摘要:

THE ANALYST. FEBRUARY, 1898. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE ANNU-4L DINNER OF THE SOCIETY O F PUBLIC ANALYSTS. THIS, the full report of which will appear in our next issue, took place at the Criterion on Tuesday, the 18th ult., the President (Dr. Bernard Dyer) occupying the chair. The Annual Meeting was held on February 2nd. REPORT OF THE COUNCIL OF THE SQCIETY OF PUBLIC ANALYSTS SALE OF FOOD ,4ND DRUGS BILL, ON THE INTRODUCED IN THE HOUSE OF COMMONS IN 1897 BY THE RIGHT HON. W. H. CHAPLIN, M.P., AND MRi T. W. RUSSELL, M.P. THE Council of the Society of Public Analysts has considered the Sale of Food and Drugs Bill, introduced by the President and Parliamentary Secretary of the Local Government Board towards the close of the last Session, and desires to express its regret that the measure deals with so few of the recommendations of the Select Committee.I t is to be remembered that the Select Committee of the House of Commons on Food Products Adulteration, which was appointed in 1894, sat for three Sessions, and collected a very large mass of evidence, from widely different sources, bearing upon the matters which it was appointed to consider. The outcome of its labours was a report, presented to Parliament in July, 1896, very fully sumniarising the evidence which had been collected, and concluding with an epitome, under twenty- three headings, of the directions in which, in the opinion of the Select Committee, the existing Food and Drugs Acts should be amended. It was confidently expected on all hands that the Government would introduce into Parliament a Bill giving effect to these recommendations, or at all events to the majority of them ; but the Bill produced at the close of the last Session falls so far short of the requirements of the case, that in most essential particulars the recommendations of the Committee appear to have been passed over.The Council of the Society of Public Analysts desires, therefore, to point out the30 THE ANALYST. chief omissions in the Bill, and the principal directions in which it appears to require amendment. The First Section of the Bill states that- “It shall be the duty of every local authority entrusted with the execution of the laws relating to the sale of food and drugs, to put in force from time to time, as occasion may arise, the powers with which they are invested, so as to provide proper securities for the sale of food and drugs in a pure and genuine condition, and in particular to direct their officers to take samples for analysis.” It appears to the Council that this Section gives no remedy for the existing unsatisfactory state of affairs, no means being provided or suggested for enforcing the performance of that which is recognised as a duty.Experience has shown, as is fully set forth in the Report of the Select Committee, that in spite of considerable pressure brought to bear by the Local Government Board, certain local authorities have persistently neglected to carry out the provisions of the Sale of Food and Drugs Acts. The Second Section, which proposes to institute a nziizimz~in fine of $5 for a second or subsequent offence, carries into effect recommendation No. 16 in the Report of the Select Committee.This is one of the very few of the recommendations of the Committee which the Council feels itself unable to support, since the Council of the Society of Public Analysts is of opinion that the fixing of a minimum fine of $5, in all cases of second conviction, would be unduly binding on magistrates, who should be free to deal with each case on its merits, having regard to the great variety of cir- cumstances requiring the consideration of the Bench which occur in connection with cases under the Acts. With regard to the Fourth Section, the Council desires t o draw attention to a recent case in which margarine was enclosed in a wrapper on which the word ‘‘ mar- garine” was distinctly and legibly printed, but in which the significance of the word was diminished by the presence of other printed matter on ‘the label.The Council therefore suggests that this Section might be improved by adding a provision that no other words or letters should be printed on the same wrapper. With regard to Section 10, which relates to warranties, the Council of the Society of Public Analysts considers that, in order to ensure the conviction of the real offender in a case of adulteration, jurisdiction should be given to the Court before which the summons is heard, to call the giver of a warranty before it, should the warranty exonerate the vendor ; and that proceedings should in such case be com- pulsorily instituted against the giver of the warranty.The Council also considers that no warranty should be accepted if given by a person abroad, or outside of such jurisdiction as it is possible to confer on the Court by Act of Parliament. Section 12 (Sub-section 1) proposes that the certificate of analysis required by the Sale of Food and Drugs Act of 1875 shall be in a form prescribed by the Com- missioners of Inland Revenue, and proposes to repeal the Schedule to that Act relating to the form of certificates. The Council of the Society of Public Analysts is of opinion that the form of certificate should not, as in the Act of 1875, be unalterably fixed, but dissents fromTHE ANALYST. 31 the proposal that the form should be prescribed by the Commissioners of Inland Revenue.The Council considers that the proper body to prescribe the form of certificates would be the Standing Committee or Court of Reference recommended by the Select Committee, the formation of which Court of Reference is not provided for in Mr. Chaplin’s Bill, an omission to which attention is called hereafter. Sub-section 2 of Section 12 provides that the production by the defendant of a certificate by a public analyst shall be sufficient evidence of the facts therein stated (unless the prosecutor requires that such public analyst be called as a witness). The Council would suggest the desirability of providing that in the absence of the public analyst whose certificate is tendered by the defendant, and in the event of a material difference between the opinions expressed in that certificate and in the public analyst’s certificate on which the prosecution was based, it should be compulsory on the Court to refer the portion of the sample retained by the Inspector to the Com- missioners of Inland Revenue.Having thus referred to some of the points suggested by the Government Bill, the Council wishes to call attention to certain of its omissions. The Select Com- mittee made an important recommendation (No. 18)- “ . . . . that the definition of the word ‘ food’ as used in the Acts should be amended so as to include expressly all articles intended to enter into or be used in the preparation or flavouring of food.” This recommendation has not been adopted in the Government Bill, although its importance was very fully insisted upon.The present definition of food, as inter- preted by the High Court, enables injurious, adulterated, or objectionable baking powders and certain other articles, to be sold with impunity, on the contention that they are not themselves “ food,” although they are sold for the express and avowed purpose of being introduced into food and consumed as such. The most important omission, however, in the opinion of the Council of the Society of Public Analysts, is the failure to carry out recommendation No. 19 of the Select Committee, viz. : (‘ . . . . that an authority should be constituted, who should act as a Court of Reference upon scientific and other questions arising under the Acts, and who should be empowered at their discretion to prescribe standards and limits of the quality and purity of food.” The report of the Select Committee deals with a very large number of questions on which, as a Committee, they refrain from making any definite recommendations, on the ground that such matters would properly be dealt with by the body whose formation they contemplated.They expressed the opinion- (‘ . . . . that it would greatly facilitate the working of the laws as to the adulteration of food, and also serve the interests of traders, if standards or definitions of food were promulgated by competent authority”; and . . . . that the question of fixing food standards should receive the attention of a specially-constituted scientific body familiar with questions of analysis and the chemistry of food.” (‘ . . . . be empowered to make such orders as they think proper respect- Their recommendation was that such body or Court of Reference should-32 THE ANALYST.ing standards of the quality and purity of food, and that such orders should, when confirmed by a Secretary of State, have the force of law ” ; and they were of opinion that I < . . . . the formation of such an authority having the functions indicated would result in the removal of many practical difficulties met with in the administration of the Acts, and by rendering more precise the law affecting adulteration would obviate the costly litiga- tion in which, under existing circumstances, traders and others have some- times been involved.” It was recommended that the proposed- (( . . . . Court of Reference should take the form of a standing Depart- mental Committee appointed by the Board of Trade; ” and that ( ( .. . . such Committee should include the principal oficer of the Government laboratory, nominees of the Local Government Board and Board of Agriculture, one or more analysts of repute, and representatives of the General Medical Council, the Institute of Chemistry, and the Pharma- ceutical Society. Other scientists,” it is added, ( ( whose services are available, and whose presence on the Committee may be expected to lend weight to its decisions, should find places thereon.” ( ( . . . . representatives of the trading and manufacturing community should also be included.” I n fact, this proposal as to the establishment of a Court of Referenqe having such powers as those alluded to, forms, from most points of view, one of .the principal features in the report of the Select Committee ; and the recommendation met with cordial and widespread endorsement.This being so, the Council of the Society of Public Analysts notes with very great regret the total omission from the Bill of any mention of such a Court or Committee. It is, in the opinion of the Council, essential for the success of any new legislation, not only that such a Court or Committee should be constituted, but that the Committee when formed shall include one or more public analysts. At the present time each individual public analyst is left to decide what does or does not constitute adulteration, what is or is not to be regarded as injurious to health, and what limits and standards are to be adopted in judging of the genuine- ness or otherwise of samples submitted to him.Disputed questions of the greatest scientific intricacy are now fought out, more or less imperfectly, in open Court at the expense of vendors or public autlhorities ; and, as a consequence, questions which might have been settled, to the benefit of the community, many years ago, are still undecided, after more than twenty years’ working of the Food and Drugs Acts. The Court of Reference recommended by tI!e Select Committee was originally suggested by the Society of Public Analysts, and the suggestion, as will have been seen from the quotations already given from their report, met with the entire approval of the Select Committee, who saw therein the means of solving the gravest difficulties which have hitherto arisen under the Food and Drugs Acts.The Council is clearly of opinion that, without such a Court or Standing Committee, any new legislation will be of little or no value, while, on the other hand, the institution of such a I t is further suggested that :THE ANALYST. 33 Cbmmittee would afford the simplest means of ensuring the effective working of anti- adulteration legislation. There are other points of omission in the Bill (such, for instance, as those connected with the Select Committee’s recommendations affecting the colouring and mixing of butter substitutes), which the Council of the Society of PubLio Analysts does not feel itself directly called upon to discuss. Generally speaking, the Council is of opinion : 1. That the draft Bill introduced by the President and Secretary of the Local Government Board is unsatisfactory, inasmuch as it does not embody the most important recommendations of the Food Products Adulteration Com- mittee, and that, if passed, it would not lead to the removal of the difficulties experienced i n carrying out the present Sale of Food and Drugs Act. 2. That the recommendations of the Food Products Adulteration Committee, subject to but few modifications, should be embodied in any Bill which may be put before Parliament during the coming Session. 3. That the most important recommendation of the Select Committee, viz., recommendation No. 19, referring to the formation of a Court of Reference constituted substantially as laid down in the body of the report (with, how- ever, the inclusion in its number of one or more public analysts) should be acted upon, if new legislation is to lead to satisfactory results. (Signed) BERNARD DYER, President.

