摘要:

OCTOBER, 1908. Vol. XXXIII., NO. 391. THE ANALYST. OBITUARY. SIR THOMAS STEVENSON. THE death of Sir Thomas Stevenson will be felt as an irreparable loss, not only by a wide circle of devoted friends, but also by many who, knowing him less intimately, have profited from his knowledge and teaching, or by his unfailing kindness. Many more will suffer, perhaps less consciously, by the removal of one whose influence- always powerful-was steadily exerted in the interests of his professional brethren. He will, of course, be always best remembered as a great medical jurist, and in pursuing that calling Stevenson was beyond doubt a conspicuous example of a, man who found his life’s work exactly suited to his genius. He had every quality of mind and character necessary for supremacy in his profession.But his influence extended widely outside this special domain. Not only within the walls of his own medical school, but in the medical world generally, he was on the side of progress and efficiency, and played an influential part, In matters relating to questions of public health his opinion was often sought and always valued, and no man did more than he in the service of professional chemistry, especially where the interests of the Public Analyst were concerned. Stevenson was born in 1838 at Rainton, in Yorkshire. He was the son of a well- known and much-respected yeoman farmer, and as a youth he had the advantages of the healthy country life offered by the moors and dales of the largest of English counties. Although all his later life was passed in London, something due to his upbringing remained with him to the last.In spite of his high culture and his polish as a man of the world, there was, for those quick to detect such things, some- thing about him which savoured of the country and of his county. When, indeed, he first came to London, he was, as the writer has often heard said by Lady Stevenson, a typical Yorkshireman-an epithet of which no one from that county was ever ashamed. His was a striking personality : prominent brows covering thoughtful eyes ; a beard exceptionally large and strong, and somewhat early grey ; a voice of exceptional quality ; certain peculiarities of speech, especially a rotund emphasis of individual words in a sentence ; very active, if somewhat ungainly, bodily movements ; an ever-ready smile, and a most hearty laugh-all these and other characteristics left a vivid impression.Stevenson was educated privately, but at one time attended a school provided with a laboratory, and here he made analyses of soil and manures for his father.386 THE ANALYST. His eighteenth year was spent in the study of scientific agriculture on the parental farm. I n 1859 he decided against farming and became medical pupil to Mr. Steel, of Bradford. I n 1859 he matriculated at the University of London, and entered Guy’s Hospital Medical School. From that time forward there could never have been any doubt as to the wisdom of his choice of a career. He was a most brilliant and suc- cessful student, gathering University honours abundantly, and winning golden opinions from the hospital staff.He graduated M.D. in 1864, and became F.R.C.P. in 1891. For a short time he practised medicine in Bradford, but afterwards returned to Guy’s to begin the scientific teaching and work which were to occupy him for the rest of his life. To judge from what he used to say in later years, I do not think he would ever have found enjoyment in medical practice. He certainly did not lack the special talents necessary for its successful pursuit, and in his younger days he was an eficient surgeon. He was, indeed, an all-round man, and would have come to the front in practice; but it was probably taste as well as opportunity that led him to give up any idea of becoming a medical consultant, and to accept the Guy’s lecture- ship in chemistry when his predecessor, Odling, went to Oxford.This was in 1870; and eight years later he succeeded Alfred Swayne Taylor as Lecturer in Forensic Medicine. The chemical lectures he resigned some ten years ago, but the forensic course he continued to the last. Having for his colleagues such distinguished organic chemists as Debus and Groves, Stevenson’s chemical teaching was chiefly confined to the inorganic side. I am not sure that in later years he found much pleasure in his chemical lectures, but his forensic lectures he seemed always to enjoy. They were altogether admirable in substance and style, and were much appreciated by successive generations of students. Home O&ce work began to come to him in 1872, and in 1881 he was definitely appointed as Senior Scientific Analyst to that department.His private laboratory was but a room in a ward-building, constituting one of those makeshifts such as the best men seem to accept in this country, though they would not be tolerated abroad. In later years it W&B structurally improved, but at one time it seemed ridiculously inadequate, though Stevenson never showed any desire to exchange it, as he might have done, for anything better. He was not endowed with special skill as a manipulator, but in connection with all his analytical problems he showed a genius for selecting the methods best suited for the case, thereby saving wastage of material which was often, of course, very precious. His care and conscientiousness were extreme. When I went to him in 1883-joining Bodmer, who had already been his assistant for five years, and was to remain with him for ten years more-the laboratory was still full of memories of the famous Lamson case of poisoning by aconitine, the investigation of which Stevenson, in conjunction with Duprb, had conducted with extraordinary skill a few months before.There is no need to discuss here the many sensational trials in which Stevenson’s evidence played a central part. Some of them, such as the Moat Farm case, the Maybrick case, the cases of Neil Cream and Chapman, the St. Neots murder, and many others, will linger in the public memory. The sensational case8 did notTHE ANALYST. 387 represent a tithe of the toxicological work done in the laboratory, and they were not usually the more difficult ones from the expert point of view.On the other hand, the more difficult cases were not always the most interesting to those engaged upon them ; often a simple analytical problem was associated with incidents providing drama. The Lipski case may be taken to illustrate this, though there were others perhaps more exciting. Lipski, a Polish Jew, was accused of poisoning a woman with nitric acid, a substance he used in his trade. He was convicted, but the general evidence for his connection with the crime was circumstantial only, and a prominent editor conducted a sensational journalistic agitation in favour of a reprieve. The Home Secretary of the day was blamed by many for refusing to interfere in the case, but he remained firm, and with good reason, for a simple but damning piece of evidence was in his possession, though it was not known to the public.For some reason the following details were not available at the original trisl : Certain stains upon Lipski’s coat were produced, not by nitric acid alone, but by a mixture of nitric and sulphuric acids. When this had been observed, Stevenson and Bodmer visited the room where the crime took place, and scraped splinters from the stained floor- boards. The police then purchased samples of nitric acid from every retailer within a wide radius from the scene of the murder. When these were tested, only one proved to be admixed with sulphuric acid, and this, when the samples were compared with the police tally, proved to have come from the shop where Lipski always bought his acid.The prisoner afterwards confessed to the crime, and suffered the death penalty. Stevenson was superb as a witness. This was felt universally by Bench, Bar, and public. Whether under examination-in-chief or when being cross-examined, he was imperturbable, and his clear, well-considered statements always carried con- viction. His success under cross-examination was not, I think, due to any special art. His evidence was always carefully prepared, was the exact, unexaggerated truth, and contained nothing for the cross-examining counsel to whittle away. If he used any art, it was not exercised in criminal cases, and was at any time only the justifiable and unfamiliar one of understating rather than overstating one’s case. Cross-examination seemed always to strengthen rather than weaken his position, and soon collapsed.But, as I have said, his great impressiveness in the witness-box was due to his innate love of truth, and to his care in making every statement exact and unequivocal. He took great interest in the welfare of the Institute of Chemistry, believing that it stood for tbe welfare of the chemical profession as a whole. He was an original Fellow and Member of the first Council. His service on the Council extended over periods amounting to about twenty-two years, during three of which he was President and another three Vice-President. He was the first Examiner in Pharmacology and Therapeutics, refusing, as he was President at the time, to receive any fee for this work. He held the strictest views on questions of professional etiquette, and for periods amounting in all to some fifteen years acted as one of the censors.Stevenson also took a prominent share in the proceedings which led to the founda- tion of the Society of Public Analysts, and was its first Treasurer. At its first regular These, too, had suffered from the action of the mixed acids. He frequently contributed gifts to the library.388 THE ANALYST. meeting he read a paper on ‘‘ The Decomposition of Milk.” He became President in 1896, the year in which the society attained its majority, and in his first Presidential address he gave an interesting account of its rise and progress. As I know well, he rejoiced in its prosperity, and in that of its official organ. His own position as a Public Analyst was familiar to all readers of this journal, and need not be dwelt upon here.He was for many years Medical Officer of Health to St. Pancras, and at one time President of the Society of Medical Officers of Health.. For research work on purely scientific lines Stevenson had no time, and perhaps no great inclination. A glance through the Chemical News and the earlier numbers of the ANALYST will reveal several papers by him dealing with the analysis of food and drugs, and he contributed to the Royal Society’s Proceediizgs a valuable paper on (‘ The Detection of Alkaloids.” Other professional contributions from his pen will be found in the B r i t i s h Medical Jozcrnal and in the Guy’s Hospital Reports. He edited, in 1883, the third edition of Taylor’s ‘; Principles and Practice of Medical Juris- prudence ” and the t ‘ Manual of Medical Jurisprudence.” He deleted a good deal of the more sensational parts of Taylor’s works, but added greatly to their accuracy and to the scientific information they contained.In his hands the former work became a really great text-book, and the latter. a most acceptable aid to the medical student. In 1904 he edited, conjointly with Sir Shirley Murphy, a “Treatise on Hygiene and Public Health.” Stevenson’s most interesting writings, could they be seen, would probably be found in the many confidential reports submitted by him to successive Secretaries of State. In 1904 his notable services to the State received recognition by knighthood. His career was clearly a highly successful one, and few men, I think, have ever enjoyed their professional labours more than he did.He was said by some to be a reserved man, but, if that were true, he was nevertheless a most popular one. H e was greatly liked as well as respected by every student he taught, and he secured the devotion as well as the admiration of many friends. Those who enjoyed any intimacy with him know that he was very human as well as most humane, appreciative himself of the pleasures of life, and eager for the happiness of others. He was a man of strong religious convictions, one expression of which was seen in the great amount of active work he did for the Church, If, in conclusion, we would seek a final brief, but just, appraisement of the man whose death we deplore, we shall find it, I think, in some words of the late Lord Brampton. During Stevenson’s Presidency of the Institute of Chemistry, a dinner took place at which Lord Brampton (formerly Mr. Justice Hawkins) made a speech, and in concluding it he used the following words : He (Stevenson) is a man who in giving evidence before me has always convinced me that he was right, and that it was useless to oppose him. I have admired him for his intelligence and knowledge, and respected him for his courage, candour, and truth. For sixty years I have known the world and all its phases, and if I were asked to name a man on whose word I could always absolutely rely I should turn to your President.” These sincere words of a great Judge will be understood by all who knew Sir Thomas Stevenson. F. GOWLAND HOPKINS.

