摘要:

MARCH, 1008. Vol. XXXIII., No. 384. THE ANALYST. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. THE annual general meeting of the Society was held on Wednesday evening, February 5 , in the Chemical Society’s Rooms, Burlington House. The President, Mr. E. J. Bevan, occupied the chair. The minutes of the previous annual general meeting were read and confirmed. hlessrs. H. Droop Richmond and John Golding were appointed Scrutators of the ballot-papers for the election of Officers and Council for 1908. The HON. TREASURER presented the accounts of the Society for 1907. These were adopted, and votes of thanks were passed to the Hon. Treasurer, Auditors, and Hon. Secretaries. On the motion of the PRESIUEET, a vote of thanks was passed to the President and Council of the Chemical Society for their kindness in allowing the Society the use of their roonis at Burlington House during the past year.The PI~ESIDENT delivered his annual address. The scrutators having reported that the Officers and Council for 1908 had been elected in accordance with the nominations announced at the last ordinary meeting, hlr. BEVAN vacated the chair in favour of the newly elected President, Mr. R. It. Tatlock. Rlr. TATLOCK said that he was glad to have an early opportunity of offering his sincere thanks to the Council for their kindness in nominating him and making arrangements for his appointment. The distinguished names of his predecessors, his great distance from London, and his advancing age, made him enter upon his ofice with hesitation and diffidence; but the Council had extended to him so much encouragement and kind consideration that he hoped, with their co-operation and that of the members generally, to be able in a small way to assist in the direction of the affairs of the Society and the promotion of its welfare.Mr. HEHNER, after welcoming the new President in the name of his colleagues, moved that a hearty vote of thanks be accorded to Mr. Bevan for his address and for his services in the chair, and that his permission be asked to print the address in THE AN.4LYST. Dr. RIDEAL seconded, and the motion was carried with acclamation.74 THE ANALYST. Mr. BEVAN having responded, Mr. TATLOCK read the list of Officers and Council President.--13. R. Tatlock. Past-Presidents (limited by the Society’s Articles of Association *to eight in number),-M.A. Adams, F.R.C.S. : E. J. Bevan ; Bernard Dyer, D.Sc. ; Thomas Fairley ; W. W. Fisher, M.A. ; Otto Hehner ; Sir Thomas Stevenson, M.D., F.R.C.I’. ; J. Augustus Voelcker, M.A., B.Sc., Ph.D. elected for 1908 as follows : Vzce-PmsicZe?zts.-A Bostock Hill, M.D. ; E. W. T. Jones ; John White. Hon. Treaswer.-E. W. T‘oelcker, A.R.S.M. Hon. Scc~etarics.-Alfred C, Chapman ; P. A. Ellis Richards. Othw MenLbew of CounciZ.-Bertrain Blount ; Cecil H. Cribb, R.Sc. ; J . T. Dunn., D.Sc. ; A. E. Ekins; John Golding ; J. T. Hewitt, D.Sc., Ph.D., MA. ; Arthur R. Ling; L. Myddelton &ash; F. W. Richardson; H. Droop Richmond; G. E. Scott Smith; L. W. Stansell. The ordinary monthly meeting of the Society immediately followed the annual meeting.The minutes of the previous ordinary meeting were read and confirmed. Certificates of proposal for election to membership in favour of Messrs. Charles E. Cassal, F.I.C. ; J. Kear Colwell, F.I. C. ; F. Dent, M.Sc., Ph.D., F.I.C. ; R. Doresa, F.I.C. ; F. S. Earp, M.A., Ph.D., F.I.C. ; and Rudolf Lessing, were read for the second time; and certificates in favour of Messrs. Robert Barton, jun., 48, Wellclose Mount, Leeds, assistant to Rlr. G. W. Slatter; Harold G. Colman, Ph.D. (Wiirz- burg), M.Sc. (Manchester), F.I.C., I, Arundel Street, Strand, JV.C., analytical and consulting chemist ; Frank William Harbord, A.R. S.M., F.I.C., 16, TTictoria Street, Westminster, S. W., analytical and consulting chemist ; Herbert Procter Smith, Shotton Lane, Shotton, Flintshire, chief chemist to Messrs. John Summers and Sons, Ltd., Shotton ; Thomas Tyrer, F.I.C., Sterling Chemical Works, Stratford, l<;. , manufacturing chemist ; and William Henry Withey, B. A. (Cantab.), 85, Lambetli I’alace Road, S.E., analytical chemist, were read for the first time. Messrs. F. H. Duprd, P. IT. Dupr;, J . C. Kirkaldy, and I{. H. Merritt, B.Sc., were elected members of the Society. The following papers were read : “ English Inks : their Composition and DifYerentiation in Handwriting,” by C. A. Mitchell, B.9., F.I.C. ; ‘‘ The Constitution of Indicators,” by J. T, Hewitt, I>.%, Ph.D., M.A. The President, RIr. R. R. Tatlock, occupied the chair.

ISSN:0003-2654    

DOI:10.1039/AN9083300073

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 75 A N N U A L ADDRESS OF T H E RETIRING PRESIDENT. (Deli wred at the Aniaucd General Meeting, Febi*z&nry 5, 1908.) BY reason of an event which we all deplore, it is my duty to address you as President for the third time. When my term of office expired in 1907, you elected as my successor Dr. John Clark, of Glasgow. Most unfortunately, soon after his appoint- ment, he was stricken with an illness from which he never recovered. His death was a serious loss to the Society. During the short period in which it was my privilege to make his personal acquaintance, he struck me as one who, by his charm of manner and wide knowledge of the world, was eminently suitable to be President of our Society, and would, had he lived, have largely added to the number of his friends, and would, I feel sure, have advanced our interests.When, unfortu- nately, his illness terminated in death, your Council, in the exercise of their powers, decided to appoint me to fill the interregnum, and I felt it a great honour to accede to their wishes. Besides the loss of Ur. Clark, which, coining so soon after that of our Editor, Dr. Sykes, was particularly sad, we have, unfortunately, lost by death during the past session three members-viz., our old and esteemed friend and Past-President, Dr. Duprk, and Messrs. Page and Macfarlane. Although by death and resignations we lose fourteen members, yet we can congratulate ourselves on the fact that our total membership shows an increase. \Vhen I addressed you in 1907 our total membership was 329; it is now 338, and I sincerely hope it will go on increasing.Last year I referred to the fact that the Society was in it state of transition. I now have the honour to address you as President of the Society of Public Analysts and other Analytical Chemists. I t is my sincere hope, and I believe the wish of all present, that under its new title the Society will continue to prosper even more than it has in the past. I t is satisfactory to know that owing to the alteration in tbe name and scope of the Society, at least one member who formerly belonged to the Society, but who had resigned, has rejoined, and others, who had held aloof because of what they thought to be the restricted aims of the Society, have signified their intention of applying for membership. I would take this opportunity of urging members to induce their friends who have aims in common with ourselves to apply for membership, so that we may become more powerful and useful. There is, undoubtedly, a considerable number of the members of our profession who have not yet joined our ranks, but who, under the new arrangement, would be eligible, and whom we should be very glad to welcome.Though the scope of the Society has been widened, the regulations with regard to membership are, in my opinion, so framed as to prevent the election of any undesirable person. I t is gratifying to know that the reconstitution of the Society has been effected with the minimum of friction. During the past session seven meetings have been held, apart from the meetings necessary for the change of name, at which the following twenty-two papers were read :76 THE ANALYST, February 6, 1907.‘‘ Mineral’Acids in Vinegar.” “ The Composition of English Fermentation Vinegar.” ‘ I The Detection of Cane-Sugar in Milk.” By W. H. Anderson (communicated by By F. D. Ratcliff. By F. D. Ratcliff. H. Droop Richmond, F.I.C.). Mmdz 6, 1907. [‘ The Disposition and Analyses of Sewage Matters deposited on Superposed “ The Composition of Milk.” “Preservatives in Milk and Milk Products ”: (1) ‘( The Souring of Milk and the Effect of Preservatives thereon ; (2) ‘( Notes on the Detection and Estimation of Preservatives.” Surfaces.” By W. J. Dibdin, F.I.C. By H. Droop Richmond, F.I.C. By H. Droop Richmond, F.I.C., and E. H. Miller. April 10, 1907. ‘‘ The Bacterial Estimation of Phenol and Cresol.” “ A New Method for the Estimation of Tartaric Acid.” “The Detection of Cocoanut Oil in Butter.” By M.Wynter Blyth, B.A., By Alfred Chaston B.Sc., F.I.C., and L. Goodban. Chapman, F.I.C., and Percy Whitteridge, B.Sc. By T”. Hinks, B.Sc., F.I.C. *?ray 1, 1907. ( ( The Composition of Irish Butter during the Winter Months.” By J. Handby ‘‘ The Estimation of Lime and Uagnesia in Water by Volumetric Methods.” “ A Further Communication on the Valuation of Oils used for Gas-making By Raymond Ross, F.I.C., and ?J. P. Leather. ‘‘ The Estimation of Minute Traces of Arsenic by the Marsh-Berzelius Method.” Ball, B.Sc., -4.I.C. By W. T. Burgess, F.I.C. Purposes.” By Alfred Chaston Chapman, F.I.C. ‘‘ Note on Horse Fat and ‘ Animal ’ Oil.” By Harry Dunlop.[‘ X Method for Determining Caustic Lime in Fertilisers.” ‘ 6 The Rapid Estimation of Total Solids in Milk.” ‘‘ The Estimation of Salicylic Acid in Milk and Cream.” By Cecil Revis and “The Reducing Action of Hydrogen”: (3) “The Reduction of Molybdic and By Alfred Chaston Chapman, F.I.C., and H. D. Law, I3.Sc. “The Action of Dimethyl Sulphate (Valenta’s Reagent) upon Oils of the Aromatic and Aliphatic Series.” By Thomas W. Harrison, B.Sc., and Frederick M. Perkin, Ph,D., F.I.C. By Thoinas W. Harrison, B. Sc., and Frederick IT. Perkin, Ph.D., F.I.C. June 5 , 1907. By James Hendrick, B.Sc., F.I.C. By Cecil Revis. George Arthur Payne. Vanadic Acids.” Deccmbcr 4, 1307. (‘ Titration with Permanganate in Presence of Hydrochloric Acid.”Routine Methods R.Tankard. l ‘ The Quantitative Kahan. THE ANALYST. 77 for the Bacteriological Examination of Water.’’ By Arnold Separation of Barium from Strontium.” By Miss Zelda I n addition to these meetings, one evening was devoted to the important subject of the ‘‘ Sealing of Samples.” The discussion was opened by Mr. H. Droop Richmond, and representatives of the Local Government Board, the Board of Agriculture and Fisheries, and the Government Laboratory, took part. Though some prominent members were of opinion that the matter was not a serious one, the meeting generally held the view that a case had been made out for action to be taken, and in this I concur. Among the papers which were read, some were the outcome of the Analytical Investigation Scheme. I have spoken in previous addresses of this scheme, and a full account of its present state will be found in the forthcoming number of THE ANALYST. The honorary secretaries inform me that several investigations are pro- ceeding, and I think we may look forward to satisfactory progress.Naturally, considerable outlay for chemicals and apparatus is entailed, and I appeal to the generosity of members of the Society for pecuniary assistance. You have already heard that the financial condition if the Society is satisfactory. This is largely due to the care exercised by our hon. treasurer. THE ANALYST continues, under the editorship of Mr. Julian L. Baker, the successor of the late Dr. Sykes, to be a credit to the Society. The Council has from time to time discussed matters of interest to members.In this connection I may perhaps mention one of pecuniary interest to those chemists who employ assistants. I refer to the Employers’ Liability Act, which came into force on July 1, 1907. Owing to the far-reaching provisions of that Act, it became of the utmost importance for analysts to.insure members of their staffs against accident. This was, however, in the opinion of the Parliamentary Committee who met to consider the matter, an extravagant amount ; and representations having been made to the companies on the subject, the rate was reduced to 10s. per cent. Even this greatly reduced rate is, in my opinion, excessive, and I hope to see it still further reduced. At least one company, which is outside the tariff, is prepared at the present moment to effect insurances at a considerably lower rate than 10s.On January 1 of this year the Butter and Margarine Act of 1907 came into force. r d o not propose to discuss this Act at any length, but I would point out that it contains several clauses which are important from the view of the Public Analyst. Thus, according to Section 7, Subsection 1, “The Local Government Board may, after such inquiry as they deem necessary, make regulations for prohibiting the use a6 a preservative of any substance specified in such regulations in the manufacture or preparation for sale of butter, margarine, or milk-blended butter, or for limiting the extent to which, either generally or as regards any particular substance or substances, preservatives may be used in the manufacture or prepaxation for sale of butter, margarine, or milk-blended butter.” This represents the sum total of the The insurance companies decided to fix the rate at XI per cent.78 THE ANALYSTo legislative wisdom which the Local Government Board has brought to bear on the question of the use of preservatives in butter and margarine during the period of seven years since the Report of the Departmental Committee on the use of pre- servatives and colouring matters in the preservation and colouring of food was published.Let us hope that the Board will deem an inquiry necessary, and that they will act upon it without further delay. I t would appear to the ordinary non- political, non-departmental mind that such an inquiry had already been held. However, Government departments move in a mysterious way, and we must be content to know that the subject is still under consideration.With the exception of the Circular issued in July, 1906, by the Local Govern- ment Board with regard to the use of preservatives in milk, nothing has been done to give legal effect to the recommendations of the Committee. Though we are grateful for the crumb this Circular represents, we cannot but regret the continued inaction of the Board, especially when it is remembered that they already possess the necessary powers. I n saying this, I should like to point out that I do not think this inaction should be laid at the door of any of those officers of the Board, with whom we have always had the most cordial relationships. To my mind, it is highly undesirable that the duty of fixing the minimum amounts of preservatives, aetc., permissible in foods should be left to individual Public Analysts.Such a condition of things hampers the course of justice, and not infrequently is conducive to the display of unedifying disputes and differences of opinion between members of our profession. I t may be of interest to members to know that in April of last year the Board of Agriculture and Fisheries expressed the opinion ‘‘ that the administration of the Fertilisers and Feeding Stuffs Acts, 1906, would be matetially assisted by the exercise of the power to make regulations as to the manner in which analyses are to be made which is conferred upon them by Section 4 (1) ( c ) of the Act.” A Com- mittee was appointed, consisting of Dr..T. E. Thorpe, C.B., W.R.S., chairman, the late Dr. Clark, and myself (nominated by the Society), Dr. Bernard Dyer, Mr. A. D. Hall, M.A., Professor Kinch (nominated by the Chemical Society), and Dr. J. A. Voelcker. A number of meetings were held and a report agreed upon, which will probably shortly be published. I t is, I think, a matter for congratulation that the assistance of the Society was sought in this important matter. At this point I would like to call attention to a recently published report by Dr. Buchanan on ‘( Certain Imported Meat Foods of, Questionable Wholesomeness,” and particularly to that section dealing with the use of preservatives. Dr. Buchanan points out that certain meats (tripe) are imported into this country containing sometimes as much as 2-14 per cent. of boracic acid.He concludes his report by indicating the desirability of action by the Board under the Public Health Regula- tions as to Food Act, 1907, to prevent the introduction from abroad at English ports of such articles of food. Let us hope that Dr. Buchanan’s labours may not be in vain. Not only do such conditions as have been indicated exist, but I am informed that considerable quantities of meat have been recently imported largely dosed with formalin. During the past year a very important work-the ‘‘ British PharmaceuticalTHE ANALYST. 79 Codes "-has been issued by the Pharmaceutical Society. Although naturally con- taining errors incidental to the issue of such a volume, it is on the whole a great improvement on the more or less stereotyped British Pharmacopceia, and is much more likely to command the respect of analysts than is the older publication. If I have achieved any success a8 President, it is due to the cordial and loyal assistance I have had from the officers and Council and members generally, and to them I offer my most hearty thanks. My last duty, and if is a pleasure also, is to introduce to you my successor, Mr. Tatlock. His name has long been familiar as a household word in the mouths of analysts. Under his guidance and direction I hope that the Society will continue to prosper as it has in the past, and I know that niy hopes will be fully realised. a + @ * * * My duties as President are now nearly over.

