the samples themselves.The PRESIDENT said that the subject of standards was a most difficult and, indeed, a dangerous one to deal with. The real question in any given case was206 THE ANALYST. probably how far the effluent approximated to the best possible effluent that could be reasonably expected, having regard to local circumstances and to the means which it was reasonably possible to employ.The great absurdity attaching to standards under some conditions had once been shown by a well-known manufacturer at a meeting of the Society of Chemical Industry, at the time when it was suggested that the standards recommended by the Rivers Pollution Comniission should be legalised. That gentleman observed that he daily ejected from his works an effluent which in very nearly every particular transgressed the limits laid down, the effluent in question being, however, merely the water of the river on which his factory was situated, which water was pumped into the works for use in cooling the condensers, and after- wards returned in its original condition to the river. The river, however, would be held to be thereby polluted, if the suggested standard were legalised.While, however, it was exceedingly difficult to lay down general standards, it was very desirable that there should, if possible, be some settled means of making the different determinations involved in analyses of this kind. I t seemed, for instance, particularly important to decide and agree whether, if an effluent contained suspended matter, it should be shaken up and analysed as a whole, including the suspended matter, or whether it should be filtered, or whether it should be allowed to settle; and also whether, if it was filtered, a close paper or a loose one should be used. Such considerations as these gravely affected the determinations of oxygen absorbed and albuniinoid ammonia.Mr. \V. J. DIHDIN desired to compliment the author upon the excellent paper which he had presented to the Society. The question of standards of quality for sewage effluents was perhaps one of the most difficult of all those raised in connection with sanitary problems. It had been suggested that the quality of the effluent should be equal to that of the strearn into which it is to be turned. This was at once met by the consideration of the case of an effluent discharged from a sewage farm even in the very best working condition, the outfall from which was on the banks of a stream which had but a few minutes before sprung from, say, the outcrop of the chalk, I t would be practically impossible to comply with the prescription, and an exception would have to be made.He had long since adopted in his own mind a physiological standard, viz., that the quality of an effluent should be such that fish could live healthily in it. Such an effluent is not a fanciful one, nor is there any difficulty in obtaining it by the employment of suitable means, and these, fortunately, -are most economical. Such a definition involves necessarily the absence of poisons and the presence of oxygen. This raises the point as to the quantity of nitrates which should be present, as, according to Mr. Moor, these present a store of oxygsn that could be drawn on. This is so ; but the statement overlooks the important fact that when water is freely in the presence of air, such as in a stream, etc., it acts like a sponge, greedily absorbing oxygen from the atmosphere as fast as it yields it up to the organisms feeding on the organic matter, so that at some point, determined by the rate at which these organisms require it, a balance is arrived at.If the aeration is kept down very low by the rapidity of the life processes, this absorp- tion of atmospheric oxygen is very rapid, varying in inverse ratio to the degree of aeration. From this consideration it will be evident that, valuable as is the indica- tion afforded by the presence of nitrates, these must not be looked upon solely as a If one exception, why not two or three ?THE ANALYST. 207 store of oxygen, and still less as the sole shore of that substance for effecting the ultimate purification of the sewage matters. With regard to the nitrites in effluents being only present after these have been kept for some days in bottles, he was afraid that he could not agree with the author of the paper.I n the course of a series of special experiments, conducted on the works, Mr. Thudichum found at Exeter that nitrites were present in every sample tested direct as it came from the fine coke- breeze filters. He was in full agreement with the author's suggestion that the lower the quantity of albuminoid ammonia the better, but, unfortunately, this point did not much help the question of standards. With'regard to the temperature of the sewage rising in some bacterial processes, this was unquestionably the fact, and was com- parable to the familiar instance of the garden hot-bed. I n some bacteria beds under his (Mr. Dibdin's) direction the temperature had risen as high as 80" F. With refer- ence to the loss on ignition being an important point, he could not agree with this in all cases.For instance, where a large quantity of mineral salts were sent into the sewage, the loss due to water of crystallization, etc., would often be so great as to swamp all that due to the organic matter, and thus no factor of any value at all from this point of view was obtainable. The value of the relation of the results of analyses must, for the present, at least in the majority of cases, be based upon the personal equation, in which large experience and knowledge of the local conditions as to necessities and possibilities were all involved. Mr. MOOB said that he very much appreciated the sympathetic criticism to which his remarks had been submitted, and, while opinions seemed to vary on points of detail, he could not help thinking that even the variety of opinion which had been expressed emphasized the desirability of having some set of figures on which an effluent could at least be condemned. He had endeavoured very clearly to indicate that the particular set which he had suggested was by no means put forward either as a final standard or as an ideal effluent.Perhaps his meaning would have been made clearer if he had described these figures, as he had in fact intended them, as constituting, not the standard for an effluent which could permanently or in all cir- cumstances be adopted, but the maximum of impurity which should in any circum- stances be allowed.By the adoption of this maximum, he in no way intended to suggest that such effluent would in all cases be permissible; for example, he would regard it as quite out of the question for an eflHuent t o be discharged in any quantity above a water company's intake. I n making this remark, he desired to add, for fear of misunderstanding, that, in his judgment, no chemical criteria could ever warrant the safety of an efiuent above an intake ; but that, as the danger would to some extent vary inversely with the chemical purity, he would insist on a much higher standard for effluents supplied to sewage-drinking communities than that which he had discussed in this paper. None of the criticism which had been offered appeared to him to conflict with the adoption of these figures for this purpose, with the single reservation pointed out by Dr. Voelcker--that the hardness of effluents should be fixed in some relation to that of the water-supply.His purpose in including this figure was of course to prevent the undue drugging of the water with chemicals employed in processes of treatment ; and he suggested, therefore, as an emendation of the absolute figure which he had at first suggested, the provision that208 THE ANALYST, total hardness of effluent should not exceed that of the water-supply by more than 25 parts per 100,000. E e was in entire agreement with Mr. Cassal that at the present time no data existed warranting the description of an efflumt as good or in- different ; but he still thought that there would be considerable advantage in having some figures by which in need it could be described as bad, as it followed logically, from what the President had rightly observed, such figures must represent the best effluent which could in all circumstarces be attained.He did not understand the President to suggest that the figures which he (the speaker) had proposed were such as mere likely to occur in a natural river ; and if by artificial pollution a river had been so c.ontaminated as to fall short of his modest requirements, he thought there would be every possible advantage in preventing ingenious and energetic persons, such as the gentleman to whom the President referred, from using such river for any purpose until they had gone up stream and compelled the persons polluting the river to leave off.Taking the determinations which he had suggested individually, he had no hesitation in saying in reply to the President’s question that analysis must take impartial account of everything which appeared in the sewage ; and, feeling as he did that suspended matter had no right in an effluent to any extent exceeding that which he had suggested, he was convinced that the only discrimination allowed to the analyst was the careful collection of an average sample, which then would be shaken up and analysed as a whole. So far as mineral matter was concerned, his experience was that it settled so much more rapidly than animal and vegetable matter, that the reservation suggested by Dr. Voelcker was not likely to be needed in practice, and he, personally, had met with no case in which it would have modified his proposed criterion.It was to be observed also, from the bacteriological stand- point, that suspended matter was usually far richer in organisms than the liquid conveying i t ; and as it certainly could be prevented by reasonable measures, he thought it needless to make any allowance for cases in which a substantial part of it might be mineral. So far as the albuminoid ammonia was concerned, no question appeared to arise a s to the figure which he had suggested being too high, He personally preferred the oxygen- absorbed determination to that proposed by Dr. DuprB, because of its greater rapidity ; but having regard to the difficulty of attacking all the organic matter in sewage by permanganate, especially where there was much suspended matter, he thought it might be worth considering whether one or other of the higher temperature processes would not be preferable for routine sewage examination to the ordinary Tidy modifi- cation of the Forchammer process, which was usually employed.He should have explained that in suggesting loss on ignition as a valuable characteristic of the same order as (‘ oxygen absorbed,” he had in mind the successive examinations of the same sewage, such as would occur in the examination of a process; and he quite agreed with Mr. Dibdin that it would not serve as a factor for comparison between sewages of different origins, and for this reason he had not proposed it as part of his suggested criterion. So far as nitrites were concerned, he was bound to say that while he had repeatedly found them in samples of which the examination had been delayed for a short time, he had never found them in freshly-examined samples. He recognised with Mr. Dibdin that there were other sources of oxygen in water than the nitrates,THE ANALYST. 209 but seeing that his (the speaker’s) figure was only proposed as a minimum, he did not think that this fact would warrant the reduction of the figure of nitrates which should be required. The utility of this factor was evident from Dr. Rideal’s meat- extract, which certainly would have been condemned for its deficiency in this respect, and with equal certainty, had it passed through any sewage process capable of bringing it up to the standard in this particular, would have ceased to be offensive. I n conclusion, he would reiterate that the whole, if any, of the figures which he had proposed was not to constitute an ideal or permanent criterion, and in that sense perhaps the word ( G standard” would be as inapplicable to these as to other figures which had been proposed for the same purpose. His figures would unquestionably be superseded by others more severe when data were available for safely defining them. They might even now be supplemented, if it was thought desirable, by Mr. Dibdin’s test of the survival of fish, or by Dr. DuprB’s requirement of perma- nent aeration. But the speakers had not suggested, nor was he aware of any sufficient evidence at present available, to justify exclusive reliance on either of these tests ; and as, therefore, a chemical criterion was undoubtedly necessary, he appealed to the Society to consider whether it was not for the public interest and for that of the profession that an agreement should be come to at least as to the figures on which all analysts would condemn an effluent.