ISSN:0003-2654    

DOI:10.1039/AN9083300385

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST 389 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE ESTIMATION OF FAT IN DRY MILKS. BY H. DROOP-RICHMOND, F.I.C. THE recent paper on this subject by Mr. B. G. McLellan (ANALYST, 1908, 353) renders it desirable to call attention to the conditions which must be observed in working the Riise-Gottlieb method for the estimation of fat. While I agree with the author of this paper that the Werner-Schmid method (provided, however, that the fat,” after being weighed, is extracted with petroleum ether, and the weight of the small undissolved residue subtracted from the total weight) gives satisfactory results, and while I am also prepared to admit that he has established the accuracy of long-continued direct extraction with ethylic ether (specific gravity 0.720) as a method for fat estimation, I entirely dissent from his con- clusion that the Rose-Gottlieb method, which he has roughly described under the title of No.1, is useless. By following the details which I describe below not only do duplicates agree very closely (proving the absence of adventitious errors), but the results are prac- tically identical with those furnished by the Werner-Schmid method. The essential points of the Rose-Gottlieb method are strict adherence to the proportions of water to the reagents, and thorough mixing of each reagent before the others are added; neglect of these precautions may cause enormous errors, and I have little doubt that Mr. McLellan, in his experiments, did not appreciate the importance of the mixing. I prefer to modify this method, as also the Werner-Schmid, by extracting the whole of the fat by successive treatment with solvents, rather than to measure the total volume of the mixed ether and petroleum ether, and to take an aliquot portion for evaporation and weighing, as this avoids one source of error.I have, however, obtained good results by taking aliquot quantities. 0.5 to 0.7 gram of the dry milk is weighed into a narrow stoppered cylinder holding about 50 c.c., and sufticient water is added to make up a weight of 515 grams; 0-5 C.C. of ammonia solution (0.88 ammonia diluted with an equal bulk of water) is measured in, and the dry milk dissolved by shaking, and, if necessary, slight warming ; 5 C.C. of alcohol are added (methylated spirit, if free from petroleum, will serve), and the mixture shaken till homogeneous.12.5 C.C. (circa) of ether (methylated, specific gravity 0.720, preferably freshly distilled, to remove the acrid substance formed on standing) are poured in, and the contents of the tube well mixed, the thorough mixing at this stage being, perhaps, the most important detail. Finally, 12.5 C.C. of petroleum ether (boiling-point below 60” C.) are added, and the contents of the tube again thoroughly mixed two or three times ; separation of the ethereal layer takes place rapidly, and -when globules can no longer be detected390 THE ANALYSTo in the lower layer, the upper layer is drawn off with wash-bottle tubes ; by the addi- tion of successive quantities of a mixture of ether and petroleum ether (the recovered solvent serves admirably) the whole of the fat is extracted. The solvent is removed by distillation and the fat dried and weighed. The fat is dissolved in petroleum ether, and the solution decanted from the minute residue, and after three or four washings with petroleum ether the residue is dried and weighed. If desired, the quantities given may be doubled, or increased in any other ratio, provided that the relative proportions are strictly adhered to. The method is so convenient, accurate, and rapid that I now use it in preference to all others for the analysis of milk (of which 5 C.C. are taken and no water added), and all milk products; it is also applicable to the analysis of eggs, egg-yolk, and dried egg preparations, provided the quantities taken are not too large.

ISSN:0003-2654    

DOI:10.1039/AN9083300389

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

390 THE ANALYSTo THE BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. Dxblirt, September 2 to 9, 1908. Transactions of Section B (Chemistry). THE Presidential address was delivered by Professor KIPPINQ, P.R. S., who discussed the steps which could be taken to place the chemical industries of the United King- dom in a more prominent position than that which they now occupy in the world of commerce. The economic importance of the new Patent Law was referred to, but although it was admitted that the Act will prove to be of great value in many respecte, it will do little to foster British chemical trade and the development of British chemistry; it places us on an equality with other countries as regards patent rights, and thus remedies an outstanding grievance; but unless we have something to patent, this equality will be valueless, and our chemical industries will continue to decline, possibly more rapidly than heretofore. In reviewing the other causes which have been suggested as contributory to our failure, after eliminating those connected with freights and tariffs, and with the alleged supineness of the Government in assisting industry, matters which may be left to the manufacturers to deal with, there still remain several which are well within the purview of section B.These are : (1) The unsatisfactory condition of secondary edncation ; (2) the nature of the training which is given to chemists in our Universities and other institutions; (3) the insufficiency of the time and money devoted to research in the manufacturing industries ; (4) the lack of co-operation between manufacturers and men of science.'' The great proportion of the original work now done in this country, judging from the published records, is absolutely fres from any utilitarian bias ; the time, brain-power, and money devoted to this work are considerable, and the results fromTHE ANALYST. 391 a scientific point of view eminently satisfactory. If even a, fraction of the same skill and energy were brought to bear under proper conditions on problems of applied science, who can doubt but that the effect on our chemical industries would be one of vast importance? And yet it is the rarest possible occurrunce to find any record of research work undertaken with a commercial object even in the natural home of such records, the Journal of the Society of Chemicul Industry." One reason for this may be that the discoveries made in the works-laboratories are not given to the world at large, but are quietly and lucratively applied in some secret manufacturing process. Another reason, unfortunately the more probable one, may be that nearly all the principal research workers are completely shut off from any industrial influences. " It is obvious therefore that, even if all the research capacity of the country were henceforth devoted to purely technical matters, any great improvement in our industries could hardly be anticipated without the active co-operation of the manufacturers. " The address concludes with an appeal for the foundation of Industrial Fellow- ships. The great benefits which are conferred on pure science by the open research scholarships at present available afford some indication of what might be done for industrial chemistry by the foundation of such scholarships in applied science.There are no doubt, scattered over the country, many men who possess originality and inventive talent, and who have practical experience in industrial operations, but who have not been sufficiently trained in science; if it were possible to attract this dormant talent by means of open scholarships, it might be directed into proper channels instead of being allowed to run to waste. The Influence of Colloids and Colloid Suspensions on the Solubility of Carbon Dioxide in Water: Preliminary Note. BY A. FINDLAY. The problem of the absorption of gases, more especially oxygen and carbon dioxide, by blood is one which has exercised the minds of physiologists and physicists for many years, the view generally held being that the gases art3 retained in the blood largely owing to the formation of chemical compounds. With regard to the absorption of carbon dioxide, the reputed alkalinity of the blood, and the con- sequent formation of carbonate and bicarbonate, have been held chiefly responsible for the increase in solubility of carbon dioxide in blood as compared with that in a, corresponding salt solution.Recently, however, various investigators (Holber, Farkas, Fraenkel, etc.) have shown that blood is 'water neutral,' in which case the generally held view regarding the absorption of carbon dioxide by blood becomes untenable.Believing that the colloids present in blood might probably play an important rdk, it was decided to investigate the influence of colloids on the absorption of gases by water, since only a very few experiments in this direction have been carried out (Geffchen). The following results have been obtained by W. H. Earby and the author. All392 THE ANALYST. determinations were made at 25' C., and the solubility values represent the ratio of gas volume absorbed to the volume of the absorbing liquid : I. Solubility in water: 0-823. II. Colloidal ferric hydroxide- Experimental error about k 0-25 per cent. Grams of Fe(OH), in 100 C.C. of liquid 1.36 ... ... 0.896 Solubility of CO, ... 111. Gelatin- Grams of gelatin in I00 C.C. of liquid.. . Grams As$, in 100 C.C.of liquid Grams H,SiO, in 100 C.C. of liquid ... Grams of dextrin in 100 C.C. of liquid.. . Grams of starch in 100 C.C. of liquid.. . Grams of glycogen in 100 C.C. of liquid Grams of albumin in 100 C.C. of liquid Solubility of CO, ... ... ... Solubility of CO, ... Solubility of CO, ... ... ... Solubility of CO, ... ... ... Solubility of CO, ... ... ... Solubility of CO, ... ... ... Solubility of CO, ... ... ... IV. Arsenious sulphide- . . . ... ... V. Silicic acid- VI. Dextrin- VII. Soluble starch- VIII. Glgcogen- XI. A lburnin- 5 0.848 0.305 0.822 0-113 0.823 20 0.735 10 0.776 1.18 0.804 0.5 0-822 0.68 0.877 3 0.834 0.244 0.825 10 0,757 5 0.801 0.34 0,837 1 0.826 0.122 0.825 0.068 0.822 5 0.768 1 0,815 0.263 0.820 0.75 0.822 0.136 0.824 0.0244 0.825 1 0.817 Experiments, still in progress, have been made with the white of egg, diluted with five times its volume of water. An increaseof about 8 per cent.in the solubility of CO, was found. Soon, however, a precipitate began to form, and the solubility of CO, diminished, some of the gas which had been dissolved passing out of solution. Finally there was an increase in the solubility of about 4 per cent. Colloidal Chemistry. BY H. R. PROCTER. A comprehensive report dealing with the present state of knowledge on this sub jeqt . The Action of the Enzymes of Malt on the Enzymes of Ungerminated Cereals. BY JULIAN L. BAKER AND H. F. E. HULTON. In a previous communication (ANALYST, 1908, 322) the authors showed that, when a flour is doughed with yeast and water, the evolution of carbonic acid under standard conditions bears no relation to the diastatic activity of the flour as expressed in degrees Lintner.When, however, a minute quantity of malt is added to the dough, the volume of gas evolved during the fermentation is increased in inverse ratio to that originally given off; and in those cases where the original gas production was low it is very largely increased. J. S. Ford and J. M. Guthrie (Journ. Inst. of Brewing, 1908, 14, 61) have shown that the filtrate obtained byTHE ANALYST. 393 digesting an aqueous suspension of flour in presence of papain is enabled to saccharify a greatly increased quantity of soluble starch. This activation is at- tributed to the protective action exerted by the papain on the diastase, which is apparently much weakened by water alone, and also to the probable liberation of otherwise insoluble enzyme.I n view of this work, it appeared to the authors probable that the increased gas production obtainable from dough by the use of malt might be due to the proteolytic enzyme known to exist in malt, which, by liberating more diastase, or owing to its protection of that already present, renders more of the enzyme available for the hydrolysis of the starch in flour, If barley or wheat, when digested with malt-a substance which contains both a starch-liquefying and a proteolytic enzyme-were to yield a filtrate more diastatic in its activity than that obtainable from barley or wheat alone, then presumably this enhanced activity of the extract might be due to the action of the proteolyst in the malt upon the enzymes of the barley or wheat.The nature of the increase was investigated by comparing its action upon soluble starch and starch- paste; for liquefying diastase, if liberated, could not be supposed to increase the amount of maltose produced from soluble starch, but would materially aid the saccharification of starch-paste ; on the other hand, if saccharifying diastase were the one formed, then the conversion of starch-paste would probably not be facilitated, but soluble starch would be further saccharified and yield more maltpse. A con- venient method of experiment was the extraction, in presence of each other, of malt and barley in equal proportions, separate extractions being made of both of these substances alone, and their activities measured in terms of the maltose pro- duced. It was found that the activity of the extract from the mixture was greater than the mean of the actions of its constituents, and this was taken to be evidence that fresh enzyme was liberated.This enzyme is one that facilitates liquefaction of starch to a far greater degree than saccharification of already soluble starch. The Preparation of Pure Maltose. BY JULIAN L. BAKER AND F. DAY, In view of the increasing demand for pure maltose in analytical and physio- logical chemistry, the authors have devised the following process for the preparation of this carbohydrate. To a 3 to 4 per cent. starch-paste or soluble starch solution the precipitated diastase from barley is added in such proportion that for every gram of starch the enzyme of 1 gram of barley is present.The conversion is carried out at 50" C. for three hours, and allowed to run on in the cold for another twelve hours. At this stage 60 per cent.. of maltose is present, the remainder of the product consisting of a-amylo-dextrin (J. L. Baker, Jozirn. Chenz. Yoc., 1902, 81, 1177). The conversion is evaporated to a thin syrup, and poured into such a volume of cold 95 per cent. alcohol that the resulting strength of the alcoholic solution is 85 per cent. The precipitated a-amylodextrin is removed and the alcohol distilled from the solution. On standing, maltose of a high degree of purity separates. I t may be further purified by recrystallising from a small quantity of water, The preparation of maltose according to these conditions is very easy, since the con- version products only contain one dextrin which is insoluble in alcohol ; whereas394 THE ANALYST. when malt diastase acts on starch the separation of dextrins of low molecular weight from the maltose frequently presents considerable difficulties.Discussion on Problems of Fermentation. This discussion was organised with the object of focussing the present state of knowledge on fermentation. Dr. BARDEN briefly described Buchner’s zymase theory, and gave an account of his own investigations. The activity of yeast-juice is due to two substances, separable by Martin’s dialyser; the residue contains the enzyme, the filtrate the co-enzyme. Separately these have no action ; united they ferment dextrose just as yeast-juice does.Sodium phosphate causes an increase in the velocity of ferment- ation by yeast-juice. The following equations have been realised experimentally : 1. 2C,H120, + 2HNa2P0, = 2C02 + 2C,H60 + 2H,O + C~Hl,O,(Na,PO,),. 2. C,H,,O,(Na,PO,), + 2H,O = C6H,,0, + 2HNa,PO,. Professor ADRIAN BROWN discussed the diffusion of sugars into the living cell, and the fact that the enzymes do not leave the cell except under certain conditions of malnutrition. Dr. SLATOR gave an account of his work on the initial velocity of fermentation by yeast, and of his theory that different enzymes ferment dextrose, mannose, or galactose. He also described his method of yeast analysis ( c j . ANALYST, 1908, 363). Dr. E. F. ARMSTRONU alluded to the rdle of enzymes in fermentation, and described experiments made with a variety of yeasts which proved fermentation to be independent of the sucroclastic enzymes.The yeasts referred to form valuable means of analytically detecting and separating the various sugars. He further developed the enolic theory of fermentation which supposes dextrose, lEevulose, and mannose to be first converted by an enzyme into a common enolic form, and that this, still in combination with the enzyme, is broken down; the first stage of Baeyer’s well-known theory of fermentation is thus realised. After some remarks on the question of adaptation of the organism to nutrition, Professor H. E. ARMSTRONG discussed the old theories explaining the formation of the by-products of fermentation from sugar. The work of Ehrlich has proved these to be derived from the nitrogenous constituents (amino acids), and it is probable that the bouquet of wine and flavour of beer is to be ascribed to similar causes. The quantitative study of the nitrogen compounds may in future become an important part of the work of the chemists associated with the fermentation industries.Lithium in Radio-active Minerals. BY W. N. HARTLEY. The question as to whether lithium is or is not a widely occurring element, and whether it is found associated with any other element, more particularly with copper than with the alkalies or the alkaline earths, arises from the assumed transmutation of copper contained in solutions into lithium, neon, and possibly other substances. It has been stated by Sir William Ramsay (Nature, 1908, p.412) : 6 d As sodium and potassium are much more widely distributed than lithium, it is more likely thatTHE ANALYST- 395 they are the chief products from copper, and that some modifying circumstance has determined the formation of a trace of lithium. . . . Lithium was mentioned because it is an unlikely constituent of dust, glass, copper, etc., which were tested specially to prove its absence.” There are two statements here which, in the opinion of the author, appear to require modification. That potassium and sodium are more abundantly distributed than lithium is true, but that these are more widely distributed is not strictly correct; nor can it be accepted as unquestionable that lithium is an unlikely con- stituent of dust, glass, copper, etc.Evidence to the contrary is based upon facts divided into three categories : firstly, those derived from the qualitative spectroscopic analysis of common ores and minerals usually associated with the alkali metals ; secondly, analysis of the crude salts of the alkalies, such as the Stassfurth minerals and nitrates from Chili and Bengal, show t-hat they contain lithium and rubidium, with not unfrequently caesium. Facts belonging to the third category are derived from experimental evidence, which is both quantitative and spectrographic, the source of the spectra, being the oxyhydrogen flame. The author and Ramage found in 170 common ores and minerals potassium and sodium, and with these common elements rubidium and lithium were very generally associated.In sixteen red hEmatites, massive minerals of the purest type, rubidium was contained in four. Where potassium and rubidium occurred lithium was invariably found. I t was found in limestones, in dust, in the Bessemer flame, in ordinary pipeclay, tobacco pipes, and a great variety of siliceous minerals, such as the Dublin granites ; in Donegal kyanite, which contains 98 per cent. of aluminium silicate; and in asbestos, I t was found in dust which fell from the clouds, in volcanic dust, in soot, in f l u d u s t from chemical works, and in that from copper smelting and refining works, This last material contained lithium, sodium, potassium, rubidium, and cssium ; copper, silver, calcium, strontium, aluminium, gallium, indium, thallium, iron, nickel, cobalt, manganese, chromium, lead, zinc, cadmium, and tin.Upon such evidence as this it is impossible to corroborate the statement that potassium is a more widely distributed element than lithium, or that lithium is an unlikely constituent of dust, glass, copper, etc. Thus, of sixty-two iron ores, rubidium was found in sixty-one. The Rapid Electrolytic Separation of Metals. BY H. J. S. SAND. In the process of electrolytic analysis, the principle of very vigorous stirring of the electrolyte has been combined with that of keeping the potential of the cathode under control by means of an auxiliary electrode. I t has thus been possible to largely exhend the scope of electro-analytical methods. The following metals have hitherto been studied : First, the metals of the silver and copper groups and zinc--i.e., silver, mercury, copper, bismuth, lead, cadmium, and zinc. These metals have all been deposited singly, separated from each other, and also separated when all present in the same solution. In the last-named case the quantity of each metal taken varied between 0.10 and 0.15 gram, and the time for the deposition of each between about ten and fifteen minutes. Secondly, new methods have been elaborated396 THE ANALYST. for the estimation and separation from each other of antimony and tin. A con- siderable number of estimations have been carried out in which the metals taken in varying ratios weighed together approximately 1 gram. The time for the deposi- tion of the antimony was usually about twenty minutes ; that for the tin about eighty minutes. Lastly, the possibility has been examined of securing a purely electro- lytic method for the analysis of an alloy consisting of copper, antimony, lead, and tin, and all the separations required for such an analysis have at the present time been carried out.