ISSN:0003-2654    

DOI:10.1039/AN9083300075

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. I known, and the more granular naturz of the cement facilitated manipulation. I n the original form the lower bulb had a capacity of about 1,500 grains and that of the upper bulb exactly 1,000 grains water measure at normal temperature. 79 A MODIFIED KEATES’ SPECIFIC GRAVITY BOTTLE FOR CEMENT TESTING, ETC. BY W. J. DIBDIN, F.I.C. the introduction of the cement and subsequent cleansing, the constriction between the two bulbs, I~IUDIS-KEATES BOTTLE. as well as the neck of the bottle, was enlarged. .In its present form the lower bulb has a capacity of 75 C.C. and the upper 25 c.c., the diameter of the neck and con-80 THE ANALYST. striction being 12 mm. The effect of this modification is such that the finest cements are easily manipulated, whilst the advantages of the original form are unimpaired. + * * 45 4-

ISSN:0003-2654    

DOI:10.1039/AN9083300079

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. ENGLISH INKS : THEIR COMPOSITION AND DIFFERENTIATION IN HANDWRITING. BY C. A. MITCHELL, B.A., F.I.C. (Beat7 at the Meeting, Febwary 5, 1908.) IN the following paper I have dealt chiefly with the differentiation of inks, more especially when forming the dried pigment in handwriting; and as I wished to describe characteristic reactions given by the products of the manufacturers whoiu I have named, I have purposely refrained from drawing conclusions as to the relative merits of the various preparations. I n the old type of iron-gall inks-those in which partial oxidation was made to take place before bottling-there could not have been very marked differences, except such as would result from the use of varying proportions of galls, ferrous sulphate, or gum; Hence, as a rule, it would have been practically impossible to distinguish with any degree of certainty between the characters made by two such inks.This old type o€ ink is now rarely met with, having been all but sbperseded by the modern unoxidised inks, in which a ‘‘ provisional ” colouring matter is intro- duced to give some colour to the writing, pending the formation of the black insoluble tannate within the fibres of the paper. I t is true that added dye-stuffs were sometimes employed to improve the colour of inks of the old type, and the use of indigo for this purpose is mentioned by Eisler (1770); and of logwood by Lewis (1763) ; but the inks themselves were still more or less oxidised before use, and it was not until early in the nineteenth century that indigo or logwood was used for their modern purpose of rendering the writing immediately visible.Alizarine was also employed as a provisional colouring matter in Germany, and although it soon gave place to indigo, the unoxidised inks into which it was introduced have retained their original name of ‘( alizarine inks ” to the present day. The discovery of the aniline dye-stuffs added largely to the provisional colouring matters at the disposal of the ink-manufacturer, and such dyes are now found in most of the blue-black inks of to-day. There is a considerable variation in the proportion of solid matter and of iron to organic matter in commercial writing fluids, as will be seen in the following table, giving the results of partial analyses made during the past twelve months of the best-known preparations.Most of these are iron-gall inks, but the list also includes samples of chrome-logwood and aniline inks. I take this opportunity of thanking those manufacturers who have kindly placed specimens of their preparations at my di apo s a1 .THE ANALYST. ~.-COMPOSITION OF ENGLISH WRITING INKS. 81 Ink. Arnold’s Blue-black ... Blackwood’s Blue-black . . . . . . Day and Martin’s Biue -black Draper’s ( ( Dichroic ” ... Faher’s Blue-black . . . ), Black ... ... Field’s ‘‘ Non-corrosive ” . . . Halsey’s Blue-black ... Lyon’s Blue-black . . . . . . Rlordtln’s “ Azuryte” ... ?, Blue-black ... “ Jet-black ” ... 11or;ell’s Blue-black ... Paul’s Blue-black . . . ... Black ... ... Prihge’s Blue-black . . . StephenR’ Blue-black * . . T’icker’s Penwing ” ... Walkden’s Blue-black .. . ,) Black ... ... ‘‘ Record ” Carr’iblue-black . . . ... Black ... ... ... ,, Black ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... Specifie Gravity a t 15” C. 1.0216 - - 1,0220 1.0244 - - 1-0205 1.0153 1.0121 1.0208 1.0239 1.0225 1.0256 1.0276 I - - 1.0499 1.0206 1.0221 1.0293 - - Water Per Cent. 96.35 96-82 92.06 96.01 95-84 92-25 95-16 95.58 96.66 97.55 95.34 95.14 95.94 95-54 94.04 95.1 G 96-12 96.68 92.22 92.32 96.21 98.11 95-58 94.39 Total Solids per Cent. 3.65 3.18 7-94 3.99 4.16 7.75 4.84 4-42 3.34 2-45 4.66 4.86 4.06 4-46 5.96 4.84 3.88 3.32 7-88 7.70 3-79 1.89 4.42 5.61 Mineral Matter per Cent. (Ash) 0-94 0.77 1.40 1.07 1.39 2.52 1.10 1.22 0.82 0.64 0.54 1-01 0.86 0.62 0.99 1 -66 0.97 2.28 1-88 1 *42 0.76 0.42 0.72 1.12 Iron per Cent.0.25 0.28 0.59 0.29 0.48 1.09 trace 0.49 trace 0.28 0.28 0.35 0.29 0.18 0.21 0.56 0.33 trace 0.84 0.49 0.32 trace 0.22 0.36 These results show that, notwithstanding the probably closely similar methods of preparation, there are yet wide variations in the composition of the different inks. Thus, the total amount of solid matter (dried at 100’ C.) ranges from 1-89 to 7.94 per cent., the ash from 0.42 to 2.52 per cent., and the iron in the iron-gall inks from 0.18 to 1.09 per cent. From time to time during the past five years I have examined samples of several of the different kinds of inks mentioned in the table, and the results indicate that the composition of an individual preparation by the same manufacturer remains fairly constant.I have been unable to devise any satisfactory method of estimating gallotannic acid and allied substancespresent in ink. A method of absorption by means of hide powder might yield satisfactory results if gallic acid were not also a usual con- stituent. On the other hand, the #‘ provisional ” colouring matter in inks interferes with the estimation of the gallotannic and gallic acids together by the colorimetric method which I devised for the valuation of tannin materials for ink-making (‘‘ Inks and their Manufacture,” p. 85).82 THE ANALYST. The tannin in freshly-prepared ink appears to be in the form of a soluble iron tannate, which slowly oxidises on contact with air, forming an insoluble tannate. I have frequently examined the deposit which forms when a solution of gallotannic acid and ferrous sulphate is allowed to stand in contact with the air, and have found that when washed with cold water and dried at 100" C.it yields from 7.8 to 8.8 per cent. of ferric oxide, corresponding to 5 4 to 6-54 per cent. of iron. Of the known insoluble iron tannates, the one that corresponds best with this proportion of iron is that described by Wittstein (Jnlzi*csber. der Cheiiz., 1848, 28, 221) and by Schiff' ( A m . Chem. Phawn., 1875, 175, 176), which contains 5-53 per cent. of iron, and has the formula- Fe ( w w 3 > 3 I If, as seems probable, this is the tannate formed in the gradual darkeningof ink upon paper, any excess of iron or gallotanic acid beyond the quantities required to forill this compound should be unnecessary, or even injurious, to the permanence of the writing.The dye-stuffs in the blue-black inks referred to in Table I. varied in colour froiii pale greenish-blue to indigo and deep violet, md no two gave identical reactions-at all events, when mixed with the iron tannate to form the pigment in writing. It is mainly owing to these differences that it becomes possible to distinguish between the handwriting done with different kinds of ink, and in some cases it is not even necessary to apply chemical tests for the purpose. Thus, in the case of words written with inks having respectively an azure blue and an indigo colour while wet, it is easy to distinguish the colours under the microscope months after the writing has attained its maximum intensity.I n examining writing to determine whether it has been done with a particular ink, it is advisable to prepare a colour scale with that ink, consisting of four washes ranging from the faintest to the darkest possible tone, the paper being left for at least twenty-four hours. The scale is then compared under the microscope with different parts of the writing in question, and is subsequently used in comparative chemical tests when such are permissible. The broad surfaces of colour are comparable with the surfaces of the written characters a6 seen under the microscope, and there is thus obtained what practically amounts to a magnified record of the microscopical appearance. Lovibond's tintometer will also be found useful in coinparing different speciineiis of handwriting and matching the colours obtained in chemical reactions with those given by the colour scales prepared from known or suspected inks.With regard to the use of photography as a means of differentiating inks in writing, I have made numerous experiments with colour-sensitive plates and screens, but find that the differences of intensity shown in the negatives are no greater than may be seen with the naked eye. I am, therefore, unable to confirm Minovici's (B~ill. della SOC. Fotogra$a Itnl., 1900, 12, 349) experience in this respect.THE ANALYST. 83 For the differentiation of inks in handwriting by chemical methods a wide choice of reagents is available, but those I have used will, as a rule, be found sufficient, viz. : 1. Hydrochloric acid (5 per cent.solution). 2. Oxalic acid (5 per cent. solution). 3. Stannous chloride (10 per cent. solution). 4. Nascent hydrogen (50 per cent. HC1 with zinc). 5. Bromine (saturated aqueous solution). 6. Bleaching powder (saturated solution). 7. Titanous chloride (the impure commercial solution). 8. Potassium ferrocyanide ( 5 per cent. solution containing 1 per cent. of HCl). Of these reagents, the two first act mainly upon the iron tannate, and leave the provisional colouring matter. The third and fourth bleach the iron tannate, and reduce the provisional pigment, changing its colour. The fifth and sixth reagents may act on both pigments, causing more or less superficial bleaching. The titanous chloride solution is a powerful reducing agent towards both pigments, whilst the acidified ferrocyanide solution acts mainly upon the iron liberated from the iron tannate.I n the table on p. 84, showing the reactions given by my samples of commercial inks, the reagents were applied by means of a brush, and the writing examined under the microscope both by reflected and by transmitted light, first after five minutes’, and again after twelve hours’, exposure to the air. The colorations which appeared upon the wrong side of the paper were sometimes also very characteristic, especially in cases where there had been superficial bleaching. In the tests with titanous chloride, blotting-paper was applied after the lapse of five minutes. I had recently to decide whether two specimens of handwriting were in the same ink and were done at one and the same time.The first question was easily solved, but from the results of my experiments I found that it was not possible to dis- tinguish between inks after they had attained their maximum degree of intensity, or until after the provisional colour had begun the fade. I t is, as a rule, possible to distinguish colorirnetrically between freshly written and old writings up to about the sixth day, after which the iron tannate has become almost completely oxidised, and differentiation is no longer possible until after the lapse of a year or more, according to the degree of permanency of the provisional pigment. As a rule, the pigments employed offer greater resistance to the action of chemical reagents, but are infinitely less stable than iron tannate when exposed to the action of light and air, and eloquent testimony to this difference is given by a comparison of certain manuscripts of the seventh and eighth centuries with type-written documents which have been put aside for a year or two.II.-REACTIONS GIVEN BY ENGLISH INKS IN HANDWRITING.Hydrochloric Acid, 5 per Cent.. Oxalic Acid, 5 per Cent. Stannous Chloride, 10 per Cent, Xascent Hydrogen. Bromine (Aqueous Solution). Bleaching Powder. Titanous Chloride. Potassium Ferro- cyanide, 5 per Cent., +HC1,1 per Cent. Inks. Dry. Dry. Dry. Moist. Dry. Moist. Moist. JIoist. Moist. Dry. Moist. Dry. Moist. Dry. Moist. DW. Arnold‘s Blue-black Blackwood’s Blue-blacl >, ‘’ Record ’ Carr’s Blue-black :, Black Blue-black j Day and Martin’s Draper’s ‘‘ Dichroic ” Faber’s Blue-black Sreenish- blue bright blue gray dark blue Larkened deep blue deep violet light blue purple deep blue bright blue deep blue bright blue bright blue larkened bright blue light blue deep blue bright blue blue deep blue reddened bright blue blue- black green- blue blue dark blue violet- gray deep blue deep violet blue deep violet deep blue bright blue bright blue blue blue blue- gray bright blue blue violet- black green- blue dull blue green- blue pink- brown bright blue blue- black green- blue bright blue light gray blue gray gray- blue red- violet bright blue purple deep blue blue bright blue bright blue bright blue gray bright blue bright blue deep blue bright blue green- blue deep blue pink- violet blue gray- violet green- blue blue pink- gray blue gray- violet green- blue red- violet bright blue pink deep biue green- blue bright blue bright blue bright blue gray bright blue bright blue green- gray pale blue Gay - blue green- blue red- pink light blue gray- violet blue- violet bright blue gray iurple- blue blue- gray deep blue violet bright blue purple violet- blue violet- blue blue bright blue bright blue light gray violet- blue bright blue rose, then Ileach’r light green- blue light green- blue violet blne- violet bright blue violet- black lilac violet Fellow- gray deep violet violet- gray deep violet mauve light bltie violet deep violet violet- blue bright blue bright blue bright blue light gray deep violet bright violet cream pale mauve blue- gray lilac pink bright violet gray- violet violet bright blue nsarly >leached violet blue- gray mauve violet bright blue red- purple violet violet blue bright blue blue light gray violet light blue deep violet- blue bright blue light green- blue violet- blue pink- violet blue gray- violet violet violet pale pink violet blue- gray mauve pink- violet green- blue red- violet violet violet violet- blue bright blue blue light blue- gray deep violet light violet violet- gray blue g.ray- violet mauve red- pink violet grag- violet deep violet deep blue little action dark blue black deep blue violet - black bright blue deep purple deep blue larkened dark blue dark purple Larkened larkened deep blue deep blue blue, some deac hing deep blue dark blue slight ileachin€ surface de.*ching blue blue black violet-black blue smudged dark blue violet -black deep blue violet-black blue with ilack patches deep violet greenish deep blue slight bleaching slight bleaching gray- black nearly black yellow on violet deep blue, some bleaching deep purple, some bleaching surfacc bleachin% surface bleaching slight b!eachin g slight bleaching bleaching d it r k e n e d surface bleaching deep blue little change blue-gray slight bleaching gray ana black yellow on violet blue with light patches yellow over violet yellow on blue yellow on blue green-gray black spot; nearly black gray and black blue-gray deep blue deep blue fawn stain nearly black dark blue, gray smudge zone yellow on blue yellow and black deep blue black lirty green peen-blue light orange blue-gray dark brown lark gray- blue deep maroon Ireen-blue purple- bro w n navy blue blue-gray deep blue lsrk green- gray leep graen light brown icep green- blue peen-gray bleached )live-green yellow- gray nearly black maroon gray-blue green-gray green- brown green- brown orange )live-green brown yellow- brown -ose-brown orange .ose-brown yellow- brown gray dark olive- green green- brown brown red-brown lark olive- yellow green - brown dirty yellow yellow - brown olive- brown brown violet- black gray gmy- brown IJUl’ple - bright green-blue r i g h t blue green- black deep blue deep blue nearly black deep violet )right blue deep purple blue green-blue deep blue dark blue deep blue green-gray indigo- blue bright blue deep blue- black deep blue green-blue deep green-blue deep violet black dark blue green- black :reen-blue blue peen and black deep blue deep blue deep blue green- violet peen-blue ;, Black ose-brown Field’s ( ( Non-corrosive Halsey’s Blue-black Lyon’s Blue-black Mordan’s ‘ ‘ Azuryte ’’ ,, Blue-black ,, “Jet-black’ deep blue dark blue dark blue dark piwple mrple-black blue-gray ;reen-blue light green-blue deep blue dark blue deep blue green-gray Morrell’s Blue-black Paul’s Blue-black ,, Black deep blue deep blue gray slight bleaching deep blue bleached blue blue black Pridge’s Blue-black nearly black deep blue green-blue ,, Black very dark blue-gray smudge deep blue yellow and black gray.blue blue-black dark blue blue-green Stephens’ Blue-black Vicker’s ‘( Penwing ” Walkden’s Blue-black ,, Black surface bleaching surface bleaching surface bleaching nearly black green-blue ?iink-brown blue blue and blackTHE ANALYST.85 DISCUSSION. Mr. E. R. BOLTON asked if the author had made any use of starch-grain plates in his photographic experiments. Mr. CHAPMAN said that in determining tannin in hops, he had found it satis- factory to precipitate the tannin as cinchonine tannate. Possibly in the case of inks also that method might be useful for the separation of the tannic acid from the gallic acid, as cinchonine tannate was very insoluble, whereas the gallate was soluble. I t was perhaps not very widely known that titanous chloride was now a compara- tively cheap reagent. The ordinary solution to which Mr. Mitchell had referred contained a littie lead, but otherwise was tolerably pure, while the perfectly pure salt was not prohibitively expensive. It was a very useful reagent in the estimation of iron, etc., being a much more powerful reducing agent than stannous chloride. The PRESIDENT asked if the author knew of any black or blue-black ink that was absolutely indelible to ordinary bleaching agents. He himself had never met with one capable of resisting the action of potassium permanganate followed by sulphurous acid. Mr. MITCHELL, in reply, said he did not know of a blue-black ink that would withstand any powerful bleaching agent. Certain type-writing inks which were impregnated with fine carbon might be taken as practically permanent in this respect, and all the so-called “ safety ” inks contained such an admixture of carbon. A thoroughly well-made iron-gall ink, however, would be permanent for eight or ten centuries, and in Germany the use of such inks for official documents was insisted upon. With regard to photography, he had used only ordinary and Cadett spectrum plates, with the ‘‘ absolutus ” screen, and here, as he had said, no greater difference in intensity was obtained than was apparent to the naked eye. The method suggested by Mr. Chapman for the estimation of gallo-tannic and gallic acids did not overcome the difficulty caused by the provisional colour.