ISSN:0003-2654    

DOI:10.1039/AN8982300197

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 209 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. A New lldethod of sophisticating Coffee. G. Wirtz. (Zeit. fiir Untersuch. der Nahr. und Geizussnbittel, 1898, 248.)-The author states that coft’ee is largely sophisticated in Hamburg, Bremen, Antwerp, and Rotterdam, as well as in the places of origin, by the process of washing, coloring, and drying 08 in centrifugal machines with sawdust, with the result that the furrows of the berries become filled with wood powder, making them a fine white and enhancing the market value of the produce. H. H. B. S. Paprika (Cayenne) as a Substitute for Alcohol, Kellermann. (Zeit. fiir Unter- such. der Nahr. und GciLussmittel, 1898, 24’7.)-The attention of the author was drawn to a description of spirit which had a, sharp taste, and produced a greater sensation of warmth than other competing spirits, though containing less alcohol.The residue left on distilling was found to produce an intense and lasting burning sensation when applied to the mucous membrane of the lips, exactly similar to that produced by “paprika.” The addition of an alcoholic extract of ‘‘ paprika ” to common spirits pro- duced a spirit possessed of the same peculiarities. H. H. B. s.210 THE ANALYST. A New Method for the Valuation of Amy1 Nitrite and Spirit of Nitrous (Amer. Josw. PlLnrm., 1898, lxx., 273-285).-This is a volu- Ether. metric process based on the reaction between nitrous and chloric acids : C. E. Smith. 3HN0, + HC10, = 3HN0, + HCI. Spirit of Nitrous Ether.-The following are successiveiy placed in a 100 C.C.flask provided with a loosely-fitting stopper: Ten C.C. of water, 5 C.C. of a cold saturated solution of potassium chlorate, 5 C.C. of the spirit to be tested, and 5 C.C. of 10 per cent. nitric acid. After shaking at intervals for thirty minutes, 10 C.C. of decinormal silver nitrate are added, the flask shaken for a moment, and the excess of silver titrated as rapidly as possible with decinormal potassium thiocyanate, a few drops of a solution of ferrous ammonium sulphate being used as indicator. The end-point of the titration is reached when, after ~nonientary shaking, the liquid remains faintly red throughout, Each C.C. of silver nitrate consumed corresponds to 0.0225 gramme of ethyl nitrite, and if the specific gravity of the sample be taken as 0.84, which is usually approximately correct, the calculation can be shortened by multiplying the number of C.C.by 0-536. Concentrated nitrous ether may be assayed by diluting with alcohol in definite proportions, and proceeding as above. The results are invariably higher than those obtained by the usual gaso- volumetric method, but from the results of comparative experiments the author considers the new process the more accurate of the two. The following results were obtained in the analysis of commercial samples, of which the last was a sample of concentrated nitrous.ether, stated to be 90 per cent, ethyl nitrite. I t was tested after dilution to 4 per cent. Per Cent. Ethyl Nitrite. Per Cent. Ethyl Piitrite. Per Cent. of Free Acid.Aldehyde Test. U.S.P. Method. Chlorate Method. 1. 3-66; 3-70 4.06; 4-01 0.14 Faintly yellow. 3. 4-28; 4.31 4-58; 4.60 0.45 Dayk. 4. 3.95; 4.00 4.38; 4.44 0.15 Straw. 5. 4.35; 4.32 4-81; 4-84 0.31 Dark. 6. 85.50; 85.90 92.60; 92-00 0.46 Straw. 2. 4.84 ; 4-88 5-30; 5-30 0.1 1 8 ) The acid determinations were made with normal soda, without dilution with water Addition of water or titration with decinormal soda gave considerably higher results, probably through saponification of the esters. All of the samples answered the requirements of the Pharmacopceia (U .S.A.) test for aldehydes, which prescribes that the colour shall not be decidedly brown after twelve hours’ contact with alkali. AmpZ Nitrite.-A 100 C.C. flask is partially filled with alcohol and weighed. Five to six grammes of the arnyl nitrite are then added, the flask again weighed, and the liquid made up to the mark with alcohol and well shaken.The determination is carried out in the same way as described for nitrous ether, except that double quantities of the reagents and of the alcoholic solution of arnyl nitrite are used. One C.C. of decinorrnal silver nitrate corresponds to 0.0351 gramme of amyl nitrite.THE ANALYST. 211 The following table gives the results obtained with commercial samples : Per Cent. Amyl Nitrite. Per Cent. Amyl Nitrite. Per Cent. of Aldehyde Test. U.S.P. Method. Chlorate Method. Free Acid. 1. 77-20; 77.0 87.0; 87.4 0-6 Dark straw colour. 2. 76.0; 76.4 86.7; 86.2 0.67 Brownish yellow. 3. 17.3; 18.8 21.0; 18.9 0.76 ’ Deep yellow. 4. 82.7; 83-5 93.9; 93.4 1.36 Dark straw colour.5. 79.0; 78.4 85.9; 85-3 1.12 Deep yellow. Of these, No. 3 was from a bott’le with an old and defective cork which had been badly attacked by the liquid; Nos. 4 and 5 exceeded the Pharmacopoeia limit of free acid, which is 1.08 per cent. as nitrous acid; and none of them were fully up to the standard required by the aldehyde test, which prescribes that on shaking equal volumes of amyl nitrite and normal potassium hydroxide the aqueous layer shall not be more than pale yellow. The author advises that a blank determination should be made in the assay and an allowance made for the impurities, since potassium chlorate and nitric acid often contain traces of chloride, and nitric acid lower oxides of nitrogen, both of which would affect the results.C. A. M. Detection of Salicylic Acid in Comestibles. F. A. Genth. (J. Fraddirt Inst., 1898, cxlv., 228 ; through Chenz. Zed. Rep., 1898, 97.)-The author considers Krause’s distillation process the best for the detection of salicylic acid in articles of food The substance is rubbed down to a cream with phosphoric acid, water being added if necessary. After a time, the mass is squeezed through a cloth, and 50 or 75 C.C. of the liquid are submitted to distillation, every 5 c.c, of the distillate being tested with ferric chloride. The salicylic acid passes over with the steam, most of it being recovered towards the end of the operation. The methyl-ester reaction is not suited for detecting small quantities of the antiseptic ; but by this process Genth has discovered the presence of salicylic acid in various preserves which nominally did not contain it.F. H. L. The Examination of Methyl Salicylate. Adrian. (Jounz. Phaym. Chim., 1898, vii., 122-124.)