ISSN:0003-2654    

DOI:10.1039/AN8982300029

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 33 A METHOD OF ESTINATING GALLOTANNIC ACID BY MEANS OF THE POLARIMETER. BY R. F. WOOD-SMITH AND CECIL REVIS. (Read at the Meeting, December 1, 1897.) IT is a well-known fact that difficulty has often been experienced in the Lowen- thal method of estimating tannic acid, in properly filtering the gelatino-tannin precipitate, the filtrate from which is apt to remain turbid and to contain traces of tannic acid; the method offers the further objection that it is not always easy to obtain a sensitive final reaction in the permanganate titration. The method proposed by the authors removes these objections, and has the advantage of great rapidity; but, at the same time, it must be borne in mind that it is based upon empirical data, that the experiinents made were carried out in the case of gallotannic acid only, and that therefore varying results must be expected where other tannin material is employed..The method consists in observing the lzvo-rotation of a, standard gelatin solution before and after treatment with known quantities of tannin material (the filtered liquids in each case being clarified by egg-albumin), when, at a constant34 THE ANSLYST. temperature, the quantity of gallotannic acid present (in the absence of other bodies optically active towards the polarized light) can be determined by a factor for the rotation difference. I t was found that at constant temperature the specific rotatory power of gelatin remained the same for any strength of solution up to 10 per cent., and it was further found that the difference between the rotatory power of the gelatin solution before and after treatment with tannin at constant temperature was directly proportional to the amount of gallotannic acid used, so long-and this wafi observed to be a most important condition--as sufficient excess of gelatin remained after treatment to cause a, laevo-rotation of not less than seven divisions on the Ventzke scale. The experiments for the determination of the factor were all carried out with a Schmidt and Haensch half-shadow quart-compensating polarimeter, an instrument which is constructed for ufie with (' white light," as it was believed by the authors that this form of instrument was most generally employed for rapid work.The gelatin used for the experiments, and for which the factors are calculated, is the well-known Coignet's gold label extra fine gelatin, since this was found to be constant in composition and in its specific precipitating power on gallotannic acid.It is extremely important that gelatin of this nature should be employed, since, as has been recently pointed out by P. Carles (Ann. de Chim. Amdyt., vol. ii. [lo], 181, lS2), different kinds of commercial gdatin precipitate very different quantities of gallotannic acid under the same conditions, and also possess different specific rotatory powers. The temperature at which the experiments were carried out was 45" C., since at that point the specific rotatory power of gelatin only varies very slightly with changes of temperature, and it was found that differences of 3" or 4" produced no appreciable difference in the final results.The gelatin solutions were also made up and kept at that temperature in a water- jacketed incubator, and all volumetric measurements occurring in the course of the experiments were made under the same conditions. The details of the method and the calculated factors are here given : A 1. 25 C.C. of an approximately 9 per cent. solution of gold label gelatin in water at 45" C. are transferred to an evaporating dish capable of holding about 100 c,c., which is placed on a boiling-water bath. A 2. As soon as the temperature of the liquid has risen to about 60" C., 1 C.C. of the soluble albumin of a perfectly fresh egg is added, and the whole is allowed to attain the temperature of the water-bath, with constant stirring.A 3. The liquid is kept at 100" C. for ten minutes, also with repeated stirring. A 4. It is now allowed to cool down to about 50" C., when, if the supernatant liquid is seen to be quite clear, it is again heated up to 100" C. and filtered, the precipitate washed with boiling water, and made up to 50 C.C. at 45" C. ; but if, as sometimes happens, the first treatment with albumin does not render the fluid free from opalescence, the above operation is repeated, when a clear liquid can always be obtained, especially if the warming on the water-bath be slightly prolonged. A 5. It is advisable, if the bulk of liquor has during the process attained unduly large proportions, not to evaporate down, but to filter, wash as far as possible, andTGE ANALYST. 35 make up to 50 c.c., and then to again wash the residue with boiling water, and inake up the second washing to another 50 C.C.A 6. The Imo-rotation of the clear filtrate is now taken at 45" C., to which must be added that of the second washing if necessary. B 1. 25 C.C. of the same 9 per cent. gelatin solution are, as before, transferred at 45" C. to an evaporating dish, and a known quantity of the tannin extract added (which should for convenience contain between -2 and 1 gramme of gallotannic acid). B 2. The above is warmed on the water-bath for five to ten minutes, when the opalescent supernatant liquid is poured off into a second dish, the gelatino-tannin precipitate which adheres to the first basin being thoroughly worked about and washed with boiling water, and the washing added to the second basin. B 3.This is now treated with egg-albumin in the same manner aE: the blank experiment (A 2-6), and is then filtered, made up to 50 c.c., and the hvo-rotation at 45" C. taken. The difference between the rotations of A and B gives the measure of the gallo- tannic acid present. The experiments A standardize the gelatin solution, and the rotation so found may be taken as constant for the same solution for some time. The following table states the gelatin differences of rotation caused by different amounts of gallotannic acid, and the factor which must be multiplied by the sugar units of difference (for white light) to give the amount of gallotannic acid present : Weight of Gallotannic Acid Used = T. 0.900 grammes 0.720 ,, 0.600 ,, 0.480 ,, 1.000 ,) Gelatin Rotation Difference in Sugar Units = R.13.50 10.60 8-90 7.15 14.90 T Factor= - K' 0-0667 0.0679 0.0674 0.0671 0.0671 T Mean factor Addenda.-(1) I t is important that the egg employed for clearing the liquid should in all cases be peifectly fresh, as otherwise the albumin does not coagulate properly, and the filtrate retains a slight opalescence. (2) To ensure rapid filtration, a fluted filter should be employed; then the process takes place quickly, and a hot-water funnel is not necessary. (3) After the tannin material has been added to the gelatin solution and warmed, the supernatant liquid should appear quite milky, this being an evidence that a sufficent excess of gelatin exists. DISCUSSION. for the above and numerous other experiments = 0,0673.Mr. HEHNER inquired whether the method was applicable to more than one kind of tannin, and, if not, to what particular kind of tannin it was applicable. I t appeared to have the same difficulties as all other methods-in being useful only for one of the very numerous kinds of tannic acids. What was to be ,desired was a method for actually determining tannin, from whatever source it came,36 THE ANALYST. Mr, ALLEN observed that a single method for the determination of tannin in any class of tanning material was as far out of reach as a universal method for the determination of all metals, for the variatims in the properties of the so-called ‘‘ tannins ” were quite as great as the differences in the analytical behaviour of, say, iron, copper, tin, and zinc.Dr. RIDEAL agreed with Mr. Hehner and Mr. Allen as to the variations in different tannins, and as to the difficulty of determining them. He had himself been in the habit of determining the quantity of potassium permanganate required by a solution of tannin (Loewenthal’s method), and the quantity required by the tannin solution after treatment with hide-powder, representing the quantity of organic matter in the solution before and after treatment, the difference between the two being the actual weight of organic matter present as tannin, or matter absorbable by hide-powder. The use of a very pure gelatin seemed to have an advantage over hide-powder, inasmuch as there was a good deal of difficulty in obtaining uniform’ hide-powder. The use had been recently suggested of a compound of gelatin and formalin, which absorbed tannin in the same way as gelatin, and which might possibly have a more constant composition.It was perfectly well-known that there were different kinds of tannin, which behaved differently in regard to their action on gelatin; but if separate processes could be devised to give accurate or approximately accurate results with, for example, bark, tea, hops, and like materials respectively, each of these processes would be extremely useful, even if it were not applicable to more than one kind of material. The PRESIDENT observed that the method, although it might not be applicable to different classes of tannin equally, was certainly an interesting one, and one which opened up new avenues of investigation. Mr. WOOD-SMITH admitted that the method was only applicable for the particular kind of tannin employed, viz., the ordinary purified commercial gallo-tannic acid, and that, further, the presence of optically-active bodies other than tannic acid necessarily interfered with the results. I t had, however, proved very useful to the authors under circumstances involving the use of one class of tannic acid only, and factors could no doubt be determined for any other variety of tanning material. I n reply to a question put by Mr. Richmond, he said that the normal weight of sugar solution for the polarimeter employed in the experiments was 26.048 grammes. Mr. A. C. CHAPMAN thought Mr. Allen’s remark too sweeping.