ISSN:0003-2654    

DOI:10.1039/AN9083300080

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 85 THE CONSTITUTION OF INDICATORS USED IN ACIDIMETRY. BY JOHN THEODORE HEWITT, D.Sc., PH.D., &LA. (Read at tlic Meeting, Febrziary 5 , 1908.) IN the course of the last few years the question of indicators has received con- siderable attention, for not only does the matter appeal to the chemist from the practical point of view, but affords material for much scientific investigation. Two hypotheses have been employed in attacking the problem of why 8 substance behaves as an indicator. On the one hand we have the physico-chemical considerations of Ostwald, which more particularly concern the dissociation-constants of the indi- cators; on the other hand, the possible changes in the constitution of the indicating substance when it undergoes salt formation. From whichever standpoint we start, we have to remember that our indicators are either acidic or basic substances.0 s t wald's remarks concerning indicators (Le hrbuc h der a1 lgeme in e u Chemie, 1891, i. 799, and Wissenschnftliche Grundlagen der analytischen Chenzie, 1901,86 THE ANALYST. p. 117) show plainly how the subject must be treated from this standpoint. ing to this view, methyl orange is an acid of medium strength. (CH,),N.C,H,.N : N.C,H,.S03' and H., of which the former exhibits a yellow cdour. The undiesociated acid is, however, red; so that in an aqueous solution the colour observed is an intermediate one. Addition of a strong acid (increase of H' ions) diminishes the dissociation, and the red colour appears. Alkalies and alkaline salts of weak acids, on the other hand, necessitate the removal of hydrogen ions, and the solution becomes yellow.Evidently the addition of very little caustic alkali will effect the removal of hydrogen ions at a rapid rate, and the colour-change will be sharp, since the methyl orange will pass rapidly into the dirnethylaminoazobenzene-sulphonate ion (yellow). Similarly, addition of strongly dissociated acids must bring about a rapid change to undissociated methyl orange (red). By the addition of weak acids to the alkaline solution the change will be gradual. This property has been utilised by Veley in an ingenious manner for the estimation of the strengths of different acids (Zeitsch. plysikal. Chenzie, 1906, 57, 147; Trnns. Chenz. Soc., 1907, 91, 155; Proc. Chenz. SOC., 1907, 23, 284). Friedenthal has also used a colorimetric method for the estimation of the concentration of hydrogen ions (Zeitsch.f. Elektroch., 1904, 10, 114), which has undergone considerable extension by Salm (Zeitsch. f. Elektroch., 1904, lo? 342 ; 1906, 12, 99 ; and Zeitsch. physiknl. Chemie, 1906, 57, 471)) who refers all his results to the concentration of the hydrogen ions, the limits of such concentrations falling between 2-normal for 6.034-normal hydrochloric acid, and 5 x 10 -15-normal for 6.744-normal potassium hydroxide (2-normal for OH'). The purely chemical view, which regards the indicator as a tautomeric sub- stance (pseudo-acid or pseudo-base, according to Hantzsch), the substance and its salts having essentially different constitutions, is well exemplified by Green's recent work on phenol- and quinol-phthale'ins (Berichte, 1907, 40, 3724, and JOUI*IZ.SOC. Chem. Ind., 1908, 27, 4). The isolation of a coloured quinonoid carboxylic methyl ester of the former substance leaves no doubt but that the coloured sodium salt of phenolphthalein is related to the parent substance in the following way : Accord- Its ions are : C'HGH4- CO ONa The explanation is in this case purely chemical. Green looks on the two views as being opposed to one another. I n a paper on the constitution of phenolphthalein, published jointly with A. G. Perkin (Tram. Chem. SOC., 1904, 85, 398), he concludes from the fact that phenolphthalein is entirely decolorised by an excess of alkali, and that the colour is not restored immediately by neutralisation with acetic acid, that the ionic hypothesis is thereby disproved, and refers to this matter again in the recent paper in the Journal of the Society of Chemical Industry. In the discussionTHE ANALYST.87 following Green's paper, Smithells observed that the ionic and chemical theories were not incompatible, and the author of this communication is strongly convinced that the two views are complementary. For a substance to act as an indicator, it must be a weak acid or a weak base ; but the ion which it forms must have a different constitution to the parent substance--i.e., the latter is a pseudo-acid or a pezcdo-base, as the case may be. Phenolphthalein and other weakly acidic indicators can be considered as showing the following equilibrium in solution : where Sn and X, are isomeric compound radicals.In the particular case of phenol- phthaleln, XU and Xv represent respectively- Xu is the more stable configuration, and the acid is very weak; therefore S;O.H and its ions are only present to a very small extent in neutral solution, and the absorption due to XU is observed (in the case of phenolphthalein this is in the ultra-violet, and the substance is colourless). Addition of bases (hydroxyl ions) remove6 the hydrogen ions, and the colour due to the XV configuration makes its appearance. Phenolphthalein actually has a dissociation constant, which Saliii (loc. cit., p. 493) has evaluated at 8.0 x 10-lO. In agreement with this low-value, phenolphthalein, as is well known, turns for a feeble concentration of the hydrogen ions, and is therefore used for the titration of weak acids.On the other hand, a caustic alkali is necessary to get a sharp reading. For weak bases, a weak base must be used as indicator. Thus, as Salm (Zoc. cit.) shows, aniline may be titrated, using dimethylaminoazobenzene (butter yellow) as indicator. The ions of salt8 of such a base should possess a different structure to the base itself. I n the case of butter yellow and its salts, the following constitutions are highly probable : C,H,.N : N.C,H,.N(CH,), and C,H;.NH.N : C,H, : N(CH,),Cl. Its sodium salt is yellow, like butter yellow. NaO,S.C,H,.N : N.C,H,.N(CH,), ; but the 6' acid " itself is violet, like butter yellow hydrochloride, so that, correspond- ingly, one may assign to the free '' acid " in the solid state or in acid solution the constitution of an internal salt : We thus come to the nearly related methyl orange (p-dimethylaminoazobenzene- p-sulphonic acid).C,H,.NH.N : C,H, : N(CH,), I [SO, 088 THE ANALYST. The aqueous solution will be an equilibrium of the internal salt, the real dimethylaminoazobenzene-sulphonic acid, and the ions of the latter : C,H,.NH.N : C6H, : N(CH,), r+ HSO,.C,H,.N : N .C,H,N (CH,), c3 I so,-- 0 Red. Yellou . H’ + ’SO,.C,H,.N : N.C6H,N(CH,),. Addition of even a weak base will remove hydrogen ions, and so produce the yellow colour. The question now arises, “Can an indicator be designed ?” To some extent this seems possible, for, as pointed out by the author in conjunction with H. V. Xitchell (Trans. Chem. Soc., 1907, 91, 1251), the oscillation frequency of a substance is slower the greater the number of alternate double and single linkages. Evidently one must synthesise a substance which is capable of tautomerism, its acid or basic functions must be weak, and, in addition, the number of conjugate double linkages must markedly differ in the configurations of the pseudo-base or acid and its ions.Paranitrobenzeneazo-a-naphthol (Meldola, Tq-ans. Clzem. Xoc., 1985, 47, 661) gives yellow or brown solutions in neutral solvents, which turn violet on addition of alkali, the free substance and its potassium salt possessing the constitutions : N02.C6H,.N : N.C,,,H,.OH and KNO, : C,H, : N.N : C,,H, : 0 ; and as it is a very weak acid, it might be used as a substitute for phenolphthalein.I t is not, however, an ideal indicator, in that its solubility in water is extremely small, and the violet colour of its alkaline salts is not very vivid. Hewitt and Mitchell hoped that p-nitrobenzeneazo-/3-methyl-a-naphthacournarin would be a better substance for the purpose, since its neutral solution is a bright yellow (the absorption spectrum shows blotting out of the blue and violet), whilst the potassium salt is a bright blue. Unfortunately, since the substance is a lactone, it takes some little time to hydroIyse, so that it cannot be used as an indicator in titrating an acid with a caustic alkali. The reverse titration can be fairly sharply effected, but the results are rather low. I find, however, that a monosulphonic acid of p-nitrobenseneaso-a-naphthol of the constitution [ Yellow.OH N NOTHE ANALYST 89 C.C. KOIi. gives extremely sharp results, the acid and its monobasic salts giving pale yellow solutions, Addition of excess of alkali turns such yellow solutions sharply to a magnificent purple. The results agree with those given by phenolphthalein, as shown by the following table, exhibiting the number of C.C. : l'henolphtlialein. ')-Nitrobenzel'e- am-a-naphthol, 7 ACETIC ACID REQUIRED TO NEUTRALISE KOH SOLUTIONS. Ni trosul phobenzene- azo-a-iiaphthol. Nitrobenzeneazo- itiethylnrtphtha- coumarin. 10 20 30 10.02 20.02 30.06 10.0 20.05 30.06 10.0 20.03 30.05 9.9 19.8 29.7 The dissociation constant (for the = N<gH group) is evidently not far different to that of phenolphthalein, since 10 C.C. Na,CO, were '' neutralised " by 4.86 C.C.;- acetic acid, using phenolphthalein as indicator ; and using the nitrosulphobenzene- aso-a-naphthol, 4-9 C.C. acetic acid were required to get an intermediate shade, and 5.4 C.C. for a complete yellow. Evidently the substance may be used as a substitute for phenolphthalein, and the colour change from yellow to purple is so marked as to be no less easy to observe than the colourless to purple of the phenolphthalein. The purple colour is not discharged by an excess of alkali, whether hot or cold; neither is it affected by alcohol, even in strongly alkaline solutions. In this respect the substance shows to distinct advantage when compared with phenolphthalein. I desire to thank Mr. A. G. A. Miller for help in examining the behaviour of this indicator towards alkaline carbonates.' DISCUSSION. Mr. CHAPMAN said that the phenolphthalein colour change had been studied by Stieglite, among others, who considered that the probability was that it was an intramolecular change, phenolphthalein being a lactone, and the salts being derivatives of a carboxylic acid. In the case of phenolphthalein, the destruction of the red colour, which occurred when alcohol or acetone was added to the aqueous solutions, was undoubtedly to be attributed to ionisation change. On the other hand, the silver salt was itself coloured in the dry state, in which case there could clearly be no question of ionisation. Both explanations would have to be taken into account in considering the colour changes of phenolphthalein, and probably other indicators.The PRESIDENT remarked that the case of corallin, which acted like litmus with phosphoric acid and some of the weaker acicls, but like phenolphthalein with sulphurous acid, showed that it was not always possible from the constitution and general behaviour of an indicator to predict what its action would be. Dr. HEWITT said that he had not meant to suggest that any indicator could be found which would be useful for all acids and alkalies, because evidently neutrality90 THE ANALYST. must be a relative term. Salm particularly quoted the case of phosphoric acid, which was monobasic to methyl orange, dibasic to phenolphthalein, and could even with trinitrobenzene be titrated as a tribasic acid. He (Dr. Hewittj thought that the greater delicacy of phenolphthalein was largely due to the great difference between the absorption spectra of undissociated phenolphthalein and of the phenol- phthalein ion. In the undissociated condition all the bands were somewhere in the ultra-violet, whereas in the case of the ion the absorption was in the green. I n the case of methyl orange no sharp change was to be expected, because the absorption of the two forms was to a considerable extent in the ~ a m e part of the visible spectrum. The free ‘‘ acid ” of methyl orange exists in solution in a state of equilibrium, and the change to yellow (complete ionization) takes place with a very small increase of concentration of the hydroxyl ions.