-Physiological experiments having demonstrated the superiority of methyl salicylate over the natural oil of winter-green, it is important to be able to distinguish between the two, although on account of its higher price the latter is hardly likely to be fraudulently substituted for the artificial product. The following table gives the comparative results of the fractional distillation of samples of undoubted purity :212 THE ANALYST. Methyl Salicylate. A little water (5 grammes) dis- tilled over below 220". Grammes. Distilled below 220" (nearly all at 219') ...110 Between 220" and 222" 105 ,, 222" and223" 155 ,, 223" and 225" 350 ,, 225" and 230" 185 Residue ... ... 90 Total ... 1000 Density a t 15" C. 1.1785 1.178 1,179 1.180 Oil of Winter-Green. A little water (5 grammes) dis- tilled over below 220". Grammes. Between 220" and 222" 615 ,, 222" and 223" 190 ,, 223" and 225" 85 ,, 225" and 230" 50 Residue ... ... 55 Total ... 1000 Density at 15" (3. 1.185 9 , Y , 2 , ,, The density and boiling-point are valuable tests, and will detect the presence of free methyl alcohol or of ethyl alcohol fraudulently added. The addition of a fixed oil would lower the specific gravity, and a residue would be left on distillation from which, on heating more strongly, acrolein vapours would be liberated. Methyl salicylate can be distinguished from oil of winter-green by its behaviour with sulphuric acid.On mixing 5 C.C. of methyl salicylate or of one of the distilled fractions (previously well dried) with an equal volume of sulphuric acid, there is no rise of temperature, but the ester assumes a faint yellow colour, with the exception of the fraction distilling below 220°, which does not give the coloration. On treating the natural product in the same manner, and especially the fraction distilling between 220" and 222", which contains the terpene, gaultherylene, there is an immediate rose coloration, changing to red and finally to dark brown, and there is also a considerable evolution of heat. C. A. M. Oil of Sassafras. C. H. La Wall and R. C. Pursel. (Amer. Jour. Pharm., 1898, lxx., 340-342.)-This oil, which is largely employed by soap-manufacturers, is very liable to adulteration.As the boiling-point shows considerable variation in pure specimens, the chief points relied upon in judging of the quality of a sample are its specific gravity, general appearance, and odour. Safrol was formerly used as an adulterant, but its price is now higher than that of the oil. I t constitutes normally about nine-tenths of the weight of the oil, and has a specific gravity of 1.108, whilst the specific gravity of sassafras oil varies from 1.07 to 1.09. Oil which has a lower gravity than the lower limit is regarded with suspicion, as it might indicate adulteration with the fractionated camphor oil which is used for that purpose. In cold weather crystals of safrol are deposited, and it may often happen that the upper, middle, and lower portions of the oil are of different gravities, and in such cases the only way to insure a homogeneous mixture is to pour out part of the oil before stirring, and then to agitate very vigorously.The authors refer to an instance in which, after apparently well mixing the whole bulk and leaving no crystals at the bottom, the gravity was found to be 1.055, but after more thorough admixture was 1.07.THE ANALYST. 213 The following table gives the maximum, minimum, and mean specific gravity of all the samples examined by the authors from 1896 to June 1, 1898. They represent an aggregate of 10,000 lb. as received from the distiller, Maximum. Minimum. Mean. 1896 ... ... 1.0840 1 *0500 1.0654 1897 ...... 1.0850 1.0610 1.0736 1898 ... ... 1.0830 1,0450 1.0713 The colour of the pure oil varies from deep yellow to nearly colorless. The artificial oil closely resembles the natural product, and an admixture is not readily detected. C. A. M. Croton Oil. Javillier. (Jourqa. Pharm. Chinz., 1898, vii., 524-527.)-1t is stated that the variations in the constants of this oil, as determined by different observers, are largely due to the method by which the oil was obtained. The author prepared three samples, the first by simple expression, the second by lixiviation with ether, and the third by digestion at 75" C. with 95 per cent. alcohol, the first two methods being those prescribed by the French Codex of 1884. I n each case a different yield and a different-coloured product was obtained, wix., (1) 12.5 per cent.of a pale oil ; (2) 38 per cent. of a light-brown oil ; and (3) 12 per cent. of a very dark-brown oil. The difference in their physical and chemical properties is shown in the follow- ing table : Solubility in Alcohol. (1 vol. of oil + 2 vol. absolute alcohol.) Solidification temperature . . . Iodine value (Hubl) . . . ... Saponification value . . . ... Acid value ... ... ... Expressed Oil. Soluble at 7t50 C. - 7" c. 109 192.9 27.3 Oil extracted with Ether. Soluble at i5". - 7" c. 108 194.6 30.9 Oil extracted with Alcohol. Soluble in the cold. -8" C. 91-2 260.6 60.1 The acid value was determined by dissolving the oil in ether and titrating directly with decinormal alcoholic potash. I t was found that Henrique's method of cold saponification was not easily effected with croton oil.The commercial oil is often prepared by the methods given in the Codex of 1837 and 1866, v i ~ , expression followed by digestion with 80 per cent. alcohol. Its iodine value is generally about 102, and the saponification of a sample examined by the author was 205.6. C. A. M. The Examination of Theobromine. M. Franyois. (Journ. Pharm. China., 1898, vii., 521-523.)-The most probable adulterant of theobrornine (which has recently been employed in therapeutics) is caffeine, which is considerably cheaper. The author describes the following tests of the purity of the drug : 1. On adding 10 C.C. of a 10 per cent. solution of silver nitrate to a solution made by dissolving 0.1 gramme of theobromine in a hot mixture of 1 C.C.of nitric .acid and 2 C.C. of water, a turbidity occurs, which on warming disappears. On cooling, a mass of needle-shaped crystals is deposited.214 THE ANALYST. 