摘要:

RECENT ADVANCES IN THE BACTERIOLOGICAL EXAMINATION OF WATER. BY W. H. JOLLYMAN A.I.C. ( R e a d at t h e N e e t i n g April 1 1903.) A PAPER of this description must necessarily be almost entirely a rdsumd of the published work on this subject which is daily gaining greater recognition at the hands of Public Analysts. To appreciate the changes which have been me?e it is necessary to hark back to the genesis of water bacteriology and to pay attention to the changes which have occurred not only in the methods but also in the aims of the water bacteriologist. When Kouh in 1893 published his brilliant and historic researches upon the specific infection of the water of the Elbe on the occasion of the great cholera out-break in Hamburg it was thought that bacteriology would afford a method o 170 THE ANALYST, demonstrating other specific infections such 8s typhoid.Though previous to this, and about this time many investigators claimed to have isolated the B. typhosus from polluted drinking water yet modern research has shown that their methods, and the incomplete knowledge of the organisms they had to deal with rendered their results quite unreliable. When it was seen that the isolation of the B. typhosus was so difficult bacterio-logists directed their attention to the more systematic study of the bacterial flora of pure and polluted waters in the hope of finding characteristic differences. To the Franklands (who in 1894 published their work on ‘( Micro-organisms in Water ”) and to Flugge (1896) is due the honour of the pioneer work in the first section and though the results of later investigators have proved some of their con-clusions to be incorrect they laid the foundation of modern water bacteriology.In 1894 Laws and Andrewes published their researches upon the sewage from St. Bartholomew’s Hospital and that horn the Barking and Grossness outfalls. The most complete work in this branch has been carried out by Houston in the course of his investigations into the disposal of the London sewage and by MacConkey and his co-workers on the Royal Commission dealing with the treatment and disposal of sewage. When the bacteriology of water was first studied it was thought that an enumeration of the number of organisms would afford a criterion of the purity of the water and Koch who had been working almost entirely with pathogenic organisms naturally used for the examination of waters the media which he had found to be most suitable for the growth of those bacteria which he had investigated.These media would give most satisfactory results if water were naturally sterile, since the contaminating organisms would be such as would develop well upon Koch’s media; but when it became known that water was the natural habitat of a large number and variety of micro-organisms it might have been reasonable to expect that a medium would have been introduced more similar in composition to the natural environment of the bacteria than meat-extract gelatin. Fraenkel in 1891 wrote : “ The objection that our nourishing gelatin does not supply the conditions of growth for all the kinds of bacteria existing in water and that therefore the results must be unreliable has already been rejected as untenable.” That Koch’s medium is in some cases unreliable the following table will prove.The results given were obtained by plating the various waters upon nutrient gelatin, and upon a ‘‘ standard ” gelatin the composition of which will be given subsequently. Nutrient Gelatin Plates. 1. 80 bacteria per C.C. . 2. 190 . 3. 109 . 4. 468 . 5. 390 . 6. 81 . 7. 111 . 9 9 9 ) 9 , 9, 9, 9 9 “ Standard ” Gelatin Plates. . 227 bacteria per C.C. . 291 99 . 168 9 . 2,288 9 9 . 1,212 9 . 440 9 . 3,808 ,> These results are taken partly from a paper by Pakes* and partly from my own notes. * Centralblatt f u r Bacteriologie 1901 THE ANALYST.171 In the above-mentioned paper it is seen that what I have called ‘( standard ” gelatin is merely a 10 per cent. solution of gelatin in distilled water made neutral to litmus. Gelatin alone is not a good food for bacteria but serves to solidify a suitable fluid and in the case of the “standard” gelatin contains a sufficient quantity of saline matter for the multiplication of water organisms when distilled water only is used in the preparation of the medium Still higher results can be obtained by using gelatin prepared with the water under observation ; but this is seldom prac-ticable and it is very desirable to have a medium of practically constant composition for purposes of comparison. The first table shows very clearly how false may be the results obtained by Koch’s method but by no means condemns its use.The next table sets forth the results of 100 analyses and attention is called to the relative proportions between the number of organisms found by Koch’s method and by the distilled water gelatin process. The waters are labelled ‘( Pure ” or “ Contaminated,” according to the result of the complete bacteriological examination. I. Higher numbers by ‘‘ standard ’’ gelatin. 11. Higher numbers by Koch’s gelatin. 111. Even numbers. Pure Waters. Contaminated Waters. 7 - \ 5 55 11. 4 111. 21 I. 10 11. 8 111. 2 It will be seen from the above that in a pure wttter we may expect to find generally a larger number of bacteria by the standard gelatin method than by Koch’s and that a polluted water will usually give the reverse result.It seems therefore that although Koch’s method gives no criterion of the number of bacteria in a water yet in conjunction with a standard method such as has been suggested it will be a most useful help in determining the purity of a sample of water. That the standard method does not give the total number of bacteria in a water I am well aware and I feel convinced that an estimation of the number of nitrifying organisms would be another great help to the bacteriologist if a simple method could be devised for their enumeration. Before leaving the subject of the quantitative examination of water, it may be pointed out that the organisms naturally present in a pure water capable of growth at 37” C. do not generally increase if the water is incubated for twenty-four hours at the body temperature but in the case of polluted waters where organic matter must have been introduced along with the bacteria a very great increase will be found These facts are often of service but the results are not absolutely reliable.I have never found a bad water to give a less number of body temperature bacteria dter incubation but have occasionally found apparently un-polluted waters giving a considerable increase. I think this examination would be made more valuable by plating the incubated water on MacConkey’s taurocholate agar as one could then easily see if the organisms were probably of intestinal origin. Now with regard to the isolation of the organisms indicating pollution. The B. coZi is the one that has attracted most attention.This bacillus has been isolated from polluted waters by every bacteriologist who has searched for the B. typhosus 172 THE ANALYST. and was in the early days of bacteriology often mistaken for that organism. Though many statements have been made that the presence of the B. coli has little value owing to its said ubiquity these statements are not supported by experimental evidence ; and on the other hand we have a definite contradiction to these opinions by bacteriologists of very wide experience. Houston says (( Certainly . . . its presence serves as an index of the possible presence of other and perhaps dangerous bacteria of recent origin.” MacConkey states of the B. c o l i ; (‘ This organism is a most accurate measure of intestinal pollution.” And again (( I t is often argued that the presence of the B.coli is of little significance because it must be widely distributed in nature and because it must often be taken internally in water and foodstuffs. Buk we have shown by very numerous analyses that the B. coli is not universally dis-tributed and that it occurs in foods and waters in those cases where pollution might obviously have taken place.” Four of the methods of isolating the B. coli may be somewhat fully discussed here. The carbol method due to Widal and Chantemesse and Parietti’s modifica-tion are perhaps the most universally used. These are open to the great objection that although some B. coli will grow upon a medium containing phenol others will not and we cannot say at present that the more robust organisms of the CoZi group signify a greater or less dangerous pollution For the purposes of quantitative esti-mation of the B.coli it is certainly advisable to use some method which does not kill an unknown number of the organisms it is desired to enumerate. The neutral red method due largely to Hunter and Savage seems better than the carbol methods since there is no inhibiting substance present but it is open to several objections. The aerobic condition of culture enables many other varieties of organisms to develop and renders the isolation of the B. coli a matter of difficulty. Other organisms than the B. coli and some not infrequently found in pure waters (e.g. B. prodigiosw) give the reaction and it is also stated that an excess of the B.mesentericw delays the reaction. MacConkeyW taurocholate agar supplies a much more satisfactory means for the detection of sewage pollution than the carbol broths and as this useful process is becoming more widely used I may deal with it somewhat fully. The agar is pre-pared by dissolving 0.5 per cent. of sodium taurocholate 2.0 per cent. peptone and 1.5 per cent. agar in tap-water adding after filtration 0.3 per cent. lactose. In this medium bacteria capable of forming acids from lactose produce a precipitate round their colonies which gives a hazy appearance to the surrounding agar. This reaction, of course is not limited to the B. coZi; but MacConkey has shown after examining ninety-four different organisms that practically all that produce the characteristic reaction are of intestinal origin and he concludes “that when the reaction is obtained it is most probably produced by organisms of intestinal origin and when the reaction is not present fascal contamination is absent.” The chief objection to the method is that one can only examine a small quantity of the water by the war plate method unless recourse is had to filtration-always a troublesome and incon-venient process.Dr. MacConkey has informed me that the agar medium inhibits the growth of the B. coli so he uses a taurocholate glucose broth in the first case, * Thompson Yates Laboratory Reports 1901 THE ANALYST. 173 plating the resulting culture on his bile agar; and this I think is quite the best method of the three I have described. Pakes’” method for the isolation of the B.coli is certainly more delicate than the first and less fallacious than the second and third and has moreover another very great advantage over all three. This will be referred to in dealing with the identification of streptococci. Varying quantities of the water under examination are incubated anaerobically at 37” C. in broth containing 2 per. cent. glucose and 0.4 per cent. sodium formate. The anaerobic condition inhibits the growth of many water organisms and the temperature of incubation has a still greater effect in this direction so that pure waters seldom give any growth even if 60 to 100 C.C. are examined ; but the two conditions of anaerobiosis and blood temperature are the normal conditions under which the B. coli develops most freely.The results are also obtained with great rapidity as it is possible to isolate a pure culture of the bacillus from a polluted water in two days. Before leaving this subject may I place before you the results of a few experi-ments I have made with the phenol broth MacConkey’s taurocholate glucose fluid, and glucose formate broth. Nine C.C. each of the various media were inoculated with 1 C.C. each of a dilute broth emulsion of the B. coli. The tubes were then incubated under identical con-ditions of temperature (37’ C.) the anaerobic cultivations being kept in the same vessel for twenty-four hours. * Each culture was then suitably diluted and plated on Koch’s gelatin. The results per C.C. are as follows : Broth. G. P. Broth, Broth MacConkey’s Fluid.G. F. Broth. 0 *05 per Cent. 0.05 per Cent. Phenol. 784,000,000 659,000,000 337,000,000 798,000,000 528,000,000 The figures may be of interest but I am aware that they do not prove the superior delicacy of either method as the conditions of experiment were not similar to those obtaining in an ordinary bacteriological water examination and a smaller number of organisms present at the end of twenty-fours does not necessarily mean actual inhibition but may indicate only a slower development. However it is desirable, other conditions being equal to use the method giving the speediest result. I have been told that Pitkes’ method has failed where MacConkey’s has succeeded. This may be so for Pakes’ method will fail under certain circumstcnces. One cannot rely upon isolating the B.coli direct from faeces crude sewage or other very septic substances as grossly polluted milk ice-cream etc. but if these substances are diluted from 1,000 to 100,000 times the characteristic gas production is marked, and the isolation of the B. coli communis is very easy. I believe that in the cases sf the substances referred to there is too much of some toxin (whether due to the coli or to some of the other inhabitants of the material I do not know) which prevents the B. coli communis from developing. However such cases can occur but seldom in * Public Benlth March 1900 174 THE ANALYST. water analysis and when they do there would obviously be little need to isolate the B. coZi in order to give an opinion upon the sample. Horrocks has made an extended study of the behaviour of the B.coli with typhoid serum and he has come to the conclusion that while the B. coli derived from normal fEces is not agglutinated by the specific serum when the latter is considerably diluted coli from typhoid patients show a very marked sensibility to the action of typhoid serum. This point seems a very important one and may prove of great service. The published researches of Klein upon the B. enteritidis sporogenes have been of considerable value to the water bacteriologist and the demonstration of the presence of this organism is another factor in the bacterioscopic analysis of water ; but as the spores of this anaerobe can exist for an apparently unlimited period in water they may be found long after the pollution has ceased to be dangerous.The streptococcus has been receiving much attention at the hands of well-known workers and I may here profitably quote some of them : Horrock says ‘‘ My experience does not support the contention that streptococci probably indicate a dangerous contamination.” Houston is of opinion that strepto-cocci ‘‘ are absent from water and soil except in those cases where there has been recent contamination with sewage or other substances equally objectionable.” Rides1 “ I have occasionally found them (streptococci) in deep-well waters of undoubted purity.” And Thresh makes a statement similar to Rideal’s. With regard to the isolation of the streptococcus Houston states “The streptococcus test is undoubtedly a difficult one and is perhaps hardly to be recom-mended as a routine measure when the samples to be examined are very numerous.” This observer examines the colonies obtained upon agar plates under a low-power objective and subcultivates suspicious-looking ones-a most laborious method and one that cannot possibly be reliable in quantitative work, The identification of the streptococcus is in my opinion one of the easiest of the problems the water bacteriologist has to solve.Streptococci grow well under anaerobic conditions at blood heat and develop better in a fluid containing glucose than in ordinary broth; hence Pakes’ method is admirably adapted for the proof of the presence of streptococci. Dr. Eastes in 1900 informed me that he always examined microscopically the growth obtained in the glucoee formate culture-tubes and he has very kindly placed at my disposal a number of his results.In these I see that he demonstrated the presence of streptococci in a number of waters which had most certainly not been subjected to recent contamination and I have frequently observed the same fact myself. I do not know if streptococci are normal inhabitants of some unpolluted waters, but I think not and feel at the present time that the presence of streptococci with no other bad feature than perhaps a larger number of organisms in Koch‘s gelatin than in the standard gelatin indicates remote contamination and is perhaps com-parable with the presence of large quantities of saline ammonia in some deep-well waters. To determine the safety of a drinking water from the bacteriological point of view it would seem necessary to make enumerations by two methods similar to those described to examine from 60 to 100 C.C.of the water for the B. coli an THE ANALYST. 