ISSN:0003-2654    

DOI:10.1039/AN8982300033

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

36 THE ANALYST. A BUTTER EIGHTEEN YEARS OLD. BY E. G. CLAYTON. (Read at the Meeting, December I, 1897.) THE butter to which these remarks apply was the subject of a reference-case under the Sale of Food and Drugs Act in 1879. In that year it was analysed by Mr. Hehner, who has kindly given me permission to mention that he found it to yield 87.75 per cent. of insoluble fatty acids, while it contained normal amounts of water, curd, and salt, and evidently was perfectly genuine.THE ANALYST. 37 Since 1881 the bottle containing the residual portion of the sample has been in my keeping, and the following are tbe results of the examination to which 1 have submitted this old butter. It should be premised that the quantity was very small, otherwise a more complete investigation would have been made. The sample had rather an offensive odour, and was considerably discolored. During most of the time the bottle was kept in a dark cupboard, but the stopper, being broken, fitted imperfectly, so that there was ainple opportunity for oxidation. ANALYSIS : Required (a) Estimated Rise of 2347% in 1895 : temper- KOH; 25.682." ature = 239.0, (b) Estimated =2a°C. saponifi- in 1897 : cation 25.09%. equiva- lent. Rancidity. 100 grms. required 160-3 C.C. normal KOH. The numbers with asterisks were obtained by me in January, 1895, the remainder in October, 1897.

ISSN:0003-2654    

DOI:10.1039/AN8982300036

出版商:RSC    

年代:1898

数据来源: RSC

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THE ANALYST. 37 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. The Adulteration of Milk with Saccharose Solutions. Cotton. (BUZZ. de Pharm. de Lyon, August, 1897 ; through Joz~r. Pharm. Chim., 1897, vi., 362, 363.)- The following is given as a rapid test for detecting the addition of saccharose solu- tions to milk : Ten C.C. of the suspected milk are mixed with 0.5 gramme of powdered ammonium molybdate, and 10 C.C. of dilute hydrochloric acid (I : 10). In a second tube 10 C.C. of milk of known purity, or 10 C.C. of a 6 per cent. solution of lactose, are similarly treated. The two tubes are placed in a water-bath, and the temperature gradually raised. At about 80” C. the milk, if adulterated with saccharose, assumes an intense blue colour, whilst the genuine milk, or lactose solution, remains unaltered.On boiling, these also turn blue, but to less extent than the adulterated milk. With milk containing only 1 gramme of saccharose per litre, the reaction is well marked, but the author states that the amount used for adulteration is never less than 6 grammes per litre. C. A. M.38 THE ANALYST. The Composition of Asses' Milk. A. Schlossmann. (Zeit. Phys. Chenz., 1897, xxiii., 258).-The author gives the results of his analyses of sixteen samples obtained from one establishment in Dresden. The density varied from 1.031 to 1-036, and the mean percentage results of the total solids were 11.15; of the ash, 0-399 ; and of the sugar, 4.94. The total nitrogen varied from 0.22 to 0.27 per cent., of which 86 per cent. belonged to albuminoid substances (precipitated by tri- chloracetic acid or salicyl-sulphonic acid).The limits of fat;, of which the globules were very small, were 0.15 and 0.6 per cent. One C.C. of the milk required for neutralization 0.06 C.C. of decinormal sulphuric acid with phenol-phthalein as indicator, and 0.404 C.C. with methyl orange or turmeric as indicator. C. A. M. On the Volumetric Determination of Casein in Milk. G. Deniges. (Jour. Fharm. Chzm., 1898, vii., 9-12.)-This is a supplementary note on the author's volumetric process (ANALYST, xxii., 11). I n the titration of milk rich in calcium salts, a turbidity occurs after the addition of ammonia which prevents the end- reaction from being clearly observed. This is obviated by the addition of a little ammonium oxalate, which does not exercise any disturbing influence.The modified process is as follows : Twenty-five C.C. of the milk are mixed with 5 C.C. of a saturated solution of ammonium oxalate, 20 C.C. of the decinormal mercuric-potassium iodide solution, and 2 C.C. of acetic acid, the volume made up to 200 C.C. and the liquid filtered. To 100 C.C. of the clear filtrate are added 10 C.C. of a, solution of potassium cyanide equivalent to a decinormal (or approximately decinormal) solution of silver nitrate, and 12 to 15 C.C. of ammonia, and the liquid titrated with the silver nitrate solution until there is a permanent turbidity. A blank determination is made to determine the exact value of the silver nitrate solution. Ten C.C. of the cyanide solution, 12 to 15 C.C. of ammonia, and 10 C.C.of the mercuric-potassium iodide solution, are mixed with 100 C.C. of water and titrated as before with the silver nitrate. The number of C.C. =c, and the casein in the milk corresponds to q - c. When the silver nitrate is exactly decinormal, c = 4.8 c,c. The value of q - c, expressed in tenths of a c.c., is then obtained from the table or the formula given in the former paper. The number of C.C. used = q. C. A. M. A Contribution to the Study of Butter. K. Farnsteiner and W. Karsch. { Zeit. fur Uizterszhch. der Nahru?zgs-md Genussmittel, 1898, 16-21.)-The authors call attention to a case of butter of unquestionable purity showing abnormally low Reichert-Meissl and saponification numbers. Different samples of the butter, which came from a farm in Holstein, gave the following numbers : Refractometer number Reichert-Meissl number.Saponification number. (25" C). 55.0 ... ... 23-98 ... ... 220.27 55.0 23.68 ... ... 219.20 55.0 22.80 ... ... 218.53 55.0 ... ... 22.74 ... ... 218-50 The case was further inquired into, and 25 cows out of the 180 kept at the farm were selected as corresponding to the whole number as regards the average period of ... ... ... . . .THE ANALYST. 39 lactation. the same abnormal results, viz. : The milk from these being treated separately, yielded a butter which gave Refractometer number. Reichert-Meissl number. Saponification number, (aso C). ... ... ... ... 53.0 22.16 92040 53.2 ... 22.22 ... ... 221.75 53.0 ... ... 22.11 ... ... 219.74 The relation of the refractometer number to the iodine number is shown in the following figures : Refractometer Iodine Reichert-Meissl Saponificatiw number.number. number. number, October 21, from 180 cows 55-0 49.57 22.80 218.53 October 26, ,, 25 ?, 53.0 40.00 22.11 219.74 The case corresponds to that reported from Hameln by Vieth, and is doubtless due to the cows having been for a long time in milk. H. H. B. S. Detecticm of Sesame-oil in Butter and Xargarine. P. Soltsien. (Pharm Zeit., 1897, xlii., 837 ; through Chenz,. Zeit. Rep., 1897, 325.)-The author ca€k attention to the fact that when furfuraldehyde, or at least the German official alcoholic solutian thereof, is mixed with hydrochloric acid (sp. gr. 1-19>, it yields of itself a red coloration, which appears slowly in the cold, but quickly on warming ; and the tint is very similar to that produced by a small amount of sesame-oil. The only difference between the two is that the former develops more slowly, soon changes to the colour of permanganate, and finally assumes a bluer tone, which is fairly permanent, F.H. L. On the Detection of Ergot in Flour. A. Miller. (Jozw. soc. Phys. Chim., xxviii., 524; through Jour. Pharm. Chim., 1897, 553.j-The author has met with a sample of flour containing only a trace of ergot (not more than 0.1 per cent.), which, nevertheless, imparted to the alcoholic extract a clear rose coloration as pronounced as though the proportion of ergot had been 1 per cent. On examination, the flour waB found to contain psrficles of the husk of the grain of a bluish-green shade, which assumed a reddish tint on treatment with acidulated alcohol, and imparted the same colour to the alcoholic extract. The difference in shade between the colour produced by this flour and that containing ergot was only distinguishable in concentrated solutions, when the former was rose-red whilst the latter was brick- red. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300037