2. A solution is prepared by dissolving 0.1 gramme of theobromine in a mixture of 2 C.C. of water and 1 C.C. of hydrochloric acid. Ten C.C. of bromine water are added, the beaker and its contents weighed, the excess of bromine expelled by heat, which is continued until the liquid becomes practically colorless, and the original weight made up with distilled water. This solution when. cold stains the skin red. On adding to 2 C.C. of the liquid 1 drop of a 5 per cmt. solution of ferrous sulphate and 2 or 3 drops of ammonia solution, an intense indigo-blue coloration is obtained.(A reaction also given by caffeine.) 3. A solution of 0.1 gramme of theobromine i n a mixture of 2 C.C. of water and 1 C.C. of hydrochloric acid, mixed with 10 C.C. of decinornial iodine solution (I, 12.7 grammes ; KI, 20 grammes ; water, 1 litre), gives a dense black precipitate. This is separated by decantation, and dissolved in a 10 per cent. aqueous solution of potassium iodide at 80" C. On cooling, greenish-black crystalline needles of theo- bromine teh-a-iodide are deposited. Theobromine should leave no residue on ignition, and should melt at 338" to 340" C. The determination of its solubility in alcohol should detect caffeine and other organic substances (alkaloids, glucosides, etc.). Ten C.C. of 95 per cent. alcohol, saturated with theobroinine at 21" C., leaves on evaporation a residue of 0.0045 gramme, whilst 10 C.C.of the sanie alcohol, saturated with caffeine; leaves 0.0930 gramme. Hence theobromine, containing 5 per cent. of caffeine, treated with alcohol, kept at 21" C. for forty-eight hours would give a solution containing in 10 C.C. 0.0290 gramme instead of 0.0045 gramme. C. A. M. The Assay of Belladonna Plasters. C. E. Smith. (Amer. Jozmz. Pharm., 1898, Ixx., 182-189.)-The belladonna plasters of the American market are nearly always prepared with a base containing rubber and various resins. In their prepara- tion the rhizome of the Sco~~olia carniolica is often used instead of the Atropa beZZadoiznn, but as the alkaloids are practically the same in both plants, and are present in more uniform quantity in the former, the author considers that there is some excuse for the substitution.The method of assay which he has found the most accurate and reliable is as follows : If the sample is of about the strength of the U.S.P. standard, one plaster (about 8 grammes) is taken, or if weaker, proportionately more. The part of the cloth on which the mass is spread is weighed, cut into strips, and stirred up with 50 C.C. of chloroform and 10 drops of 10 per cent. ammonia-water, until the mass is completely dissolved off the cloth. The chloroform mixture is decanted, the rubber precipi- tated by the addition of 40 C.C. of 91 per cent. alcohol, and the supernatant liquid decanted into a separatory funnel. The cloth left in the first beaker is washed with 25 C.C. of chloroform and 5 drops of arnnionia-water, and the washings decanted into the second beaker, where they redissolve the precipitated rubber.The solution is well stirred, the rubber again precipitated by the addition of 20 C.C. of alcohol, and the supernatant liquid added to that in the separatory funnel. This process is repeated until the whole of the mass is removed from the cloth and the beaker.THE ANALYST. 215 The combined chloroform-alcohol solutions in the separatory funnel are mixed with 20 C.C. of water containing 2 C.C. of hydrochloric or sulphuric acid and shaken gently for five minutes. The chloroform solution is then drawn off into another funnel, together with any solid matter that may have collected at the line of contact of the two layers, while the acid solution at the top, which contains most of the alkaloid, is transferred to a third separatory funnel.The extraction of the chloroform-alcohol solution with acidulated water is repeated three or four times, or so long as any considerable amount of solid matter collects at the juncture of the liquids. The combined acid solutions are made alkaline with ammonia, and the alkaloid gently shaken out with successive portions of 20, 10, and 10 c,c. of chloroforni. (Violent agitation produces an emulsion.) The combined chloroform extracts are washed with water and transferred to a flask, where the chloroform is evaporated on a water-bath. The alkaloidal residue is shaken with 4 C.C. of N/20 acid until all the alkaloid is dissolved. Fifty C.C. of water are then added, followed by 0.5 C.C.of a 1 per cent. alcohol solution of hzmatoxylin, and N/20 alkali is run in until the colour of the liquid changes to dull 1-ed. The number of C.C. used is subtracted from 4, and the remainder multiplied by 0.0145 (the Nj20 factor for atropine and its isomers), and by 100, and the product divided by the net weight. For example, a plaster weighing 12.25 gramiiies with the cloth, and t.he cloth weighing 3.55 grammes, required 1-58 C.C. of Nj20 alkali to neutralize the excess of acid. (4 - 1.58) x 0.0145 x 100 - - 12.25 .. i-3.55- -- - =0.404 per cent. of alkaloid. manufacturers, including all the prominent American makers, mere : The results of the analyses of eleven samples comprising the products of six 1. ... ... ... 2. ... ... ... 3. ... ... 4. ... ... ... 5. ... ... ... 6. ... ... ... 7. ... ... ... 8. ... ... ... 9. ... ... ... 10. ... ... ... 11. ... ... ... Weight of Mass i n one Plaster. Grammes. Per cent. of Alkaloid in Mass. 0.571 to 0,594 8.55 0.403 ,, 0.416 8.7 0.509 ,, 0.497 .- 0.112 ,, 0.108 8.65 0.103 ,, 0.110 __ 0.060 7 , 0.058 8-2 0.084 ,, 0.081 7.35 0.125 ,, 0.116 3.25 0.098 ,, 0.101 8.35 0.042 ,, 0.047 5.7 0.093 ,, 0.096 - All the samples responded to Vitali's test for solanaceous alkaloids except No. 11, a foreign sample which contained some interfering impurities. Judging by the presence of chlorophyll, No. 2 and No. 11 were prepared from the leaf extract. Only three samples conformed to the U.S.P. standard of strength, all the remainder being much below it. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300209