175 streptococci-and in some cases it may be advisable to search for the B. enteritidis sporogenes and the Proteus group. To illustrate the value of this extended examination the results of an investigation into one water-supply may be given. This water has been examined monthly by Dr. Eastes and myself. In August last it contained 67 bacteria per C.C. (Koch’s method) and 1,060 (standard method) and no coli were found in 60 C.C. This might on the above analysis pass as a pure water. However suspicion was cast upon the apparent purity largely owing to the fact that streptococci were found in every 5 C.C.In November the sample examined contained 94 organisms by Koch’s method and only 13 by the standard gelatin. It then became necessary to investigate thoroughly the water-supply. I took samples from the well and at various points in the headings. A small amount of impure river water was found to be leaking in and also what was undoubtedly surface water was also discovered coming through a small fissure in the wall of the heading. A sample taken at a point where apparently pure oolite water was entering proved the source of the main volume to be practically sterile. No bacteria could be found by gelatin plate cultivation and no organisms capable of anaerobic growth at 37” C. were found in 60 c.c. and no coli or streptococci were found in 120 C.C.The river water was found to contain 735 per C.C. (Koch) 270 (standard) coli in every 3 c.c. streptococci in every 1 C.C. The surface water contained coli in 5 c.c. and streptococci in each C.C. The contaminating waters could not be measured but formed only a very small proportion of the total half-million gallons daily drawn from the well. The discussion of the B. typhosus has been left until now as the subject is one of quite secondary importance in everyday work. In the present state of our knowledge the isolation of this pathogenic organism is rather a matter of chance and even if we had a reliable method for its identification its absence from a water would not justify the bacteriologist in pronouncing such a water safe if there was evidence of faecal contamination.However on special occasions it may be most desirable to prove the specific pollution of a water-supply by the B. typhosus and this has been accomplished by several investigators among whom I may mention Rideal who isolated the bacillus from a cistern in a house in which there was a case of enteric fever. To illustrate the difficulty of detecting the typhoid bacillus in water I may refer to the work of Laws and Andrewes who only obtained two colonies of the bacillus in an examination of a considerable quantity of the unsterilized sewage from the Homerton Fever Hospital. The methods that have been brought forward for the separation of the Eberth bacillus from water are innumerable and as there is not one really satisfactory one amongst them it is not worth while to weary you with any descriptions.Horrocks, in his book on ‘( The Bacteriological Examination of Drinking Water,” has treated this subject in a most thorough manner and any bacteriologist called upon to examine a water for the B. typhosus cannot do better than examine the methods described by Horrocks. In those very rare cases in which the typhoid contamination is by mean 176 TEE ANALYST. of infected urine only the isolation of the bacillus should be much more simple as the B. coli will probably be absent. A few words in conclusion upon the relative values of bacteriological and chemical examination of drinking water from the point of view of the general analyst. Seeing that perhaps the most valuable examination-inspection of the source-is generally impossible it is well worthy of consideration which of the two methods of analysis gives the most reliable results and I am of opinion that not only in the case of isolated analyses but also in periodical investigations the bacteriological examination affords the more delicate and definite means of determining harmful pollution, I do not in any way belittle chemical analysis ; it has served for so long a period to assist in the maintenance of the public health and will always have to be resorted to to determine the potability of a water so far as its mineral constituents are concerned.Bacteriology must however soon if not now take the premier place as the means for determining the safety of a water for human consumption. DISCUSSION. Mr. SYDNEY ROWLAND of the Jenner Institute said that he had listened with very great interest to Mr.Jollyman’s exposition of recent researches in the bacterio-logical examination of water. I n following the paper his opinion-the common opinion of himself and of his colleagues at the Jenner Institute-had been reinforced as to the difficulty of deciding among the great multitude of methods that were in use which methods should be adopted in the routine examination of water for report purposes. It was of course open to those engaged in research to use any particular method they liked and to modify their methods in searching for particular organisms and so forth ; but to the practical bacteriologist who had samples of water sent to him for report it was he thought very important that some definite method should be employed which would give the assurance that if the same water were sent to two different bacteriologists for examination comparable replies might with reasonable certainty be expected from both.H e believed he was correct in stating that if one sent a water for chemical examination to two analysts the proportions of say chlorides nitrates or ammonia returned by them would not differ by more than very small amounts. It was not the case however that one could rely on getting such concordant results if one sent the same water to two different bacterio-logists; and his object in speaking on that occasion was with the permission of the meeting to emphasize if possible the importance of establishing some standard method of bacteriological examination and to suggest whether some definite action on the part of the analysts of this country in combination with the bacteriologists, might not be inaugurated so that a standard method could be introduced which would be universally accepted and so that when one sent a sample of water for bacteriological examination one could be reasonably certain of getting the s&me opinion from different people.An instance of this kind had happened in his experience recently at the Jenner Institute where for some years past a monthly examination had been made of a certain public water-supply samples of which had also been sent to other analysts for bacteriological examination. In the former case, owing to the continued presence of B coZi the water had been reported upo THE ANALYST.177 unfavourably whereas the other analysts did not find it more than once and stated that the water was extremely good. Occurrences of that kind were unsatisfactory, and did not serve to enhance the prestige of bacteriological examination. If, therefore it were possible to obtain the opinion of the meeting as to the possibility of some concerted action between the analysts and the bacteriologists in this matter, he thought a very useful purpose would have been served by Mr. Jollyman’s paper. With regard to Mr. Jollyman’s statement of opinion as to the utility of bacteriological methods in the examination of water he (the speaker) did not think that any analyst was entitled to give an opinion as to the purity of a sample of water without both a bacteriological and a chemical examination.Professor HEWLETT said that he had listened with very great pleasure to Mr. Jollyman’s paper which as Mr. Rowland had said emphasized the need for the adoption of some definite standard method in the bacteriological examination of water. The methods in use were multifarious and applied as they were by different people in slightly different ways under slightly different circumstances were bound to give varying results which was much to be deplored as it brought bacteriology into disrepute. He had had a certain amount of experience in the bacteriological examination of water and had adopted various methods and he had come to the conclusion that carried out carefully it certainly was of very great value in the examination of water for purity.On the whole he was not quite inclined to agree with Mr. Rowland in thinking that chemical examination was absolutely necessary, but it was certainly very desirable. His own impression was that bacteriology had now gone far enough to stand by itself if the proper methods were adopted; but as he had said there was not the slightest doubt that it was highly desirable to have both chemical and bacteriological examination. He would not call an examination complete in fact without both. I t would he thought be a great step in advance if this Society could introduce some co-ordination of methods between different workers in the science of analysis as applied to hygiene. Dr. RIDEAL thought that while both chemists and bacteriologists would agree that uniformity of method was to be aimed at if possible it would be exceedingly difficult to standardize any method o€ bacteriological work at the present time, Those who were more particularly acquainted with the history of bacteriological investigation during the last few years would recollect that much of the progress which had been made towards standardization had really emanated from the United States and American investigators had approached different bacteriologists in this country with a view to formulating some uniform method but unfortunately the negotiations had at present fallen through.Many bacteriologists too found that their own methods gave information which others did not agree in so that until there was unanimity amongst the different investigators the processes must be subject to that suspect if the word might be used which he thought bacteriologists at present felt as to their work.The methods of chemical analysis were undoubtedly very accurate but after all they certainly were not nearly so delicate as those of bacteriology On the other hand these latter might be too delicate and he was not at all certain in his mind whether the scares which periodically arose with regard to oysters watercress cockles ice-cream and so on did not really exaggerate th 178 THE ANALYST. significance of the presence of pathogenic organisms in those particular foods. Some years ago he had ventured to suggest that instead of depending upon any particular method or methods one should base one’s opinion not upon the absolute number of organisms capable of growing on any particular medium but upon the ratio between the organisms capable of growing on a given gelatin medium at the ordinary temperature and those capable of growing on a given agar-agar medium at blood-heat.That ratio represented the relative preponderance of two distinct sorts of organisms in the water. If the blood-heat organisms were found to be increasing in number a t a greater rate than those growing at the ordinary temperature then it might be said, in the language of the Sale of Food and Drugs Act that a presumption was raised that organisms capable of growing inside the human being a t the body temperature were being added. He had found in his own practice during the last eight or nine years that that ratio gave information which was really not yielded by any other method.For the identification of specific organisms special tests were of course necessary. The three specific organisms mentioned in the paper however-namely, B. coli B. enteritidis and Streptococcus pyogenes-although more or less indicative of sewage contamination had neither one of them been (( ear-marked ” as causative of any particular disease. It had certainly been repeatedly stated by Dr. Klein that B. enteritidis sporogenes was causative of infantile diarrhoea; but since one would scarcely expect diarrhcea produced in infants to be the result of the consump-tion of oysters he (Dr. Rideal) thought that the mere fact of the occurrence of that organism in certain oysters in the Thames was hardly in itself sufficient for con-demnation.With regard to Mr. Jollyman’s statement as to the numbers of organisms growing in broths containing various inhibitive substances he (Dr. Rideal) had looked upon these restrainers as added in order to accentuate the presence of organisms allied to the pathogenic organisms and to kill off the remainder. In this particular investigation of Mr. Jollyman however it appeared that the number of organisms growing in the broths containing these antiseptics was smaller than in the broth which contained no restraining influence. That made one consider whether it was desirable to rely very much upon these methods of getting hold of the organisms which it was particularly desired to study; for it must be borne in mind that pure cultures of coli had been used and if the coli were not developed in these fluids which were destined €or their growth it would seem that something must be wrong in the methods of investigation.Mr. MOOR said that he must confess that he was somewhat disappointed in this paper for he had hoped that in it some proof would be shown of the value of the science of bacteriology and that it might have contained a tabulated statement showing that in cases where waters had been shown practically to be polluted the pollution although it had not been detected by chemical analysis had yet been detected by bacteriological methods. That did not appear to be the case and, although he had not lately had much opportunity of studying this science he did not think it had ever been the case that a water known to produce disease had not been detected by chemical analysis and yet had been detected bacteriologically.One very great inherent difficulty which could not be overcome in all bacterio-logical work was the difficulty of sampling. The bacteria were not in solutio THE ANALYST. 