ISSN:0003-2654    

DOI:10.1039/AN9083300085

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. The Estimation of Alcohol in Wine. M. Duboux and P. Dutoit. (dniL. tSc Chim. anal., 1908, 13, 4-'3.)-The determination of the critical temperature of solution affords a more rapid and sensitive method of estimating alcohol than the determination of the specific gravity. The liquids found to give the best results as solvents were : (A), a mixture of 5 volumes of aniline with 3 volumes of 95 per cent. alcohol; and (B), a mixture of 1 volume of nitrobenzene with 9 volumes of 95 per cent, alcohol. On mixing 15 C.C. of liquid A with 10 C.C. of an aqueous solution of alcohol, and heating the mixture, the critical temperature of solution varied propor- tionately with the amount of alcohol in the aqueous solution, at the rate of 2-35" C.for each 1 per ceut. Similarly in the case of liquid B each 1 per cent. of alcohol caused the critical temperature of solution to vary by 1.2" C. The apparatus required consists of a test-tube 3.5 cm. in diameter and about 15 cm. long, closed by EL cork, through which is passed a thermometer graduated in tenths of a degree, and ti glass stirring rod (bent to a circle at the end), which can move freely through another opening. Fifteen C.C. of the liquid A and 10 C.C. of the distillate from the wine are gently heated and stirred in the tube until the turbidity suddenly disappears. On now cooling the liquid the turbidity should reappear at the same temperature, and this is noted as the critical temperature of solution.The result may then be checked by a determination with liquid B in place of A. To establish the relation- ship between the critical temperature of solution and the proportion of alcohol, three solutions are prepared, containing approximately 8, 10, and 12 per cent. of alcohol, the exact quantities being found by determinations of the specific gravities. Then, by plotting a curve in which the percentages of alcohol form the ordinates andTHE ANALYST. 91 the respective critical temperatures of solution the abscissae, the percentage of alcohol corresponding to any given critical temperature of solution may be found. I n the case of the distillates from wines the percentage of alcohol found by determining the critical temperature of solution is invariably higher than that obtained from the specific gravity.The difference averages 0.1 per cent., and must be attributed to the fact that the distillate from wine contains, in addition to alcohol and water, traces of substances which have a greater influence on the critical temperature than upon the specific gravity. C. A. M. Kamr Beer. A. C. Chapman and F. G. S. Baker. (Joirwt. Inst. Brewing, 1907, 13, 638-643.)-Two samples of this product gave the following results on analysis : Total solid matter ... ... ... ... Reducing carbohydrates (as maltose) ... Absolute alcohol (by weight) ... . . . ( = Proof spirit ... ... ... . . . Fixed aciditv (as lactic acid) ... ... Volatile acidity (as acetic acid) ... ... Present gravity ... ... ... Insoluble matters ... ... ... ... Ash .I . . . . ... ... . . . ... ‘‘ Lcting.” Per Ceiit. 5.19 0.23 3.19 6-97 1% 0.48 1014.4O “ Kaffir 13ecr.” l’er Cent. 5.76 0.07 2-44 1.03 0.4 1 3-62 0.38 101 4.4’ 5.37) The samples were similar in appearance, and both contained suspended matters consisting chiefly of maize starch, many of the granules being ruptured. A. R. T. The Detection of Tartaric Acid in Cider. G. A. Le Roy. ( h ? z . de. Chinz. mZfl/., 1908, 13, 16-17.)-The method is based upon the colour reactions given by resorcinol or pyrogallol in sulphuric acid solution with different organic acids --viz., with tartaric acid, a carmine red colour ; with citric acid, no coloration ; with malic acid, a lemon-yellow colour, changing to orange on prolonged heating; and with lactic acid a similar yellow colour, but of a more orange shade at the beginning.The cider under examination is treated with an excess of basic lead acetate, the precipitate washed and decomposed with hydrogen sulphide, the filtrate from the lead sulphide boiled, neutralised with sodium bicarbonate, and evaporated to dryness on the water- bath, and the residue stirred and heated with a few drops of a 1 to 2 per cent. solu- tion of pyrogallol or resorcinol in pure sulphuric acid. The appearance of a violet coloration, masking the yellow colour due to the malic acid, indicates the presence of tartaric acid. C A. M. Estimation of Cineol in Eucalyptus Oil. C. T. Bennett. (Cl~ent. mzd Di*ugg,ist, 1908,72,55.)-The author finds that the resorcinol method for the determina- tion of cineol, recently described by Schimmel and Co.(ANALYST, 1908, 15)) gives untrustworthy results. Although with artificial mixtures good results may be obtained, when eucalyptus: oil is examined other constituents, soluble in resorcinol solution, considerably affect the accuracy of the method. The author points out92 THE ANALYST. that the specific gravities of two eucalyptus oils examined by Schimmel and Go. (-9185 and ~9142) are corroborative evidence in favour of the results obtained by the phosphoric acid method (namely, 51, 62 ; and 40, 51 per cent. of cineol respectively) rather than of those given by the resorcinol process (71 and 81 per cent. respectively). In the author's opinion the phosphoric acid method, weighing the pressed cake of cineol phosphate, gives fair results when the proportion of cineol in the sample is not less than 60 per cent.; while washing the compound with petroleum-ether, as directed in the United States Pharmacopoeia met hod, invariably gives low results.Fractionation of eucalyptus oil is a valuable guide to the proportion of cineol present, the fraction distilling between 175' and 185' C. consisting mainly of cineol. A. R. T. A Study of the Changes taking place in Whisky stored in Wood. C. A. Crampton and L. M. Tolman. (Jown. Amer. Chem. SOC., 19G8, 30, 98-136.) -The investigation was commenced in the year 1898, when thirty-one barrels of new spirits were set aside in as many different warehouses and from as many different distilleries. Each year, for eight years, quart samples were drawn from the barrels and placed in glass receptacles, the barrels being resealed.By this arrangement the sample of new spirit was kept in glass for eight years, the one-year-old spirit was kept in wood for one year and seven years in glass, and so on. All the samples were examined chemically when the last had been collected, except that the alcoholic strength, solids, and colour were estimated at the time the samples were drawn. - The average results obtained on the analysis of the samples were figures expressing grams per 100 litres of 100 per cent. proof spirit : as under, the Age. f New 1 year 1 I 3 years \ I 3 years ( l 4 years I ( 5 years k G years t 7 years \ I I 8 years . Kind. Rye Bourbon Rye Bourbon Rye Bourbon Rye Bourbon Rye Bourbon Rye Bourbon Rye Bourbon Rye Bourbon Rye Bourbon Origiii a1 Proof.101.2 101.1 103.5 101-H 104.9 102.2 10'7.; 103.0 111.2 104.3 11i3.8 106.1 118.0 107.9 121.4 109.6 123.8 111.1 Colonr. Solids. 13.3 26.5 119.7 99.6 144.7 136.8 1'71.4 149.3 185.0 151 -9 206.5 173.3 333.1 185.1 242.2 200.9 256.0 210.3 Acids. 4.4 10.0 46.6 41.1 51.9 45.6 62.7 54.3 65.9 58.4 (57.6 66.3 '72.4 6'7-1 76.7 71.9 82.9 76.4 Esters. 16.3 18.4 37.0 28.6 54-0 40.0 61.5 48.1 69.3 33.5 75.0 55.9 80.4 64.0 84.2 63.3 89.1 65% Alde- hydes. 5.4 3.2 7.0 5.8 10.5 8.4 12.5 10-5 1 3 9 11.0 15.0 11.4 14.6 11.9 15.5 12.4 16.0 12.9 1.0 0.7 1.8 1.6 2.2 1.6 1.5 1.7 2.8 1.9 3.2 1.9 3.3 1.8 3.2 1.9 3.4 2.1 Fuse1 Oil. 90.4 100.9 111.5 110.1 112.4 108.9 112.7 112.4 125.1 123.9 128.1 125.3 145.5 135.3 145.2 137.2 154.2 143.5THE ANALYST4 93 The colour of the samples is given in degrees of the brewer’s scale of Lovibond’s tintometer, and the fuse1 oil was estimated by the Allen-Marquardt process.The results show that there is an important relationship between the acids, esters, colour, and solids in a properly aged whisky, which will differentiate it from artificial mixtures and from young spirit, All the constituents are undergoing changes as the ageing process proceeds, and it is evident that the matured whisky is the result of these changes. The amount of higher alcohols increases in the matured whisky only in proportion to the concentration; the latter was due to the passage of the spirit through the pores of the wooden barrels, and it was demonstrated that water passes through the wood with much greater rapidity than alcohol.The wood had a very decided selective action on the materials passing through it, It will be seen that the acids and esters reached an equilibrium which was maintained after about three or four years. The rye whiskies-that is, whisky in the manufacture of which rye is the principal cereal used-show a higher content of solids, acids, esters, etc., than do the Bourbon whiskies which are made from maize ; but this is explained by the fact that heated warehouses are almost universally used for the maturing of rye whiskies, and unheated warehouses for the maturing of Bourbon whiskies. The characteristic aroma of American whiskies is derived almost entirely from the charred barrels in which they are stored, and the improvement in flavour of whiskies in charred barrels after the fourth year is largely due to concentration. The oily appearance of a matured whisky is caused by material extracted from the, charred barrel, as this appearance is lacking in whiskies aged in uncharred barrels.The so-called ‘‘ body ” of a whisky is due to the solids extracted from the wood. w. P. s. Estimation of Gliadin in Flour. W. E. Mathewson. (r702W% Anzer. Chent. SOC., 1908, 30, 74-81.)-The results recordeJ demonstrate the unreliability of the usual methods for estimating gliadin. From 8 to 17 per cent. more nitrogenous matter is extracted from flour when 4 grams of the latter are treated with 100 C.C. of 70 per cent. alcohol than when 16 grams of the flour are taken. After drying for six hours in a water-oven, from 10 to 20 per cent.less gliadin is obtained on extracting with cold alcohol; with hot solvent, the figures were nearly the same, being slightly lower. No tendency for glutenin to remove gliadin from its alcoholic solution could be detected. The use of 70 per cent. propyl alcohol gives results which are equally untrustworthy. It was also found that, whilst anhydrous phenol dissolves a, high percentage of protein matter from flour, the dissolved matter is not pure gliadin ; nor does it appear to be even gliadin mixed with but one other protein. w. P. s. The Unsaponiflable Constituents of Cacao Butter. H. Matthes and 0. Rohdich. (Ber. deut. Chem. Ges., 1908, 41, 19-23.)-1n the course of an investigation carried out on 13 kilos of cacao butter, the authors failed to isolate any constituent to which the peculiar flavour of the cacao could be attributed.The unsaponifiable matter from this quantity of fat amounted to 28 grams, consisting of a pleasant-smelling oil, with an odour of hyacinth and 22 grams of “ crude phytos- terol.” From the latter were isolated a hydrocarbon, C30H4S, identioal with amyrilene,94 THE ANALYST. a phytosterol which combines with 2 atoms of bromine by addition, identical with the stigmasterol prepared from Calabar beans by Windaus, and a phytosterol which combines with 1 atom of bromine, identical with the sitosterol of Calabar beans. This phytosterol possessed the properties of the ordinary ‘‘ phytosterol,” which forms the unsaponifiable residue of most vegetable fats. COLOUR REACTIONS OF THE PRODUCTS OBTAINED.Hydrocarbon . . . ‘‘ Stigmasterol ” . . . ‘‘ Phytosterol ” . . , Phy tos terol acetate Phytosterol acetate dibromide Phytosterol acetate tetrabromide Tsc hougaje 11”s Reagent (Trichloracetic Acid) and Zinc Chloride. First pale pink, First pale pink, then orange-red. then red. Red. Pink. Impure red, soon faded. T,ieherniann- RurcharC Test. First blue, then green. 