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

216 THE ANALYST, ORGANIC ANALYSIS. A New Reaction of Tertiary Alcohols. G. Deniges. (Cowzlites Rend., 1898, cxxvi., 1277-1279.)-The test here described is applicable to the detection of all compounds which readily yield hydrocarbons of the ethylene series, but especially to tertiary alcohols. The reagent consists of mercuric oxide 50 graninies, sulphuric acid 200 c.c., and water .lo00 C.C. On warming two or three drops of a tertiary alcohol with a few C.C. of this solution, a yellow precipitate is rapidly produced, the tint varying with the particular alcohol tested. In the case of butylic alcohol the yellow compound, when washed and dried in the dark over sulphuric acid, has a composition corresponding to the formula, ( S04\Hg,o)3*C4H, /Hg\ 9 which is also the formula for the substance yielded by dissymetric dimethyl ethylene, the corresponding olefiant hydrocarbon.I t is soluble in hydrochloric acid with effervescence yielding butylene and mercuric chloride. On boiling the precipitate in its mother liquid for ten minutes, the colour disappears, and finally mercurous sulphate is produced with oxidation of the butylene residue. The test is very sensitive, and is capable of detecting 0.001 gramme of the alcohol. Tertiary amylic alcohol mixed with three to four times its volume of the reagent and gently warmed, gives a yellow precipitate identical with that yielded by the corresponding ethenic hydrocarbon. On boiling, it is immediately decomposed, giving mercurous sulphate, which is rapidly reduced to metallic mercury, There is a characteristic difference in the behaviour of pental and tertiary amylic alcohol with the reagent.The former gives an immediate yellow coloration in the cold, followed by the gradual formation of a precipitate of which-there is an abundant deposit after ten minutes. Tertiary amylic alcohol scarcely shows any alteration in the cold, though on warming it gives the three stages of the reaction described above. When a drop of the liquid under examination is added to 2 C.C. of the boiling reagent a yellow precipitate is obtained which does not alter on standing in the case of pental, whereas with tertiary amylic alcohol the precipitate becomes white and crystalline and finally gray. The other tertiary alcohols give analogous compounds with the reagent, always provided they are capable of yielding hydrocarbons of the ethylene series on dehydra- tion.Isopropylic alcohol, however, which is readily dehydrated with the formation of propylene, gives a precipitate with mercuric sulphate, but with much less readiness than the tertiary alcohols. The esters of tertiary alcohols also give a yellow precipitate with the reagent, and the test is very characteristic in the case of the tertiary amylic nitrite employed in medicine. Primary and secondary alcohols do not form these compounds. C. A. M. preparation of Soluble Starch. A. Wroblewski. (Chem. h i t . , 1898, xxii., 375.)-20 grammes of rice starch are rubbed down with 100 C.C. of cold water, poured into a 2-litre flask, 1 litre of a boiling 0.5 per cent. solution of caustic potash added quickly, and the whole boiled for I+ or 2 hours under a reflux condenser tillTHE ANALYST. 217 the liquid becomes thin and pale yellow.The solution is filtered, neutralized with dilute acetic acid (to remove the free alkali and so facilitate the subsequent washing), and precipitated with an equal volume of 95 per cent. alcohol. The starch is filtered off, washed successively with 50 per cent., 95 per cent., and 100 per cent. alcohol, then with ether, and finally dried in vacuo. The substance thus obtained is a snow- white powder containing 0.4 to 0.6 per cent. of ash, soluble in'about 33 parts of water, and insoluble in cold 35 per cent. or hot 45 per cent. spirit ; it does not reduce Fehling's solution, and gives a pure blue colour with iodine. If a very pure material is required, the first product may be dissolved in water and precipitated with alcohol three or four times; it then retains but 0.15 or 0.18 per cent.of ash, while the yield is about 70 per cent. The solubility of soluble starch in dilute spirit is largely dependent upon the amount of inorganic salts present ; and in the same manner with dextrin, etc., if the liquids are too pure, it may be necessary to introduce a small quantity of potassium acetate before precipitation can be effected. F. H. L. The Solubility of Pentosans in the Reagents employed in the Estimation of Starch. (Jour. Amer. Chenz. Soc., 1898, xx., 266-268.)-1n the determination of starch in a cereal or fodder by digesting the substance at a high pressure with water containing some organic acid, the action of the latter on the pentosans and hemi-celluloses results in the formation of reducing substances.The authors have determined the amount of the pentosans dissolved in this way with the following results : 1. Solubility of the pentosans by digesting for two and a half hours at three and a half atmospheres with 30 C.C. of water and 25 C.C. of 1 per cent. lactic acid. W. H. Krug and H. W. Wiley. Pentosans Dissolved. Per Cent. of Pentosans In'Per Cent. of I n Per Cent: of in Substance. Substance. Pentosans. Substance. Wheat No. 1 ... ... 5-80 4.63 79.83 Wheat No, 2 ... ... 5-17 4-66 90.13 2. Solubility of pentosans by digesting for two and a half hours at three and a half atmospheres, with 55 C.C. of water and 0.5 gramme of salicylic acid.Pentosans Dissolved. c A Per Cent. of Pentosans I n Per Cent. of I n Per CenC of in Substance. Substance. Pentoeans. Substance. Wheat No, 1 ... ... 5.80 4.54 78-27 Wheat No. 2 ... ... 5-17 4-08 78.91 J. Konig (LmdzcirtILsch. Ver. Stat., xlviii., 81) states that diastase also acts as a solvent for pentosans and hemicelluloses, and gives figures to show that from 15 to 44 per cent. of the total amount of those substances present pass into solution. The authors have made a number of starch deterininations in various cereals by means of malt-extract and taka-diastase solution, from the results of which they conclude that diastase has 110 solvent action on the pentosans, and that this method of determining starch is an exact and reliable one. C. A. M.218 THE ANALYST.A Comparison of the Standard Methods for t.he Estimation of Starch. H. W. Wiley and W. H. Krug. (Jouyn. Amer. Chm. Soc., 1898, xx., 253-266.)