179 in water but in suspension and they might not be distributed equally through the whole mass and it was quite impossible to shake up and mix a river or a well. The time expense and uncertainty involved by bacteriological examination would certainly make it very inferior in its results to chemical analysis. I n chemical analysis the substances it was desired to determine-at any rate those in solution-were evenly distributed in every part of the water. That was never the case bacterio-logically.Then again the multiplication of the bacteria in water which admittedly took place with extreme rapidity precluded any certainty that because a given organism was not found in one sample it might not be present in another sample of the same water where it might in a very few hours develop into an enormous number of colonies. I n the case of past pollution chemical evidence was often afforded by the proportions of chlorides nitrates and so forth; but if the bacteria which indicated pollution had flourished and then disappeared as they were known to do how was any bacteriological evidence to be obtained? In the examination of raw sewage by chemical methods the rate and efficiency of a method of pollution could be traced as regards the disappearance of those bodies which yielded ammonia by Wanklyn’s method or which were attacked by alkaline permanganate.Bacteriology however, was of no assistance in the examination of raw sewage or effluents because even if specific organisms were not found nobody could say merely on that account that it would be safe to drink a sewage effluent or water mixed with effluent NO doubt if bacteriological methods were complete the results obtained by different workers with the same water would be in better agreement; but it was also necessary that the methoas should be thoroughly understood. It would be news for instance to many bacteriologists that most of the gelatins which they used contained con-siderable quantities of zinc sztlts. He did not know the effect of that on bacteria, but it seemed likely that in a good many cases where diecrepztncy had occurred it might be due to the presence of zinc salts in the gelatin used.Very small traces of copper stopped the growth of some organisms altogether. He would like to ask the author what precisely he meant by pollution. In the paper fi polluted water was as he understood it defined as one in which a certain number of organisms were found. But he thought it was necessary also t o know the history of the pollution. Finally the author practically admibted that, after all the best plan was to go and look at the source of the water and he (Mr. Moor) was inclined to agree with that. Certainly in the case of river water used for a town supply the analyst ought to go and see the river. I n the case of singIe wells it was not possible to make such an inspection; but for the examina-tion of waters from single wells he thought it would be generally admitted that chemical analysis did practically all that was required.He (Mr. Moor) had intentionally put forward those considerations which could most obviously be urged in criticism of the usefulness of bacteriological methods. He had been led to do so principally by what seemed to him the quite inadequate im-portance which had been attached in the paper to chemical methods. It was, unfortunately useless to discuss the relative value of the two for what they all knew to be the most satisfactory test; of the water-viz. constancy of composition -because the opportunities of such examination rarely occurred. At the sam 180 THE ANALYST.time in its proper place he was far from belittling the service which might be rendered by bacteriological examination. Many years ago he had himself pointed out that an amount of bacterial pollution which wa,s enormous end incapable of being missed could be introdueed artificially into a water under circumstances which made its chemical detection practically impossible. There could be he thought no doubt that the truth lay in the constant use of all available methods of examination ; and while it might be profitable to discuss any fresh applications of either method, any attempt to claim for either a monopoly of usefulness was always to be deprecated. Mr. F. J. LLOYD thought that it should be borne in mind that the nature of the bacteria present in water would depend largely upon the nature of the food which they found there.In a contaminated water the organisms present were such as required organic matter in a certain state of decomposition. In a pure water, however other organisms were present which did not require that organic matter. He thought therefore that very careful consideration should be given to the question of the desirability in the bacteriological examination of water of using a medium which was somewhat deficient in organic matter and which yielded as it appeared from Mr. Jollyman’s figures much higher results with pure waters than with contaminated waters because the organisms which required organic matter were incapable of growth in such media. He (Mr. Lloyd) thought that the figures referred to rather supported the use of a medium like Koch’s gelatin in which there was plenty of organic matter for the bacteria to feed upon.Mr. JOLLYMAN said that it would probably be better to use both. Mr. LLOYD said he was about to suggest that the use of both kinds of media would be an advantage inasmuch as it would enable Dr. Rideal’s idea to be utilized of obtaining a ratio which he (Mr. Lloyd) thought would lead to results much nearer the truth. He considered the use of the word “standard” as applied to gelatin most undesirable. He strongly objected to the use of the word ‘‘ standard” in connection with any method of analysis until such method had been universally adopted. With regard to the subject of B. coli about twelve or thirteen years previously in working upon milk he had isolated a number of organisms which were apparently B.coZi communis but which upon further examination showed marked differences in their nature and character and in their chemical action. He thought it was now generally admitted that the B. coZi communis group of organisms included a great number of varieties showing very marked and distinct differences and he did not think it was justifiable to take any pure culture of a particular R. c0Z.i without knowing the exact variety and to assume that because one organism or one variety acted in a certain way all the others would do likewise. The organisms which he had isolated in the investigation referred to had been compared by Dr. Andrewes with pure cultures of coli obtained from quite different sources and striking differences had been found between them although they were still so similar that they would all practically have to be called coli bacilli.He thought that probably many of these varieties were not indicative of any important degree of contamination though some of them certainly did indicate contamination such as needed careful investigation. With regard to the question of the relative utility o THE ANALYST. 181 bacteriological and chemical methods his own opinion was that it was not desirable that either should be discarded but that they must go hand in hand. Mr. Ross said it seemed to him that even if a standard method of working were agreed upon nothing in particular would be gained unless it was also agreed that the determination of the number of organisms present should be commenced after the lapse of a standard interval of time and that practically speaking would be impossible.The value of chemical analysis came in with very great certainty where the analyst was acquainted with the geological formation of the district and with the results that were to be expected in the water derived therefrom. Under such circumstances he thought it possible to work with practical certainty without a bacteriological examination. For example on the left-hand side of the Malvern Hills the water might be perfectly good witE about 8 grains of chlorine per gallon, whereas on the right-hand side nearer Worcester as much as 2 grains would indicate that some contamination had entered into the water.Mr. J. B. P. HARRISON agreed with the opinions expressed by Dr. Hewlett and Mr. Rowland as to the relative efficiency of the bacteriological and chemical examinations. He also admitted that the statement that had been made as to the preference of the former examination to the latter was true enough when the pollution had comparatively easy access to the supply but supposing the polluting matter to have filtered through a considerable depth of strata whereby many of the organisms may have been removed he thought it quite possible that a chemical analysis would afford more evidence of pollution than a bacteriological examination. Dr. RIDEAL referring to Mr. Moor’s remark as to the presence of possibly inhibitive substances in gelatin said that there were many gelatins on the market at present which contained formalin the object of the addition being he believed to raise the melting-point of the gelatin.Mr. HEHNER thought that while some proportion of the discussion must be regarded as not absolutely relevant to the real subject of the paper that fact must be attributed entirely to the few remarks which the author had made in conclusion; for having given a most interesting paper he had ultimately without any data whatsoever and without any tittle of evidence drawn a subtle comparison between chemical analysis-of which he had not spoken before and as to which no data were given-and bacterioscopic examination and had thus so to speak applied a match to the powder-barrel and caused the explosion represented by the portion of the discussion referred to.He (Mr. Hehner) thought it must be acknowledged that in many circumstances bacteriology mould fail and had failed; and it must also equally be acknowledged that in many other circumstances chemical analysis was incapable of detecting pollution and that it depended and would always depend, upon the discretion of the operator to find out when and how these two classes of methods should be combined. The PRESIDENT (Mr. Fairley) agreed with Dr. Rideal that the ratio which the organisms growing at the ordinary temperature bore to those which developed at blood-heat was a very important factor and one which is frequently used with great advantage. Mr. JOLLYMAN? in reply said that with regard to the relative utility of chemica 182 TEE ANALYST.and bacteriological methods for the detection of pollution it was unfortunate that in the majority of cases he was unable in the case of samples submitted for bacterio-logical examination to make a chemical analysis also though samples for chemical analysis were always examined bacteriologically as well so that he was unable to produce full proofs in support of his suggestion which however he had given merely as an expression of opinion for what it might be worth. With regard to Mr. Lloyd’s remarks it would be noticed that the word ‘‘ standard,’’ in reference to gelatin was italicized. It had been used merely for want of a better word and without of course, any idea of suggesting that it was incapable of improvement. Indeed it was men-tioned that probably it would be improved by adding to its mineral contents and rendering it more alkaline.He did not quite know why bacteriological methods were so unfavourably regarded by Mr. Moor as compared with chemical methods, for the detection of past pollution. Mr. MOOR Because the chemical factors by which past pollution is determined remain in the water for a long time. Mr. JOLLYMAN said that B. enteritidis sporogeizes had been found in water after the lapse of something like two years while streptococci remained for a considerable time and even B. coli remained for a certain time. He was unable to make a definite statement on the subject of the multiplication of these organisms but he believed that they did not multiply in water under natural circumstances. They would however very often live longer in water than they would under the conditions of a laboratory experiment He thought that bacteriological examination gave every bit as reliable indications of past pollution as chemical analysis.The presence of B. enteritidis sporogeizes indicated pollution of a remote character ; the presence of streptococci alone without any other bad feature might be taken as indiwtive of remote and probably not dangerous pollution ; while the presence of coli which died out relatively quickly indicated comparatively recent and more dangerous con-tamination. With regard to the question of sampling he thought it was quite practicable to make a suspension of the solid matter in which the solid particles were practically speaking as well distributed as substances in solution; and as a matter of fact cultivations from diflerent parts of a sample so mixed would show practically the same number of organisms.He agreed with Dr. Rideal as to the advantage of ascertaining the ratio between the organisms growing at the ordinary temperature and those growing at blood-heat. It must be borne in mind however, that different results were obtained with different media as was exemplified particu-larly in the case of sample No. 7 which yielded 111 colonies on one gelatin and 3,808 on another so that any alteration in the media might alter the ratio to a con-siderable extent. He thought that as much value might be attached to the ratio of organisms obtained with two different gelatins at the ordinary temperature as to the blood-heat ratio. Dr. Rideal had referred to the causativeness of disease of certain bacteria. The point however raised in the paper was not that the organisms mentioned were the cause of disease any more than the organic matter albuminoid ammonia and so forth by which pollution was indicated chemically. They simply indicated pollution and if it was accepted that these organisms must be derived from intestinal sources surely a water could not be passed in which they were found to be present THE ANALYST. Mr. HEHNER said that the source of the water made a very great difference indeed. An upland surface water for instance might be many miles from any human habitation and yet would be subject to pollution by birds and sheep. Yet such water would be perfectly harmless although it might and probably would, contain B. coli. There was always the question that water exposed to the access of animals or birds might contain B. coli ; but although bacteriological methods were very delicate it would be too much to expect them to discriminate between bacteria from human and those from animal intestines