7 , Very faint green after some time. Sal kow sk i Test. Not tried. Chloroform, first yellow, then violet. Sulphuric acid, greenish fluores- cence. 9 7 7 , Not tried. J. F. B. The Effect of Nitrogen Peroxide on Wheat Flour. F. J. Alway and R. M. Pinckney. (Jozmz. Anze~. Cliem. SOC., 1908, 30, 81-85.)-Continuing their investigation on bleached flours (cj. ANALYST, 1907, 32, 418), the authors find that the yellow colour of flour is due to a very minute quantity of coloured substance contained in the fat.When the fat is removed, high-grade flours become colourless. Exposure to sunlight, or treatment with nitrogen peroxide, changes the coloured compound into one or more colourless substances. The fat from bleached flour is practioally colourless, but the use of an excessive quantity of the bleaching agent causes both the flour and the fat obtained from it to assume a, yellow to brownish- yellow colour. Unless used in excess, nitrogen peroxide does not increase the acidity of the flour or affect the expansion of the gluten. Bread made from bleached flours does not differ in weight, texture, odour, or taste from that made from unbleached flour ; it is in all cases whiter where high-grade flours are used.Low-grade flours, however, when bleached produce bread possessing an uninviting colour. Whilst bread prepared from bleached flour sometimes contains nitrites, the quantity of the latter is always smaller than that present in the flour. The authors consider that many of the conflicting opinions recorded regarding the effect of nitrogen peroxide on flour are to be attributed to the probability that the flours examined had been over- treated with the bleaching agent. w. P. s.THE ANALYST. 95 The Composition of 6 6 Noodles ” (Nudeln) prepared with Milk and Eggs. W. Plucker. (Zeit. C’?ztcrsuch. Nahr. Genzissm., 1907, 14, 748-754.)-The following are the average results obtained on the analysis of specimens of this article of food, and they are recorded with the object of affording some data as regards the detection of the presence or absence of eggs in the product.The “noodles ” were prepared by the author himself : Flour used (10 samples) ‘‘ Noodles ” made with water and 1 egg per pound of flour (5 sam- Ditto, with 2 eggs per pound of flour (5 samples) Ditto, with milk and 1 egg per pound of flour (5 samples) ... Ditto, with 2 eggs per pound of flour (5 samples) Ditto, with milk but no eggs (5 samples) ... ples) ... ... Water. Per* Cent. 13-05 12-37 11.84 12.30 10.48 11-22 Ash. Per Ceut. 0.60 0.77 0.73 0.87 I -09 1.05 Total ’hosphoric Acid (1’206). Per Cent. 0.277 0 *37 5 0-355 0.448 0.483 0.473 Lecithiii- ’hosphoric Acid (P,O,). Per Cent. 0.028 0.051 0.078 0.048 0.071 0.028 Ether E xtrsct .Per Ccnt. 1.29 2.09 3.52 3.13 4.19 3.04 Iodine Pat. 17tLiue 104.71 84-99 81.07 65.01 69-65 62-26 Iteich ert- Meisd Value of Fat. 3.79 3-81 3-65 12.53 12.20 18.53 With the exception of the water and ash, the results are calculated on the dry I t was found that the iodine value decreased with the age of the substance. “ noodles ” (see also ANALYST, 1905, 30, 245). w. P. s. Estimation of the Tannin of Hops. A. C. Chapman. ( J o w n . Inst. Brewing, 1907, 13, 646-652.)-The author has applied the method of precipitation of tannin by means of an alkaloid to the estimation of the tannin in hops, Cin- chonine was found to be preferable to quinine and strychnine, a saturated aqueous solution of the sulphate immediately precipitating the hop-tannin as a yellow flocculent compound only slightly soluble in water, and practically insoluble in cin- chonine sulphate solution.Experirnentfi with pure gallotannic acid (C,,H,,,O,.SH,O) showed that 0.1 gram gave 0.146 gram of the cinchonine compound prepared by the method to be described, corresponding to a content of 63 per cent. of gallotannic acid. The compound of hop-tannin contained 4 per cent. of nitrogen-equivalent to 42 per cent. of cinchonine-and 58 per cent. of tannin, and was thus similar in96 THE ANALYST. composition to the gallotannic acid compound. For calculation purposes, 60 per cent. of hop-tannin in the dry alkaloidal precipitate may be taken as an average figure. For the estimation, 10 grams of hops are placed in a flask marked at 508 c.c., 400 C.C.of boiling water added, and the flask immersed in a boiling water-bath for two hours. During the extraction the hops are macerated with a glass rod. After cooling the contents of the flask to 15" C., water is added to the containing mark. The liquid is filtered, and 50 C.C. of the filtrate evaporated to about 15 c.c., and, when cool, 50 C.C. of a saturated aqueous solution of cinchonine sulphate are added, the liquid set aside for one to two hours in a cool place, and then filtered on to asbestos in a Gooch crucible. The precipitate is washed several times with a diluted cin- chonine sulphate solution, prepared by mixing equal volumes of the saturated solution and water, and then dried to constant weight at 100" C. The Gooch crucible before weighing should be treated with a little of this washing solution, and dried at 100" C.The weight of the cinchonine compound, multiplied by 0-6, gives the amou3t of hop-tannin in 1 gram of the sample. The following results were obtained : Description of Hop. Choice Bohemian, 1907 . . . Choicest Hallertau, 1907 Choice Hallertau, 1906 ... Choice Bavarian, 1907 . .. Alsace, 1907 East Kent Goldings, 19Oi" Kent Fuggles, 1906 ... Choice Worcester, 1905 ... East Kent, 1907 , . . ... Moisture. Per Cent. 11-48 10.76 10.96 10*00 10-14 15.10 11.82 10.76 14-24 T\' oigh t of Cinchoiiinc Prccipitate. Gram. 0.068; 0,066 0.069 0.054; 0.055 0.058; 0.055 0-048 0.035; 0,038 0.039 0,035; 0.035 0.032; 0.034 Tarinin per Cent. on- ( I ) Sample. 4.02 4.14 3.30 3.42 2-88 2.28 2.34 2.10 2 .oo ( 2 ) Dry Hop 4-54 4-64 3.70 3.80 3.20 268 2-65 2.35 2-32 The Estimation of Tannin in White Wines.M. Koebner. A. R. T. (Chenz. Xeit., 1908, 32, 77.)-The following simple colorimetric method is stated to give good results: Ten C.C. of the wine are mixed successively with 10 C.C. of tartaric acid solution (1 : lo), 3 drops of ferric cbloride solution (I : lo), and ammonia in excess, and the whole diluted to 50 C.C. The depth of coloiir of the clear solution thus obtained is proportional to the amount of tannin, and may be matched with that given under the s&me conditions by different quantities of a solution containing 1 gram of tannin (dried at 100" C.) and 50 grams of concentrated hydrochloric in 1,000 C.C. of water. C. A. M.THE ANALYST. 97 Estimation of Water in Foods and Other Substances.W. Thorner. (Zeit. angezo. Chem., 1908, 21, 148-151.)-The method described is similar to that recommended by Aschrnan and Arend (ANALYST, 1907, 32, 21); the substance in which the water is to be estimated is heated with ordinary petroleum in a flask, and the distillate is collected in a burette surrounded by a water-jacket. The delivery-tube from the flask reaches well into the top of the burette, and it is stated that the water separates rapidly from the petroleum which also distils over. From 10 to 20 grams of the substance are taken for the estimation; the quantity of petroleum employed is about 50 c.c., and a few pieces of pumice-stone are added to prevent the contents of the flask from “ bumping.” I n the case of liquids, such as milk, etc., which are liable to froth on heating, a little tannin may be added to the distillation flask.The results of estimations of water in butter, sausages, meals, meats, spices, soap, cocoa, inorganic salts, etc., are given, the figures agreeing with those obtained by estimating the water gravimetrically. w. P. s. BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Quantitative Estimation of Pentoses in Urine. A. Jolles. (Xeits. a d . them., 1907, 46, 764-771.)-1n a previous paper (Biochewt. Zeits., 2, 243) the author described a method for the detection of pentoses in urine which consisted in forming the osazone from 15 C.C. of the urine, washing the precipitate, and distilling it with a small quantity of hydrochloric acid. The distillate was then' tested with Bial's reagent, which would give a distinct green colour if only 0.05 per cent.of pentose were present in the sample. The author has now applied his volumetric method for the estimation of furfural by means of sodium bisulphite (ANALYST, 1906, 31, 116) to the estimation of pentoses in urine. One hundred C.C. of urine are placed in a flask of about 1-5 litre capacity together with 150 C.C. of hydrochloric acid of 1-06 specific gravity. In a second flask are placed 900 C.C. of water, and the steam generated by boiling this water is paased through the liquid in the first flask. The distillate con- taining the furfural is collected, an aliquot portion of it is carefully neutralised with 20 per cent. sodium hydroxide solution in presence of methyl orange, and 10 C.C. of standardised bisulphite solution are added, the excess of bisulphite being titrated back after two hours with -& iodine solution.The author has proved by a large number of analyses that, in the absence of pentoses, neither healthy nor patho- logical urines yield any appreciable quantity of substances capable of combining with bisulphite when treated in this manner. The highest; error due to substances other than pentoses amounted to 0.032 per cent. (calculated aa pentose), and was caused by the presence of large quantities of glycuronic acid derivatives. I n cases of pentosuria, however, the quantities of pentose found range from 0.1 per cent, upwards. The error mtty be still further reduced by previously boiling the urine with dilute acetic acid. J. F. B. them., 1907, 764-771.)-1n a previous paper 243) the author described method for the detection of pentoses in urine which consisted in forming the osazone from C.C.of the urine, washing the precipitate, and distilling it with a small quantity of hydrochloric acid. The distillate was then' tested with Bial's reagent, which would a distinct green colour if only 0.05 per cent. of pentose were present in the sample. The author has now applied his volumetric method for the estimation of furfural by means of sodium bisulphite 116) to the estimation of pentoses in urine. One hundred C.C. of urine are placed in flask about litre capacity together with C.C. of hydrochloric acid of specific gravity. In a second flask are placed C.C. of water, and the steam generated by boiling this water is paased through the liquid in the first flask. The distillate con- taining the furfural is collected, aliquot portion it is carefully neutralised with per cent. sodium hydroxide solution in presence of methyl orange, and C.C. of standardised bisulphite solution are added, the excess of bisulphite being titrated back after two hours with iodine solution. The author has proved by a large number of analyses that, in the absence of pentoses, neither healthy nor patho- logical urines yield appreciable quantity of substances capable of combining with bisulphite when treated in this manner. The highest; error due to substances other than pentoses amounted to 0.032 per cent. (calculated pentose), and was caused by the presence large quantities of glycuronic acid derivatives. I n cases of pentosuria, however, the quantities of pentose found range from per cent, upwards. The error mtty be still further reduced by previously boiling the urine with dilute acetic acid.