- Referring to Stone's modified method (ANALYST, xx., 19), the authors show that a digestion of the starch with diastase for 24 hours at 50" C., instead of for one hour at 60" C., gives a result about 1 per cent. higher. Further, by grinding the sample to a much finer powder than Stone prescribes, a considerably higher result is obtained. The comparative mean results obtained with a sample of wheat, analysed by (1) this method, (2) by Reinke's method (digestion under pressure with water containing lactic acid, to prevent the decomposition of sugars formed in the hydro- lysis), and (3) by a method differing from Reinke's, by the substitution of salicylic acid for lactic acid were (1) 62.46, (2) 62-32, and (3) 63.09 per cent.In another paper the authors show that by the two latter methods considerable quantities of the pentosans present are also dissolved (cf. preceding Abstract). Of the two, the salicylic acid is preferable, since much less cnramelization takes place. When it is employed, the amount of starch may be very approximately determined by diminishing the apparent percentage by 1.25. If greater exactness is required, the pentosans should be determined and the percentage divided by three and subtracted from the apparent percentage of starch. From the results of experiments with the various polarimetric methods, the authors conclude that none of them can be relied upon to give accurate results.They find Lindet's method (solution of the proteid envelope of the starch cell by means of pepsin and weighing the starch directly, ANALYST, xxii., 20) is more tedious than the common processes, and not so accurate. Small particles of sub- stances other than starch pass through the sieve cloth and are weighed with the starch. On the ot-her hand, a portion of the starch remains attached to the filter, and these two errors may often compensate one another, and an approximately correct result be obtained. The following are some of the figures given in illustration of this : LINDET METHOD. DETERMINSTION AFTER CONVERSION INTO DEXTROSE. Starch Residue Total Starch Residue Total Fibre in Starch CEREAL. per cent. per cent. per cent. per cent.per cent. per cent. per cent. Oats 44.31 0.00 44.31 43.73 0.00 43.73 0.58 Barley 71.41 0.97 72.38 66.47 0.97 67-44 4.94 Rye 61-24 0.79 62.03 58.18 0.79 58.97 3.06 Wheat 6605 0.60 66-65 60- 11 0.60 60.71 5.94 The percentage of starch in the same cereals as determined by the salicylic acid method and the diastase method were : Salicylic Acid Method. Diastase Method. Oats ... ... ... ... 46-75 45.05 Rye ... ... ... ... 62-64 61-55 Wheat ... ... ... 64-41 63.17 Barley ... ... ... 68.38 67.56 A combination of the Lindet method with the salicylic acid was tried with the object of securing a more thorough solution of the starch. Three grammes of the cereal were digested for fourteen hours at 45" C., with 30 C.C. of pepsin solution, the hydrochloric acid neutralized with sodium carbonate, and the substance heatedTHE ANALYST.219 in the autoclave at 38 atmospheres, after the addition of 0.5 grarnme of salicylic acid. The percentages of starch obtained showed a close agreement with those given by the salicylic acid method alone. The mean results from the same cereals as used in the other experiments were : Oats, 47.26; Rye, 62.35; Wheat, 64-48. The combination of the Lindet method with the diastase method is said to have given most satisfactory results, but this part of the subject is still being investigated. In general, the use of pepsin is recommended as a safeguard to ensure the starch completely dissolving. The diastase method without pressure is very satisfactory with the precautions referred to above. The materials should be ground to the finest possible powder, and extracted with ether to remove the fat.The treatment with diastase should always be repeated after boiling and cooling to about 50" C. (the temperature at which, according to Lintner, the enzyme is most active), and the residue should not show any starch granules when stained with iodine and examined under the microscope. The use of taka-diastase presents many advantages, as it can readily be obtained free from reducing sugar. The small amount of matter unaccounted for in a compIete analysis of cereals is regarded by the authors as probably belonging to the coniplex class of carbo- hydrates known as pentosan-ligno-celluloses, but they consider that the quantity is only very minute in cereals, though probably much larger in stalks and straw, and other substances containing a large excess of liguo-cellulose compounds.C A . M . Estimation of Urea. G. Meillhe. (Repcrt. Phamz., 1898, [3], x., 59; through Chm. Zeit. Rep., 1898, 96.)-Sodium hypobromite solution being very unstable, the author prefers to employ the reagent in a nascent condition, preparing it in the nitrometer from a bromide and strong sodium hypochlorite solution, which evolves 30 volumes of active chlorine. 10 C.C. of the urine are diluted with 40 C.C. of water and mixed with 5 C.C. of sodium hypochlorite solution, 5 C.C. of 10 per cent. caustic soda, and 1 C.C. of 20 per cent. potassium bromide. Owing to the dilution of the liquids, warming is scarcely necessary, and a reading can be made in five minutes. F.H. L. A New Process for Determining Molecular Weights by the Boiling-Point Method. W. Landsberger. (Bcrichte, 1898, xxxi., 458-473.1-The apparatus employed in this process consists of a test-tube, a , in the side of which near the top is a perforation, b. The tube is closed by means of a cork, c , through which passes a, thermometer, d, and a conducting-tube, e, bent twice at right angles, and is fitted into a larger tube, i, connected by means of a side tubulure, k , with a condenser, 1. One end of the conducting-tube passes to the bottom of the inner test-tube, whilst the other is connected with a flask, f, in which the pure solvent is heated over a small flame or on a water-bath. The vapour enters the inner tube in which is placed some of the solvent, and in from 2 to 6 minutes a constant temperature is reached, and the boiling-point determined. The inner tube is then emptied, a weighed220 THE ANALYST. quantity of the substance-of which the molecular weight is to be determined- introduced together with some of the solvent, and the vapour again passed in from the flask. The temperature is observed every 8 seconds until 3 consecutive readings in agreement have been ob- tained. The apparatus is then discon- n e c t e d , t h e inner tube, a, rapidly with- d r a w n , t h e opening b and the open end of the tube, e, c l o s e d w i t h small rubber c o r k s , t h e t u b e wiped ex ternally and weighed. I t is then washed out with alco- hol and ether, d r i e d , a n d again weighed, the difference between the two weighings giving t h e weight of solvent and the substance in the tube. The weight of the substance being known, that of the solvent is obtained by subtraction, and the molecular weight calculated by means of the usual formula. The author gives a table of the results obtained with this apparatus, and these show a close agreement with the figures of other observers. The thermometer employed was graduated in &ths of a degree. It is stated that a determination can be made within 25 minutes. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300216