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DOI:10.1039/AN903280169b

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年代:1903

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THE ANALYST. 183 NOTE ON THE DETERMINATION OF MINERAL OIL I N ROSIN OIL. By J. LEWKOWITSCH, PbD. (Read at the Zeetzng, May 6, 1903.) LAST year Walker and Robertshaw published a paper on this subject (ANALYST, 1902, p. 238), embodying experiments carried out in my laboratory. Inter alia, they had examined the Holde method. I n the directions given by Holde, 96 per cent. alcohol was mentioned as a solvent. It is quite true that 96 per cent. by weight ought, therefore, to have been used, but it so happened t h i t 96 per cent. by volume alcohol was employed, and in view of the results obtained the matter was not con- sidered further. Holde recently explained in a note (Mztth. Konigl. Versuchs., 1902, p. 253) that the employment of alcohol of 96 per cent. by volume instead of 96 per cent.by weight made all the difference, and in a further publication he states that the error made by the experimenters ought to have been discovered if they had been more caseful; also that all his experiments gave him reliable results. In view of these strictures, I thought it necessary to look into the matter once more, although it hardly seemed credible that such enormous errors as those stated by Walker and Robertshaw could disappear by using alcohol of 96 per cent. by weight, as the whole difference between the two respective alcohols amounts to only about 2 per cent. Ten C.C. of a rosin oil of specific gravity 0.9955, containing 4.9 per cent, of rosin acids, were treated side by side with alcohol of 96 per cent. by volume and 96 per cent. by weight. In the former case there remained undissolved 1.5 c.c.-Le., 15 per cent.-and in the second case 1.25 c.c.-i.e., 12.5 per cent. A mixture was then pre- pared with 60 C.C. of this rosin oil and 40 C.C. of mineral oil. The mineral oil had the specific gravity 0.8297; in 96 per cent. by volume alcohol, 30 per cent. were soluble, and in the 96 per cent. by weight alcohol, 34 per cent. were soluble. The mixture of rosin and mineral oils treated in the same manner gave :-Insoluble in the 96 per cent. by volume alcohol, 55 per cent., and in the 96 per cent. by weight alcohol, 48 per cent. The experiments were carried out in measured flasks and measured test-tubes, these being considered sufficiently accurate for tests of this kind.