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 39 TOXICOLOGICAL ANALYSIS. On the Detection of Phosphorus in Toxicological Work. H. Watterman and A. Eilger. (Forsch. Bey., 1897, iv., 241-258.)--The methods employed for the detection of phosphorus in forensic work are : (1) Scherer's, which depends upon the fact that steam containing phosphorus vapour reduces silver nitrate. The substacme under examination is mixed with water, acidified with sulphuric acid, and warmed at 30" to 40" C., yhilst strips of the reagent paper are suspended in the mouth of the40 THE ANALYST. flask. (2) Mitscherlich’s, which is based on the volatility of elementary phosphorus in steam, and its becoming luminous on contact with oxygen. ( 3 ) Dussart-Blondlot’s, which is especially suitable for the detection of phosphorus in an oxidized state, It depends on the fact that phosphorus, and many of its compounds, when treated with nascent hydrogen, yield a gas which, when ignited, gives a flame the inner cone of which is of a deep-green colour.With regard to Scherer’s reaction, the author points out that many substances may cause a darkening of the silver nitrate paper, and that the test must be regarded as a negative one (the absence of any discoloration proving the absence of free phosphorus) rather than as a positive one, unless phosphoric acid can be identified in the blackened paper. In Mitscherlich’s test the experiments described at length in the paper show that in the distillation of the phosphorus in the ordinary way the amount recovered is only a fraction of the whole, though the yield increases as the quantity of phosphorus present becomes larger.This is largely due to a certain amount of oxidation taking place within the flask and the non-volatility of the oxidation products. To obviate this the author has devised EL modification of the process, in which a current of carbon dioxide is led into the flask during the distillation. The steam carrying the phosphorus passes upward through a narrow tube which is bent twice at right angles, first horizontally, then downwards, is condensed in a vertical condenser, and falls into an Erlenmeyer flask. Connected with the side-tube of the flask is a suction- pump, by means of which air is drawn into the horizontal part of the narrow tube through a smaller tube fused on, and closed when not in use by an indiarubber tube and spring clamp.I n this way the oxidation takes place entirely in the tube, whilst the interior of the distillation-flask remains absolutely dark, and it is possible to recover in the distillate over 90 per cent. of the phosphorus present in the original substance. The smallest quantity of phosphorus capable of detection by the Mitscherlich process is 0-00006 gramme. Where oxidation is prevented by drying, or by the course of putrefaction, a small amount of free phosphorus can be detected in organic matter long after it has been mixed with it. Thus, 0.003 gramme af phosphorus was mixed with organic matter in a state of putrefaction, and could still be detected after a lapse of six months. I n the Dussard-Blondlot test certain substances, noticeably ether and .proteid derivatives, interfere with the reaction.This is obviated by passing the phosphuretted hydrogen first through potash to remove sulphuretted hydrogen, and then into silver nitrate solution and applying the test to the precipitate of phosphor silver. The author recommends the following modification of the test as more simple and sensitive than the ordinary process : The filter containing the silver phosphide precipitate is placed, together with a little pure zinc and some water, in a small flask fitted with a cork with three perforations. Through two of these pass tubes bent at right angles, whilst a third is fbr a thistle funnel. One of the tubes is connected with a Kipps’ hydrogen apparatus, the gas generated in which is proved by the spectroscope to be free from phosphorus, whilst the other tube is connected with a U-tube filled with pumice saturated with potash, and in which is inserted the platinum jet.THE ANALYST, 41 Hydrogen is then generated within the flask by introducing through the thistle funnel a few C.C.of dilute sulphuric acid (1 : 5), and this is swept onwards by means of the current of hydrogen from the Kipps’ apparatus, and a strong flame is obtained at the jet. The smallest amount of phosphorus capable of detection by this reaction with the naked eye is 0~00000006 gramme, but even less than this can be recognised with the spectroscope. The chief drawback to the process is the length of time required to reduce phosphorus in the form of acids to phosphuretted hydrogen. From ten to fourteen days are required for the reductionof only a few milligrammes, and then never more than one-fifth of the total amount present is converted. The author finds, too, that the precipitate of silver phosphide does not account for the whole of the phosphorus, and that the solution of silver nitrate often contains as much as the washed pre- cipitate. He suggests that advantage may be taken of the complete absorption of phosphuretted hydrogen in a solution of copper chloride. Thus, a solution prepared by dissolving 4 grrtmines of pure copper chloride in 20 C.C. of hydrochloric acid (sp. gr. 1*19), adding 30 C.C. of a 12 per cent. solution of potassium hydroxide, and pouring off the liquid from the crystals separating, absorbs the gas completely, and readily parts with it again on warming. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300039