出版商:RSC    

年代:1898

数据来源: RSC

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220 THE ANALYST. I NO RGAN I C ANALYSIS. Separation of Lead from Copper and Zinc; the Determination of Lead in Presence of Tin, and of Zinc in Bronze, etc. (PYOC. Eng. soc., Western Pennsylvaizia, 1898, xiv., 80.)-Lead chromate is quite unaffected by ammonia, whereas copper chromate is known to be readily soluble. If, therefore, to a nitric acid solution containing the three metals an excess of potassium bichromate is added, W. E. Garrigues.THE ANALYST. 221 followed by a decided excess of ammonia, and the liquid heated till the precipitate settles, the lead chromate may be filtered out on a single disc of paper in a Gooch crucible, washed with dilute ammonia, hot water, and alcohol, and finally dried in the water-oven and weighed. Antimony, iron, and probably bismuth interfere with the process.If 0.5 gramme of a solder containing about 59 per cent. of lead is oxidized with nitric acid, 20 C.C. of strong sulphuric acid added, and the solution evaporated to the point of dense fuming, the meta-stannic acid dissolves completely. On diluting with not more than 80 C.C. of cold water, and stirring for a few minutes, the lead sulphate can be removed by filtration; then by making the filtrate alkaline with ammonia, and again acidifying with sulphuric acid till the liquid reddens methyl-orange, the tin can be recovered, ignited and weighed as stannic oxide. If care be taken not to use too much sulphuric acid, lead and tin may be removed in one operation; in fact, if the copper be thrown down with thiocyanate, the lead, copper, and tin can all be filtered off together, for washing with 3 per cent.sulphuric acid has no effect on either of the two latter precipitates. When small amounts of zinc have to be deter- mined in bronze, the method is unequalled for exactness and speed. F. H. L. Electrolytic, Estimation of Manganese, and the Separation of Iron therefrom. F. Kaeppel. (Zeits. anorg. Chem., 1898, xvii., 268.)-By the use of acetone it is possible quantitatively to deposit manganese from its solution as peroxide, to obtain it in the form of a sound coherent layer which can be safely washed even in amounts exceeding 1 gramme in weight, and to weigh it, after drying at 150" or 180" C., as MnO, with the certainty that it corresponds exactly to the composition represented by the formula. The original manganese solution, which should contain from 0.3 to 3.0 grammes of anhydrous sulphate, is made up to about 150 c.c., and mixed (pro- portionately) with 1.5 to 10 grammes of acetone, The liquid is raised to, and strictly maintained at, 50" to 55" C., and electrolysed with a current of 0.7 to 1.2 ampere at a tension of 4 to 42 volts for 2 to 54 hours, the loss by evaporation being constantly made up.To prevent the formation of traces of permanganic acid at the cathode, this electrode should consist of two platinum plates suspended in the basin. The basin is the anode; and wheu large quantities of peroxide have to be recovered, it may with advantage be roughened with the sand-blast, as recommended by Classen in the case of lead. The deposit is washed without stopping the current (this operation being much simpler than when chrome alum, etc., has been employed), and finally dried for 1 to 24 hours as aforesaid.Manganese peroxide is, of course, hygroscopic; but if the weighing be done quickly, or repeated after a second interval of drying, the error thus introduced is trivial. The examples quoted show results varying between 36.37 and 36-52 per cent. (mean 36.42 per cent.) in determining 36-42 per cent. of metallic manganese. A rough separation of iron and manganese-the former being deposited as metal, and the latter (almost entirely) held in solution as permanganic acid-may be effected as follows; and though it leads constantly to a deficit of 0.3 to 1-0 per cent. in the iron recovered, as it requires no attention, but, proceeding at ordinary temperatures,222 THE ANALYST.may be left going all night, the author thinks it may be found serviceable for some commercial purposes. Moreover, it is the more accurate the larger the proportion of iron in the sample tested. The liquid, which may contain between 0.35 and 1.0 gramme of FeSO, + 7H,O with 0.08 or 0.17 gramme of MnSO,, is poured with constant stirring into a boiling solution of 6 grammes of sodium pyrophosphate; as soon as the whole is clear, 3 or 4 drops of phosphoric acid are added, and, if they produce a turbidity, a little more pyrophosphate. When the liquid is cold, it is electrolysed for 10 to 14 hours with a current of 0.7 to 1.8 ampere and 3.75 to 4.25 volts. The metallic iron adheres firmly to the platinum vessel, which, therefore, need not be given a matt surface; it is washed without stopping the current, rinsed several times in absolute alcohol, and dried at a moderate temperature. If the electrolysis is conducted at a temperature of 35" to 40" C., the amount of pyrophosphate may be increased to 12 granimes, while the total bulk of the liquid is about 250 C.C. Under these conditions, with a current of 1-8 to 2.5 amphres, the operation is complete in 8 or 9 hours, the quantity of manganese precipitated is very greatly diminished (only a few flakes of oxide are to be seen), and the above- mentioned error in the weight of the iron is practically eliminated. Working on a mixture of about 1 gramme of crystallized ferrous ammonium sulphate with 0.2 to 0.7 gramme of the corresponding manganese salt, the percentage of iron found in the former varied from 14.02 to 14-19 (mean 14.105) per cent. instead of the theo- retical 14.28 per cent. Unfortunately, the residual manganese cannot be recovered by electrolytic agency. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8982300220