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DOI:10.1039/AN9032800183

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年代:1903

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184 THE ANALYST. Besse ._. ... ... Reilhes ... ... ... St. Jean-le-Haut ... Petit Toulouse . . . ... ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. 10 9 8 10 -~ FOODS AND DRUGS ANALYSIS. The Composition of Sheep's Milk. Trillat and Forestier. (Bull. soc. Chim., 1903, xxix., 286-288.)-A sheep yields in twenty-four hours on the average about 500 C.C. of milk, the quantity usually ranging between 400 and '700 C.C. as the maximum, and falling to 150 or 200 C.C. towards the end of lactatioh. The authors have made analyses of 171 samples of milk obtained from flocks of sheep in the districts about the Causses, and the following figures represent the average results obtained from four different dairies : Dairy. Number of Samples. Total Solids. Per Cent. 18.12 19.93 17.90 19.05 Fat.Lactose. Casein. Per Cent. 6.21 7.76 6.50 6-90 Per Cent. 4-82 5.30 5.45 5.34 Per Cent. 5-07 5.95 5.01 5.67 Ash. -. Per Cent. 0.917 1.027 0.942 1.025 Acidity Oxide. Alk&. Calcium =-N_ I- Cent. 0.273 2.5 0.243 2.4 0.266 3.31 Detection of Hydrogen Peroxide in Milk. C. Arnold and C. Mentzel. (Zeit. fGr Untersuch. der Nahr. und Genussmittel, 1903, vi., 305-309.)-As hydrogen peroxide is sometimes used as a preservative of milk, the authors have investigated the various reactions for its detection. In the case of raw milk the para-phenylen- diamine test was found to be the most sensitive, it being possible to detect as little as 0.0025 gramme of hydrogen peroxide in 100 C.C. of milk by this reaction. (Com- pare ANALYST, 1902, xxvii., 89.) I t is also applicable to heated milk, but as the reaction only takes place in the presence of oxydase, a little raw milk must be added to the sample of heated milk under examination. A reaction, independent >of the presence of oxydase, and consequently suitable for the detection of hydrogen peroxide in both raw and heated milk, consists in adding to 10 C.C.of the sample about 10 drops of a 1 per cent. solution of vanadic acid in dilute sulphuric acid. A red coloration is produced by the presence of 0.01 gramme of hydrogen peroxide in 100 C.C. of milk. Titanic acid dissolved in dilute sulphuric acid gives a yellow coloration with 0.015 gramme of hydrogen peroxide. The milk should be tested as soon as possible after the sample is received. w. P. s. The Water-content of Creamery Butter.-&cular No.39, Bureau of Animal Indzutry, U.S. Department of Agriculture, lately issued, gives the results of theTHE ANALYST. 185 Month in which the Butter was made. analysis of 800 samples of butter selected from such parts of the United States as to furnish a thoroughly representative collection. The investigation was undertaken partly because of a widely-extended belief that creamery butter contains a very high percentage of water, and partly because in the recent discussion on the legislation on renovated butter the manufacturers of that product claimed that the limit of 16 per cent. of water as a maximum was an unfair discrimination. The water found in the 800 samples ranged from 7.2 per cent. to 17.6 per cent., with a general average of 11.78.The packages were from 400 creameries, scattered over eighteen States. Nearly all the butter was made in August, when the highest percentage of water was expected. Great care was taken with sampling and analysis. The results show that American creamery butter has an average of not over 12 per cent. of water. An experienced judge of the quality of butter examined all the samples, and gave an opinion as to the amount of water they contained, but the analyses showed that his judgment was often far wrong. 3 $6 :g :& P aE 1$ 25 :-& ," SUMMARY OF WATER-CONTENT IN SAMPLES OF CREAMERY BUTTER. (Eight hundred Samples from 400 creameyies in eighteen States of the United States: Per Cent. 7.20 8-19 7-23 8'30 7-20 taken in 1902.) -- Per Cent. 11-81 11-91 11-79 11'59 11-78 -- May .... June .. .. August .. .. September .. ----- 122 18 119 18 377 17 112 18 160 119 377 146 Totals . . I730 1 18 1 802 Percentage of Water. Per Cent. 16.40 17 -62 16-89 1.5-28 17-62 --- .____ Claseification of Samples by Water-content. NO. 1 0 2 0 3 __ No. 4 4 8 1 17 __ 4 a& 48 s' Q, No. 9 11 25 10 55 __ & a; z g s v 0 - No. 25 15 61 23 124 - & 28 ,ov H n - N O . 58 35 126 48 ?67 - No. 30 32 86 30 I78 - Canadian Butter.-During the months of July and August, 1902, officials of the Canadian Department of Agriculture collected samples from 105 lots of creamery butter, representing the product of five different provinces of the Dominion. The percentage of water of these was determined, with the following results : Minimum, 7.94 per cent.; maximum, 16-77 per cent. ; average of 105 samples, 12-31 per cent, H. L. The Composition of Process or Renovated Butter. Charles A. Crampton. (Journ. Amer. Chem. Xoc., xxv., 358.)-The raw material, or so-called '' stock," for the manufacture of renovated butter, which is now taxable in the United States at + cent per pound, is butter which is unfit for direct sale owing to rancidity, mould, or unskilful preparation. This material is melted and allowed to settle, after which water and curd are removed from the fat, which is next aerated or (( blown" with air, and sometimes washed with water. It is claimed by the makers that no chemicals186 THE ANALYST. are used to deodorize the fat. After adding freeh milk, which has been inoculated with a bacterial culture, to the fat, the whole is chilled and granulated in ice-water, churned, and prepared for the market 8s usual for butter. The tests used in the identification of renovated butter are : The appearance of the fat when viewed by polarized light (Brown-Taylor-Richards test, Journ,. Amer.Chem. Soc., xxii., 703) ; the behaviour of the fat when boiled in an open vessel (‘f spoon ” test) ; the granulation of the fat when cooled in milk (Waterhouse test, Proc. Assoc. Oficial Agric. Chem., 1901, 126, and U.S. Dep. of Agric., Farmer’s Bulletin, No. 131). The chemical data, obtained in the examination of seventy-five samples of renovated butter, in no way serve to discriminate between fresh and renovated butter . The physical tests on the melted fat appear so far to be the best means of identification of renovated butter, but occasionally they fail to yield positive results.A. G. L. _________ Determination of Fat in Food-stuffs and the Like. T. Pfeiffer and R. Riecke. (Mittheil. landw. Inst. Kgl. Univ., Breslau, 1902, ii., 295; through Chem. Zed. Rep., 1903, 70.)-The authors find that the ethereal solution obtained in Nerking’s hydrochloric acid process contains nitrogen, so that the yield cannot be They deem it preferable to treat the material with Dormeyer’s solution of pepsin and hydrochloric acid at the temperature of the blood. Their apparatus and process are as follows : A is a 500 C.C. flask into which the sample is weighed, and where it is treated suitably with the pepsin solution, a few fragments of pumice being added to assist in the subsequent extraction.When the peptonization is finished, the liquid is made neutral by means of potassium carbonate, which causes the fat to be quite free from nitrogen. Water is next added to A until, when the apparatus is put together as shown in the sketch, the level of the liquid is about 1 centimetre below the end of the tube C. About 300 C.C. of ether are then equally dis- tributed between A and B, the latter being a 300 c . ~ . flask previously empty. The stoppers of both flasks are of glass, held in position by a pair of springs, A is next heated on the water-bath for about fifteen minutes till the ether boils briskly, thus causing the bulk of the fat floating on the aqueous liquid to pass into solution ; if the fluids separate badly common salt is introduced.The water-bath is taken away from A, the cock on C is opened, and B is warmed till the ether distils over and intermittently returns to B. This process is con- tinued for twenty-four or thirty hours; but every two hours or so, when A contains about 150 C.C. of ether, the operation is interrupted, A is disconnected, its ethereal contents made to boil, and its whole contents are mixed together by the most vigorous agitation possible, while its mouth is lightlyTHE ANALYST. 187 covered by the hand. With a little practice the vaporized ether may be permitted t o escape without losing any of the fat solution. Finally the cock is shut, as much ether as can be driven out of B is collected in A, B is disconnected, dried in the water-oven to constant weight, and the net gain noted.Another flask is put in place of B for six hours, and the extraction repeated, a third flask being used if necessary. Tests on wheat gluten have given 4.92 per cent. of fat by Dormeyer's process, and 5.05 per cent. by the authors' method; tests on beer dregs have shown 11-19 per cent. by Dormeyer's method, and only 4.49 per cent. by that of Pfeiffer and Riecke. This last difference the authors explain by the circumstance that beer dregs contain free acids having insoluble calcium salts, these not being returned by the present process because of the neutralization of the peptonized liquid. The authors therefore consider their method best whenever neutral fats only are to be determined, or when a separate estimation of fatty acids is desired, the latter being carried out without a neutralization.Liebermann and SzBkely's process is only suitable for an estimation of the total matter soluble in ether, including liquid fatty acids; but in it several faults are irremediable. [ Cf. Beger, ANALYST, 1902, xxvii., 120.1 F. H. L. Determination of Sugar in Chocolate. P. Welmans. (zed. fGr 5fentl. Chem., 1903, ix., 93-101, and 115-120.)-Ten grammes of the finely-divided chocolate are shaken in a separating funnel with 100 C.C. of water-saturated ether until all fat is dissolved. One hundred C.C. of ether-saturated water are then added, and the shaking continued for some time. When separation has taken place, the fat is determined in an aliquot portion of the ether layer. f the aqueous layer are then transferred to a 55 C.C.flask, 2 C.C. of lead acetate solution are added, and water up to the mark. After filtering the solution is polarized, and the amount of Fifty c. sugar calculated from the reading obtained. w. P. s. The Determinationrof Vanillin in Vanilla Beans. A. Moulin. (BUZZ. soc Chim., 1903, xxix., 278-280.)-0n treating vanillin (which contains the group C,H,-OCH,) with fuming nitric acid methyl picrate is formed, and the yellow colour of the solution can be matched by that given by a standard solution of vanillin. I n preparing the colour scale a known weight (0-5 gramme) of vanillin is treated with a mixture of 10 C.C. of sulphuric acid and 100 C.C. of acetic acid, and after the solution is complete a few crystals of potassium nitrate are introduced, and the liquid heated on the water-bath at 60" C.for an hour, and then allowed to stand for twelve hours. I t is then diluted to 100 c.c., each C.C. of the liquid representing 0,005 gramme of vanillin. Of this standard solution 2, 4 and 6 C.C. are diluted to 100 C.C. In the determination 3 to 6 grammes of the beans are finely powdered and shaken with successive portions of ether at 65" C. until completely exhausted. The united extracts (150 to 200 C.C. in all) are decolorized with about 10 grammes of animal charcoal, and then filtered, and the filtrate and washings evaporated to dryness on the water-bath. The residue is then treated as described above, and the188 THE ANALYST. c o h r matched by means of the standard colour scale. The results thus obtained are stated to be in close agreement with the results of gravimetric determinations of the vanillin.C. A. M. Oil of Peppermint : a New Adulterant. C. T. Bennett. (Chemist and Druggist, 1903,59l.)-A sample of oil of peppermint which gave abnormal results on analysis was found to contain about 15 per cent. of triacetin, or more probably a, mixture of the three acetic esters of glycerol. The physical and chemical characters of the oil were : Specific gravity at 15" C., 0.964 ; rotation in 100 millimetre tube, - 15" ; esters as menthyl acetate, 71.2 per cent. ; esters after acetylation, 53.1 per cent. ; refractive index at 20" C., 1.4581. On fractional distillation at ordinary pressure a, residue was obtained boiling above 240" C., which had a specific gravity of 1.147 and refractive index 1-4450.By distilling a larger quantity of the oil under reduced pressure and subjecting the residue to further fractionation the presence of a mixture of the acetic esters of glycerol was proved by chemical tests in the final residue so obtained. w. P. s. New Reactions of Morphine. C. Reichard. ( Z e h anal. Chem., 1903, xlii., 95-100.)-The reduction of tungstic, vanadic, titanic, and molybdic acids by morphine is attended by colour reactions, of which that given with molybdic acid has already been described. In the case of vanadic acid (ammonium metavanadate) a green or bluish-green colour is obtained according to the strength of the solution on warming the liquid. The test is best applied by adding sulphuric acid drop by drop to 2 to 3 C.C.of a 0.1 per cent. solution of ammonium vanadate until on the addition of the last drop the yellow coloration of vanadic acid just disappears. On now adding a little of the solid morphine salt, and applying heat if necessary, a stable green coloration is obtained. In the case of sodium tungstate a 0.1 per cent. solution is shaken with a few drops of sulphuric or hydrochloric acid, and the morphine added in the solid form or in concentrated solution, a bright blue or violet coloration being produced. The coloration is less stable than that given by vanadic acid, and after a few hours a white deposit of tungstic acid is formed. Stronger solutions of sodium tungstate cannot be used for the test, since on the addition of a mineral acid the separation of tungslic acid takes place immediately, whilst without the addition of acid there is no reaction.In like manner a cold solution of titanic acid in concen- trated sulphuric acid becomes black at the point of contact on adding morphine or its hydrochloride, and on shaking the liquid a blood-red coloration is obtained. This colour disappears on the addition of water. C. A . &I. A Reaction of Hydrastinine. A. Jorissen. (Ann. de Chtim. anal., 1903, viii., l26,127.)-Hydrastinine, which is obtained by the oxidation of hydrastine, is known either as a yellowish-white odourless powder or in the form of crystalline needles. It has a bitter taste, melts at 210° C., and is readily soluble in water and alcohol, though only dissolving with dificulty in ether and chloroform.Dilute aqueous solutions are characterized by their bright blue fluorescence. It can be distinguishedTHE ANALYST. 189 from most other alkaloids by its behaviour on adding a few drops of Nessler’s reagent to a solution of its hydrochloride, a precipitate that changes to black almost instan- taneously being formed. In the case of other alkaloids no reduction of Nessler’s reagent is caused by the following : Atropine, cocaine, acouitine, strychnine, brucine, hydrastine, pilocarpine, theobromine, caffeine, quinine, cinchonine, sparteine, nicotine, emetine, narcotine, narceine, and papaverine. On the other hand, morphine and apomorphine bring about a more or less rapid separation of mercury. Of the bitter principles not belonging to the alkaloids proper, picrotoxine, which reduces Fehling’s solution, and an ammoniacal solution of silver nitrate, also cause reduction of Nessler’s reagent in the cold.C. A. M. The Volumetric Determination of Chloral Hydrate. C. G. Hinrichs. (Pharm. Journ., 1903,530-532.)--The method described i n the British Pharmacopoeia (1898) was found to be unreliable when performed under the conditions there laid down, the errorsvarying from 180 to 200 per cent. of the value determined. Furbher experiments, however, showed that when carried out as follows good results may be obtained : An accurately weighed amount of the chloral hydrate is dissolved in 50 to 100 C.C. of water, and excess of $ alkali is run in (15 C.C. per gramme taken). When a turbidity due to separation of chloroform is noted, the solution is stirred until perfectly clear. The excess of alkali is then titrated back. Each gramme of chloral hydrate should require 12-084 C.C. of This usually takes from one to two minutes. $ alkali. w. P. s. Volumetric Estimation of Sodium Methyl Arsenate (krhenal). Adrian and Trillat. (Compt. Rend., cxxxiv., 1231; through Zeits. f. angew. Cham., 1903., ix. , 184.)-According to the authors’ researches, arrhenal has the composition CH,AsO(ONa), + 6H,O. The corresponding silver salt is almost insoluble in water, and may be utilized for the estimation. The substance is dissolved in water in a graduated flask, an excess of decinormal silver nitrate solution is added, and the flask is filled to the mark. After standing twelve hours the solution is filtered, and the excess of silver is determined by titration. An allowance is made for the solubility of the silver salt by deducting 0.53 C.C. of TG solution for every 50 C.C. of filtrate. Each C.C. of solution corresponds to 0.0146 gramme of arrhenal. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9032800184