ISSN:0003-2654    

DOI:10.1039/AN9083300390

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

396 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. A Colour Reaction of Alypine and other Local Anaestheties. P. Lemaire. (ilrzn. t7o Chim. And. A&., 1908, 13, 301-303.)-When benzoic acid is heated with sulphuric acid until white vapours appear, sulpho-benzoic acid is formed. On treating this with potassium nitrate it is converted into meta-di-nitro-benzoic acid, which may be transformed by ammonia and ammonium hydrosulphide into ammonium meta-diamido-benzoate. In applying this series of reactions to the detection of alypine (benzoyl-tetra-methyl-di- amino-pentanol hydrochloride) and other anaesthetic agents of the aromatic series, 0.05 gram of the substance is heated with 2 C.C. of sulphuric acid until the appearance of white fumes.The hot solution is then treated little by little with 0.4 gram of potassium nitrate, and the solution, when cold, decanted into 25 C.C. of ammonia solution (1 : l), and finally treated with one drop of ammonium hydrosulphide. In the presence of alypine, or stovaine, there is an immediate reddish-brown colour ; whilst with novocaine and subcutine an orange-red colour is obtained after the addition of the ammonia, the final reaction with ammonium sulphide being masked. The hydrochlorides of cocaine, tropacocaine, and P-eucaine give the reaction plainly, whereas no such coloration is given by nirvanine, holocaine hydrochloride, or orthoform. After the first addition of potassium nitrate, however, a brownish-red coloration is obtained with orthoform, and an orange-red coloration with holocaine hydrochloride, nirvanine, and subcutine, whilst with alypine, stovaine, and the hydrochlorides of tropacocaine, a-eucaine, P-eucaine, and cocaine, the mixture is orange, yellow, or nearly colourless.After the addition of ammonia the solution is colourless, or nearly so, in the case of nirvanine, stovaine, alypine, and the hydrochlorides of cocaine, a-eucaine, P-eucaine, and tropacocaine; it is more or less orange or reddish-orange with novocaine, orthoform, subcutine, and holocaine hydrochloride. Halphen’s Reaction for Cotton-Seed Oil. H. Wagner and J. Clement. (Zeits. Unterszich. Nahr. Gewssm., 1908, 16, 153-160.)-The method of applying C. A. M. #THE ANALYST. 397 this test described by Rupp (ANALYST, 1907, 32, 95), in which the oil and reagents are heated together in a closed tube or flask, is considered to have advantages over the older way of carrying out the test in open test-tubes, particularly when many tests have to be done at the same time.One per cent. of cotton-seed oil in another oil should give a bright red coloration when heated with the reagent for 30 minutes when the test is carried out in this manner. The authors were unable to isolate the compound which gives the colour reaction with Halphen’s reagent. W. P. S. The Influence of Preservatives on the Reichert-Meissl Value of Fats. C. Grimaldi. (Chem. Zeit., 1908, 32, 794.)-Of the preservatives which are used in connection with fats, only benzoic and salicylic acids increase the acidity of the distillate when the fat is distilled as in the ordinary Reichert-Meissl process.Sodium fluoride is insoluble in the fat, and is consequently not present in the filtered fat used for the estimation. Whilst the author agrees with Bemelnians (ANALYST, 1907, 32, 218) in his statement that the presence of considerable quantities of benzoic acid may appreciably increase the Reichert-Meissl value of a fat, it is pointed out that the effect of benzoic acid in the proportion in which it is usually added as a preservative (0.1 to 0.2 per cent.) would be very small. The effect caused by the presence of salicylic acid is smaller than in the case of benzoic acid. The presence of a quantity of benzoic acid sufficient to cause an increase in the Reichert- Meissl value corresponding with the decrease brought about by the addition of 9 per cent.of margarine and 9 per cent. of cocoanut oil to a butter would be detected, in the first place, by the abnormally high acidity of the fat. w. P .s. Detection of Artificial Honey. J. Fiehe. (Zcits. Untersuclh. Nalw. Gewssnz., 1908,16? 75-76.)-The test described is based on the detection, by means of resorcinol and hydrochloric acid, of the decomposition products which are formed in small quantity during the manufacture of the invert sugar from which artificial honey is prepared. One gram of the honey to be tested is rubbed down in a mortar with ether ; the ether is then filtered off and evaporated. The residue obtained is next moistened with a drop of the reagent, which is prepared by dissolving 1 gram of resorcinol in 100 C.C.of hydrochloric acid of specific gravity 1.19. If invert sugar be present in the sample, an orange-red coloration is at once obtained, which changes quickly to cherry-red and then to brown-red. Pure natural honeys do not give the reaction ; a momentary pink coloration may sometimes be obtained, but it cannot be mistaken for the colour yielded by artificial honey. w. P. s. Concentrated Commercial Feeding-Stuffs. A. McGill. (Canadian Idand Rewewe Department, Bull., 1908, No. 156, 1-26.)-With recent improvements in milling, and especially since the extensive manufacture of cereal breakfast foods, there have resulted large quantities?of by-products varying extremely in their nutritive value. The expansion of the cotton-seed, of beet-sugar and molasses, of maize oil, glucose waste manufactures, etc., has brought into existence other classes of by-products, which, while not available in themselves as cattle foods, are manufactured into so- called concentrated foods.There is, therefore, every necessity for buyers to insist398 THE ANALYST. on the manufacturer guaranteeing a, minimum percentage of protein and fat in such products. In the following table are given the results of analyses of various feeding- stuffs (Canadian), together with the legal standards in such of the United States as have fixed a standard for the article : Bran : Canadian, 1906 ... ... ... Ditto 1908 ... ... Legal standard, North ' Carolina Ditto Kentucky ... Canadian, 1906 ... ... ... Ditto 1908 ... ... ... Legal standard, North Carolina Ditto Kentucky ...Middlings : Fat. Per Cent. 9-47 3.48 4-00 4.00 2.72 3.05 4-00 4.25 Proteiii. P e r Cent. 13-47 14.74 14.50 15.00 13.59 16.09 15-00 15.75 Crude Fibre. Per Cent 11.11 8.69 9-50 8.00 8.33 9.50 6.00 6.50 Since the introduction of the use of a solvent for the extraction of the oil from linseed and cotton-seed, the quantity of residual oil in the meal is much less than is the case with meals from which the oil has been pressed. These (' new process" meals contain from 1.80 to 2-91 per cent. of oil, as is shown by the results of analyees of thirty-nine samples. w. P. s. Estimation of Sulphurous Acid in Food Products, and especially in Gelatin. L. Pad& (Ann. de Chim. Anal. Appl.) 1908,13, 299-301.)-The dificulties in the estimation of sulphurous acid in gelatin are obviated in the following method : Twenty grams of the dry gelatin (or 100 grams of a jelly) are soaked for twelve hours in 500 C.C.of boiled water in a round-bottomed litre flask. This is closed by means of a cork with three openings, through one of which passes a tube reaching nearly to the bottom of the flask and connected at the oiher end with a carbon dioxide generator, whilst the other openings receive the outlet tube and a stoppered thistle funnel having its inner end below the surface of the liquid. The outlet tube is connected with a Will's absorption tube containing 50 C.C. of iodine solution (iodine 5 grams, and potassium iodide 7.5 grams per litre). A fairly rapid current of carbon dioxide is passed through the flask to expel all air, after which the flask is heated on the water-bath, care being taken that the temperature of its contents does not, exceed 70" C., and that the current of carbon dioxide is reduced to a speed of two to three bubbles per second.When all the gelatin has dissolved, 25 C.C. of a 10 per cent. solution of syrupy phosphoric acid is introduced through the thistle funnel, and the current of carbon dioxide accelerated to four to five bubbles per second. After about an hour the whole of the sulphurous acid will have been removed, and the resulting sulphuric acid in the absorption tube may then be estimated in the usual way. The amount of sulphurous acid thus found in 100 samples of dry gelatin ranged fromTHE ANALYST. 399 0 to 7 grams per kilo. I n the case of free sulphurous acid the current of carbon dioxide is passed through the hot solution for an hour before the introduction of the phosphoric acid, and the sulphuric acid estimated as above described.C. A. 1%. Rapid Estimation of Alcohol in Fermented Liquors. W. Antoni. (Journ. Amw. Glum. SOC., 1908, 30, 1276-1278.)-The author employs a special pycnometer, of about 50 C.C. capacity and of the Sprengel type, in which the sample is measured and the distillate afterwards collected and weighed. The pycnometer is cylindrical, with a diameter of 3 c.m. and a height of 7 cam. The straight side tubes are 8 c.m. long, and have bores of 1-5 mm. and 0.75 mm. respectively, the wider one having a circular mark, while both are fitted with caps. The pycnometer is filled with the sample by means of a funnel and rubber-tubing connected with the wider arm. The apparatus is allowed to stand for some time at 15.6" C., and the volume then adjusted.The liquid is transferred to a distilling-flask, and by means of a special arrangement the pycnometer is rinsed out with water, which is added to the liquid in the distilling-flask; the pycnometer is then attached by its wider arm with rubber- tubing to the lower end of the condenser. When the distillation is completed, water is added to the contents of the pycnometer until it is nearly filled, the liquid is mixed by shaking, adjusted to the mark, and brought to 15.6" C. The pycnometer is counterbalanced by a tare of approximately the same weight and volume as the pycnometer filled with water at 15.6" C., when only a few small weights are required for each weighing.A. R. T. The Rose Method for Estimation of Fuse1 Oil, and Comparison with the Allen-Marquardt Method. W. L. Dudley. (Journ. Arner. Chew. SOC., 1908, 30, 1271-1276.)