摘要:

FEBRUARY, 1909. Vol. XXXIV,, No. 395. SOME ANALYSES OF CREAM CHEESE. By CECIL H. CRIBB, B.Sc., F.I.C. (Read at the Meeting, December 2, 1908.) HAVING recently had occasion to examine a number of samples of ‘( cream cheese ” under ths proviaions of the Sale of Food and Drugs Acts, I found that several were so deficient in fat that it was apparent they had been manufactured from machine- skimmed milk, and the question at once arose as to whether or not they were to be considered adulterated. It seemed obvious that the name of the article was intended to convey some information as to its composition, and that it might reasonably be expected to do something more than look like cream. Standard dictionaries afforded only a partial support to this idea. Thus, while the ‘‘ Century Dictionary” defines cream cheese as 1‘ a cheese made from new or unskimmed milk with an added portion of cream,” Webster’s, on the other hand, does not go so far ; according to it cream cheese is L‘ a cheese made from curd from which the cream had not been taken off, or to which cream had been added.”46 THE ANALYST.In scientific works:: analyses of cream cheeses as distinct from ordinary cheeses are comparatively rare, and definite statements as to the amount of fat that should be expected in them are rarer still. The recorded analyses show the widest varia- tions as regards fat contents, but the figures are high enough to indicate that in the majority of cases the cheese had been made either from whole milk or whole milk plus cream, while even the worst samples must have been prepared from hand- skimmed milk.These low fat figures must not, however, be accepted without hesita- tion, as some of the authors referred to include under the head of “ Cream Cheese ” the York cheeses sold on straws which are admittedly derived from skimmed milk. If these are disregarded, practically all the figures for fat lie between 20 and 80 per cent. Even with the reservation already made, these do not strictly represent the range of variation of English cream cheese, as various foreign cheeses of a widely different appearance and consistency have been grouped under this category by some of the workers to whom I have already referred. The only suggestions for standards for this kind of cheese that I have been able to find are (I) that of the United States, the meaning of which is doubtful, according to which cream cheese should be made from milk or cream containing not less than 6 per cent.of fat, or from cream (Leach, u Food Inspection and Analysis,” p. 158), and (2) that put forward by C. G. Moor (‘‘ Standards for Food and Drugs,” p. 85), that the fat should form at least 40 per cent. of the whole. With a, view to ascer- taining the composition of the cream cheeses being sold at the present time, a number of samples were purchased indiscriminately in the West End of London. In all cases (‘ cream cheese ” was asked for, and in most instances the article supplied was labelled either with the name of the manufacturers, with a proprietary name, or with the word ‘‘ Bondon ” on the package, with perhaps some qualifying description.The following table contains complete analyses of sixteen samples, and the pro- portion of fat in another twelve. Whether the samples are judged by the proportion of fat or by the ratio of fat to proteins, it is quiteplain that four of the samples were prepared from separated milk (Nos. 1, 2, 3, and 6), one (No. 4) from milk less completely deprived of its fat, five (Nos. 17, 18, 19, 20, and 21) from what was probably whole milk, and the remainder from cream or mixtures of cream and milk. It is noteworthy that the produce of the well-known English dairy companies (Nos. 11 to 15) all contained upwards of 69 per cent. of fat, while the worst cases are t o be found amongst the varieties labelled as Bondon,” one at least of which was made in this country. The true I ‘ Bondon” cheese, as made in France, was, and possibly still is, made from whole milk ; and if it is to be sold here as a cream cheese, the least that can be expected is that it should havet he composition of a, whole-milk cheese.Taking the whole series of analyses into consideration, two facts seem fairly clear : (1) That it has not yet become, to any large extent, the custom of the trade to sell as I ‘ cream cheese” preparations made from either skimmed or separated milk, and (2j that in the higher branches of the trade the idea evidentlyprevails that a cream cheese should be made from cream. Sample No. 3, which had been purchased under the provisions of the Sale of Food and Drugs Acts, was bought as cream cheese, and was enclosed by the vendor in a wrapper bearing the words “Bondon, La Creme,” and was chosen as the subject ALYsr, * Fide the works of Richmond, and Fleischman, Pearmain and Moor, and papers bY Muter (AT 1884, 10, f ) , and by Vieth (ibid., 1885, 11, 162) ; also reports of the Paris Municipal Laboratory.THE ANALYST.NO. 47 Description. I Fat. for a prosecution which ended successfully. In such a case as this there could be little doubt