ISSN:0003-2654    

DOI:10.1039/AN9083300090

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年代:1908

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THE ANALYST. 97 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Quantitative Estimation of Pentoses in Urine. A. Jolles. (Xeits. a d . them., 1907, 46, 764-771.)-1n a previous paper (Biochewt. Zeits., 2, 243) the author described a method for the detection of pentoses in urine which consisted in forming the osazone from 15 C.C. of the urine, washing the precipitate, and distilling it with a small quantity of hydrochloric acid. The distillate was then' tested with Bial's reagent, which would give a distinct green colour if only 0.05 per cent. of pentose were present in the sample. The author has now applied his volumetric method for the estimation of furfural by means of sodium bisulphite (ANALYST, 1906, 31, 116) to the estimation of pentoses in urine. One hundred C.C. of urine are placed in a flask of about 1-5 litre capacity together with 150 C.C.of hydrochloric acid of 1-06 specific gravity. In a second flask are placed 900 C.C. of water, and the steam generated by boiling this water is paased through the liquid in the first flask. The distillate con- taining the furfural is collected, an aliquot portion of it is carefully neutralised with 20 per cent. sodium hydroxide solution in presence of methyl orange, and 10 C.C. of standardised bisulphite solution are added, the excess of bisulphite being titrated back after two hours with -& iodine solution. The author has proved by a large number of analyses that, in the absence of pentoses, neither healthy nor patho- logical urines yield any appreciable quantity of substances capable of combining with bisulphite when treated in this manner. The highest; error due to substances other than pentoses amounted to 0.032 per cent. (calculated aa pentose), and was caused by the presence of large quantities of glycuronic acid derivatives. I n cases of pentosuria, however, the quantities of pentose found range from 0.1 per cent, upwards. The error mtty be still further reduced by previously boiling the urine with dilute acetic acid. J. F. B.

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DOI:10.1039/AN9083300097

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年代:1908

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98 THE ANALYST. ORGANIC ANALYSIS. The Estimation of Acetone. G. Heikel. ( C l m z . Zeit., 1908, 32, 75-76.)- llessinger’s method, in which the acetone is converted into iodoform by treatment with an excess of iodine solution, gives excellent results with pure acetone, but in the case of crcde acetone the presence of higher ketones which also yield iodoform causes the results to be too high. On the other hand, the method of DenigCs (ANALYST, 1899, 24, 92), based upon the formation of au insoluble compound of acetone with mercuric aulphate, has the dmwback that numerous bodies besides acetone in crude acetone yield a, similar precipitate. By the use of the two methods, however, approximately accurate values may be obtained. In the manufacture of acetone, three final products are obtained in addition to the pure (over 99 per cent.) acetone, viz.: (1) The so-called ketones ” (mainly methyl-ethyl-ketone), boiling at 65” to 75” C., and having a specific gravity of 0.811 to 0.815 at 15” C ; (2) light acetone oil, boiling at 75” to 130’ C., and having a specific gravity of 0.82 to 0.83; (3) heavy acetone oil, boiling at 130” to 250” C., and having a specific gravity of 0.88 to 0.89. Samples of these products examined in aqueous solution by the two methods mentioned above gave the following results : L)enig&s’ Metliod. Per Cent. Jlessinger’s JIetliod. I)enigt‘.s’ Mctliod. Jlessingcr’s Method. Per Cent. Per Cent. Per Cent. ______ __ “ Ketones ” ... ... 89.9 63.5 0-706 Light oil ... ... ... 57.2 32.6 0.570 Heavy oil ... ... ... 39.5 25.4 0-643 The mercury precipitate in DenigBs’ method, which is almost white in the case of pure acetone solutions, is yellowish-white when obtained from “ ketones,” brownish- yellow when from light oil, and nearly brown when from heavy oil. Hence it is possible to determine rapidly whether a given sample consists of pure acetone or contains the higher-boiling constituents of the crude product. The values given above for the three constituents are, as a rule, sufficiently accurate for practical purposes, as is shown by test analyses.In one instance cited a sample with specific gravity 0.813, sold as ketones,” yielded 35-5 per cent. of acetone by Messinger’s method, and 34.9 per cent. by DenigBs’ method (precipitate perfectly white) ; so that the substance producing iodoform could only have been acetone, and not a homologous ketone.C. A. Rl. Estimation of ‘‘ Crude Fibre ” and Separation of Cellulose, Lignin, and Cutin. J. Konig. (Ber. deut. Ckem. Ges., 1908, 41, 46-49.)-1n reply to the criticism by Matthes and Streitberger (ANALYST, 1908, 15) on the author’s process for the estimation of crude fibre,” the author quotes severa.1 opinions in favour of the method. Konig’s method yields a fibre which is freer from pentosans than that obtained by any other method, and the estimation can be carried out in three to four hours. But in order that different analysts may obtain concordant results, it is necessary to adhere closely to the conditions prescribed by Konig. Substances, suchTHE ANALYST. 99 as cocoa, which are rich in fat must be thoroughly extracted before the estimation of the fibre.The glycerin employed should have a specific gravity of 1.23, and contain 20 grams of concentrated sulphuric acid per litre. The product must be washed first with sufficient boiling water (generally about 400 c.C.), then with warm 90 to 95 per cent. alcohol, and lastly with a warm mixture of alcohol and ether. The washing is so carried out that the filtrate comes through perfectly colourless. In the case of very finely ground powders, including cocoa, it is advisable to largely dilute the steamed or boiled product in large beakers, allow to settle, decant off the clear liquid, and then to dilute the sediment before boiling it up and filtering. If the decanted liquid be not quite clear, it should be further diluted and filtered before.the sediment is brought on to the filter. The author points out that what agricultural chemists term '' crude fibre " or " lignin " is not an individual substance, the propor- tion of which can be expressed in absolute terms, but is a residue of mixed coin- position which varies according to the process employed for its isolation. All that can be expected is that, provided the process be carried out exactly under standard conditions, the results shall be concordant and possess a comparative value among themselves. J. F. B. Action of Ozone on Multiple Bonds. C. Harries. (Be?.. d c i i t . C l ~ i z . Ges., 1907, 40, 4905-4908.)-The author denies the statement of Molinari (ANALYST, 1908, 22) that compounds containing triple bonds of the acetylene type may be distin- guished from those containing double bonds by means of ozone.The means pre- scribed by Molinari for ascertaining whether ozone is fixed or noi are stated to be quite inadequate, and the conclusions founded on the test (toe. cit.) are therefore unsound. As a matter of fact, compounds containing acetylenic bonds form perfectly definite ozonides, several of which have been isolated. The use of ozone for deter- mining the structure of the nucleus in aromatic compounds is likewise unjustified by the experimental facts. J. F. B. Melting-Points of Phenylhydrazine and Certain Osazones. E. Fischer. (BET. cleut. Chem. GES., 1908, 41, 73- 77.)-The author has re-determined the melting- point of phenylhydrazine, which has been previously recorded by himself as 2 3 O to 23-5" C., and by Berthelot as 17.5" C.Working on a particularly pure specimen with the thermometer immersed in the semi-fused mass, he has now found 19.6' C. to be the true melting-point. The true melting-points of the osazones are very uncertain and difficult to determine, since they depend on the rapidity of heating. Tutin (ANALYST, 1908,25) has recently stated that phenylglucosazone melts at 217' C., but the author cannot confirm this. Heated in a capillary tube, at the rate of lo C. per 2-3 seconds, the glucosazone begins to melt at about 205' C. (208' C. corr.), and complete fusion will take place at this temperature if the flame be extinguished ; but if heating be continued at the same rate the fusion, which takes place with decom- positition, is not complete until the thermometer indicates 209' C.(213' C. corr.). When the osazone is heated so slowly that the temperature rises from 195O to 200' C. in one minute, fusion begins at the latter temperature with decomposition and softening. Phenylgalactosazone melts, according to the rapidity of heating, at100 THE ANALYST. temperatures ranging between 180" and 193' C. When heated at the rate of lo C. per 2--3 seconds, the melting-point is about, 1 8 6 O C. (188OC. corr.), but slight differences are unavoidable in different determinations. Maltosazone, under the same con- ditions, melts at about 205' C. (208" C. corr.). Lactosaxone begins to melt at about 200' C., but fusion is not complete until 210' to 212' C. (213' to 215' C.corr.). I t i8 not advisable to prepare osazones by means of phenylhydrazine base and acetic acid unless the base be freshly purified. The original prescription of 2 parts of phenylhydrazine hydrochloride and 3 parts of sodium acetate is preferable. The hydrochloride should be recrystallised from alcohol until it is quite colourless. J. F. 13. The Detection of Sesame Oil. H. Sprinkmeyer. (&it. UntersucIi. Nrihi-. G~Ic~Lss?~L., 1908, 15, 20-21.)-The author finds that rancid cottonseed oil containing sesame oil gives no red coloration when shaken with hydrochloric acid and furfural, unless at least 17 per cent. of sesame oil is present. This fact is of Borne importance, as, according to German law, margarine must contain so much sesame oil that a distinct red coloration is produced when 0.5 C.C.of the clear melted fat is mixed with 9.5 C.C. of cottonseed oil and the mixture is shaken with an equal volume of hydrochloric acid and a few drops of 2 per cent. alcoholic furfural solution. Rancid cottonseed oil also interferes with Soltsien's reaction for sesame oil. H. Kreis (Chew. Zeit., 1908, 23, 87-88) states that rancid sesame oil gives a less intense coloration with furfural and hydrochloric acid than does fresh sesame oil. The addition of cottonseed oil appears to influence the delicacy of the test to a certain extent; the coloration obtained is more permanent than that given by mixtures of sesame oil with olive oil. w. P. s. Estimation of Starch. E. Parow and F. Neumann. (Zeit. Spiritzuiitd., 1907, 30, 561-562.)-1n the common method of estimation, in which the starch is djssolved by means of malt extract, the hydrolysis completed by hydrochloric acid, and the dextrose estimated by means of Fehling's solution, the authors have obtained too low results when they have used the theoretical factor, 0.9, for calculating the dextrose into starch, and therefore employ an empirical factor, 0%.For the rapid valuation of commercial products they have devised the following simple modification of Gschwendner's polarimetric method : Ten grams of the sample are mixed with 50 C.C. of acid brine (prepared by dissolving 200 grams of salt in 800 C.C. of water, adding 220 C.C. of hydrochloric acid of specific gravity 1.125, and filtering the liquid), and heated in a boiling water-bath under a reflux condenser.The 100 C.C. flask is shaken at intervals, and kept immersed in the boiling water for exactly one hour, after which 10 C.C. of basic lead acetate solution are introduced, and the liquid cooled and made up to the mark. It is then treated with a little purified bone charcoal, filtered, and polarised in the 200 mm. tube. As the con- version of the starch into dextrose is incomplete, three parallel estimations should be made and concordant results obtained. The following factors for convertingTHE ANALYST. polarimetric values into starch were obtained from a large number results by this method and by the ordinary diastase-acid method : Polarisation Factor for Dry Starch. 101 of concordant Soleil-Veatzke c i r c 21 a r .cltal.Ch. Scalp. Degrees. Potato ...... ... 2.872 ... ... 8.28 Maize ... ... ... 2.938 ... ... 8.47 Rice ... ... ... 2.944 ... ... 8.49 Wheat ... ... ... 2.918 ... ... 8.42 C. A. M. Polarimetric Estimation of Starch. E. Ewers. (Zeds. oflent. C~CWL., 1908, 14, 8-19.)-Further investigation of the process devised by the author (ANALYST, 1906, 31, 25) showed that in the polarimetric estimation of starch the influence of optically active bodies other than starch is by no means negligible. Corrections have had to be applied, ranging in the case of wheat flour up to 3.7 per cent., and in the case of maixe to 9 per cent. In the case of dry samples, the material is finely ground and sifted; potatoes are rasped to a pulp and carefully sampled, The estimation consists of a main determination and a blank. For the former, 25 C.C.of glacial acetic acid are placed in a 200 C.C. flask without wetting the neck ; 10 grams of the substance are then introduced, the flask is closed and shaken vigorously until. the mixture is uniform. The stopper and neck of the flaek are then washed down with a further 25 C.C. of glacial acetic acid. I n the case of potato pulp, 10 to 13 grams of pulp are weighed out and introduced into the flask with 50 C.C. of acetic acid. The flask is placed in a boiling water-bath, and kept there for ten minutes. Then 10 C.C. of dilute hydrochloric acid (10 C.C. of the 25 per cent. acid per 100 c.c.) are added, and the flask is left in the water-bath for exactly six minutes, being shaken round every minute. Hot water is next added to bring the volume up to about 180 c.c., and the flask is kept for fifteen minutes longer in the boiling water-bath.It is then cooled to 20' C., 2 to 3 C.C. of a saturated solution of potassium ferrocyanide are added, and the contents are diluted to the mark, filtered, and polarised. Should the filtrate not be clear, a few crystals of zinc sulphate may be added to assist clarification. The blank experiment is performed as follows: Five grams of the substance are placed in a 100 C.C. flask with 70 C.C. of water at 50" C. (in the case of potato starch 35" C , ) , and mixed by shaking. I n the case of potato pulp, 10 grams are digested with 70 C.C. of water at the ordinary temperature for one hour. Potato starch is digested for half an hour at the ordinary tempera- ture; the grists, flours, and starches of cereals are digested at 48' to 50" C.for half an hour in the case of starches, an,[ one hour for the other products. Then 25 C.C. of glacial acetic acid are added, and digestion is continued at the same temperature for half an hour (starches only fifteen minutes). The temperature is finally adjusted to 20" C., ferrocyanide is added, and the liquid is diluted to 100 C.C. before filtering and polarising. The specific rotatory power of starch under the conditions prescribed varies according to its origin. The following values for [ a ] ~ , at 20" C., at a, con- centration of 5 per cent. are given : Wheat, 183.62" ; rice, 186.07" ; maize, 184.19' ;102 THE ANALYST, potato, 186.46". The values are practically constant for different concentrations. The moisture is determined by drying 10 grams of material for one hour at 40" to $0' C., and then for four hours a t 120" C. J. F. B. The Specific Gravity of Different Kinds of Starch. E. Parow. (Zeit. Spirit?tsind., 1907, 30, 432 ; Chem. Zeit. ,z2ep., 1908, 32, 17.)--The values given below were for the most part the mean results obtained in several determinations by means of the picnometer at 17.5' C. (water at 17.5" C. = 1) : Starch from Potato ... Wheat ... Xaize ... Rice ... Spccitic Gravity of Anhydrous Starch in Water. 1 -648 1.629 1.625 1.620 Specific Gravity of An hy drons Starch in Toluene. 1.513 1.502 1.499 1.504 Specific Gravity of Starch containing Water, in Water. Water per Cent. 18-72 19-35 20.14 13.38 13-80 14-60 11.06 12.88 14.36 11.92 13.10 14.14 Specific Gravity. 1.463 1.436 1-453 1.515 1.496 1.492 1:522 1 -504 1.490 1.514 1.500 1 -501 Specific Gravity of Starch containing Water, in Toluene. Water per Cent. 15.03 13-90 12.60 14.03 Specific. Gravity. 1.361 1-365 1.378 1.360 C. A. 31.