-The following precautions are necessary to ensure success with the Rose method. The specific gravity of the alcoholic distillate (from whisky, etc.) must be exactly 0.96541 at 15-6" C. ( = 30 per cent. alcohol by volume), preferably determined by the Reischauer pycnometer, the allowable error being only k 0.00002. No '' correc- tions " for applying to the chloroform-volume reading in case of variation from this alcoholic strength are of any value. Precautions must be taken to have exactly 20 C.C. of chloroform at 15.6" C. in the apparatus, and the part of the apparatus containing the chloroform must be completely immersed in a water-bath at this temperature.The author recommends the old Hertzfeld form of the Rose apparatus, and considers the newer, Bromwell, modification to be open to objection on account of possible leakage through the stop-cock. The alcoholic liquid of the required strength should be intro- duced into the apparatus, containing exactly 20 C.C. of chloroform at 15.6O C., by means of a 100-c.c. pipette, this having a stem so graduated as to show the volume at any temperature from 15" to about 35" C., in order that the spirit may be measured at room temperature. The stopper must be perfectly dry before insertion in the tube, and after a, preliminary shaking of the apparatus, the stopper is carefully removed once only to relieve the pressure, and again inserted after drying. I t is then covered with a rubber cap to prevent wetting, and the apparatus placed in a water- bath at 15.4' C., this temperature being adopted in order to quickly bring the apparatus to standard temperature after its frequent removals and shakings.The apparatus400 THE ANALYST. is shaken at intervals of five minutes during half an hour, when it is transferred to a water-bath at 15.6' C. for half an hour, and the reading taken. With these special precautions the author states that the results are satisfactory ; and, while they are much higher than the figures obtained by the Allen-Rlarquardt process, yet a marked relationship is observable between the results given by the two methods. The Allen-Marquardt method is stated to be superior in that it more accurately records the amyl alcohol content, while it is quicker and possesses fewer sources of error (cj.Schidrowitz, ANALYST, 1907, 32, 289). A. R. T. Estimation of Malic Acid in Food Products. H. W. Cowles, Jr. (Joum Amer. Chem. SOC., 1908, 30, 1285-1288.)-Calcium chloride does not precipitate free malic acid, since the latter cannot separate the calcium from its combination with a mineral acid. Calcium acetate, however, may be used with good results; and while 95 per cent. alcohol precipitates this salt from its solutions as a jelly- like mass, alcohol of 85 per cent. strength does not cause this separation, and yet it allows of the coiiiplete separation of the malic acid on heating at 100' C.for half an hour. The author finally adopted the following method for the examination of maple-sugar and syrup, and also of cider and cider-vinegar : 6.7 grams of the sugar or syrup are dissolved in 5 C.C. of water, which is suficieut to effect complete solution. TWO C.C. of a 10 per cent. solution of calcium acetate are added, followed by 100 C.C. of alcohol (95 per cent.) stirred in, and the solution warmed on the water-bath for half an hour, or until the precipitate readily settles, leaving a clear supernatant liquid. The liquid is filtered, the precipitate washed with 85 per cent. alcohol until the soluble calcium salts are removed, the residue is ignited, dissolved in an excess of standard acid, the solution boiled, cooled, and titrated back with standard alkali.One-tenth of the number of C.C. of decinoriiial acid required gives the percentage of malic acid in the product when 6.7 grams have been taken. Two samples of maple-sugar examined by this method showcd 0.87 and 1.22 per cent. of malic acid, while three maple-syrups gave 0.51, 0.52, and 0.68 per cent. A. R. Method for the Detection of Incipient Decomposition of Meat. A. Scala and G. Bonamartini. (Chem. Zeit., 1908, 32,77l.)-The authors condemn methods based on the evolution of ammonia as inaccurate. They recommend that the meat in question be distilled, and the distillate treated with i& soIution of iodine, a comparison test being carried out with fresh meat. Examination of different kinds of meat showed that the distillate from fresh meat required 6 to 10 C.C.of the iodine solution, that from meat not so fresh 10 to 15 c.c., and that from meat beginning to decompose considerably more. A. G. L. The Detection of Added Water in Milk by Means of the Refractometer. C. Mai and S. Rothenfusser. (Zeits. Untersuch. Nahr. Geizussm., 1908, 16, 7-19.)- The authors have examined some 5,000 samples of milk by the method described by Ackermann (ANALYST, 1907,32,117), and find that the refractometer value for normal milks is about 39. Any sample giving a reading lower than 36.5 undoubtedlyTHE ANALYST. 401 contains added water. Whilst the process is considered to be of use in detecting the presence of added water in fresh or only slightly soured milks, it fails to give reliable results when the acidity of the milk is such that 100 C.C.require more than 9 C.C. of alkali for neutralisation, using phenolphthalein as indicator. W. P. S. A New Reaction for Distinguishing between Raw and Heated Milk, and for Detecting the Presence of Hydrogen Peroxide in Milk. W. P. Wilkinson and E. R. C. Peters. (Zeits. U?tterszich. Nahr. Ge7zz~ssm., 11308, 16, 172-174.)--The reaction is based on the fact that a mixture of unheated milk and hydrogen per- oxide gives a blue coloration when treated with an alcoholic solution of beneidine (p-diamidodiphenyl) acetate. The test is carried out in a similar way to the well- knownp-phenylenediamine test. To 10 C.C. of the milk to be tested are added 2 C.C. of a 4 per cent. alcoholic benzidine solution, then two or three drops of acetic acid, and, finally, 2 C.C.of 3 per cent. hydrogen peroxide solution. I t is best to allow the hydrogen peroxide to flow over the surface of the milk, etc. If the milk be unheated, a blue coloration at once appears, whilst no change takes place in the case of milk which has been heated to a, temperature of, or exceeding, 78OC. The test is stated to be more sensitive than the p-phenylenediamine reaction, and the alcoholic solution of the reagent keeps without change for a considerable length of time. The reagent may also be used as a test for the presence of hydrogen peroxide in various solutions. Unheated milk is mixed with the reagent, a little acetic acid is added, and the solution to be tested is then introduced. A blue coloration is obtained if hydrogen peroxide be present.w. P. s. The Detection of “Sugar-Lime” in Milk and Cream. E. Baier and P. Neumann. (Zeiis. Untersuch. ATc~7~i-. Genussm., 1908, 16, 51-63.)--Attention is drawn to a product sold under the name of ‘( Zuckerkalk” (sugar-lime), which is used for correcting the acidity and iniproving the ‘‘ thickness ” of milk and cream. I t consists of an aqueous solution containing from 3.4 to 4.4 per cent. of calcium oxide, and from 17.3 to 25.4 per cent. of sucrose ; about 6 grams of the solution are added to every litre of milk or cream. The actual quantity of calcium oxide thus added to the milk or cream is very small, and cannot be detected with certainty in the ash of the sample, as the lime-salts natural to milk vary in amount. For the detection of added lime the author recommends that 250 C.C.of the milk be treated with 10 C.C. of 10 per cent. hydrochloric acid, filtered after standing for thirty minutes, and the calcium determined in the usual way in a measured quantity of the filtrate. The quantity of calcium oxide present in normal milk serum varies from 0.013 to 0.018 per cent., whilst milk which has been treated with the above- inentioued solution yields a serum containing from 0.020 to 0.028 per cent. of calcium oxide. In order to detect the presence of sucrose, 25 C.C. of the milk are treated with 10 C.C. of 5 per cent. uranium acetate solution, the mixture is filtered, and 10 C.C. of the filtrate are mixed with 2 C.C. of saturated ammonium molybdate solution and 8 C.C. of dilute hydrochloric acid (1 : 7).The mixture is next heated in a water-bath for five minutes, when a blue coloration is obtained if sucrose be present. w. P. s.402 THE ANALYST. Two New Tests for Elemi Resin. P. Stoepel. (Apoth. Zeit., 1908, 440; Jozmz. d e Phnrnz. e t de Chim., 1908,28, 116.)-Elemi is particularly liable to adultera- tion, generally with some form of coniferous turpentine. These turpentines appear to be particularly adapted to restore the desired soft consistency to elemi which has become hard, especially since a slight terebenthine odour is not foreign to the genuine drug. Elemi melts on the water-bath to a clear yellowish-green liquid, which changes to a fine eosin-red on the addition of dilute sulphuric acid (1 : 4). For the detection of turpentine, the resin is dissolved in 10 parts of absolute alcohol; the alcoholic Bolution of pure elemi has a neutral reaction, but the solution of turpentine reddens blue litmus paper.An alcoholic solution of pure elemi, when diluted with water, gives a pure white emulsion, whereas, if turpentine be present, yellowish-brown resinous flocks separate. J. F. B. The Analysis of Scammony Resin. P. Guignes. (Bull. SOC. Chim., 1908 [iv.], 3, 872-878.)-1n the French Codex it is stated that jalap may be distinguished from scammony by being insoluble in ether. The author, however, points out that certain scammony resins are quite insoluble in ether, whilst, on the other hand, jalap resin is partially soluble. Moreover, fusiform jalap resin (Ipomcea ol-izabensis j is soluble in ether, and under the name of Alexican scammoizy root has largely taken the place of the true scammony root in the English market.More valuable results may be obtained by a determination of the optical rotation. Andouard (Nozweazm -&'ldme?tts de Fhnm., 1905) gives the rotatory power of scammony resin as [aIn= - 25" 2', and states that the reading may be as low as - 20" in the case of resins extracted from the root. I n the author's experience, the highest value observed for resins extracted from the gum resin was - 24" 30', whilst for resins extracted from the root the readings varied from - 18" 30' to - 23" 30'. The optical rotation is independent of the solubility in ether. long time with ether, the soluble portion showed = - 18" 20', and the insoluble portion - 18" 44'. The rotatory powers [.ID of other purgative resins extracted by the author from genuine samples were as follows: Commercial Tampico jalap, -- 34" 20' ; genuine Orizaba jalap, - 24" 45'; official jalap, - 36"; oficial turbith, -30" 10' to -31" 35'; ordinary colophony, +6" to +7"; Sandarac from Arabian bazaar, + 46' 20' ; pure Sandarac, + 31" to + 34"; recent genuine mastic, + 29" 30' ; mastic (second quality), + 21" 50' ; and guaiacum, - 17". Sccording to these results, only fusiform jalap and guaiacum resin can be substituted for scammony resin without affecting the optical rotation. Since, how- ever, scammony resins extracted from the gum resin do not occur in commerce (for they cost at least double the price of the resins extracted from the root), the author concludes that a sample with an optical rotation exceeding [.ID = - 23" 30' may be regarded as the resin of fusiform jalap. Gusiacum resin, again, becomes green in the light, and is easily distinguished by its chemical characteristics. The following method of applying the optical test is recommended:-The resin is extracted with alcohol, and the residue from the alcoholic extract thoroughly washed with hot water. A quantity of it, corresponding to about 4 grams of the dry product, is dissolved in 100 C.C. of alcohol, and the solution decolorised with animal charcoal. Thus, in the case of a resin extracted forTHE ANALYST. 40 3 The rotation of the liquid is then determined in a 200-mm. tube, whilst 10 C.C. are evaporated and dried at 105" to l l O o C. to obtain the exact amount of resin in 100 C.C. of the solution, C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9083300396