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST, 41 ORGANIC ANALYSIS. Estimation of Small Quantities of Methyl Alcohol, Formaldehyde, and Formic Acid. (Bull. SOC. Chim., 1897, xvii., 839, 840.)-This is an exten- sion of the author’s process for determining ethyl alcohol in very dilute solution, based on the reduction of potassium bichromate by the alcohol in the presence of sulphuric acid (BUZZ. de la Xoc. Therap., iii. , 860). I n each case the solution under examination must contain only one of these bodies, and must also be free from other organic substances capable of reducing bichromate. In the determination, 5 C.C. of pure concentrated sulphuric acid are added to 5 C.C. of the solution, the mixture heated for a minute and titrated with standard bichromate (the strength of which varies accord- ing to the substance to be determined) until a green tint is obtained.It is advisable to compare the colour with that of a series of standard colour samples recently prepared so as to obtain the exact value of the standard solution. The strength of the bichromate solution is : for methyl alcohol, 19 gremmes ; for formaldehyde, 17 grammes ; and for formic acid, 11 grammes of bichromate per litre respectively In each case 2 C.C. corresponds to 5 C.C. of a solution containing 1 gramme of the substance per litre ( c j . ANALYST, xii., 25 and xxii., 161 and 263). Nicloux. C. A. M. On the Detection of Formalin. A. Jorissen. (Jour. Pharm. de Liege. 1897, iv., 257 ; through BzdZ. de la SOC. belge, 1897,211, 212.)-The author gives a summary of different tests used for the detection of formalin, but objects to all of them with the exception of Hehner’s reaction (ANALYST, xxi., 95) on the ground that they are not peculiar to formaldehyde. He finds that in the case of the last it is possible42 THE ANALYST, to r.eplace the milk by certain alkaloids, of which several give characteristic reactions of extreme sensitiveness.Thus, on placing a little morphine hydrochloride in a pprcelain basin, adding a few drops of concentrated sulphuric acid, and touching the mixture with the end of a glass rod previously dipped in a solution of formaldehyde, even if exceedingly dilute, a purple colour is produced which changes to an indigo blue. C. A. M. Analysis of Fats. Extraction of Cholesterin and Phytosterin. A. Bomer. (Zeit. fiir Urttersuch. der Nahrungs-und Geizzhssmittel, i., 21-49.)-The following process is recommended : 50 grammes of fat are saponified with 100 C.C.of alcoholic potash solution, the solution diluted with 200 C.C. of water, and the whole shaken for from a half-minute to a minute with 500 C.C. of ether. After standing for two or three minutes, the etheric extract is separated and distilled. The soap solution is then again extracted two or three times with 200 to 250 C.C. of ether, each extract being distilled off as before. After the ether has all evaporated, a little alcohol usually remains in the residue, and this is removed by blowing air through it, while the vessel containing it is immersed in a bath of boiling water. The residue still con- tains a little unsaponified fat, which is removed by a further saponification with 10 C.C.of alcoholic potash. The contents of the flask are now washed out into a separating funnel with 20 C.C. of water, 80 to 100 C.C. of ether added, the whole shaken for half a minute, allowed to stand for a few minutes to separate, the aqueous- alcoholic portion drawn off, and the etheric extract washed three times with 5 to 10 C.C. of water. After removal of the last wash-water, the etheric extract is filtered into a small beaker or Erlenmeyer flask, and the ether slowly evaporated off. On drying in the water-bath, a crystalline residue is obtained containing the cholesterin and phytosterin, from which these bodies can be obtained in a pure state by crystal- lization. Cholesterin can be easily distinguished from phytosterin by the form of the crystals and the manner of its crystallization.If, however, both bodies are present together, the mixture crystallizes in one form only, the crystals either approximating to the form of phytosterin crystals, or, if cholesterin is present in the greater quantity, differing in form from the pure crystals of either body. H. H. B. S. On the Cause of the Rancidity of Fats. A. Mjoen. (Forsch. Bey., 1897, iv., 195-203.)-The author’s experiments, which were chiefly made with butter, olive-oil, and liver-oils, confirm the statements of other observers (c.g., Spaeth, ANALYST, xxii., 46) ; but it is further shown that there is a marked difference between the oxidation changes caused in the composition of the fat by a current of air, and by the action of direct sunlight.Thus in the caBe of butter placed in the sun for three days the acidity number rose from 1.2 to 10.7, whilst the iodine number fell from 52.9 to 30.7 ; whereas the same butter, subjected to the action of a current of air alone, did not show that degree of acidity until after five weeks, and then the iodine number had fallen to 19.8. There is also a difference in the appearance of the oxidized fat, butter becoming rancid in the sunlight assuming a deep yellow colour, thatTHE ANSLY ST. 43 oxidized by the air keeping its colour for two or three weeks, and then becoming snow-white. The author suggests that this change may be due t o the action of an enzyme similar to those which cause the discoloration of freshly-cut apples, etc., to which the name of I' oxydase " has-been given.Although he has proved that bacteria and moulds do not act upon fresh fat, he is not prepared to say that they play no part in a further change when once a decomposition process has commenced. Ritsert (Natzw. Woch., v., 196) asserts that oxygen does not produce rancidity in fat in the absence of light ; I but this the author considers is conclusively disproved by his experiments. These also show that the decomposition is accelerated. by raising the temperature (45" C.). C. A. M. Japanese Wood-Oil (Tung-Oil). (Chcm. Tech. Zeit. Lack u. Farb. I d . ; through Deutsche Chem. Zeit., 1897, xii., 419. Also Rev. Chirn. I d , 1897, viii., 338.) -This glyceride oil is obtained in China and Japan from the seeds of the Aherites cordata, and it is being introduced into Europe as a substitute for linseed-oil in varnishes and paints.It is a clear, yellow, viscous liquid, with an odour resembling linseed-oil ; when freshly prepared it is extremely poisonous ; and it is used for the adulteration of gurgun balsam. Glacial acetic acid produces a turbidity at 47" C. .When 5 grarnmes are treated with 2 C.C. of chloride of sulphur and an equal volume of carbon disulphide, the mixture solidifies on stirring for a minute and a half at ordinary temperatures ; but the paste is not so hard as that yielded by linseed or castor-oil. -4 thin layer exposed to the air dries in about twenty-four hours to an opaque white film. If 4 grammes are heated (temperature not specified) in a 7 cm. dish, a skin forms at the edges in fifteen minutes, which in two hours becomes so tough that the contents will not fall out as the vessel is invertled ; while during four hours the gain per hour is 0.36 per cent.When heated with 0.5 per cent. of litharge and a current of air passed through it, the oil acquires the consistency of a jelly in about fifteen minutes. Warmed with silver nitrate for fifteen minutes, a reddish-brown colour is produced. Strong sulphuric acid converts it into a black mass; nitric acid (sp. gr. 1.4) into a solid body in two minutes, which finally becomes dark and friable. If 1 gramme of the oil is dissolved in 5 C.C. of chloroform and shaken with 5 C.C. of a saturated solution of iodine in the same liquid, a thick paste is soon produced. The constants of tung-oil are as follows : I t yields a solid elaidin.Specific gravity at 15-5" .. ... Solidifying point (about) ... ... Iodine number ... ... ... Saponification number ... ... Specific temperature reaction ... Insoluble fatty acids ... ... Unsaponifiable matter ... ... Free fatty acids ... ... _.. Melting and solidifying point of acids ... Iodine number of acids ... ... ... , I . ,.. ... ... ... ... . . . ... ... ... 0,8385 ... 17" ... 165.7 ... 194 ... 372 ... 96.4% ... 0.44% ... 3.84% ... 37" ... 150.1 I?. H, I;. [According to Rev. Chzm. Ind. (Zoc. cit.), the free acid corresponds to 1.8 per Deering (Impeyial Inst. J., 1896, cent. of KHO, and the sp. gr. rtt 30" C. is 0.9405.44 THE ANALYST. 303) gives the bromine absorption as 98 per cent. : it should seem that there are a t least two varieties, pale and dark ; two kinds also are distinguished in China, coming from Canton and Hankow respectively.Lippert (Zeds. Aizgew. Clzem., 1897, 779) states that owing to the large amount of free acid it contains, tung-oil thickens (or '' sets up ''1 in presence of oxide pigments with inconvenient rapidity,-A~s.] The Determination of Fat and Casein in Feces. H. Poole. (Jour. Amel.. Chem. SOC., 1897, xix., 877-881.)-The various methods of analysing faeces have been summarized by Grausnitz ( 2 e i t . f . B i d , 1894, 328), but the author takes exception t o all of them on the ground that the separations are only imperfect. Thus, the fat, which in each case is determined by extracting the dried faeces with ether and weigh- ing the residue, contains also biliary and other products, whilst hitherto no method of separating casein from epithelium cells has been described.Having occasion to make a number of determinations of the amount of undigested fat and casein in the faeces of children fed on milk, the author devised the following process, which he claims gives results perfectly comparable among themselves, and much nearer the truth than those of any of the older methods : The ether extract, containing the fat, cholesterol and coloring matters from the bile, is evaporated at; 100" C. and the residue dried at 110" C. I t is then saponified with alcohol potash (which as a rule leaves only a trifling amount unsaponified), water is added, and the alcohol expelled by boiling. More water is added if necessmy, and the solution filtered, The filtrate is extracted twice with an equal volume of ether in a separatory funnel, The liquid, thus freed from cholesterol, is evaporated nearly to dryness, water added, and the fatty acids liberated, determined in the usual way and calculated into fat.I n the determination of the casein, the faxes are extracted successively with ether, water, and alcohol, and dried, the three solvents removing most of the nitrogenous substances other than undigested casein and epithelium cells. The residue, which also contains insoluble fatty acid compounds (usually salts of iron, aluminium and calcium), is digested for several hours at 50" C. in a mixture of hydrochloric acid thirty parts, and water seventy parts, which dissolves the casein and leaves the epithelium cells and other substances.After cooling, the liquid is filtered, evaporated, and the nitrogen in the residue determined by Kjeldahl's process, and calculated to casein. I n a full analysis the amount of fatty acids in the insoluble soap would also be determined, but as these usually represent digested or partially changed fats, they did not come within the scope of the author's work, which was concerned only with the undigested portions. C. A. M. A New Reagent for Urinary Albumins. Bourceau. (c. R. Soc. de Biol., 1897, 317 ; through Bull. de Za SOC. belge, 1897, 248.)-Urine may contain coagulable albumins or proteoses which have not the same clinical significance, Oxyphenyl- sulphonic acid containing a trace of salicyl-sulphonic acid will detect the albumins in the presence of the other compounds.A drop or two of the reagent added to 1 C.C.THE ANALYST, 45 of the urine gives an opaque white precipitate with albumins and alkali-albumins, whilst no precipitate is obtained with proteoses, peptones, alkaloids, antipyrin, salicylates, phosphates, or urates. C. A. M. The Detection of Santonin in Urine. L. Daclin, (Jowr. Pharnt. Claim., 1897, vi., 534.)