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年代:1903

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THE ANALYST. 189 ORGANIC ANALYSIS. Determination of Formaldehyde in Commercial Formalin. C. Wallnitz. (D. Gerberzeit., 1903, xlvi., Nos. 1, 2, 3, 4, 6, 8, 1 2 ; through Chem. Zeit. Rep., 1903, 85.)-In Blank and Finkenbeiner’s process (ANALYST, 1899, xxiv., 92) the time of reaction is given at three or ten minutes. This is too short; it should be half an hour. I n Romijn’s iodometric process (ANALYST, 1897, xxii., 221) at least 70 C.C. of iodine solution must be added for every 5 C.C. of 2 per cent. formalin solution, and the time of reaction must be at least ten minutes. With the alterations men-190 THE ANALYST. tioned, these two methods are most to be recommended. Legler's process (Bey,, 1883, xvi., 1333) is fit for ordinary work, but gives somewhat lower results ; rosolic acid does not make a good indicator, as the end-point is not always easy to see, A factory process used in Germany is as follows : 5 C.C.of hhe formalin solution are mixed with 50 C.C. of normal ammonia in a closed vessel, and either heated to 50" C. for fifteen minutes or kept at ordinary temperatures for two or three hours, finally titrating back with normal acid,* and multiplying the number of C.C. of ammouia used by 9 to give the percentage of formaldehyde by volume. This method yields results about 0.4 per cent. below those of the two processes first mentioned, and the colour change is not sharp. The gravimetric process proposed by Trillat (Compt. Rend., 1893, cxvi., 891) and converted by Klar into a volumetric one (Pharm. Xed., 1895, xl., 548) requires perfectly pure aniline, and the colour change is difficult to observe when Congo red is used as indicator ; otherwise it gives figures agreeing with those of Blank and Finkenbeiner's and Romijn's methods.Vanino's silver process (ANALYST, 1902, xxvii., 93) gives low results. Schiff's method is useful (this vol., p. 78) if the mixture of formalin and ammonium chloride or sulphate solution is immediately treated with 50 C.C. of seminormal potassium hydroxide (i.e., an excess), and then, after standing either three hours at ordinary temperatures or an hour and a half at 50" C., is titrated back with decinormal sulphuric acid; litmus, however, does not give tt sharp end-point. F. H. L. The Composition of Flax Wax. C. Hoffmeister. (Berichte, 1903, xxxvi., 1047-1054.j-The fatty substance with which flax fibres are coated, and to which they owe their lustre and odour, is soluble in ether or benzene, and on evaporation of the solvent is left as a white or yellowish-green or brown mass resembling wax.The amount obtained varies with the fineness and degree of purity of the fibres. The so-called flax dust from the factories yielded about 10 per cent. of the product. This substance, to which the author gives the name of flax wax, melts at 61.5" C. (average of ten samples), and has a specific gravity of 0.9083 at 15" C. It burns with a smoky flame, leaving practically no residue. A specimen examined by the author had the following characteristics : Unsaponifiable residue, 81.32 per cent. ; acid value, 54-49 ; saponification value, 101.51 ; Reichert-Meissl value, 9.27 ; Hehner value, 98.31 ; and iodine value, 9.6.I t was found t o consist mainly (70 to 80 per cent.) of a paraffin closely allied to ceresin, with a small quantity of phytosterin and ceryl alcohol, whilst the saponifiable portion contained palmitic, stearic, oleic, linolic, linolenic, and isolinolenic acids. A small proportion of a volatile aldehydic substance was also found. C. A. M. Detection of Small Quantities of Ceresin in Paraffln Wax. El. Graefe. (Chem. Zeit., 1903, xxvii., 248.)-Quantities of ceresin up to 10 per cent. do not affect the meltingpoint of a paraffin wax (melting-point 5 5 4 O C.) such as is used in the manufacture of candles. If 1 gramme of the sample is dissolved in 10 C.C. of carbon * Indicator not mentioned.THE ANALYST. 191 bisulphide at a temperature of 20°, the solution is clear provided less than 10 per cent.of ceresin is present, but contains a glittering, silky turbidity if the proportion is higher. If, now, the original paraffin had a melting-point below 54" C., on mixing 1 C.C. of the solution with 5 C.C. of ether and 5 C.C. of 96 per cent. alcohol at the same temperature of 20" pure paraffin remains clear ; but quantities exceeding 1 per cent. of ceresin cause a proportionate turbidity, which in appearance resembles alumina, thrown down from a weak liquid. Genuine paraffin wax melting above 54" does not give a clear solution with the mixture of ether and alcohol, but the undissolved matter looks different ; and if solution is made complete by warming the tube in the hand, and it is then allowed to cool again, high-melting paraffin separates in a wholly crystalline condition, but ceresin appears as before described, chiefly at the surface of the liquid.When '( Montan" wax is mixed with paraffin instead of ceresin, the product may be recognised by its milky-white appearance, by its cloudy solution in carbon bisul- phide being clarified by an addition of ether-alcohol, and by its acid value, 1 gramme of '' Montan " wax neutralizing 17 C.C. of decinormal alkali. F. H. L. Detection of Small Quantities of Ceresin in P a r a m Wax. (1) F. Sommer, (2) E. Graefe. (Chem. Zeit., 1903, xxvii., 298, 408.)-Sommer states that Graefe's process (see preceding abstract) is only applicable to the examination of American and German paraffins, because Scotch and Galician paraffin which melts below 540 c,, and also high-melting Java paraffin, do not yield clear liquids when their solutions in carbon bisulphide are diluted with Graefe's mixture of alcohol and ether, but often give copious deposits which look exactly like precipitates of ceresin.If the test is to be of any value, the working temperature must be raised to, say, 25" C. ; but it would be preferable to add the precipitant at 20°, and then to warm gently and shake the tube. By operating in this manner, ceresin yields a flocculent precipitate, as Graefe has described; pure paraan generally passes into solution, a few drops at most remaining undissolved. Sommer also takes exception to Graefe's statement about the melting-point of paraffin being unaffected by small quantities of ceresin, observing that, as the proportion of ceresin rises, SO there is 8, wider difference between the melting and the solidifying points of the sample.I n his reply, Graefe admits that he was writing of German and American parafin wax only. I n the case of other paraffins, which melt below 54' C., yet do not give clear solutions owing to the presence of high-melting ingredients, they should be examined by the process he gave for specimens melting above 54' C. A sample of Scotch paraffin, having the English test 121' to 123' F., answered the test perfectly. As regard8 the question of the melting-points, Graefe gives a new table of solidifying- points, which shows that the soZzdi,fyhzg-point of a parafin solidifying at 54.8O C.is not affected by the presence of 1, 3, 5, 7 or 10 per cent. of ceresin melting at 62" c. Even with 10 per cent. of ceresin, the thermometer in the Shukoff apparatus remained stationary for eight minutes. F. H. L.192 THE ANALYST. Titration of High Xolecular Fatty Acids. A. Kanitz. (Ber., 1903, xxxvi., 400 ; through Chem. Zeit. Rep., 1903, 85.)-From experiments upon pure palmitic, stearic, and oleic acids, the author finds that the errors introduced into the titration owing to the hydrolysis of the soap formed can only be avoided provided the soap solution contains at least 40 per cent. of ethyl alcohol. Impurities must be avoided, for so small a quantity of amyl alcohol as is soluble in a 15 per cent. solution of aqueous ethyl alcohol is sufficient to completely arrest the hydrolysis.F. H. L. Estimation of Beta-hydroxybutyric Acid in Urine. E. Darmstadter. (Zeits. physiol. Chem., 1903, xxxvii., 355 ; through Chem. Zeit. Rep., 1903, 85.)-One hundred C.C. of urine are made faintly alkaline with sodium carbonate and evaporated on the water-bath almost to dryness. The residue is rinsed into a 1-litre flask by means of 150 or 200 C.C. of 50 or 55 per cent. sulphuric acid. The vessel is fitted with a rubber stopper joined to a condenser and a dropping funnel, and the liquid is heated, cautiously at first for fear of frothing, for 2 or 24 hours till 300 or 350 C.C. have distilled over, constantly making the loss good by allowing water to enter through the funnel. The distillate is extracted two or three times with ether, and the solvent is driven off.The residue is heated on a sand-bath to 160" C. for a few minutes in order to volatilize any fatty acid, allowed to cool, taken up in 50 C.C. of water, and filtered from any insoluble matter. The aqueous solution of crotonic acid so obtained is titrated with decinormal sodium hydroxide, using phenolphthalein as indicator. One hundred C.C. of decinorrnal soda equal 0.86 gramme of crotonic acid, and crotonic acid x 1.21 equals hydroxybutyric acid. The process is available in all cases, and gives very accurate results. F. H. L. Precipitation and Separation by Weak Organic Bases. E. T. Allen. (Jounz. Amer. Chm. SOC., xxv., 421.) -The author shows that aniline precipitates quantitatively titanium, zirconium, cerium, thorium, ferric iron, aluminium, and chromic chromium as hydroxides from dilute and slightly acid solutions of the chlorides, nitrates, or sulphates. Phenylhydrazine also precipitates the above metals, with the exception of cerium and iron, both of which are reduced by this reagent to a lower state of oxidation.Zinc, cadmium, mercury, cobalt, and nickel, in suffi- ciently concentrated solutions, form difficultly soluble addition products with phenyl- hydrazine ; zinc, cadmium, and mercury also give similar compounds with aniline. Titanium and zirconium may be separated from iron by means of phenyl- hydraaine. Campbell and Hess's process (Journ. Amer. Chem. Soc., xxi., 776) of separating aluminium from iron with phenylhydrazine is especially useful when the quantity of aluminium present is relatively small.Titanium, zirconium, and thorium may be separated from beryllium by means of phenylhydrazine or aniline, best in chloride solutions. A double precipitation is necessary in all these, as well as the preceding, separations. A. G. L.THE ANALYST. 193 A Proposed Method of testing Wood treated to resist Fire. Chas. F. McKenna. (Journ. Amer. Chem. SOC., xxv., 406.)-In this method a cylinder of the wood to be tested, about 0.5 inch long, 0.25 inch wide, and weighing 0.5 gramme, is heated in an electrical retort, the gases evolved, as well as the charcoal left, after a definite time of heating being determined. The retort consists of a hemispherical vessel of Jena glass, 4 centimetres in diameter, having its upper edge ground flat, and fitted with a glass dome, also provided with a ground flange, terminating in a tube which connects the retort to the gas burette.The joint between the dome and retort is made tight with a small quantity of lubricant, the edges being also clamped together. The lower vessel is fitted below with a tube 1.5 centimetres in diameter, which is provided with a side tube fitted with a tap to admit air, and terminates in a wooden base up which go two copper wires, by means of which a constant current of 120 volts and 7 to 12 amperes is conducted through a basket-like coil of platinum wire, which is placed in the centre of the retort and carries tlie cylinder of wood. The author generally used a current of 7.5 amperes, and heated for two minutes, the final temperature reached being 680" C.He concludes that the more effective the treatment is, the less gas and the more charcoal will be produced when workiq on the same lot of wood, the test being only comparative in its nature. A. G. L. Determination of the Durability of Wood. J. Schorstein. (Baumaterialen- kunde, vii., 226; through Zeits. f. angew. Chem., 1903, ix., 207.)-The method depends on the fact that fresh wood contains 6 to 31 per cent. by weight of optically active xylan, which, however, is rapidly destroyed by wood fungi. The optically active constituent of xylan is soluble in soda solution. In order to ascertain to what extent a wood is still sound, hwo similar wedges or sections are cut from it, and one of them is sown with the fungus. Raspings axe then taken from both, and treated with 10 per cent. caustic soda. The solutions are filtered, decolorized, and examined in the polarimeter. In spite of statements to the contrary, the author has satisfied himself that dry-rot destroys the xylan in the substratum. A. M. The Pigments of Radix Anchusa Tinctoria as Indicators. A. Gawalowski. (Zeit. anal. Chem., 1903, xlii., 108, 109.)-The red pigment obtained by extraction with benzine behaves differently towards alkalies to the second red pigment obtained by subsequently extracting the root with ether alcohoL The former, to which the author assigns the name anchusa red, is converted by ammonia into a violet-green compound, and by fixed alkalies into a sap-green compound. The second pigment (alkanna red) is changed to violet-blue by ammonia, and to indigo-blue by fixed alkalies. Alkanna green is changed to a more bluish shade by both alkalies. Of the three pigments alkanna red is a very sensitive indicator for alkalimetry, whilst anchusa red is less suitable, and alkanna green unsuitable for the purpose. C . A. M.