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 40 3 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. The Vitality of the Typhoid Bacillus in Artificially Infected Samples of Raw Thames, Lee, and New River Water, with Special Reference to the Question of Storage. A. C. Houston. (Report to the Metropolitan Water Board, 1908, 1-32.)--Eighteen series of experiments were carried out on the longevity of the typhoid bacillus in samples of raw Thames, Lee, and New River water, and the results show that in practically all the experiments over 99 per cent. of the typhoid bacilli artificially added to the water died within one week. I n the majority of the experiments, however, a few of the typhoid bacilli remained alive for one or two months. The conclusion is that, whilst it may be difficult to store water for such a length of time as to insure the death of all the typhoid bacilli which may be present, there is no difficulty in storing it sufficiently long to reduce enormously any element of danger likely to arise from this cause.Storage for four weeks may, therefore, in the present state of our knowledge, be regarded as affording a sufficient margin of safety. The advantages gained from even a few days’ storage may be so material that, exceptional cases apart, the us0 of raw unstored river water for filtration purposes should be strongly deprecated; moreover, the advantages are of a general character, and not limited to the elimination of danger from typhoid fever. Atten- tion is also drawn to experiments carried out in America by Jordan, Russell, and Zeit (JOW’IE. hgectioacs Diseases, 1904, 1, 641-689), who found that the vast majority of typhoid bacilli introduced into several waters perished within three or four days ; certain resistant cells appeared, however, to be present which were able to withstand for 8 longer period the hostile influences evidently present in the water.These cells were very few in number, and constituted only a small fraction of the number of the bacilli originally entering the water. I n discussing these statements, the author considers that it is almost certain that such resistant cells occur, and that they are capable of existing for a much longer time than the majority of the bacilli. Further, these specially resistant individuals ” may possibly be relatively more numerous in typhoid excreta than in artificial cultures. w.P. s. Estimation of Indol in Bacteriological Cultures. M. Nonnotte and R. Demanche. (Comptes Rend. SOC. Riol., 1908, 658 ; BzcZZ. SOC. Chim., 1908 [iv.], 3, 878-879.)-A standard solution of indol (34 mgms. per 100 c.c.) is introduced into a burette delivering 17 drops per c.c., so that each drop contains 0-02 mgm. of indol. To each of ten test-tubes oontaining 10 C.C. of peptone solution is then added a progressively increasing quantity of the indol solution, beginning with 1 drop and ending with 10 drops (0.02 to 0.2 mgm.). The cultivation to be tested for indol should have been made in a test-tube containing 20 C.C. of a neutralised 2 per cent. peptone solution (Byla’s pancreatic peptone) and 0-5 per cent. of sodium chloride. After404 THE ANALYST.growth of the cultivation the liquid is clarified centrifugally, and 10 C.C. of the clear fluid transferredCto a tube of the same size as those of the standard series. Into each of the tubes are then introduced ten drops of a 0.1 per cent. solution of potassium nitrate and 4 drops of strong sulphuric acid, and all of them immersed for 10 minutes in boiling water. The contents of the standard tubes will then form a, colour-scale ranging from pale rose to deep vinous red, and the colour of the liquid under examination may thus be matched and the proportion of indol present estimated. C. A. M. Reactions Distinguishing between Indol and Scatol. G. Deniges. (Comptcs Beizd. SOC. BioZ., 1908, 659-691 ; BZLEZ. SOC. Chirn., 1908 [iv.], 3, 879-880.)- On treating 5 C.C.of a very dilute alcoholic solution (less than 0.5 gram of 90 per cent. alcohol per litre) of indol or scatol, with 0.2 to 0-3 C.C. of an alcoholic solution of vanillin (5 grams per litre), and 3 C.C. of pure hydrochloric acid of specific gravity 1.18, characteristic colorations are produced. In the case of indol there is an immediate eosin-red coloration, and the liquid shows a large absorption band in the green part of the spectrum. The coloration lasts for some hours, and then gradually changes to Bordeaux red, with a blue-violet fluoresconce. I t is thus possible to identify 0.1 to 0.2 mgm. of indol per litre. With scatol there is at first a faint yellow or yellowish- rose coloration, much less pronounced than in the case of indol. Hence, by working rapidly it is often possible to detect indol in the presence of scatol.The colour gradually alters, and after a few hours becomes a deep violet, which is very intense with solutions containing from 0.20 to 0'25 gram per litre, and is still perceptible in a dilution of 1 mgm. per litre. If 5 C.C. of hydrochloric acid be used in place of 3 c c., there is an immediate rose-pink or red coloration sufficiently pronounced to permit of the detection of one part of scatol in a, million. When vanillin is replaced by cinnamic aldehyde an intense red-yellow colour is obtained with indol, whilst scatol gives a light yellow coloration, slowly changing to light green. If 5 C.C. of hydro- chloric acid be added to the original mixture instead of 3 c.c., the colour changes to red, becoming green or bluish on the addition of 5 C.C.of alcohol, and then violet on the further addition of a, few C.C. of hydrochloric acid. By the use of a 5 per cent. alcoholic solution of dimethylamino-benzaldehyde, instead of vanillin or cinnaniic aldehyde, an intense rose-pink coloration, slowly changing, after a long time, to vinous red, is obtained with indol. In the case of scatol, the colour is at first almost identical with that given by indol, but gradually becomes more violet, and finally, after some hours, a very stable blue. When the solution is concentrated the blue coloration is preceded by a persistent greenish tint. The spectrum, whiah at first resembles that of indol under the same conditions, is finally changed, showing, when the blue stage arrives, only a single absorption band in the red. C. A. 11. New Chemical Test for Blood. Delearde and A. Benoft. ( J o z I ~ . c7e Pharm. e t de Chinz., 1908, 28, 128-129.)-The reagent is prepared by boiling 2 grams of phenolphthalein with 20 grams of anhydrous potash dissolved in 100 grams of water, and 10 grams of zinc dust until reduction is complete and a colourless liquid is obtained. The solution is then filtered while hot. I n order to detect the presenceTHE ANALYST. 405 of blood in any liquid, 2 C.C. of the liquid are placed in a test-tube; there are then added consecutively, without shaking 1 C.C. of the phenolphthalein reagent and two or three drops of hydrogen peroxide of 12 vols. strength. The blood contains an indirect oxidising enzyme, which instantly colours the liquid red owing to the forma- tion of phenolphthalein. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9083300403