that the sale was to the prejudice of the purchaser. Where the percentage of fat or the ratio of fat to proteins is greater, the matter becomes more difficult, as the plea that there is no standard will be raised by the defence. cream cheese,” then the fat should be well over 20 per cent., and the ratio ~ should exceed 1. If, however, the Bondon is to be excluded from this category, then the standard suggested by Moor, already referred to, would be a perfectly reasonable one.I have to express my indebtedness to Mr. A. S. Joy, F.I.C., for help in making the analyses. If the Bondon cheese is to be accepted as a fat proteins CREAM CHEESES. Water. (N Ci.3i). Ash. I Protein I Fat (N). Boric Acid. 1 IBondon Sudrieure I 0-63 72-30 72.72 66.95 67.10 25.85 25.34 24-93 23.25 3.20 2.57 4.60 1.20 0.02 0.04 0-06 0.53 1.21 2.60 3.84 3.79 4.13 7-57 Absent. ,$ 1 ) 7 ) 32 grs. per lb. Absent. 1 , 1 9 9 1 1 1 Ngufchktel 1-28 La, Creme l 1.61 W. S. ... 12.31 4 5 6 7 8 9 10 11 12 13 14 15 Sold 36-24 42.23 48.66 48.55 52.06 64.09 Cheeses 70.10 69-12 73-84 75-32 77.35 under Fancy Name. 31.77 43.60 41.70 34.70 37-80 30.10 29.86 16.24 12.67 19.80 12.58 8.46 4.47 0.65 0.65 1.90 0.60 0.32 c .. . . . . . P . . . . . . . F . . . . . . . N. F. (a) ... ( b ) ... D . . . . . . . English Cream matde by Well-known Dairy Companies. Absent. $ 9 9 1 25 grs. per lb. 9.8 $ 9 Absent. 5 grs. per lb. Absent. 6 grs. per lb. Absent. 9 , 9 9 7 7 * 3 I , 3 3 ,? 29.35 26.70 21.60 19-90 22.40 9.83 8.21 8.71 7.76 6.37 0.55 0.40 0.15 0.45 0.10 7-13 8.41 8-47 9.70 12.14 0.22 Of Unknown Origin. 6.07 22.70 23.60 24-50 24.50 27.90 37-20 50.00 50.00 50.00 50.00 69.50 75.60 16 17 18 19 20 21 22 23 24 25 26 27 28 - 72.25 26-94 1.0048 THE ANALYST. DISCUSSION. The CHAIRMAN (Mr. John White), in inviting discussion, said that he was interested to hear that Mr. Cribb’s Authority had been successful in a prosecution for “cream cheese” containing only 1.6 per cent.of fat. In the case of a sample of Dutch cheese which he (Mr. White) had found to contain only 1.5 per cent. of fat, the summons had been dismissed on the ground that there was no standard for fat in cheese. The Board of Agriculture were, he believed, averse to fixing a standard for fat in any kind of cheese, thinking that it might have too disturbing en effect on trade and manufacturing customs. Mr. F. J. LLOYD said that in his opinion the true definition of cream cheese was cheese made from cream--i.e., cream separated from the milk before the cheese was made. Real cream cheese according to this definition was almost impossible to obtain in the London market. He had done his best to get a standard fixed by the authorities at Agricultural Shows, and to induce them to disqualify cheeses sent for exhibition under false names, but stronger action wag needed.In his opinion the Public Analysts should take steps to prevent the public being defrauded as they were at present. Mr. GOLDING said that, according to his view, and to what was generally understood in the Midlands, there were two kinds of cream cheese-one made from cream with the aid of rennet, and the other made by solidifying cream without the use of rennet. Cream cheese of that kind would contain up to 80 per cent. of fat. He was surprised at the lowness of the fat in some of Mr. Cribb’s samples. Even separated milk would scarcely contain less than 0.1 per cent. of fat, and it was difficult to understand how cheese with such low percentages of fat as those referred to could be made.Mr. G. CECIL JONES, while agreeing that the percentage of fat on the moisture- free sample was valuable in ascertaining whether the cheese was made from whole milk or from whole milk plus cream, thought that from the purchaser’s point of view it was more important to know the percentage of fat in the cheese as delivered, and that this should be kept in mind if standards were ever determined on. Mr. CRIBB, in reply, said that five of the samples he had examined were made by well-known English dairy companies, and in these the proportion of fat was from 69 per cent. to 75 per cent., so that, as had been pointed out in the paper, in the better classes of the trade there was no doubt as to what cream cheese was, He did not know what was the difference between ‘‘ Swiss ” and ‘‘ English ” cream cheese. One of his samples, while being described as ‘( Bondon,” was made in England. The flat cheese on straw to which Dr. Rideal had referred was the ‘‘ York ” cheese. It had been suggested by Mr. Richmond that standards for cheese in general should be expressed as ratio of fat to proteids. This had considerable advantages, as it not only left out of account the water present, but affords some idea as to the origin of the sample. With regard to the manufacture of cheese from cream alone, it seemed to him that machine-separated cream might well contain so much fat that cheese could not be made from it at all. Very low proportions of fat, such as some of these samples contained, were sometimes met with in Dutch cheese, but how such cheese was made he did not know.