ISSN:0003-2654    

DOI:10.1039/AN9083300098

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年代:1908

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102 THE ANALYST, INORGANIC ANALYSIS. The Iodometric Determination of Arsenious Acid. E. W. Washburn. (Journ. Amer. G'hem. SOL 1908 30 31-46.)-The equilibria in this well-known method are considered at some length and the calculation of the proper conditions to be observed at the end-point of the titration is given as well as the method for securing them conditions. It is considered preferable to weigh all the solutions instead of measuring them and the solutions are made up so that 1,000 grams of normal solution contain one equivalent weight of the substance. The quantity of solution required for an estimation is placed in a burette which can be hung on a balance the weight of solution used being ascertained by reweighing the burette at the end of the titration. The -:$ arsenious acid solution employed for standardising the iodine solution is prepared by dissolving 4-95 grams of pure arsenious oxide in a solution containing 10 to 12 grams of sodium hydroxide ; the solution is then diluted to 100 c.c.saturated with carbon dioxide and water is next added until the total weight of the solution is 206.73 times the weight of the arsenious oxide used. Sodium phosphate may be used in place of the sodium bicarbonate in preparing the solution THE ANALYST. 103 in this case the arsenious oxide is dissolved in a solution containing 12 grams of sodium hydroxide and when solution is complete a quantity of phosphoric acid equivalent to 0.15 molecule of H,PO is added the whole being then diluted to the weight before mentioned. The use of sodium phosphate is to be preferred as there is then no danger of loss of carbon dioxide during the titration a loss which may entail mechanical loss of the reagents.I n titrating unknown solutions of arsenious acid, the solution is neutralised with hydrochloric acid or sodium hydroxide as required, using phenolphthalein as indicator. Sodium hydrogen carbonate or sodium phosphate is then added and the titration carried out more of the neutralising agent being added from time to time until the quantity amounts to about 5 grams of the former or 11 grams of the latter (Na,H1’0,.12H20) for every 100 C.C. of ccr iodine solution used. Starch solution is used as indicator and the end-point of the titration is definite and permanent. w. P. s. Modified Volumetric Method for the Rapid Deterlnination of Carbon Dioxide in Mineral and especially in Acid Waters.J. Stransky. (Chem. h i t . , 1908,32 100-101.)-A layer of ether 2 or 3 rnm. in depth is poured into a measuring cylinder. Tbe sample of water is then introduced through a very fine tube terminat-ing below the level of the ether which prevents escape of carbon dioxide. The volume of water introduced having been ascertained the carbon dioxide is at once titrated with :& potassium hydroxide solution and phenolphthalein the tip of the burette used being also drawn out to a very fine tube terminating below the level of the ether. ,4. G. L. Action of Silver Nitrate and Mercuric Nitrate on Certain Inorganic Hydroxides. W. Biltz and F. Zimmermann. (Bey-. h 6 t . Chew. Ges. 1907 40, 4979-4984.)-When a colourless metallic hydroxide is treated with silver nitrate or mercuric nitrate the hydroxides of which are coloured the precipitate will become coloured or will remain colourless according to the relative basicities of the two hydroxides or according to the relative solubilities of the ions.The colourless hydroxide is precipitated hot or cold by means of ammonia ; the precipitate is collected and washed and then placed in a & solution of the silver or mercuric nitrate. With silver nitrate the hydroxides of magnesium and cadmium give a strong yellowish-brown colour; zinc gives only a trace of brown; lead gives a slight violet-brown colour ; and the hydroxides of beryllium aluminium indium zirconium antimony, bismuth and stannic hydroxide remain colourless.The violet tint observed in the case of lead is due to reduction of the silver hydroxide and the same phenomenon occurs still more strongly with manganous and stannous hydroxides which imme-diately turn black with silver nitrate. By using mercuric nitrate containing 5 C.C. of nitric acid per litre this complication due to reduction is not so much in evidence. The colour of the mercuric hydroxide ranges from pure yellow to yellowish red, according to the rapidity of its formation. Mercuric hydroxide possesses a lower solubility than silver hydroxide so that a greater number of metallic hydroxides show colours with mercuric nitrate than with silver. Thus with mercuric nitrate, beryllium and lead turn yellowish red; magnesium and cadmium show a stron 104 THE ANALYST.yellowish red ; zinc and aluminium give a faint yellow ; manganous hydroxide an egg-yellow ; whilst indium zirconium antimony and biBmuth remain colourless. These reactions may therefore be of use in certain cases in qualitative analysis and they are particularly useful for the identification of the rare earths the reactions of which are set forth in the following tables : SILVEH. NITRATE REACTIONS. Neo-dymium. Yttriiini. precipi -tated hot precipi-tated cold slowly becomes grey yellowish brown yellowish brown, slightly grey same as yttrium very faint violet -grey paler than y ttriuiii strongly grey to grey-brown paler than lanthanum, yellowish brown saiiie as lanthanum same as lan t h mu tn MERCURIC NITEATE REACTIONS.Pi*ttseo-dymium. NCO-d y m iuni . Lan -thnnnm. Ceroiis Hydroxide. Erbium. Yttrium. Sairiarium. precipi -tated hot precipi-tated cold yellow yellow slightly yellow yellow yellow, slightly reddish yellowish red yellow, brown tinge yellow, brown tinge strongly yellowish red strongly yellowish red strongly yellowish red yellowish red strongly yellowish red slightly yellowish red The hydroxides of the cerium group are more soluble when precipitated cold than when precipitated hot ; they also show a stronger tendency to reduce the silver hydroxide than the last three hydroxides. I n fact a warm very slightly ammoniacal solution of silver nitrate is a delicate test for cerous salts which give a black pre-cipitate or if dilute a brown coloration.Thorium hydroxide appears to exist in two modifications a relatively soluble and an insoluble form. The hydroxide precipitated in the cold from the nitrate gives a strong coloration with both silver and mercuric nitrates but that precipitated from the sulphate only shows a colour after about twelve hours. Hot precipitation tends to retard the appearance of the colour and if the thorium hydroxide be precipitated hot and then boiled for fifteen minutes it is converted into a modification which gives no colour at all with silver or mercuric nitrate. J. F. B. Volumetric Estimation of Iron in Ferric Compounds. M. M. Pattison Muir. (Chem. News 1908 97 50.)-A known volume of the solution containing iron is placed in a flask fitted with a cork carrying a glass tube narrowed at its upper end THE ANALYST.105 20 grams of iron-free granulated zinc and about 200 C.C. of dilute sulphuric acid are added and the liquid warmed until a brisk current of hydrogen is evolved. When reduction is complete about 100 C.C. of a nearly saturated aqueous solution of mercuric chloride are added and the contents of the flask shaken for a few minutes when the liquid is cooled. The deposition of mercury on the surface of the zinc effectually stops the evolution of hydrogen. The liquid is finally titrated witb standard permanganate solution in the usual way. A. R. T. Examination of Red Lead. J. F. Sacher. (C'hem. Zeit. 1908 32 62-63.)-The insoluble residue should be determined by treating the sample of red lead with nitric acid and a sinall quantity of formaldehyde or of pure hydrogen peroxide, evaporating to dryness to remove excess of nitric acid and taking up in water.Partheil's method (ANALYST 1'307 32 395) of reduction with nitric acid and lactic acid is not to be recommended because lactic acid exerts a considerable solvent action on lead sulphate; moreover the excess of nitric acid which also dissolves lead sulphate cannot be removed by evaporation as large quantities of insoluble lead oxalate are formed. A. G. L. The Estimation of Manganese in Water. E. Ernyei. (Clrenz. Zeit. 1908, 32 41-42.)-The method is based upon Narshall's observation (ANALYST 1901 26, 195) that manganese compounds in acid solution are quantitatively oxidised to permanganates by persulphates in the presence of silver salts and upon the iodometric estimation of the permanganate thus formed.A few C.C. of the water are treated with a few drops of sulphuric acid and potassiuin iodide starch solution and if a blue colour is produced (in the absence of nitrites) too much iron is present. I n such a case the water should be acidified with sulphuric acid shaken with a slight excess of zinc oxide and filtered. 100 C.C. of the water freed from iron are mixed with about 5 C.C. of 30 per cent. sulphuric acid rather more silver sulphate solution than is required for precipitation of the chlorine and 1 to 2 grams of potassium persulphate and the whole boiled for 20 minutes. When cold the liquid is treated with a little potassium iodide followed by starch solution as soon as the rose coloration has disappeared aud the separated iodine titrated with & sodium thiosulphate solution.Each molecule of permanganate liberates from the potassium iodide 10 atoms of iodine and the silver iodide in suspension does not affect the end-point of the reaction. Natural waters contain so little manganese that only a few C.C. of the thiosulphste solution are required. Nitrates nitrites organic matter and ammonium salts have no appreciable influence upon the results even when present in greater quantities than are found in natural waters. For the estimation of manganese in ferruginous deposits the substance is dissolved in sulphuric acid the iron precipitated with zinc oxide and the filtrate treated as above described.C. A. N. Volumetric Estimation of Mercury in Minerals. J. A. Muller. (Bztll. SOC. Chim. 1907 4 [l] 1169-1173.)-The mineral is decomposed with aqua regia, the solution evaporated to dryness a t 50' C. and the residue dissolved'in hot water 106 THE ANALYST, Potassium iodide sodium carbonate and finally a little sodium hydroxide are added to the liquid which is then filtered the insoluble residue being washed first with a little potassium iodide solution and then with hot water. The filtrate is made up to 100 C.C. with water and an aliquot part containing about 0.1 gram of mercury is treated in the cold with 20 C.C. of 20 per cent. sodium hydroxide solution and an excess of formaldehyde. After standing for twenty hours the solution is poured off from the precipitated mercury which is then washed finally with a little alcohol air being blown in to remove traces of formaldehyde.The mercury is next treated with an excess of a standard solution of iodine in potassium iodide in an atmosphere of carbon dioxide. The last traces of mercury are dissolved if necessary, by adding a little fresh iodine solution and gently warming. The excess of iodine is then titrated with sodium thiosulphate. The only metals which interfere with the method are gold and platinum. If either of these is present the mineral is decom-posed by heating in a current of chlorine instead of treating with aqua regia and mercury is estimated in the distillate as above. The test results quoted are slightly low. A. G.L. Colour Test for Molybdenum in Ores etc. W. Bettel. (Chem. Nws. 1908, 97 40.)-The author observed in 1903 that if to an acid solution of molybdic acid in which hydrogen peroxide had given the well-known yellow colour (permolybdic acid) sufhjent dilute ammonia solution was carefully added to faint alkalinity the colour changed to an intense brownish-red presumably due to the formation of a permolybdate. This red colour is partially discharged on dihtion and disappears on standing oxygen being evolved. A large excess of ammonia destroys the colora-tion as also do more than traces of fixed alkalies and thus the reaction is a good indicator of neutrality in forming neutral molybdates. For the detection and approximate estimation of molybdenum the liquid is evaporated nearly to dryness, and if alkaline is neutralised with sulphuric acid and treated with hydrogen peroxide.If a yellow colour be produced a very little dilute ammonia solution is next added when the brown-red coloration will appear in the presence of 0.001 mgm. of molybdic acid. -1. R. T. The Detection of Nickel. E. Pozzi-Escot. (A12n. d e Clziiit. mzcil. 1908 13, 16.)-The double molybdate of nickel and ammonium the formation of which may be used as a test for nickel in the presence of cobalt (ANALYST 1907 32 432) is not only insoluble in ammonium rnolybdate solution but also in solutions of other ammonium salts. Thus in testing a neutral or slightly acid solution for nickel ;t small quantity of a saturated solution of ammonium molybdate solution is introduced, followed by a large excess of a saturated solution of ammonium chloride and the liquid gently heated and shaken.In the presence of nickel a turbidity and eventually a precipitate appears in a few minutes. Or a reagent for the detection of nickel may be prepared by adding 10 per cent. of ammonium molybdate solution to a saturated solution of ammonium chloride. C. A. M THE ANALYST. 107 Volumetrie Estimation of Nickel. H. Cantoni and M. Rosenstein. (BUZZ. SOC. Chim. 1907 4 [l] 1163-1169.)-The authors examined the volumetric method of estimating nickel by titrating with potassium ferrocyanide solution using ferric chloride or uranium acetate as indicators and with potassium ferricyanide, using ferrous sulphate as indicator in the presence of acetic acid sodium and ammonium acetates and potassium sodium and ammonium sulphates.They find it best to titrate with potassium ferrocyanide solution in the presence of a small but constant amount of acetic acid and to standardise the solution in the same way against pure nickel. The indicator should be applied to a drop of the solution filtered through a single or double filter-paper according to the fineness of the precipitate. A. G. L. On the Detection of Ozone Nitrogen Peroxide and Hydrogen Peroxide in Gas Mixtures. E. H. Keiser and L. McMaster. (Arne? Chenz. Jown. 1908, 39 96-104.)-Ozone may be detected in presence of hydrogen peroxide and nitrogen peroxide by passing the mixed gases through a dilute solution of potassium perman-ganate and through a solution containing potassium iodide and starch.Both hydrogen peroxide and nitrogen peroxide are instantly reduced by the permanganate, which has no action on ozone. To detect nitrogen peroxide the mixed gases are passed through a tube containing powdered manganese dioxide which decomposes both ozone and hydrogen peroxide but leaves the nitrogen peroxide unchanged ; this gas may then be identified by its action on permanganate or by the formation of nitrite on leading it into pure sodium hydroxide. Hydrogen peroxide may be detected by the formation of Prussian blue in a solution containing potassium ferri-cyanide and ferric chloride ; neither ozone nor hydrogen peroxide causes this reaction, which may however be obtained if the solution is exposed to air for some hours. By means of the above tests the authors show that hydrogen peroxide and nitrogen peroxide are formed when hydrogen is burnt in air.A silent electric discharge at 9,160 volts produced only ozone in air. The action of concentrated sulphuric acid on barium dioxide resulted only in the production of ozone unless barium nitrate was present when nitrogen peroside also was obtained. Moist phosphorus osidising ~ 1 0 ~ 1 ~ in air gave both ozone and nitrogen peroxide but not hydrogen peroxide. Air passed through an electric arc contained all three gases. A. G. L. Modification of Petermann’s Method for the Estimation of Citrate-soluble Phosphoric Acid in Phosphate Fodder Meals. G. Fingerling and A. Grombach. (Zeds. a n d Chem. 1907 46 756-760.)-1t is recognised that dicalcium phosphate is assimilated by animals far more readily than tricalcium phosphate and that phosphatic fodder meals should consist of precipitated calcium phosphate and not merely of steamed or extracted bonemeal.Petermann’s process originally used for the estimation of citrate-soluble phosphoric acid in superphosphates is therefore applicable for the valuation of these fodder meals but it has the dis-advantage that the substance is to be digested with the citrate solution for fiftee 108 THE ANALYST. hours at the ordinary temperature with occasional shaking.” This is generally impossible without night work and the authors’ experiments have been directed to finding a more convenient procedure which will give results practically identical with those afforded by the original method.The modified process is as follows One gram of the substance is placed in a 200 C.C. flask with 5 C.C. of alcohol and 100 C.C. of Petermann’s citrate solution. The mixture is agitated by means of a rotary shaking apparatus for half an hour After shaking it is digested for one hour at a temperature of 40” C. with agitation then cooled diluted to 200 c.c. and filtered; 100 C.C. of the filtrate are treated with 20 C.C. of concentrated nitric acid evaporated to half the original volume cooled neutralised with ammonia and treated with 50 C.C. of Hallens,’ solution. After cooling 30 C.C. of magnesia mixture a.re added drop by drop the liquid is shaken for half an hour and the phosphoric acid is estimated in the usual manner. J. F. B. The Detection of Ruthenium in Platinum Alloys.N. A. Orlow. (Chem Zcit. 1908 32 77.)-A sample of the alloy is fused with lead the mass extracted with nitric acid and the residue ignited in the air to expel osmium. The ignited mixture which may contain iridium rhodium and ruthenium (in addition to platinum) is fused with potassium nitrate and potassium hydroxide the mass, when cold extracted with cold water and the liquid treated with excess of nitric acid to bring about the reaction-~KARuO + 4HN0 = RuO + Ru(OH) + 4IiN0,. The brown liquid is left for twelve to twenty-four hours in a vessel covered with filter-paper and in the presence of ruthenium the under side of the paper will have become black through absorption of the vapours of the ruthenium tetroxide (RuO,). In this way it is possible to detect 0.01 gram of ruthenium in an alloy.The blackened paper may be ignited the ash fused with potassium nitrate and potassium hydroxide and the orange-coloured ruthenate extracted with water from the mass. The darkening of the paper occurs more rapidly on heating but there is then a risk of the vapours escaping. The preliminary removal of all osmium (which gives a similar reaction) is essential. C. A. M. The Analysis of Commercial Silicon. F. Limmer. (ClLenz. Zeit. 1908 32, 42.)-Silicon may be quantitatively separated from silica by volatilisation as silicon chloride in a current of chlorine. From 0.25 to 0-50 gram of the finely divided sample is heated at a moderately red heat in a porcelain boat in a glass tube through which is passed a slow current of perfectly dry chlorine free from all trace of oxygen.The heating is not started until all air has been expelled from the tube by the chlorine and after the end of the reaction (one to three hours) the boat is allowed to cool in a current of the gas. The silicon and iron and aluminium chlorides con-dense on the colder parts of the tube whilst the residue in the boat may contain in addition to silica traces of carborundurn (especially in the case of silicon prepared by electrolysis) magnesium chloride and calcium chloride. The separation of silicoc from silica cannot be regarded as complete until the residue becomes constant i THE ANALYST. 109 weight. From thirty minutes’ to one hour’s heating is sufficient in the case of crystalline and fused silicon but with amorphous silicon as long as three and a half hours’ heating may be required before the residue becomes white and constant in weight.This is possibly due to the large proportion of silica in the amorphous pre-paration. Thus commercial s ~ ~ ~ p l e s examined by the author yielded from 23.24 to 65.56 per cent. of residue whilst two samples of fused silicon gave 11.90 and 2.35 per cent. respectively and two samples of crystalline silicon 1.47 and 1.56 per cent. respectively. The silica in the residue may be estimated in the usual way whilst the amount of silicon is found by fusing the sample in a platinum crucible for thirty minutes with sodium and potassium hydroxides so as to obtain the total silicon and deducting from the result the silica found in the residue from the chlorine volatilisa-tion. A complete analysis of a sample of commercial silicon gave the following results Residue from chlorine treatment 2.35 per cent. (consisting of 0.90 per cent. of silica 1-40 per cent. of magnesium chloride and traces of calcium and carbon silicides) ; iron 2.35 per cent. (including a little aluminium) ; silicon 95.27 per cent. ; and traces of a phosphorus compound. C. A. 1%