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 405 ORGANIC ANALYSIS. Composition of Aleurites Seeds from Cochin China. Ballard. (Jounz. Pharm. Chim., 1908, 28, 162.)-The oil expressed from the seeds of various kinds of alezuites is now extensively used in the manufacture of soap. Two samples examined by the author had the following composition: Water, 4.40 and 4.90; nitrogenous substances, 21-80 and 24.30; fat, 58.7 and 52.50 ; extracted by water, 7.8 and 10.27 ; cellulose, 340 and 3.75; and ash, 3.90 and 4.26 per cent. I n the author’s opinion cases of poisoning attributed to alezLrites seeds are probably due to the presence of seeds of abrasin. C. A. M. Bang’s Method of Estimating Sugar. I. Bang. (Biochem. Zeits., 1908,11, 538-540.)-1n answer to the criticisms of Jessen-Hansen (ANALYST, 1908, 324), the author maintains the reliability of the pro‘cess described by him (ANALYST, 1907, 32, 180); the conditions of the method must, however, be adhered to.W. P. S. Some of the Constituents of Cigar Smoke. J. Habermann and R. Ehrenfeld. (Zeits. Physiol. Chem., 1908, 56, 3G3-372.)-The authors have estimated the amounts of nicotine, ammonia, and sulphur in the smoke of various brands of cigars sold in Austria. The cigars were smoked by means of an aspirator connected with a series of absorption vessels. I t was found that the average quantity of sulphur in the smoke of different kinds of cigars was 0.02 per cent., calculated on the weight of the air-dried cigar. A brand known as ‘‘ Specials ’’ yielded smoke con- taining 0.015 per cent. of sulphur, but, on the whole, the amount of sulphur varied so little that it could not be used as a means of differentiating one class of cigar from another.On the other hand, the quantities of ammonia varied greatly, the smoke from three cigars of the same brand contained 0.01, 0.12, and 0.72 per cent. of ammonia respectively, whilst in other cases the quantity varied from nothing to 0.49 per cent. The amount of nicotine found in the different smokes ranged from nothing to 0.15 per cent. calculated on the cigar ; the alkaloid was concentrated in the unsmoked stumps of the cigars, as these contained from 3.22 to 4.71 per cent., whilst the cigars themselves contained from 1.02 to 1-53 per cent. of the base. There was but little difference in the quantities of moisture and ash in the various brands.(See also ANALYST, 1904, 29, 166.) w. P. s. Analysis of Copal Lacquers. H. Rebs. (Lack and 3”nrbeuind, 1908,122-123 ; Chenz. Zeit. Rep., 1908, 32, 435.)-The analysis of lacquers containing copal and rosin is carried out in the following manner : Ten grams of the lacquer are freed from oil of turpentine by distillation, and the turpentine is weighed. Three gram8 of the406 THE ANALYST. ~ Method 11. residue are mixed with about 200 C.C. of light petroleum spirit, and shaken with about 5 C.C. of dilute acetic acid. The copal is precipitated, whilst the rosin and oil remain dissolved in the petroleum. The solution is filtered, and the rosin is precipitated by the addition of ammonia to the filtrate; alcohol is then added until the precipitate is re-dissolved.Two clear layers are thus formed, the lower, alcoholic- ammonia layer, containing the rosin, and the upper, petroleum layer, the oil. The oil is estimated by evaporating the petroleum from an aliquot portion of the upper layer, and the rosin is calculated by difference. J. F. B. Method 111. Estimation of Formic Acid in Glacial Acetic Acid. H. Ost and F. Klein. ( Chem. Beit., 1908, 32, 815-816.)-Commercial glacial acetic acid frequently contains appreciable quantities of formic acid which are not detected by the usual cold permanganate test unless the liquid be allowed to remain with the permanganate for forty-eight hours. The authors have ascertained that the following four methods are available for the quantitative estimation of formic mid in presence of acetic acid : (1) Ten C.C.of the glacial acetic acid are heated with 50 C.C. of concentrated sulphuric acid in an apparatus from which tho air has been expelled by a current of carbon dioxide. The carbon monoxide evolved by the decomposition of the formic acid is collected over potash in a nitrometer. One hour’s heating at the temperature of the water-bath is sufficient, but the method is not suitable for diluts acids, nor for solutions of the salts. (2) The liquid is made alkaline with sodium carbonate, heated on the water-bath and titrated with & permanganate, which acts rapidly in alkaline solution. (3) The acid is oxidised with potassium bichromate and sulphuric acid at the boiling temperature, and the excess of bichromate is titrated back with thiosulphate after the addition of potassium iodide. I t is necessary to oxidise in highly dilute solutions with at least eight times the theoretical quantity of bichromate ; the reaction is complete in half an hour on the water-bath.(4) The acid is diluted and treated with sodium acetate and excess of mercuric chloride. On heating, mercurous chloride is precipitated, and may be collected and weighed. This reaction also requires at least six times the calculated quantity of mercuric chloride, and several hours’ heating. I n the table below the authors set forth the results obtained by the different methods on six different samples of glacial acid : Saml’lc. Method I. 0.007 0 - - - 0.48 Percentage of Formic Acid. 0.009 0 0.48 0.012 0.52 0.46 Method I V 0.008 0 0 40 0.014 0.59 047THE ANALYST.407 Method I. is the best for glacial acetic acid. The most satisfactory method for obtaining pure acetic acid is by crystallisation and separation of the inother liquors by means of the centrifuge. J. F. B. “ The Hydrogen Number ” as a Means of Determining Unsaturated Organic Compounds in a manner similar to the Iodine Values of Hub1 and Wijs. S. Fokin. (Journ. Russ. Phys. Chenz. SOC., 1908, 40, 700-709; Journ. Chem. SOC. (abstract), 1908, 94, ii. 637.)-The ‘‘ hydrogen value ” of an organic compound is defined as the number of cubic centimetres of hydrogen (at 0” and 760 mm.) which are absorbed by 1 gram of the compound. For the test, an apparatus is devised consisting of a distillation flask (50 to 150 c.c.), having a small beaker fused inside on the bottom, and connected by means of the side-tube to a gas burette and a gasometer containing hydrogen.I n the small beaker are placed 0.1 to 0.2 gram of platinum, moistened with 0.25 to 10.5 C.C. of water, and active in the flask, the substance to be examined and 20 to 30 C.C. of alcohol free from dissolved oxygen. The flask is shaken by a machine. The following hydrogen values were obtained by the author, the figures in brackets being either the hydrogen values corresponding with Wijs’ iodine value, or, where indicated, the theoretical hydrogen values: Elaidic acid, 78.6 to 81-4 (78.8) ; oleic acid, 86.2 to 87.2 (86.2); fatty acids from sunflower oil, 119.6 to 120.8 (122.9); fatty acids from linseed oil, 164.9 to 166-3 (166.0); castor oil, 73.7 (75.5); Owton oil, 2609 (theoretical, 258.4) ; undecoic acid, 115.6 (114.1) ; erucic acid, 39.4 (65.6) ; maleio acid, 190.6 to 191.6 (theoretical, 191.0) ; aconitic acid, 131.0 (theoretical, 127.7) ; citraconic acid, 175.2 (theoretical, 171.1 ; cinnamic acid, 215.0 (150.1).Colophony, naphthalene, benzoic acid, resorcinol, quinol, catechol, pyrogallol, and cymene do not absorb hydrogen under the conditions of the test. Notes on Messinger and Vortmann’s Method of Estimating Phenols. Estimation of Salicylic Acid. J. Bougault. (Journ. Pharna. Chim., 1908, 28, 145-154.)-The author concludes, from experiments here described, that the two hypoiodous esters described by Messinger and Vortmann (ANALYST, 1891, 16, 75)- viz., di-iodophenol iodide, C,HsT,OI, and the potassium salt of the hypoiodous ester of an iodo-salicylic acid, C,H,I(OI)CO,K-were not chemical entities, but mixtures.Ths final product of the action of iodine, in the presence of alkalies or alkali carbonates. upon phenol, salicylic acid, or p-oxybenzoic acid, is one and the same compound, identical with Lautemann’s ‘‘ red body,” and named by Benzinger and Kamrnerer tetraiododiphenylene - quinone or tetraiododiphenylene dioxide (C,H,I,O),. This compound is so insoluble that it can be used in the gravimetric estimation of salicylic acid, and for the separation of that acid from acids which do not react with iodine under the same conditions. Phenol and p-oxybenzoic acid may also be estimated in the same way. In the author’s opinion, the aristol of thymol is probably an iodine derivative of a quinone compound closely related in constitution to Lautemann’s (‘ red body.” Estimation of Salicylic Acid.-In separating 0.1 gram of salicylic acid from 0.3 gram of cinnamic acid, the mixture is treated with 1 gram of dry sodiuu408 THE ANALYST.carbonate, and dissolved in 50 C.C. of water. The solution is heated on the water- bath, treated with an excess of a solution of iodine in potassium iodide solution, the heating continued for thirty minutes on the water-bath, and the liquid finally boiled for ten minutes under a reflux condenser. A few drops of sodium sulphite solution are now added to destroy the excess of iodine, and the red precipitate collected in a tared Gooch's crucible containing asbestos, washed, dried at 100" C., and weighed.The weight multiplied by the factor 0.4012 gives the corresponding amount of salicylic acid, The cinnamic acid in the filtrate and washings may be recovered by extraction with ether from the liquid after acidification with hydrochloric acid. In the test experiments quoted, the amounts of salicylic acid taken and found agree within a fraction of a milligram. C. A. 14. The Detection of Saponin. J. Ruhle. (Zeits. Uutersuch. Nahy. Gemssm., 1908,16, 165-171.)-The method proposed by the author as giving trustworthy results is a modification of the process described originally by Brunner, in which the saponin is extracted by means of phenol; the phenolic solution is then shaken with water and ether, and the aqueous portion containing the saponin is separated and evapo- rated.I n dealing with the separation of saponin from beverages such as aerated waters, etc., certain dotails of procedure, which are given below, have to be observed in order to obtain the saponin in a sufficiently pure state to give its characteristic reactions. One hundred C.C. of the sample under examination are neutralised by the addition of magnesium carbonate, 20 grams of ammonium sulphate are added, and the mixture is vigorously shaken in a separating funnel with 9 C.C. of pure phenol. After removing the aqueous layer, the phenol is shaken with about 50 C.C. of water and 100 C.C. of ether, about 4 C.C. of alcohol being added, if necessary, to break down the emulsion. When the layers have separated, which usually takes from twelve to fourteen hours, and the layer of emulsion between the ethereal and aqueous portions has diminished to a thickness of from 1 to 2 mm., the aqueous portion is drawn off' and evaporated. The residue, after being dried in a desiccator, is treated with about 10 C.C. of acetone, allowed to stand for twenty hours, and the acetone is then poured off; after a second similar treatment with acetone the residue is dried in the water- oven, at a temperature of looo C ., weighed, and tested for saponin. I n the case of liquids containing dextrin, 100 C.C. of the sample are evaporated 60 a volume of about 20 c.c., and 150 C.C. of 96 per cent. alcohol are then added. After the lapse of thirty minutes the mixture is heated until the alcohol just boils, and filtered immediately. The alcoholic filtrate is evaporated, after the addition of water, until all the alcohol has been removed, the residual solution is diluted to a volume of 100 c.c., and the process is then carried out as described above. Results of experiments are given in which known quantities of saponin were added to various solutions containing saccharose, invert sugar, dextrin, glycerol, tartaric acid, etc., from which it is seen that from 70 to 90 per cent. of the saponin can be recovered by the method. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9083300405