-From 30 C.C. to 40 C.C. of the urine are treated first with lead acetate, then with crystalline sodium sulphate and filtered. The clear filtrate is divided into two parts, and evaporated in porcelain basins. The residue in one is gently warmed with one or two drops of sulphuric acid, and should santonin be present, gives an immediate violet coloration.To the other residue a few drops of alcoholic potash are added, which gives with santonin a rose colour. Or the urine may be extracted with chloroform, the solvent evaporated, and the residue tested a8 above. Rhubarb gives a negative result with these reagents. C. A. M. The Determination of Phenols in Urine. J. Amam. (Rev. Med. Suiss- ronzande, xvi., 657 ; through Jozi~. Plaarm. Chim., 1897, vi., 361.)-The method described is a colorimetric one, based on the reaction given by phenols with Millon’s reagent, and with para-diazo-benzene-sulphonic acid. Millon’s reagent gives a reddish colour on warming, which however does not remain long without alteration. The other test is more characteristic and more sensitive. On adding para-diazo- benzene-sulphonic acid to phenols in alkaline solution (sodium carbonate), acid or neutral azo-benzene-phenyl sulphonates are produced, the colour of which varies from orange to red, according to the nature of the phenol.Neither of the tests can be applied to the urine itself, and the phenols must first be separated by adding sulphuric acid and distilling. The aqueous solution of diazo-benzene-sulphonic acid must be prepared immediately before use, but it has the advantage over Millon’s reagent of giving the reaction in the cold, and of producing a much more permanent coloration. C. A. M. The Analysis of Glycero-phosphates. A. Astruc. (Journ. Pharnz. Chim., 1898, vii., 5-8.)-For the determination of the phosphoric acid a known volume of a solution of the glycero-phosphate is neutralized with sulphuric or hydrochloric acid, with methyl orange as indicator, and the solution then titrated with a, standard solution of alkali and phenol phthalein.Taking calcium glycero-phosphate as the type, the reactions are indicated by the equations : 0 /’ ‘Ca + H,SO, = CaSO, + (P0,C,H70,),CaE, 2PO-O/ ‘O--C,€L70, in which one molecule of sulphuric acid corresponds to two molecules of phosphoric acid, and (P0,C,H70,),CaH, + 2NaOH = (PO,C,HiO,),CaNa, + 2H,O, or (P0,C,R70,),CaH, + 2NaOH = P0,C,H70,Ca + P0,C,H70,Na, + 2H,O, in which one molecule of phosphoric anhydride corresponds to two molecules of soda-44 TEE ANALYST. From this the quantity of phosphorus pentoxide in solution can be calculated. The results thus obtained are about 0.5 per cent.lower than those obtained by calcining a known weight of the glycero-phosphate, dissolving the ash in hydrochloric acid, and determining the phosphorus as magnesium pyrophosphate, so that the process gives very approximate figures in a very short time. Glycero-phosphates of mlcium, when dissolved, are alkaline to methyl orange, but sometimes acid and sometimes alkaline to phenolphthalein. The acid salts are almost entirely soluble without residue, whereas the alkaline salts dissolve with more difficulty and give a slightly turbid solution; but the alkalinity is always excessively feeble. Acidity to phenolphthalein indicates a certain amount of decomposition during the preparations of the caloium glycero-phosphate. In the case of adulteration to any extent of calcium glycero-phosphate with disodium phosphate, the solution would be strongly acid to phenolphthalein, and the quantity of sulphuric acid required for neutrality with methyl orange would be far from being equivalent to the quantity of soda subsequently required for neutrality with phenolphthalein, C.A. M. On Retarnine, a New Alkaloid. Battandier and Malosse. (Jow. Phurm. Chim., 1897, vi., 241, 242.)-The authors have extracted from the young leaves and the bark of the retnma siihmocarpa by the ordinary methods of extraction an alkaloid, to which they have given the name of retamine. One kilogramine of the fresh plant yields about 4 grammes of the alkaloid. Retamine crystallizes in long needles on coolisg a saturated solution of it in ether or petroleum spirit, and in prismatic plates on cooling an alcoholic solution, whilst spontaneous evaporation of the alcoholic solution yields rectangular tablets. It has a very bitter taste and has no marked physiological action.I t melts at 162" C., and decomposes at a higher temperature, It gives the general reactions for the alkaloids, and yields a characteristic precipitate with bismuth potassium iodide. Platinic chloride does not precipitate it. With ammonium sulphate it gives feebly the re- action of sparteine. I t forms well-marked salts, which crystallize readily, and which usually contain for one molecule of retamine either one or two molecules of mono- basic acid. The mean results of the elementary analysis correspond to the formula CljH26N20 ; so that retamine appears to be an oxysparteine, although different to the known artificial oxysparteines. C.A. M. A Delicate Test for Ammonia and Organic Matter containing Ammonia- cal Nitrogen. E. Riegler. (BuZ. Soc. Sciente den Bucuresci, 1897, vi., 335 ; through Chem. Zeit. Bep., 1897, 307.)-Para-diazo-nitraniline forms a very sensitive reagent for detecting ammonia, ammonium salts, and all nitrogenous organic compounds which evolve ammonia on treatment with strong bases (e.g., albuminoids and some alkaloids). One gramme of paranitraniline is dissolved by heating with 20 C.C. of water and 2 C.C. of hydrochloric acid, the liquid is diluted and well shaken with 160 C.C. of water, and, when it is cold, 20 C.C. of a 2.5 per cent. solution of sodium nitrite are added. Ten C.C. of the liquid to be tested are treated with ten or fifteenTHE ANALYST.47 drops of the reagent, and 10 per cent. caustic soda solution is slowly dropped in. If ammonia is present, an orange turbidity is produced; and on agitation the liquid becomes yellow, orange, or red, according to the amount present. On acidifying with sulphuric acid the solution loses its colour, and a mass of yellow, microscopic, needle-shaped crystals collects on the surface. This body is very soluble in alcohol, and on adding a little caustic soda it gives an intense red violet coloration. The reagent becomes cloudy on keeping, but after filtration it is still serviceable. F. H. L. A New Process for the Determination of Crude Fibre in Food Stuffs. J. Eonig. (Zeit. .fiir Uiztersuch dey Nuhruizgs-und Geizussmittel, i., 3-16.)-This paper is the outcome of endeavours to devise a process which shall furnish crude fibre as free as possible from pentosans. The process is based upon the following results of experiments : 1.A temperature of 120" to 130" C. is not sufficient to ensure the solution of the pentosans in all vegetable substances. The most suitable temperature lies between 130" and 140" C. A higher temperature causes the hexosans to be more strongly attacked. 2. The complete solution of the pentosans by the glycerin process depends less upon the proportion of sulphuric acid added to the glycerin (within the limits of 1 to 3 per cent.) than upon the length of time allowed for the action. A 3 per cent. addition of sulphuric acid effects the solution quicker than a 1 per cent., but not proportionately to the increased quantity.3. 200 gramrnes of glycerin of 1.230 specific gravity (12.5 per cent. water and 87-5 per cent. glycerin) for 3 grammes of substance appears to be the most suitable proportion, as well as the bed strength, 4. The pentosans are brought into solution quicker by the employment of higher temperatures and larger proportions of acid than by the employment of lower temperatures and less acid. The most suitable length of time for boiling is on the average one hour at 131" to 133" C., reckoned from the commence- ment of ebullition, or half an hour at 135" to 137" C. The process is carried out as follows : Three gramrnes of the air-dried substance are placed in a porcelain basin with 200 C.C. of glycerin of 1.230 specific gravity con- taining concentrated sulphuric acid in the proportion of 20 grammes per litre.After mixing, the basin is placed in a steam bath and subjected for one hour to a tempera- ture of 137" C., corresponding to a pressure of three atmospheres. The lamp is then removed, and when the temperature has fallen to from 80" to 100" C., the basin is taken out, 200 to 250 C.C. of boiling water added, and the contents filtered through an asbestos filter. Should the fluid filter slowly, it must be maintained at a temperature of 80" to 90" C. throughout the filtration. The residue is washed first with 300 to 400 C.C. of boiling water, then with 50 C.C. of warm, 93 per cent. alcohol, and lastly with a warm mixture of ether and alcohol, until the washings are quite colorless. The filter is then dried and weighed,after which it is incinerated and re-weighed, the diiference between the two weights giving the ash-free crude. fibre.A cold solution of glycerin filters badly.48 THE ANALYST. Brewers' grains The extraction may also be carried out a t the ordinary atmospheric pressure by boiling in a flask fitted with a reflux condensor. The pentosan (furfural) determins- tion is carried out by the phloroglucin method of Tollens. The process has been tried side by side with Henneberg's method, and the results of a number of deter- minations, calculated in eacb case upon the material in the dry state are given in the following table : .13.98 I, 13.24 Boiling with Glycerin of 1-230 specific gravity and 2 pcr cent.Sulphuric Acid. Pento- I Nitro- Crude sans gen Fibre. in Crude Fibre. Steam Digestion under Pressure with Glycerin of 1.230 specific gravity and Pento- I Nitro- Hen neberg's Process. In the original substance. Pento- 1 Nitro- sans qen in Crude Fibre. Pento- sa11s. Crude Fibre. Nitro- gen. sans 1 gen n Crude Fibre. Crude Fibre. Per cent. 52.32 40-50 32.45 33'05 10.65 16-60 17-41 12.29 8.93 0.99 O - i l ~ Per cent. 9.65 6.09 4.47 4'21 0.28 1 *39 2-49 1 *03 0.78 0 0 ~ Per cent. 1-14 0.52 1.44 0.99 0-37 0.35 0.62 0 0.13 0.34 0.12 0 0 0 - - Per cent. 26.98 14*95 17.03 12-42 li%l 19-15 10.28 8.02 7'91 .- - Per cent. 0'83 2.21 2'52 3-28 3-33 4-85 4 *93 4.33 4-57 - - Per cent. 48.56 43'99 43-61 44-28 30.41 25.78 26.5: 26.18 24-07 11.17 11-04 15.45 15.81 14-78 14.77 11.24 (11'89) 7-63 7'85 1 -05 0'33 Per cent.43.44 ( 30.41 1 1 29-74 j 26-29 f 24.46) 24-30 j 10.68 16.17 [ E 11.15 7 -53 1 *02 0.27 Per j;r3 0.1 9 ;- 0.37 0.17 0 2 0 0.18 0.14 0.21 0.1 9 - - Per cent. 0.90 0.87 0.37 0.52 0 0 trace 0 0 0 0 Per cent. 0-14 0.27 0 -29 (0.41) 0.23 0.13 0.15 0 2 0 0.13 - -- Rye straw Pea straw Meadow hay Clover hay Wheat bran Brewers' grains Asparagus Cabbage Linseed Rye meal Wheat meal Fairly good results can also be .obtained by heating with 200 C.C. of acidified glycerin in an open basin, only in this case it is more difficult to maintain an even temperature between 135" and 137" C. It can, however, be kept within the limits of 133" and 140" C. for half an hour, and the following results, calculated upon the dry substance, were obtained in this way : Crude Fibre. Pentosans I Nitrogen in the Raw Fibre. Crude Pentosans I Nitrogen in the Ryw Fibre. Feeding Stuffs. ~ Fibre. 1 Feeding Stuffs. I I- I Per cent. 44.71 25.90 25.84 125.95 Per cent. Per cent. {i::: ~ 0.14 Pek cent. Per cent. Per cent. Wheat bran I{ :::; I I ::;: Rye straw Grass hay 0.47 0.37 The superiority of the glycerin process to the older one of Henneberg is shown very clearly in the following table, from which it appears that whereas by the Henne-THE ANALYST. 49 berg process considerable quantities of pentosans remain undissolved, varying with each material up to 40.73 per cent. of the pentosans originally present, by the glycerin process the quantity remaining undissolved does not exceed 6.62 per cent. Rye straw Pea straw Grass hay Clover hay Wheat bran Brewers’ grains Asparagus Cabbage Linseed or Old Pro- cess. Pentosans remaining i n the Crude Fibre in percentage of the pentosans inallg prese By steam- ing with Glycerin. Per cent. 35-77 40.73 26-24 33.89 1-58 7.26 24.20 12.84 9-86 Per cent. 3 -88 6-62 2.11 4.99 0 0.68 3 -30 1.49 0 By boiling with Glycerin. Per cent. 3.33 5-82 2-17 4.19 0 0 trace 0 0 1. Crude Fibre by Old Process. Per cent. 52.32 40.50 32.45 33.05 10.65 16.60 17-41 12-29 8.93 2. Contain- ing Pento- sans. 3. Crude Fibre free from Pentosans by old Process. (1-2) Per cent. 9.65 6.09 4.44 4.21 0.28 1-39 2.49 1.03 0.78 Per cent. 42-67 34-41 27.98 28-84 10.37 15.21 14.92 11.26 8.16 4. I 5 . Crude Fibre by Treatment with Glyc SFeam- ing. Per cent. 43.86 30-41 26.16 24.04 11.11 15.63 14.78 11-57 7.74 rin . Boiling. Per cent. 43.44 30.08 26-29 24-38 10.68 16.17 15.03 11.15 7.53 H. H. B. S.