ISSN:0003-2654    

DOI:10.1039/AN9083300102

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年代:1908

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THE ANALYST. 109 APPARATUS, ETC. A New Vacuum Regulator. J. W. Holterman. (Cheylt. Zeit., 1908, 32, 8.) -The use of the regulator here shown reduces to a minimum the effect of variations in the water-pressure when a water-pump is used to create a vacuum. It consists of nine glass manometer tubes fixed in a stand and connected by means of rubber tubing, and a tenth manometer tube which is movable. On the other side of this tube is a small washing-flask, the inner tube of which is drawn out to a fine point, whilst the other tube contains cotton-wool to filter the air as it enters. The manometers are charged with the requisite measnred quantity of water, and the apparatus connected with the pump and the distillation apparatus. With the aid of this apparatus it is possible to distil i i z Z~CCCPLO for a whole day with no greater variations in pressure than 0.25 mm.in the height of the mercury. I t isessential, however, that the opening of the small tube in the flask shall be of the right size, so that the air bubbles may follow one another in the smallest possible time throughout the apparatus. Variations in the atmospheric pressure may be compensated by altering the position of the movable manometer tube. Still better results may be obtained by the use of petroleum or olive oil (especially the latter) in place of water in the apparatus, but mercury is unsuitable110 THE ANALYST. owing to its becoming oxidised, and to its possessing a considerable surface tension which is greatly influenced by impurities. C. A. M. An Accurate Form of Gas Analysis Apparatus.William A. Bone and Richard V. Wheeler. (Jourit. SOC. Ch,ent. Ind., 1908, 27, 10-l2.)-The authors’ research apparatus (see Proc. Cliem. SOC., 1898, 154) has been adapted to meet the general requirements of accurate commercial work, and in its modified form is prscticnlly universally applicable in the examination of gaseous mixtures. The I apparatus comprises three parts : (1) A water-jacketed combination of measuring and pressure tubes, A, B, communicating with the reservoir, D, and connecting also with the special sampling tube, I<; (2) an absorption vessel, F, standing in a mercury trough; and (3) an explosion-tube, E, connected with its own mercury reservoir, If. All the connections are of capillary bore, and the whole of the apparatus, including all the connections between -4, E , and E’, is filled with niercury before the analysis is commenced.The sample is introduced into I<, or under the wide-open end of the absorption vessel, F. The glass taps should be kept lubricated with a solution of rubber in vas- eline, and the whole apparatus washed out with dilute acid after each analysis. The principle of memurewent followed in the apparatus is the measurement of the pressure of the gas, in mm. of mercury, at constant volume. For this purpose the gas is brought to a certain “constant volume” mark in the measuring-tube, d, and its pressure as registered on the tube B noted. Each of the series of ‘‘ constant volume ” marks on A corresponds with a100 mm. pressure markonB, SO that the actual pressure is obtained by subtracting from the reading the numbers 0, 100, or 200, etc., according to the volume inark selected in the analysis.The tubes A, I’THE ANALYST. 11 1 are made in one piece and are surrounded by a water-jacket, and their inner surfaces are kept moist with 1-ery dilute sulphuric acid (1 in 20), in case the measuring-tube is accidentally fouled by alkali. The wetting of these tubes with the flame liquid eliminates the influence of water-vapour on the measurements, the pressures thus representing thosc of the dry gas. The tap at the end of B, which allows of the vacuum being easily made in the tube, is connected with the latter by means of stout pressure tubing, giving a tight joint and suEcient elasticity to prevent fracture of the tube in case the mercury is allowed to run up too quickly.The measurement of pressure at a constant volunie has the advantages of allowing of the use of smaller volumes of gas tor analysis-q., 5 to 10 C.C. of gas can be made to have a pressure of 100 mni., and this can be read off directly to within 0.2 mm.-and the measurements are independent of barometric pressure, and unaffected by the tension of aqueous vapour. The length of the pressure-tube I' (700 mm.) allows of the proper dilution of the " explosive mixture." Dilute gases (producer-gas, etc.) may be examined in an apparatus having a tube, I;, of, say, 400 mm. and a correspondingly reduced explosion- tube, E , but this would be quite unsuited for the examination of richer gases. All the absorptions are carried out in the vessel F, only a small volume of the reagent being necessary, and this being discarded after once using.To introduce the absorp- tion reagent, and the water or dilute sulphuric acid between each successive addition, 3 to 3 c.c. of the solution are delivered from a suitable pipette into F from under the surface of the mercury in the trough, any bubble of air being drawn out by the capillary three-way tap through its lower branch, which conimunicates with a pump. X bottle is interposed between the latter and the vessel F, to serve as a trap for the mercury or the reagent after use. The insertion of a tap between the pump and the bottle renders only one exhaustion necessary a t the beginning of the analysis, and the reagents and washings can be successively withdrawn from the absorption vessel.The necessary operations can be carried out without disturbing any of the connections, and the apparatus is thus rapid in its working. The analysis of a producer-gas recluires forty-five minutes, and that of a sample of coal-gas about one hour. &4. 1%. T. Porous Materials as Substitutes for Stopcocks in Work with Gases. A. Stock. (Be].. dcrtt. Cl~ciir. Gcs., 190'7, 40, 4956-4959.)-The author describes apparatus in which glass stopcocks are replaced by plugs of porous clay. These plugs are made by calcination of a mixture of clay, waterglass, and gum ; the pores are very uniform ; the plugs resist the action of dilute acids and boiling water, and possess the great advantage of being fixed firmly in glass tubes by simple fusion of the latter without the use of any cement.The principle on which these plugs are used was first enunciated by Pryts ( - 1 1 1 ~ t l . Phys., 1905, 18, 617). I t may be under- stood from the following example : Given a glass tube A , with a porous plug fixed a short distance below its upper end, this tube may be closed by a layer of mercury poured upon the porous plug. If now another tube, 11, fitted with a similar porous plug flush with its lower end, be pushed through the mercury in A until the two porous plugs touch each other, gaseous connection is established between the two112 THE ANALYST. tubes. A may then be evacuated by a pump connected with B, and is perfectly sealed when B is lifted out of the mercury, the arrangement acting exactly as a stop- cock. Such valves are useful on air-pumps, particularly on water-air pumps, as automatic back-pressure valves. J. F. B. Soda-Lime Apparatus for Elementary Analyses and Carbon Dioxide Estimations. M. Dennstedt. (C'hem. Zeit., 1908, 32, 77.)-The apparatus shomii in the figure con- sists of two cylinders uniting in a circular base with flat bottom. The cylinder through which the gas enters the vessel passes nearly to the bottom, and ends in a constriction, whilst the remainder of the apparatus is filled with granulated soda-lime. The weight of the vessel does not exceed 40 t o 50 grams when empty, or 100 grams when charged. It is advisable to intersperse a little glass wool with the soda-lime, which should be loosely packed. c. A. 31.

ISSN:0003-2654    

DOI:10.1039/AN9083300109

出版商:RSC    

年代:1908

数据来源: RSC