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST, 409 INORGANIC ANALYSIS. Distillation or Ammonia in Presence of Magnesium or Calcium Salts. P. A. Kober. (Jount. Amer. Chem. SOC., 1908, 30, 12'79-1281.)-1t is very diecult, if not impossible, to distil ammonia from an alkaline saturated solution of magnesium or calcium chloride containing an ammonium salt, and thus quantitative ammonia distillations should not be carried out in the presence of much of these salts. The action of these substances in inhibiting or preventing the evolution of ammonia provides an explanation of the prolonged distillation necessary in Folin's method for determining urea (Zeits. PhysioZ. Chem., 36, 333), which Folin erroneously attributes to the partial conversion of the urea into cyanuric acid, only slowly decom- posable by alkali. In Saint-Martin's modification of Folin's method, in which the urea-containing liquid is digested with lithium chloride instead of magnesium chloride, the distillation can be completed in half an hour.As many workers have shown, the reaction MgCl, + 2NH,OH +- __3 Mg(OH), + 2NH,CI is reversible, and if one of the products be removed, the reaction will proceed in the direction to form more of that product. Since in Folin's method the solution contains much magnesium chloride and a comparatively small quantity of magnesium hydroxide, equilibrium will be established only when the ammonia is present chiefly &B ammonium chloride. If a portion of the ammonia be removed by distillation, more will be formed to reproduce equilibrium in the solution, and so o n ; and since magnesium hydroxide is formed with evolution of heat, an increased temperature (distillation) means less hydroxide, and therefore more ammonia, formed.But obviously the last traces of ammonia are only with great difficulty removed by distillation. A. R. T. Volumetric Estimation of Carbon Monoxide by Combustion. E. Hauser. (Chem. Zeit., 1908, 32, 783.)-A mixture of pure carbon monoxide and oxygen will not burn; the presence of hydrogen or water vapour is absolutely necessary. From this and other evidence the author concludes that the production of formaldehyde or formic acid is always a preliminary stage in the combustion of carbon monoxide. For the estimation of carbon monoxide by combustion in presence of methane, certain precautions are necessary to insure complete combustion of the carbon monoxide without affecting the methane.The necessary quantity of oxygen and a little hydrogen are introduced into the gas mixture. Combustion must then be effected at a temperature below 180" C. in order that the methane may remain unburnt. For this the author employs palladium asbestos and rhodium asbestos, which is prepared in the same way as palladium asbestos, according to Winkler's prescription. The two contact substances are contained, separate from each other, in a U-tube 20 to 25 cm. long and 3 mm. inside diameter. The effect of the volume of this tube on the results may be corrected in the following manner : The U-tube is connected with a gas burette, and the whole is filled with air containing about 4 per cent. of carbon dioxide (respired air).The carbon dioxide in the gas burette is absorbed and410 THE ANALYST. measured, and the residual air in the burette is then mixed with the air in the U-tube, which still contains carbon dioxide. The mixed air is again admitted to the burette, and the carbon dioxide is again absorbed and measured. Then if V be the volume of the original air, and carbon dioxide in the burette, and A the volume of carbon dioxide contained thorein, and if A' be the volume of carbon dioxide absorbed from the second A X mixture, the volume of the gas in the U-tube, X, is obtained by the formula -= - A V ' The estimation of this volume may be made more exact by repeating the mixing operation and absorbing a third quantity of carbon dioxide. J. F. B.Estimation of Hydrogen Sulphide in Gases. F. Carpenter. ( J o z m . Gas Liqhting, 1908, 103, 167-168.)-The results of a number of experiments are given in which it was attempted to render quantitative the ordinary lead acetate-paper test for detecting the presence of hydrogen sulphide in gases. The papers used were prepared by immersing strips of filter paper (Schleicher and Schull's No. 589, black- band) in 12 per cent. lead acetate solution, and drying them; other papers were prepared by using a 12 per cent. lead acetate solution to which 5 per cent. of glycerol had been added. The glycerine-free papers were employed either dry or after being moistened with ammonia, whilst those containing glycerol were used directly in a moist condition or after being treated with ammonia vapour.The gas mixtures used'consisted of air to which hydrogen sulphide, and in some cases sulphur dioxide, had been added : in each test 1,100 C.C. of the gaseous mixture were allowed to act on the strip of paper for five minutes, and the strongest colorations were obtained when the current of gas flowed at a right angle to the side of the strip of paper. I t was found that in the case of gaseous mixtures containing hydrogen sulphide in the pro- portion of 1 : 100,000, but no sulphur dioxide, the condition of the lead paper (moist or dry) was of no importance ; when the concentration fell to 1 : 1,000,000 it was necessary to use the moist ammonia-treated papers in order to obtain a decided coloration. Under exactly similar conditions it was possible to prepare papers which showed distinct differences of coloration between concentrations of 1 : 10,000,l: 20,000, 1 : 50,000, and so on.The limit of sensibility of the dry papers was reached with concentrations of hydrogen sulphide of 1 : 1,000,000, whilst the moist ammoniacal papers would detect 1 part in 10,000,000. The presence of more than 1 part of sulphur dioxide in 2,500 parts of the gaseous mixture considerably diminished the sensitiveness of the reaction, and rendered the colorimetric estimations valueless. w. P. s. The Separation of Chlorine, Bromine, and Iodine by means of Hydrogen Peroxide in Acid Solution. P. Jannasch. (Jo'urn. Prakt. Chem., 1908, 78, 28-35 ; through Chem. Zeit. Rep., 1908, 32, 417.)--Continuing his previous work (ANALYST, 1906, 31, 127), the author separates iodine from chlorine and bromine by distillation in a current of carbon dioxide, after adding acetic acid and hydrogen peroxide to the mixture.The iodine is collected in an aqueous solution of hydrazine sulphate containing ammonia, and is estimated as silver iodide. The bromine,THE ANALYST, 411 separated as described previously, is absorbed in a .solution of hydrazine sulphate made alkaline with sodium hydroxide instead of ammonia, A. G. L. The Rapid Electrolytic Deposition and Separation of Metals. Part 11. Antimony and Tin. H. J. S. Sand. ( J o ? ~ . Chem. SOC., 1908, 93, 1572-1592.)-Using his special apparatus with rotating electrodes, for which reference must be made to the original, the author dmws that it is possible to deposit antimony completely, and free from tin, by work- ing in sulphuric acid solution (1 : 1) containing hydrtlzine sulphate, at temperatures above 100" C., and with a cathode potential measured against an auxiliary 2N sd- phuric acid electrode of 0.65 volt.Tin is not deposited unless the auxiliary potential rises above 0.8 volt. The tin left in the solution is conveniently deposited after adding oxalic acid, neutralising with ammonia, and again acidifying with sulphuric acid. The author also describes experiments in which the anode was enclosed in a diaphragm of parchment paper, in order to prevent the electrolyte containing the metals from being oxidised, when working with chloride solutions. The Employment of a Diaphragm. A. G. L. A Rapid Method for Estimating Impurities in Selenium.R. Kann. (Chem. Eizgiizeer, 1908, 8, 32,)-Iron and tellurium are estimated by dissolving 5 grams of the finely powdered selenium in 10 C.C. of concentrated nitric acid in a weighed 25-C.C. porcelain dish on the water-bath, evaporating the solution to dryness after adding 2 drops of sulphuric acid, and gently igniting the residue. After weighing, the mixed tellurium dioxide and ferric oxide is dissolved in hydro- chloric acid, and tellurium is precipitated with hydrogen sulphide, and iron with ammonia in the filtrate. A. G. L. Rapid Estimation of Sulphur in Coal according to 0. Brunck. A* Komarowsky. (Chem. Zeit., 1908, 32, 770.)-Having found that Brunck's method for estimating sulphur in coal (ANALYST, 1905, 30, 381), in which the coal is mixed with cobalt oxide and sodium carbonate and burnt in oxygen, the resulting sulphate being estimated gravimetrically, gives accurate results, the author has modified the method by applying his volumetric estimation of sulphates (ANALYST, 1907, 32, 276).For this purpose, the mass left after combustion is boiled with water and a little pure hydrogen peroxide to oxidise sulphites, and then treated with hydrochloric acid and barium chromate as previously described. A complete estimation requires only one and a half hours, and the results obtained agree well with those given by the Eschka method. A. G. L. Direct Combustion of Steel for Carbon and Sulphur. H. Isham and J. Aumer. (Journ. Amer. Chem. SOL, 1908, 30, 1236-1239.)-The authors find that the direct combustion of steel, by burning for twenty minutes in oxygen in t-i Shimer crucible heated by a blast-lamp, gives results for csrbon about 0.004 (0.001 to 0.015) per cent.higher than those obtained by solution in acid potassium cupric chloride solution, and subsequent combustion of the separated carbon, although about 0.003412 THE ANALYST. per cent. of carbon is left in the burnt steel. Under the same conditions, the evolution of sulphur was incomplete even when silica was mixed with the steel. A. G. L. A New Method for the Estimation of Vanadium in Steel. E. D. Campbell and E. L. Woodhams. (Journ. Amer. Chem. SOC., 1908, 30, 1233-1236.) -Five grams of the steel are dissolved in a 250-C.C. flask in 14 C.C. of sulphuric acid (1 : 1) and 25 to 30 C.C. of water.The insoluble residue is filtered off, washed with hot water, ignited, and treated with hydrofluoric acid to remove silica. In the mean- while, the filtrate is boiled down in a flask to a volume of 50 c.c., saturated with hydrogen sulphide, further concentrated to 35 c.c., and cooled. No crystals of ferrous sulphate should separate out at this point. The flask is then agitated, and 100 C.C. of alcohol are gradually added. After shaking the flask occasionally during five or ten minutes, the precipitated ferrous sulphate is filtered off, and washed with 75 per cent. alcohol. To the filtrate 100 C.C. of water and 15 to 20 C.C. of hydrogen peroxide are added, the whole is boiled to oxidise the small quantity of iron left in solution, and made slightly alkaline with sodium carbonate. After boiling for ten to fifteen minutes, the precipitate, which contains vanadium, iron, chromium, and manganese, is filtered off, and thoroughly washed with a 0.5 per cent.solution of sodium carbonate. The precipitate is ignited in the crucible containing the residue from the insoluble matter ( D . s . ) . The oxides are then fused at a low temperature with 5 grams of sodium carbonate, 0.3 to 0.4 gram of powdered charcoal is added, and the fusion continued for another ten minutes. The melt is then extracted with hot water, and the insoluble residue, which contains the whole of the chromium, washed with hot water. The filtrate (which may be slightly yellow from the presence of traces of sodium sulphide) is boiled with 20 C.C. of sulphuric acid (1 : 1) and 3 to 4 C.C.of a 3 per cent. solution of potassium permanganate. Sulphur dioxide is then added until the solution becomes blue, when it is evaporated to fuming. The solution is diluted with water to about 60 c.c., and titrahed warm with potassium permanganate solution, the vanadium being oxidised from V,O, to V,O,. A good qualitative test for vanadium is obtained by fusing the insoluble residue freed from silica, obtained as above, with sodium carbonate, acidifying the aqueous extract of the melt with nitric acid, and adding hydrogen peroxide, a pink colour indicating vanadium. About half the vanadium present is usually left in the insoluble residue. A. G. L. The Estimation of Vanadium, Molybdenum, Chromium, and Nickel in Steel. A. A. Blair. (Journ.Amer. Chem. SOC., 1908, 30, 1229-1233.)-Two grams of the steel are dissolved in nitric acid, with the addition, if necessary, of hydro- chloric acid. The solution is evaporated to dryness, the residue dissolved in hydrochloric acid, and this solution evaporatpd until syrupy. After diluting with a little hydrochloric acid of specific gravity 1.1, the bulk of the iron, together with the whole of the molybdenum present, is separated from hhe other metals by two extractions with ether. The extracted acid solution is evaporated nearly to dryness, nitric acid added, and the evaporation repeated, and the residue dissolved in 20 C.C.THE ANALYST, 413 of hot water. After adding a few drops of sulphur dioxide solution, the boiling solution is slowly poured, with vigorous stirring, into a boiling 10 per cent.solution of sodium hydroxide. The liquid is boiled for a few minutes, filtered, and the precipitate washed until the filtrate measures about 300 C.C. The filtrate is acidified with dilute nitric acid, made slightly alkaline with sodium hydroxide solution to precipitate traces of chromium still present, boiled, and filtered. The filtrate is heated to boiling, after adding 10 C.C. of a 10 per cent. solution of lead nitrate and an excess of acetic acid, and filtered. The precipitated lead vanadate is washed with hot water, and diesolved in hydrochloric acid. The solution is evaporated nearly to dryness, 50 C.C. of hydrochloric acid are added, the liquid is again evaporated, 10 C.C. of concentrated sulphuric acid are added, and the liquid is evaporated to fuming. The solution is diluted with water to 150 c.c., heated to 60" to 70" C ., and the vanadium is titrated with standard potassium permanganate solution, being oxidised from V,O, to V,O,. The two precipitates obtained with sodium hydroxide are ignited and fused with a mixture of sodium carbonate and potassium nitrate. The melt is extracted with water, the filtered solution concentrated after adding ammonium nitrate and a little ammonia, and again filtered to remove silica and oxides of manganese. In the filtrate chromium is precipitated by ammonia, after reducing with sulphur dioxide, and weighed as oxide. The insoluble matter from the fusion is dissolved in hydro- chloric acid, copper precipitated by hydrogen sulphide, the filtrate evaporated with sulphuric acid, made ammoniacal, and nickel deposited electrolytically. From the ethereal solution obtained above, iron and molybdenum are extracted with water. The aqueous solution is evaporated to fuming with 10 C.C. of sulphuric acid, 100 C.C. of water and an excess of ammonium bisulphite are added, and the excess of sulphur dioxide is boiled off. The cold solution is saturated with hydrogen sulphide in a 200-C.C. pressure-bottle, the bottle is closed, and heated on a water-bath for several hours, The molybdenum sulphide precipitated is filtered off on a Gooch crucible, washed first with dilute sulphuric acid, finally with alcohol, and ignited to constant weight, the Gooch crucible being placed on a triangle inside a larger porcelain crucible during the ignition in such a way that the Gooch crucible does not touch the porcelain crucible. The molybdenum trioxide is then dissolved in dilute ammonia, and the Gooch crucible again ignited and weighed, a little ferric oxide being always left in the crucible. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9083300409