出版商:RSC    

年代:1898

数据来源: RSC

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222 THE ANALYST. APPARATUS. (Chem. Zeit., xxii., 226.)- The part a in the centre of the foot of the burner is drilled out as shown by the Bunsen Burner with Screw Cock. R. Meyer. arrows, and carries the cone b, which is firmly screwed to it. The burner-tube d is screwed to the part a at c. Over this is passed a, tube provided with a disc e, and through this tube the screw f is passed, and made fast to the burner-nozzle g. The lower end of the burner-nozzle screws into the part a, so that it can be made to approach or recede from the cone according as it is screwed up or down. The supply of gas is regulated by turning the disc e. When it is turned to the right, the lower end of the nozzle- tube gradually shuts down on to the cone b, stopping the supply, the reverse taking place when it is turned to the left.H. H. B. S. Some Improved Measuring Apparatus. 0. Bleier. (Chem. Zeit., 1898, xxii., 298 and 376.)-The apparatus which the author has previously described (ANALYST, xxiii., 55, and 111) is only suitable for the measurement of a pre-determined volume of liquid, and does not lend itself to the process of titration; the following modification,THE ANALYST. 223 however, overcomes this disadvantage. A burette (A), graduated in the usual manner, and holding altogether x c.c., is joined base to base with a 5-bulbed tube (B), such as already figured, except that each graduated portion is of the same size, and also holds x C.C. If desired, a second tube (C) of similar construction may be added, in which every division should contain 5x C.C.Each vessel preferably carries its own stopcock, while the exit tubes are united into one common orifice closed with a clip. By suitable manipulation of the stopcocks, the bulk of the liquid (corresponding to a certain number of the graduated spaces) can be run out of B and (or) C ; and the residue, which requires measuring exactly, out of the burette. Or, if only the latter is provided with a cock, the whole of the liquid caii be drawn from B while the cock at the bottom of A is shut, and then by opening the cock, inserting a cork and rubber tube in the top of A and blowing in or withdrawing air, the liquid in B cau be brought exactly to the level of one of the marks, and the total volume calculated from the space emptied both in A and 13. F. H. L. A Safety Pipette with Caoutchouc Tube Attachment. K. Zulkowski. (C7zenz. Zed., xxii., 226.)-The usual form of pipette, whether graduated or constructed to deliver definite quau- tities, has many disadvantages. When the liquid is sucked up by the mouth, the eye is in an unfavourable position to observe the mark on the instrument and the level of the liquid, and conse- quently its use is not always altogether free from danger. I n the case of large pipettes, the suction has often to be carried out intermittently, and the pipette cannot then be closed with the finger so quickly as could be wished. The adjustment is also often difficult, and there is a danger of the liquid becoming contaminated with the moisture from the mouth. The pipette shown in the accompanying sketch, which sufficiently explains itself, is designed to overcome these drawbacks. H. H. B. S.

ISSN:0003-2654    

DOI:10.1039/AN8982300222

出版商:RSC    

年代:1898

数据来源: RSC

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224 THE ANALYST. R E V I E W S . THE ANALYSIS OF FOOD AND DRUGS.-PART I. : MILK AND MILK PRODUCTS. By T. H. PEARMAIN AND C. G. NOOR. Considering that samples of milk and butter form the majority of all the samples taken under the Sale of Food and Drugs Act, and further that samples of milk and milk products are examined in large numbers for various purposes, a treatise on the analysis of dairy products must be regarded as a very desirable manual, the more so as the matter is by no means so simple and easy as on first. sight it may appear to many an analyst. Proprietors of the back volumes of the ANALYST have the opportunity of instructing themselves very intimately on the subject, by studying the numerozxs articles on the composition and examination of dairy. products contained in that journal; but the very fact that these are very numerous, and that they are scattered over the whole series of the twenty-two volumes of that journal, makes their perusal a difficult and time-taking task.Under these circumstances, one might say that the book under review meets a decided want. In their preface, the authors state that ‘‘ in order to keep the book within manageable limits, they are compelled to deal briefly with, or sometimes merely to refer to researches, which would be rightly included in a larger work.” Keeping this in mind, it is somewhat surprising to find so many pages devoted to remarks on practical dairying which might readily have been omitted, since inany of them are inaccurate ; indeed, we find in the book generally a deficiency in correctness of statement and exactitude of expression.Some of the obsolete methods of analysis might well have been omitted, and other processes described in greater detail ; while the list of methods actually in use at the present time is not complete. The question of standards and limits is treated at length, without, however, advancing its solution. The chapter on the bacteriology of milk is too short to be exhaustive, and too long for merely touching upon this matter ; it contains an accoiint of some of the work lately done in this field of research. The best parts of the book are those treating of the detection of preservatives, and that on condensed milk. If the book, on reaching a second edition, which we hope it will do, is judiciously revised and corrected, it will become a valuable companion, not APPLIED BACTERIOLOGY.Second Edition. (London : BailliBre, Tindall and Cox.) This work, which we had the opportunity of favourably reviewing some eighteen months since (ANALYST, vol. xxii., 28), now appears in a second edition, and the fact that this is required in a little over twelve months from the publication of the original edition would appear to indicate that the book has fulfilled its mission. The new work is considerably enlarged, there being 457 pages of reading matter against 354 in the old; the arrangement of the several articles has been improved, and the whole work thoroughly revised and brought up to date. References to foreign publications are inserted for the first time. X new chapter on the bacteriology of sewage has been added, and also a new plate illustrating Mr. Stoddart’s “Halo” cultures of the typhoid bacterium and its congeners, These additions and improvements cannot fail to render this useful book still more serviceable to all those who are concerned either in the study or in the practical application of bacteriology. (London : BailliBre, Tindall and Cox, 1897.) only to the analyst, but also to the better-educated dairyman. P. v. By T. H. PEARMAIN AND C. G. MOOR. Price 12s. 6d. W. J. S.

ISSN:0003-2654    

DOI:10.1039/AN8982300224

出版商:RSC    

年代:1898

数据来源: RSC