ISSN:0003-2654    

DOI:10.1039/AN9032800189

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年代:1903

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194 THE ANALYST. INORGANIC ANALYSIS. Electrolytic Estimation of Mercury. Solubility of Platinum in Potassium Cyanide. F. Glaser. (Zezts. f. Electrochem., ix., 11; through Zeits. f . angew. Chem., 1903, ix., 212.)-When mercury is deposited from cyanide solution a loss is found to occur. This has been traced to the fact that the platinum cathode dissolves in cyanide solutions, especially when warm. The presence of potassium or sodium amalgam increases the dissolution. Under the same conditions gold and silver are not dissolved. A. M. The Electrolytic Estimation of Bismuth and i t s Separation from Other Metals. Alfred Lewis Kammerer. (Jourrt. Amer. Chem. SOC., xxv., 83.)-As the result of a large number of experiments with different methods of determining bismuth electrolytically, the author shows that the metal is readily separated quantitatively from a sulphuric acid solution to which potassium sulphate has been added.Sodium sulphate may be used instead of potassium sulphate ; ammonium sulphate cannot be employed, as it c&uses a very slight precipitation of bismuth peroxide at the anode. The most favourable conditions for the deposition of 0.1 to 0.15 gramme metal dissolved in 1 C.C. nitric acid (specific gravity 1.42) consisted in the addition of 2 C.C. sulphuric acid (specific gravity 1.84) and 1 gramme potassium sulphate, after diluting to 150 C.C. ; a current of N.D.,,, = 0.02 amphe and 1.8 volts, which is increased to 0.15 ampere during the last hour, is allowed to act for eight or nine hours, the liquid being kept at a temperature of 45’ to 50’ C., and maintained at exactly the same level throughout the operation.The electrolysis may be carried out in smooth platinum dishes, a platinum spiral or basket acting as anode; or two platinum gauze cylinders in a glass beaker may be used. The deposited metal must be washed finally with a, mixture of alcohol and ether (not alcohol alone), and then with ether before drying, to prevent oxidation. The above method serves a sharp means of separation of bismuth from zinc, cadmium, chromium, nickel, cobalt, manganese, and uranium. With iron a slightly greater current is necessary for complete precipitation, and if both iron and chromium are present, no bismuth is deposited. A. G. L. -. The Volumetric Determination of Manganese in Iron and Steel.Harry E. waiters. (Jourrt. Amer. Chem. SOC., XXV., 392.)-The author communicates results which show that in using Stehman’s modification (ANALYST, xxviii., 83) of his own method (ANALYST, X X V ~ . , 27) it is unnecessary to precipitate the silver with sodium chloride before titrating with sodium arsenite, provided only that the solution is cooled before titration. Hydrogen peroxide may also be used as a substitute for sodium arsenite. In any case, the titration must be made quickly. A. G. L. On the Quantitative Determination of Iron in the Presence of Zirconium by RiVOf’s Method. (Zeds. Alaorg. Chem., xxxiv., 293.)-The authors have tried this method, in which the iron is determined by the Karl Daniel and Hans Leberle.THE ANALYST. 195 loss in weight of the mixed oxides of iron and zirconium when ignited in a current of hydrogen, on a, number of mixtures containing iron and zirconium in different proportions.They encountered difficulties due to the hygroscopic nature of the mixed oxides and to the pyrophoric character of the reduced mixture, which necessi- tated its being weighed in an atmosphere of hydrogen, and they found the method to yield very low results, the divergence from the theoretical values being upwards of 5 per cent. in mixtures containing 50 per cent. zirconium dioxide, and becoming smaller as the quantity of zirconium present diminishes. The authors severely criticise the work of Gutbier and Huller (ANALYST, xxvii., 305), who obtained good results by the use of the same method. A. G. L. Estimation of Manganese in Steel. E.Jaboulay. (Rev. gdndr. Chim. pure ef appZ., 1903, vi., 119; through Chem. Zeit. -Rep., 1903, 84.)-This is a modification of L. Schneider’s method. One gramme of the sample is raised to the boiling-point with 20 C.C. of 1.20 nitric acid, and when solution is complete 25 C.C. of the same acid are added. A small excess of bismuth tetroxide is immediately introduced, and the whole is shaken and observed to see if any remains at the bottom of the flask. When the proper excess has been added, the solution is filtered through ignited asbestos, the filtrate diluted to about 100 C.C. with cold water, and hydrogen peroxide is run in from a burette till the liquid is entirely decolorized, noting the quantity used. The author employs 12-volume peroxide diluted with 20 times its volume of water, and for titration uses a solution of permanganate containing 1.5 grammes per litre.F. H. L. The Use of Hydrofluoric Acid in Steel Work8 Analyses. R. Fried. (Zeits. f. angew. Chern., 1903, viii., 176.)-Determination of Phosphorus in Ferro-Silicon.- The method recommended is practically identical with that of Ibbotson and Brearley (see ANALYST, 1901, xxvi., 82). The following elements may be determined in ferro- silicon by the methods given below, some of which involve the use of hydrofluoric acid : Nanganese.-Weigh out 4 grammes of the sample and diasolve in concentrated hydrochloric acid, with the addition of 5 to 7 C.C. hydrofluoric acid. Filter, wash with water and hydrochloric acid, oxidize the filtrate with nitric acid, and evaporate with 20 C.C. of sulphuric acid (1 : 1) until fumes appear.Dissolve in water, and titrate with permanganate according to Volhard’s method. For approximate results the solution in hydrochloric and hydrofluoric acids may be at once oxidized with concentrated nitric acid and titrated. Copper.-Dissolve 5 grammes in concentrated hydrochloric acid to which has been added 6 to 8 C.C. of hydrofluoric acid, filter, wash, dilute considerably, and precipitate with sulphurett ed hydrogen. li.on.-Take 1 gramme of the powdered ferro-silicon, and dissolve at a moderate temperature in concentrated hydrochloric acid, with the addition of 1 to 14 C.C. hydrofluoric acid. Filter, wash with water and hydrochloric acid, and titrate by196 THE ANALYST.Reinhardt's method, or reduce with zinc after evaporating with sulphuric acid. Approximate results may be obtained by titration without filtering. Sulphur is determined in the usual way, by dissolving in hydrochloric acid and collecting the sulphuret ted hydrogen in hydrochloric acid and bromine. Totat Carbon.-Ignite in a stream of chlorine, wash the residue with water, and oxidize with oxygen or sulphuric and chromic acids. Graphite.-Dissolve 2 grammes in about 35 C.C. of nitric acid (specific gravity, 1-2) and 3 C.C. of hydrofluoric acid at 60' C., dilute at once, allow to stand half an hour in a warm place, filter on ignited asbestos, and oxidize with chromic and sulphuric acids in a Corleis flask. Determination of Phosphorus in Ordinary Cast-iron.-Much time may be saved by the use of hydrofluoric acid, as filtration from silica is avoided.AizaZysis of Slags.-This is greatly assisted by the addition of hydrofluoric acid when dissolving, especially in the determination of iron. All these operations may be carried out in glass vessels, as the concentration of the hydrofluoric acid is very small. A. M. A Delicate Test for Molybdenum. L. Spiegel and T. A. Maass. (Bey., 1903, xxxvi., 512; through Chem. Zeit. Rep., 1903, 84.)-One part of phenyl- hydrazine is dissolved in 4 parts of 50 per cent. acetic acid, and 5 C.C. of this solution are added to 10 C.C. of the liquid under examination. The mixture is boiled for a minute or two, cooled to about 50" C., and extracted, if necessary, with a few drops of ethyl acetate or preferably chloroform.The non-aqueous liquid then takes up the colouring matter of the impurities in the phenylhydrazine, leaving the watery portion with a red colour if molybdenum compounds are preeent, this red colour also gradually passing into the non-aqueous liquid. 0.01 milligramme of molybdenum in 10 C.C. of water can be detected with certainty by this test, while it usually shows 0.005 milligramme. The phenylhydrazine sbould be as colourlesg as possible, and is best freshly distilled under diminished pressure. F. H. L. The Determination of Potash in Fertilizers by Substituting Milk of Lime for Ammonia and Ammonium Oxalate as the Precipitant. C. L. Hare, (Journ. Amer. Chern. SOL, xxv., 416.)-The following method possesses the advantage over the Lindo-Gladding method that the troublesome evaporation necessary to destroy ammonium salts is entirely avoided.Ten grammes of the fertilizer are boiled for thirty minutes with 350 C.C. of water, whilst hot milk of lime is added till the solution is slightly alkaline, after which it is cooled and made up to 500 C.C. Of this solution 50 C.C. are taken, acidified with hydrochloric acid, and evaporated just to dryness on a water-bath, after the addition of platinic chloride. The residue is washed with 80 per cent. alcohol and ammonium chloride solution, as in the Lindo- Gladding method, six washings with ammonium chloride being sufficient to remove the calcium sulphate (about 0.1 gramme) present in the residue. In the case of fertilizers containing organic matter, 10 grammes of the sampleTHE ANALYST.197 are incinerated with dilute sulphuric acid (1 : 1) ; the ignited mass is moistened with sulphuric acid (1 : l), heated, boiled with 350 C.C. of water, and then treated as above. It gives results practically identical with those yielded by the Lindo-Gladding method, the extreme divergence of sixty-three determinations by both methods being 0.29 per cent., and the mean 0.02 per cent, To fertilizers containing ammonium salts the method is not applicable. A. G. L. On a New Gravimetric Method of Determining Selenium. A. Gutbier and E. Rohn. (Zeits. Anorg. Chem., xxxiv., 448.)-The method depends on the reduction of selenious acid to selenium by means of hypophosphorous acid in an alkaline solution, the solution being boiled until the selenium has passed completely into the black modification and the liquid above it is clear, when it is filtered on a Gooch platinum crucible, and dried to constant weight at 1 0 5 O C.The filtrate may be examined for any selenium left in solution, but from the test analyses quoted the method appears to give very good results. Any compounds of selenic acid present in the original solution must be reduced to the selenious condition by prolonged boiling with hydrochloric acid before applying the method. If hypophosphorous acid is added in acid solution, reduction is carried beyond the stage of selenium, and seleniuretted hydrogen is produced. A. G. L. Volumetric Estimation of Free and Combined Sulphuric Acid, G. Frerichs. (Arch. Pharm., 1903, ccxli., 159 ; through Chzem.Zeit. Rep., 1903, 97.)-This process depends on the insolubility of silver sulphate in alcohol. The solution to be analysed (e.g., one of potassium sulphate) is evaporated to dryness with an excess of silver nitrate, rubbed to fine powder with a little 95 or 96 per cent. alcohol, brought on to a, filter, and washed with the same liquid till a few C.C. are no longer rendered turbid with hydrochloric acid. The residue, which consists of silver sulphate and potassium nitrate, is transferred to a beaker, and boiled for about five minutes with 10 C.C. of dilute nitric acid and 100 C.C. of water, till the former has passed into solution. The liquid is then mixed with iron-ammonium alum solution and titrated with decinormal thiocyanate, 1 C.C. of which is equivalent to 0-0040 gramme of SO,.F. H. L. Application of the Theory of Electric Batteries t o the Quantitative Separa- tion of Metals. A. Hollard. (BUZZ. SOC. Chim., 1903, xxix., 116-122.)-The deposit obtained on immersing a strip of any metal in a saline solution of a more electro- negative metal is sometimes spongy and difficult to wash, whilst in other cases it completely encloses the precipitating metal so that the reaction stops. To obtain quantitative results, the vessel should be divided by means of a membrane of parch- ment paper into two compartments, in one of which is placed the electrolyte (e.g., a solution of nickel and zinc), whilst a conducting saline solution (e.g., magnesium sulphate) is placed in the other. On now immersing a strip of platinum in the zinc and nickel solution and connecting it by means of a copper wire with a strip of zincTHE ANALYST. plunged in the magnesium sulphate solution, a layer of pure nickel is deposited on the platinum.In a practical estimation the zinc and nickel are dissolved as sulphates in a 650 C.C. beaker of about 7 centimetres in diameter, the solution (about 250 c.c.) containing an excess of 20 C.C. of ammonium hydroxide (S.G.0.9241) and 100 grammes of dry ammonium sulphate. A cylinder of platinum gauze, 65 millimetres in length and 43 and 35 millimetres in diameter at the two ends, is placed in the beaker, whilst a glass cylinder of 55 millimetres internal diameter, with one end closed by parchment paper, is also introduced, so that the parchment is as close as possible to the platinum cone without touching it.This compartment is filled to a height of 70 millimetres with a solution of magnesium sulphate (250 grammes per litre), whilst a disc of amalgamated zinc, about 5 centimetres in diameter, is suspended in this solution at about 15 or 20 millimetres above the parchment and connected with the platinum cone by means of a copper wire insulated throughout its length by an indiarubber tube. During the electrolysis the liquid in the outer compartment is kept at a temperature of about 95" C., and after a few hours the nickel will be found completely deposited as a, very adherent layer on the platinum, which is then washed, dried, and weighed. C. A. M. The Influence of the Nature of the Cathode on the Electrolytic Separation of Metals.(BUZZ. SOC. Chim., 1903, xxix., 217-221.)-The author states that certain metals, the critical voltages of which in strongly-acid solution are above that of hydrogen and do not differ greatly from each other, cannot be separated electrolytically when a platinum cathode is used, but that they can be sepaxated if the cathode be composed of the metal with the lower critical voltage, or of some other whose critical voltage lies between those of the two metals. In practice it is convenient, instead of using cathodes of the metals themselves, to employ platinum cathodes previously coated electrolytically with the required metal. An example of the process is given by cadmium and zinc, which can readily be separated by the use of a platinum cathode electrolytically coated with cadmium or tin.In the following typical experiments the cadmium and zinc were dissolved in the form of sulphates, and the solution mixed with 10 grammes of ammonium sulphate and 5 C.C. of strong sulphuric acid, then diluted to 300 c.c., and electrolysed with a current of 0.3 amphe. Some of the results thus obtained were : A. Hollard. Gramm es Grammes taken. found. Cadmium ... 0.1991 Zinc ... ... 2.000 0.1972 - 1 On tinned platinum. Cadmium ... 0.1991 0.1984- On platinum coated Zinc ... ... 2.000 - 1. with cadmium. Cadmium ... 0-2000 Zinc ... ... 2.000 NoTE.-The current stated is not related to any given surface. C. A. M.THE ANALYST. 199 Standardization of Permanganate by means of Potassium Ferrocyanide. A. Gwiggner. (Stahl u. Eisen, 1903, xxiii., 260 ; through Chewz. Zeit. Rep., 1903, 54.)-Gintl and Schroder (ANALYST, 1899, xxiv., 303) have already recommended the use of potassium ferrocyanide for preparing standard ferric solutions. The present author prefers to decompose 4 grammes of the recrystallized salt by warming it in a covered Erlenmeyer flask with 50 C.C. of aqua regia until all the gas has been given off. The liquid is then evaporated almost to dryness, taken up in hydrochloric acid, mixed with 10 C.C. of 1 : 1 sulphuric acid, and concentrated again till vapours of the latter appear ; next boiled with 10 C.C. of water and 15 C.C. of hydrochloric acid, and titrated according to the Reinhardt process. I t is advisable not to add the acid mixture of manganese sulphate and phosphoric acid to the iron and mercury solution until sufficient permanganate has been run out of the burette to form a dark red protective layer at the surface of the liquid. Neglect of this may make the results low, otherwise they agree well. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN9032800194