出版商:RSC    

年代:1908

数据来源: RSC

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THE ANALYST, 413 APPARATUS, ETC. Huttner’s Vacuum-Jacketed Pipettes. G. Muller. (Chenz. Zeit., 1908, 32, 805.)-In pipetting off hot liquids, such as saturated salt solutions, trouble is frequently experienced from the separation of solid matters owing to the cooling of the liquid. This difficulty is overcome by con- structing the pipette with a vacuum-jacket (see figure), after the principle of Dewm’s tubes for liquefied gases. The vacuum-jacket provides an insulating envelope, which allows the liquid to retain its heat for a suffi- cient length of time whilst it is being measured off in the pipette. J. F. B.414 THE ANALYST. A Combined Aspirator and Condenser. H. Vigreux. (BUZZ. SOC. Chim., 1908 [iv.], 3,855-858.)-The condenser consists of a glass tube, B, with a series of constric- tions surrounded by an outer tube through which the water circulates.At the topof the outer tube is an aspirator, A , one branch of which, a, is attached by rubber tubing to the top of the inner tube, B, whilst the other branch, by is fused on to the outer tube. The water circulating through the latter enters the aspirator and creates suction sufficient to draw into the condenser anyvapours given off by a liquid beneath. The apparatus may thus be used as a reflux condenser for volatile liquids such as alcohol, ether, etc., without the necessity of connecting the vessel contain- ing them with the inner tube of the condenser. When it is desired to use the condenser for the evaporation of liquids, it is still used in the inverted position, but the inner tube is replaced by one in which there is an inner bulb to catch the condensed liquid, and this bulb communicates, by means of a side tubulure, with a boiling-tube. The liquid acoumulates in this, and seals the apparatus until the tube is full, when it passes by a side tube into a storage bottle.C. A. M. Use of Electric Heating in Fractional Distillation. T. W. Richards and J. H. Mathews. (Joum Aqner. Chenz. SOC., 1908, 30, 1282-1284.)-1n the usual method of heating by a gas-burner from outsid6 in fractional distillations, considerable super- heating necessarily occurs, and this is not entirely obviated by the use of capillary-tubes placed in the boiling liquid. The success of fractional distiIlations is obviously impaired by this superheating, because the temperzt- ture of the liquid should never exceed the true boiling-point of the mixture. The authors find that very little superheating occurs when the liquid is heated by means of an electric current passing through a suitable resistanceiwholly immersed in the liquid, and so this method might be expected to give a better separation than the ordinary methods.To oite one experiment, the authors found that 100 C.C. of dried normal butyl alcohol required six distillations (by ordinary gas heating) to obtain 75 C.C. of product ofTHE ANALYST. 415 boiling-point l l 7 O to 118' C., while two distillations by the electrical method sufficed to obtain the same quantity of a purer product boiling at 117.3" to 117.9" C. A heating resistance-coil may be immersed under the liquid in any ordinary distillation apparatus, but in order to economise material the authors used a stout distillation flask with side tube, in the bottom of which was blown a narrow cistern.Into this depression the heating-coil was introduced, consisting of 40 cm. of platinum wire (resistance =0.7 Ohm). A current of 10 to 15 amperes was led to the resistance wire from above by heavy copper wires encased in glass tubes, into the ends of which the ends of the platinum wire were sealed, contact being made by a drop of mercury. The copper wires must be heavy (of about 2-5 to 3.0 mm. diameter), so that they may not become heated by the current, and so superheat the vapour coming into contact with the glass tubes encasing them. The coil and mercury contacts must be entirely covered by the liquid at all times.Electrolytes may partially decompose when heated in this apparatus, and the method is therefore scarcely suitable for their distillation. The bubbles of vapour arise only from the small area of the hot resistance wire, and so ebullition proceeds quietly without any tendency to bumping. Thus the method is specially applicable to the heating of substances which are to be fractionated under reduced pressure, where explosive formation of vapour so frequently occurs. A. R. T. An Ice-making Machine. The Pulsometer Engineering Company, Reading. (Chem. Trade Journ., 1908, 43, 172.)-This ice-machine works on the principle that water freezes when rapidly evaporated by the joint action of a vacuum and powerful absorbent of water- vapour, such a6 sulphuric acid. The machine consists of the acid-container or absorber and the ice-mould, and is easily rocked (by hand) by means of the hand-wheel and crank, which also work the vacuum-pump. The machine is charged by pouring half a gallon of sulphuric acid into the absorber after removing its plug, which is then re- placed and held in position by means of springs, as shown in the figure. A flexible pipe connects the absorber with the ice-mould, and the nozzle of this pipe is introduced into the mould. The crank is then revolved gently at first, from 20 to 30 revolutions per minute after which the speed is increased to 100 revolutions, to thoroughly shake the acid. In a few minutes the formation of ice commences, and when the frost outside the ice-mould extends to its under-side the water contained in it will be found to be frozen solid. The machine occupies only a small space, and yields 1 lb. blocks of ice in twenty minutes. A. R. T.

ISSN:0003-2654    

DOI:10.1039/AN9083300413

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

416 THE ANALYST. “ TENDERING” FOR PUBLIC APPOINTMENTS. THE Metropolitan Borough of Shoreditch and the City of York, having recentIy advertised inviting applications for the position of Public Analyst, and asking candi- dates to state the terms on which they would be prepared to accept such appoint- ments, the following letter has been addressed to the Town Clerks of the two authorities in question, by the Registrar of the Institute of Chemistry : Septcnzbcr 19, 1908. DEAR SIR, The attention of the Institute of Chemistry has heen directed to the terms of an announcement to the effect that the Council of the Metropolitan Borough of Shoreditch is about to appoint a Public Analyst in the place of the late Sir Thomas Stevenson. The Council of the Institute, while feeling that they need not impress on the Borough Council the great importance of securing the services of a fully competent analyst, desire me to express their regret that the appointment should have been offered in terms which might suggest that it is to be given to the candidate making the lowest tender.My Council venture to express the opinion that, in the case of an appointment of this kind, the qualifications for which are of a purely personal character, the system of inviting professional men to tender for an appointment has the effect of lowering the status of their profession, to the detriment of the public service. It precludes, and in this case has precluded, many ansllysts of repute from becoming candidates for the appointment, and therefore limits the selection; while it is not likely that the Borough Council will secure the services of the best man by entrusting the position to the practitioner who places the least value on his skill, experience, and professional position.I am desired to request you kindly to bring this letter to the notice of the Borough Council when the appointment in question is under consideration. I beg to remain, dear Sir, Yours faithfully, (Signed) RICHARD B. PILCHER, Registrar and Secretary. At a special Council Meeting of the Society of Public Analysts and other Analytical Chemists held on October 1, the above matter was discussed, and the following resolution unanimously carried : 6 ‘ The Council has had under consideration the practice which has been adopted recently by certain public bodies of inviting applicants for the office of Public Analyst to state the terms upon which they are prepared to accept such appointments, “The Council is of opinion that it is against the interests of the public and degrading to the profession of analytical chemistry for appointments to be offered ‘ on tender,’ and calls upon the Members of the Society to resist the practice.”

ISSN:0003-2654    

DOI:10.1039/AN9083300416

出版商:RSC    

年代:1908

数据来源: RSC