ISSN:0003-2654    

DOI:10.1039/AN8982300041

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 49 INORGANIC ANALYSIS. (T. Plzysik og Chenz., 1897, i., 341; through Chem. Zeit. Bep., 1897, 307.)--The author finds that in an acid solution gold can only be titrated accurately by means of oxalic acid or ammonium oxalate when the whole process is conducted in an atmosphere of carbon dioxide. I n the presence of oxygen the finely-divided metal appears to behave like platinum- black, oxidizing the oxalic acid, and causing the volume of standard solution employed to be from 18 to 7 3 per cent. above the theoretical. By the use of sodium oxalate in a, neutral liquid, however, perfectly satisfactory results may be obtained. The gold is dissolved in aqua regia containing a large proportion of hydrochloric acid, sodium chloride introduced, the mixture evaporated to dryness, taken up in water, and again dried down.The excess of oxalate is titrated with permanganate as usual. The chlorides of mercury and copper do not affect the process; but sufficient sodium oxalate must be added in the first instance to hold any copper oxalate in solution after the reduction of the gold. The method is not available when the gold is combined with platinum. Volumetric Estimation of Gold. J. Petersen. F. EL L. Volumetric Estimation of Antimony. J. Hanus. (Vestnik kral. ceske spolec- nosti %auk, 1897 [II.], No. 40, 1; through Chenz. Zeit. Rep., 1897, 324.)-0.2 to 0.3 gramme of precipitated sulphide of antimony is filtered and washed, rinsed into a beaker, the paper added, and treated with ferric sulphate, either solid or in solution, in the proportion of 6 molecules of the latter to 1 of the former.The mixture is boiled for fifteen minutes, the following reaction taking place : Sb,S, + 5Fe,( SO,), + 8H,O = 2H,SbO, t 10FeS0, + 5H,SO, + S,.50 THE ANALYST. After considerable dilution, 15 C.C. of strong sulphuric acid are introduced for every 1 gramme of ferric sulphate, the liquid is cooled below 25" C., and titrated with permanganate containing 1 or 1.5 gramme per litre. The error lies between +0*3 and -0.26 per cent. of the original sulphide of antimony. F. H. L. A New Volumetric Method for Determining Copper. W. E. Garrigues. (Jour. Amer. Chem. SOC., 1897, xix., 940, 941.)-This method depends on the pre- cipitation of the copper as cuprous thiocyanate and the alkalimetric determination of the combined thiocyanic acid.The solution is evaporated with the smallest possible amount of sulphuric acid to expel any volatile acids, is then diluted, gently warmed, and sulphurous acid added until the liquid smells perceptibly of it. The copper is precipitated with an alkaline thiocyanate, the liquid gently warmed to promote the separation of the precipitate, and the latter filtered off and washed with water. The filter and contents are then boiled for a few minutes with a measured excess of standard caustic alkali, the liquid cooled, made up to 200 c.c., filtered, and 100 C.C. titrated with standard acid and methyl orange. The caustic alkali converts the cuprous thiocyanate into cuprous hydroxide and alkaline thiocyanate, the latter substance being neutral to methyl orange.The reaction is in accordance with the equation : 2CuSCN + 2NaOH = Cu,(OH), + 2NaSCN. For the separation of zinc from copper, ammonium thiocyanate must be used to precipitate the copper, and the zinc determined as phosphate in the filtrate. When potassium thiocyanate is used, the zinc precipitate is contaminated and the results valueless. The author claims for this process greater accuracy than the iodide method is capable of, and an additional advantage is that no empirical standard is required. C. A. M. The Electrolytic Determination of Cadmium. D. L. Wallace and E. F. Smith. (Jowr. Amer. Chem. Xoc., 1897, xix., 870-873).-Avery and Dales (ANALYST, xsii., 295), being unable to obtain satisfactory results by Smith's method of pre- cipitating the metal from an acetic acid solution, the authors have made experiments to determine the original working conditions, and find that when a definite strength of current is employed and a definite surface (which, however, were not given by Smith), the method is perfectly reliable.For instance, 0.1329 gramme of cadmium oxide was dissolved in acetic acid, the solution evaporated to dryness, and the residue dissolved in 30 C.C. of water. The liquid was then heated t o 50" C., and electrolyzed with a current of 0.02 ampAre for 37 sq. cm. of cathode surface, the voltage was 3.5. The metal, which was completely precipitated in four hours, was crystalline and perfectly adherent. The acid liquid was siphoned off and replaced by water without interrupting the current. It was found that the time required could be diminished and good results obtained by adding 1 gramme of ammonium acetate toTHE ANALYST.51 the solution after the current had acted for an hour. I n this particular instance the quantity of cadmium found was 0.1158 gramme, instead of 0.1162 gramme. Experiments are also described to show that, contrary to the experience of Avery and Dales, it is possible to obtain good results by precipitating from a solution containing free sulphuric acid if the right conditions obtain. Thus, 0.1270 gramme of cadmium oxide was dissolved in 2 C.C. of sulphuric acid (specific gravity, 1-09), and the solution diluted with water to 30 C.C. It was then heated to 50" C., and electrolyzed for four and a half hours with a current of 0.08 ampire for 37 sq.cm., cathode surface, the voltage being 2.5. The deposit was crystalline and adherent, and weighed 0.1105 grainme instead of 0.1111 gramme. With regard to the electrolytic separation of cadmium from copper, Smith showed that in the presence of free nitric acid copper was deposited, whilst the cadmium remained in solution. But Heidenreich (Bey., xxix., 1,585) could not obtain satisfactory results by this process. In reply to his criticism, the authors describe experiments, of which the following is representative : To a solution containing 0.3893 gramme of copper sulphate (= 0.0988 gramme copper) and 0.1152 gramme of cadmium oxide (= 0.0985 gramme cadmium) were added 2 C.C. of nitric acid (specific gravity, 1.43). The solution was diluted to 100 c.c., heated to 50" C., and electrolyzed with B current N.D,,,=0-10 amphre.The metal, which was completely precipitated in three hours, was bright and satisfactory in every respect. It weighed 0.0988 gramme, and contained no cadmium. Voltage, 2.5. C. A. M. The Detection of Traces of Alkaline Carbonates in the Presence of Bicar- bonates or Borax. A. Leys. (Jozw. Plzamz. Clzint., 1897, vi., 440-442.)-saltS of magnesium (e.g., the sulphate) distinguish between alkaline carbonates and bicar- bonates, giving a precipitate with the former and not with the latter. But the author shows that this reagent, though excellent with the single salts, is not t o be relied on with mixtures. Thus, a solution of a mixture containing 68 per cent. of neutral carbonate and 32 per cent.of bicarbonate of soda gave no precipitate with magnesium sulphate, and the same negative result was obtained with a mixture consisting of 60 per cent. of neutral carbonate and 40 per cent, of borax. A saturated solution of calcium sulphate forms a much more sensitive reagent. When this is added to a solution of pure bicarbonate the liquid remains clear for some time, and then slowly begins to form microscopic crystals, but if there be only a minute trace of neutral carbonate present, an immediate white opaque precipitate is formed. The test is equally reliable in the presence of borax. C. A. M. Acidimetric or Alkalimetric Determinations in highly-coloured Substames. F. Jean. (Ann. de Chim. Analyt., vol. ii., p. 445.)-The ordinary indicators being inapplicable in the case of highly-coloured products such as ink, blacking, etc., the author recommends the following method :52 THE ANALYST.If the substance give an alkaline reaction, a weighed quantity is distilled with ammonium sulphate; and the quantity of the alkali, the nature of which has been previously determined by qualitative analysis, estimated by titrating the ammonia liberated, Acid substances should be distilled in a Schloesing apparatus with ammonium sulphate and 10 C.C. to 20 C.C. of normal alkali, the ammonia liberated by the excess of alkali being absorbed by 10 C.C. or 20 C.C. of normal acid. The excess of the latter is then titrated. c. s. Estimation of Total Carbonic Acid in Water. S. Robertson. (Arch. Hyg., 1897, xxx., 312; through Clumz. Zeit. Rep., 1897, 268.)-According to the volume of carbon dioxide probably present, 10 to 20 C.C.of trinormal alcoholic soda (or potash), prepared from metal and absolute alcohol, are placed in a 600 C.C. flask of hard Jena glass, a rubber stopper is inserted in the neck, and the whole weighed. About 500 C.C. of the sample are next cautiously introduced through a leading tube in order to avoid contact with the air, and the exact amount of water taken is determined by a second weighing. The liquid is then distilled till only 100 C.C. are left in the flask, the exit tube for the vapours being provided with a bulb to prevent loss of solid matter by splashing. Finally, the vessel is connected with a series of drying tubes, hydrochloric acid is run in through a tube funnel, the carbonic acid driven out by gentle warming and a current of pure air, and absorbed in potash bulbs, where it is estimated by weight as usual.The process can also be employed for the determination of the combined carbonic acid by omitting the caustic alkali. F. H. L. Detection of Alkalinity in Pot8ble Waters. A. Qavalli. (Sehzi, 1897, vii., 65 ; through Chem. Zed. Rep., 1897, 288.)-An extremely sensitive reagent for this purpose is found in a 1 per cent. solution of tolylene red (dimethyldiamido- tolylphenazine hydrochloride). If two or three drops of this dye are added to 50 QC. of an ordinary alkaline water, the red colour changes to yellow. Alessandri has suggested the addition of a few drops of red wine, the colour of which is altered under similar conditions. F.H.,L. The Determination of Oxygen dissolved in Water. G. Romp. ( z e d . angezo. Chem., 1897, 658.)-The author uses a cylindrical pipette with a tap at each end and a tube above the upper tap. The pipette is completely filled with the water to be examined and the taps closed. One C.C. of a solution containing 12 grammes of manganese chloride and 8'5 grarnmes of potassium iodide in 100 C.C. is placed in the upper tube and allowed to enter the pipette by momentarily opening both taps. The liquids we well mixed, and then 1 C.C. of a solution of Rochelle salt (specific gravity, 1.255) and 1 C.C. of soda lye (specific gravity, 1.105) introduced in the same way..THE ANALYST. 53 After leaving for ten minutes, 1 C.C. of hydrochloric acid (specific gravity, 1.126) is added, the p,ipette emptied into a flask, and the liberated iodine titrated with standard thiosulphate.The alkaline manganese tartrate combines with the dis- solved oxygen, and on the subsequent addition of the hydrochloric acid liberates from the potassium iodide an amount of iodine equivalent to the oxygen. A deduc- tion of 4 C.C. must be made from the volume of the pipette for the reagents introduced. The pipette may be obtained from Greiner and Friedrichs, Stiitzerbach. C. A. M. Estimation of Potash in Fertilizers. L. Ronnet. (Rev. Chim. AizaZyt. AppZ., vol. v. [all, pp. 421, 422.)-To obviate the inconvenience arising from the use of ammonium carbonate for precipitating the excess of barium in the Schloesing perchloric method of estimating potash, the author proposes to throw down the barium by means of a current of carbon dioxide.In the case of potassium chloride fertilizers, 50 grammes are dissolved in water, made up to 1 litre and filtered ; 20 C.C. of this solution are then taken and treated with 10 C.C. of a saturated solution of barium hydroxide. Acurrent of carbon dioxide passed through the liquid for a few minutes throws down the excess of barium; and, after boiling for a few moments to drive off the residual carbon dioxide and decompose any soluble bicarbonates formed, the liquid is filtered and treated by the perchloric acid method in the ordinary manner. For potassium sulphate fertilizers 40 C.C. (and for Kainit 30 c.c.) of baryta water will be required, and the precipitate requires more careful washing. I n the case of more complex fertilizers, 25 grammes are digested in hot waier, and the volume made up to 500 C.C. After filtration 100 or 200 c.c,-according to the presumptive richness in potash-are evaporated to dryness in a porcelain capsule with 1 or 2 grammes of calcium hydrate, and ignited at a low temperature. The residue is taken up with small quantities of boiling water, and baryta water added so long as a precipitate continues to form. The excess of barium is thrown down, and the further treatment proceeded with as before. In all cases the liquid through which the carbon dioxide is passed should be well boiled afterwards. c. s.