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年代:1903

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THE ANALYST. 199 APPARATUS. An Apparatus for Continuous Vacuum Distillation. Charles F. Maberry. (Amer. Chem. Jozbrn., xxix., 171.)-The apparatus shown in the figure is claimed by the author to meet all the requirements of actual practice, it having been in con- tinuous use for a number of years. The successive fractions are introduced into the still B through the tube A , without interrupting the distillation or releasing the vacuum. The still is exhausted by means of the tube N, which connects the intermediate receiver 0 with the vacuun reservoir D; this also serves to catch any water running back from the pump. The tube M leads to a manometer, P to the pumps. The receiver C is exhausted separately by means of the tube H, whilst air can be admitted to it through the tap I, the tap K then closing the connection with the pump.By closing F, a receiver may thus be filled with air, removed, and another one substituted and exhausted without interrupting the distillation or allowing any air to get into the still containing the hot oil. The tube 0 is the only piece of glass used which requires to be specially made. A condenser may be inserted between the still and 0 if necessary. A. G. L. New Desiccator. W. Scheermesser. (Chem. Zeit., 1903, xxvii., 175.)-The accompanying sketch represents an improved form of desiccator in which substances200 THE ANALYST. can be dried at elevated temperatures under diminished pressure while the residual air is in 8 state of constant circulation. The plate on which the articles stand carries an electrical resistance, and is so insulated under- neath that the heat is only given off from the upper side; it also supports a, small motor that propels the fan shown in the diagram. The current necessary is very small, about 0.25 ampere at 110 volts being sufficient for all purposes; if desired, the energy can be obtained from a dry battery. The resistance is so made that its wires never exceed 120° in temperature. The essential portion of the apparatus can be procured in square or circular shape, fitted either with the fan or with the heater, or with both, suitable for insertion in an ordinary drying cupboard ; and an electrical thermostat can be added to the whole. The maker is F. Hugershoff, of Leipzig. F. H. L.

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DOI:10.1039/AN9032800199

出版商:RSC    

年代:1903

数据来源: RSC

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200 THE ANALYST. REVIEW. TECHNICAL MYCOLOGY : THE UTILIZATION OF MICRO-ORGANISMS IN THE ARTS AND MANUFACTURES. By Dr. FRANZ LAFAR. Vol. II., Eumycetic Fermentation. Part I. Translated by CHARLES T. C. SALTER. (London: Chas. Griffin and Co. Price 7s. 6d.) This is the continuation of a work the first volume of which was reviewed in the ANALYST, vol. xxiii., p. 308, and the subjects embraced in this new portion are treated in the same thorough and exhaustive manner as those in the first volume were. Since the publication of the first volume, the second has been so frequently asked for that the German publishers have decided to issue it in partg rather than to await the completion of the work by the author, and as advance sheets have been placed in the English publisher’s hands, they have been able to issue the present part of VOl.11. The part under review treats of the Eumycetes, the Zygomycetes, and the Yeasts ; the general morphology of these various organisms, their chemical composition, the mineral nutrients they require, the influences which stimulate them, and the enzymes they secrete, are all fully described. As might naturally be expected, the yeasts claim a large share of attention, a good half of the book being devoted to them, such interesting problems as their position in the botanical system and that of their origin being fully dealt with. Altogether the volume is one which ought to be in the hands of everyone interested in any of the great fermentation industries ; indeed, such persons can scarcely afford to be without it, The book is printed in good clear type, the illustrations are numerous and of excellent quality, and it is commendably free from printers’ errors, the only one noticed being “Tortula’’ for ‘‘ Torula” on page 9. Mr. Slater may be again con- gratulated on the excellent manner in which he has accomplished his arduous task. W. J. S.

ISSN:0003-2654    

DOI:10.1039/AN9032800200

出版商:RSC    

年代:1903

数据来源: RSC