ISSN:0003-2654    

DOI:10.1039/AN909340045b

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 49 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. African Elemi. (BUZZ. Imperial Inst., 1908, 6, 252-255.)-The name '( elemi " is in commerce practically restricted to the soft, aromatic oleo-resin collected in the Philippines from Cnuarzzm lzmnziczwz, but similar resins from other localities occasionally appear on the market. The botanical origin of this class of resin from West Africa, is unknown; that from Uganda is derived from Caizarizm Schwein- furthii. The examination of three samples of African elemi gave the following results : Elemi from- 1. Southern Nigeria : (a) White or pal€ yellow, t c b r o w n i r patches .. ( b ) Y e l l o w i s h . green .. W h i t e t o p a l ( y e l l o w , witk some d a r k e i pieces ... .. 2.Uganda : Ash, Per Cent. 0.6 0.53 0.3 Acid \Turnbey. 55.3 37-8 29.4 Iaponifica tion Number. 71.9 46.2 Volatile Oil, per Cent. (Steam Distilled). 8-1 44 Characters of Oil. ~ Colour. Pale straw - Pale straw Specific Gravity, 15" C. 0.8686 - 0.8451 Specific Rotation in 100-mm. Tube. + 50*5* - + 7 9 - 3 O The Nigerian oleo-resin was completely soluble in benzene, in a mixture of turpentine and alcohol, and with difficulty in turpentine and cold alcohol. The Uganda sample was readily soluble in benzene, in a mixture of benzene and alcohol, and in a mixture of turpentine and alcohol, but only sparingly in cold alcohol and in turpentine. The results show that these African elemis present a general resemblance to Manila elemi, though the former yield a smaller quantity of volatile oil.The oil from all these varieties contains a considerable proportion of phellandrene. A. R. T. Estimation of Vegetable Alkaloids by Means of Mercury-Potassium Iodide. G. Heikel. (Chem. Zed., 1908, 32, 1186-1187, 1212-1213.)-Further results are given of the estimation of alkaloids by the method published previously50 THE ANALYST, by the author (ANALYST, 1909, 27), from which it is seen that the quantity of reagent required to precipitate 0.1 gram of the following alkaloids is : Heroine, 8.2 C.C. ; hydrastine, 8.6 C.C. ; hyoscyamine, 10-8 C.C. ; ipecacuanha alkaloids, 11.2 C.C. ; morphine (neutral solution), 9-6 C.C. ; morphine (acid solution), 9.0 C.C. ; physostig- mine, 11.9 C.C. ; pilocarpine, 13.1 C.C. (or, if allowed to stand for twenty-four hours, 27.1 c.c.) ; sparteine, 34.2 C.C.; strychnine, 12.0 C.C. ; and veratrine, 5.2 C.C. Whilst the method does not yield perfectly accurate results in all cases, the figures obtained are approximately correct, and the time taken for the estimation is much shorter than that required in the old way of estimating alkaloids by Mayer's reagent. The method is useful for the estimation of quinine, cocaine, morphine, strychnine, and sparteine when these are put up in the form of tablets, and also for the estimation of the alkaloid in fluid extracts of quinine, colchicum, hydrastis, ipecacuanha, nux vomica, and opium, w. P. s. An Error in the Estimation of Caffeine by Juckenack and Hilger's Method. K. Lendrich and R. Murdfield. (Zeits. Unterszuh. Nahr. Genussm., 1908, 16, 647-658.)-Several observers have pointed out that the method described by Juckenack and Hilger (ANALYST, 1897, 22, 190) for the estimation of caffeine yields low results, and the authors now confirm this, and show that the error is due to the fact that caffeine is by no means completely extracted from a dry residue such as is obtained in the process.If an aqueous solution of caffeine be evaporated to dryness with paper-pulp, pumice-stone, etc., and the mass dried for ten hours at a temperature of 100" C., a subsequent extraction for ten hours with carbon tetrachloride in a Soxhlet apparatus only results in the removal of from 60 to 70 per cent. of the caffeine ; the remainder appears to have become for some reason insoluble in the solvent. However, on slightly moistening the extracted residue with water and continuing the extraction, the whole of the caffeine is obtained.The authors therefore recommend that the dry mixture, consisting of the coffee extract and paper-pulp as obtained in Juckenack and Hilger's process, be placed in a chamber filled with steam ; the mass thus thoroughly moistened is then extracted with carbon tetrachloride, and the process carried out as described. W. P. S. Artificial Means of Increasing the Reichert-Meissl Value and Saponifica- tion Value of Butter-Fat, H. Fincke. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 666-673.)-As the height of the Reichert-Meissl value of a sample of butter depends on the quantity of glycerides of the lower fatty acids present in the fat, the addition of fats containing considerable proportion of these glycerides to a mixture of butter and other fats may cause the Reichert-Meissl value of the mixture to be increased to such an extent that it becomes as high as that given by genuine butters.The oil mentioned by Buttenberg (ANALYST, 1908, 33, 189) may be used for this purpose, although the author is not aware that the oil is yet a marketable product ; the glycerides of the lower fatty acids may also be employed, and of these acetin, triacetin, and tributyrin come chiefly into consideration. Acetin is, however, soluble in water and insoluble in fats, whilst tributyrin is rather costly; on the other hand,THE ANALYST. 