ISSN:0003-2654    

DOI:10.1039/AN8982300049

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 53 APPARATUS. An Apparatus for determining the Solubility of Substances in Boiling Liquids. (FOYSC~Z. Ber., 1897., iv., 173-177.)-The usual method of determining the solubility of a substance in a boiling liquid (Fresenius, Quant. Anal., ii., 794; Lassar Cohn, Aybeitsmethodciz, 1893, 224) is to filter the boiling saturated solution through a warmed and covered funnel into a weighed flask, which is then closed with a stopper, allowed to cool, weighed, and the amount contained i n an aliquot part of the liquid determined. H. Gockel.54 THE ANALYST. The author points out that in this process a considerable loss of the solvent by evaporation is inevitable, whilst the slightest cooling causes a separation of the dissolved substance on the funnel, and that these causes may lead t o enormous discrepancies in the results obtained by different observers.Thus, according to Dragendorff, 1 gramme of theo- bromine requires for solution 422-5 grammes of boiling abso- lute alcohol, whereas Eminger found that 818 grammes were necessary. In the apparatus here de- scribed, evaporation of the solvent during the filtration is impossible, and results in good agreement can be obtained. The substance and solvent are placed in the flask, c, which holds about 25c. c., and in which is also placed the filter-tube, a, which is filled with wool. The flask is heated for about thirty minutes on the water-bath, with d acting as EL reflux condenser. Meanwhile, the liquid in the flask is kept i n motion and prevented from entering the filter, a, by means of gentle air-pressure supplied by bellows connected with the condenser, Tc, at q.After the thirty minutes' boiling, the bellows are detached from the top of k and connected with the condenser, d, by means of the tube, e. On now gently blowing, the boiling saturated solution passes through the filter, CL, and tube, b, and falls into the flask,f, where loss by evaporation is prevented by the condenser, k. I n order to prevent crystallization in the tube, b, the latter is surrounded by a jacket, g , through which passes a current of warm water heated in the beaker, h, to a tempera- ture of from 1" to 2" above that of the solvent. The tube, b, delivers into a wider tube, 12, to which a stopper can subsequently be fitted, and a stopper is also provided for the tube, m, when disconnected from the condenser, k.The flask,f, with the tubes, whose combined weight when empty is known, is weighed when containing the saturated solution, and again after the evaporation of the solvent. The results obtained by the ordinary method (as given by Fresenius), and those with the apparatus described above, are compared in the subjoined table, in which are shown the quantities of boiling solvents required to dissolve 1 gramme of caffeine.THE ANALYST. 55 ORDINARY METHOD. WITH APPARATUS DESCRIBED. Grammes of Solvent for 1 gramme Caffeine. Solvent . M ~ ~ ~ . Ether (anhydrous) B.P. 35.5" C. ... Acetic ether . . . B.P. 72.7" C. ... Benzene ... ... B.P. 80-4" C. ... Chloroform . . . B.P. 61.0" C. ... Carbon tetra- chloride .... . 33.P. 78.1" C. ... Grammes of Solvent for 1 gramme Caffeine. Mean. 454-5 25.5 20-4 5.15 132.9 339.3 23.9 18.9 336.8) 25.0 19.2) 341.8 j 141.2 143.5) ~ 142'4 C. A. M. R Simple Hydrogen Apparatus. C. Aschmann. (Chem. Zeit., 1597, xxi., 1049.)-This device is sufficiently explained by the diagram. A is a filter-pump flask holding about 18 litres, two-thirds filled with dilute sulphuric acid. B is a solid block of zinc 6 cin. long and 2 em. in diameter, cast round a copper wire with a loop at the top, by means of which it is suspended, as shown. The cylinder is pushed into or drawn out of the acid, according as a current of gas is required or not. F. H. L. A New Measuring Pipette. Otto Bleier. (Chevz. Zeit., 1897, 1028.)-By means of the comparatively short pipette, illustrated in the accompanying cut, any quantity of liquid up to 50 C.C.can be accurately measured. The instrument is divided into five sections, each of which has a capacity of 10 c.c., the lowermost being graduated in tenths of 1 C.C. The amount of liquid delivered is regulated by the screw clamp 32. The constrictions between the bulbs have the same diameter as the graduated portion. W. J. S. Drying Oven for Maintaining Constant Temperatures. M. C. Schuyten. (Clzmz. Zeit., 1897, xxi., 1049.)-This consists of a constant level apparatus placed in connection jwith an ordinary copper water-oven. When a temperature of 97.5" C. is required, both parts contain water, and the whole is worked in the usual way. But if a higher temperature (98" to 105") is desired, theioven is filled with a, strong solution of sodium nitrate, while the reservoir is charged with plain water as before. The wooden block is of such height that equi-56 THE ANALYST.librium obtains when the drying-oven is practically full of liquid; the cock a is closed, the burner lighted, and as soon as ebullition sets in, a is opened. If a thermometer shows that the temperature is too low, more solid sodium nitrate is introduced through one of the openings in the oven ; but if it is too high, a is shut, and some of the solution is drawn off from b. After a few trials, the proper con- centration will be obtained; and then the temperature will remain steady,/even if the gas-flame varies in size, so long as the liquid con- tinues to boil; for the loss by evaporation is consfantly made good by the addition of pure water.Sodium nitrate seems best adapted for this purpose because it does not act appreciably on copper ; but it must be very pure, and especially free from chlorides or sulphates. F. H. .L. New Electrolytic Diaphragm. H. Pauli and L. Pincussohn. (Che?n. Zeit., 1897, xxi., 1048.)-The ordinary commercial porous pot is inconvenient for electrolytic analysis, as it is difficult to watch the process going on inside, and the outer electrode must be bent into a circular form. The im- proved cell recommended by the authors is niade much shorter and wider, as will be seen in the accompanying illustrations. At its upper end it is strengthened by a flange in which four holes are bored; two wires are passed through them, and in this manner the cell is suspended within the outer vessel. The latter need not be a beaker ; a flat crystallizing-pan is preferable. The electrodes are therefore not curved, but straight and parallel; and thus it is easier to maintain a uniform current density. The apparatiis has been successfully employed in carrying out iI; F. H. L. €zz IVeyl’s process for the estimation of carbon in hard steels. MISCELLANEOUS. WE are pleased to hear that the governing body of University College, Nottingham, has conferred the title of Emeritus Professor on Dr. Clowes on his retirement from the Professorship of Chemistry in the College to undertake the duties of Chemist to the London County Council.

ISSN:0003-2654    

DOI:10.1039/AN8982300053

出版商:RSC    

年代:1898

数据来源: RSC