51 triacetin is not very soluble in water, but fairly soluble in oils and fats. Although the author has not yet met with a butter or butter mixture adulterated with triacetin, he shows by a number of experiments that its use is quite feasible, and also gives a process for detecting its presence. The results show that the acetic acid of the triacetin distils-over in the Reichert-Meissl process to a considerable extent, but not completely, the butyric acid distilling more readily than the acetic acid under the conditions of the distillation, If, after the distillation, water be added to the distillation flask and the distillation continued, the distillate will contain a considerable quantity of volatile (acetic) acid; and even the fifth distillate will still contain acetic acid.The addition of 5 or 6 per cent. of triacetin to a fat other than butter will cause the Reichert-Meissl value of the mixture to be equal to that of genuine butter-namely, about 27.One per cent, of triacetin, therefore, increases the Reichert-Meimsl value 'by about 4.4. The saponification value is increased by about 5% for each 1 per cent. of triacetin added, whilst the refraction is lowered by about 0.5". On account of the pronounced taste of triacetin, butter-free mixtures containing this substance would be unsaleable, but mixtures containing about 60 per cent. of butter and 2 per cent. of triacetin might have the appearance of genuine butter. For the detection of triacetin in butter and butter mixtures the following process is recommended : I n the first place, the relation between the first and second Reichert-Meissl values give some indication of the adulteration, for, as has been mentioned above, the second distillate yielded by a fat containing triacetin is far more acid than that given by pure butter or other fat.Thirty grams of the sample are then boiled for one hour under a reflux condenser with 150 C.C. of water and 150 C.C. of 98 per cent. alcohol. After cooling, the cake of fat is removed, freed from water and alcohol by warming it on the water-bath, and the Reichert-Meissl and saponification values of this residual fat are then determined. I n the case of butter and other fats, the values for the original sample and the residual fat are practically the same. If the fats contain triacetin, the values obtained for the residual fat are considerably lower ; in other words, the triacetin is removed by extraction with dilute alcohol.w. P. s. Estimation of Chloroform in Lozenges. E. Dowzard. (Amer. Journ. Pharnz., 1908, 80, 511-514.)-This method is based on that of Nicloux (ANALYST, 1906, 31, 114), and consists in treating the substance, containing not more than 0.1 gram of chloroform, with alcoholic potash at boiling temperature, after which the chloride in the liquid is titrated with silver nitrate solution. One-half (in one piece) or one lozenge of known weight is introduced into a flask containing 70 C.C. of alcoholic potash (2.5 per cent. solution in 75 per eent. alcohol), and the liquid heated just short of boiling, under a, reflux-condenser, until the lozenge dissolves or disintegrates. The contents of the flask are then gently boiled for forty-five minutes, after which 25 C.C.of water are added, followed by a few drops of phenolphthalein solution and suflicient dilute nitric acid (1 part acid to 4 of water by measure) to render the liquid slightly acid. Half a gram of calcium carbonate is next added with shaking, and the liquid, after cooling, titrated with standard silver52 THE ANALYST. nitrate (8.545 grams AgNO, per litre ; 1 C.C. = 0.002 gram chloroform). The lozenge must not be broken up or powdered, as in such case a very serious loss of chloroform occurs, amounting, after a few minutes, to about 50 per cent. of the total originally present. Plain sugar lozenges lose their chloroform rapidly, the loss when kept under ordinary conditions in cardboard boxes for one month amounting to nearly 87 per cent.of the original quantity. Lozenges containing liquorice extract often retain the full amount of chloroform for a long period. Two corrections must be applied to the above method, due to the possible presence of chlorides in the reagents and in the lozenge before treatment with alkali. A blank experiment should be made with the reagents, but the boiling may be omitted. The chlorides in the lozenge are determined by acidifying the hot- water solution (30 c.c.) of the weighed lozenge with a little nitric acid, neutralising with pure calcium carbonate (0.5 gram) and titrating as before. The combined correction is deducted from the chloride found in the actual estimation, the mean of three results being taken, as slight variations in chloroform-content of the lozenges occur, especially if the amount exceeds 3 per cent.The author found quantities ranging from 1.02 to 5-86 per cent. of chloroform in nine lozenges examined. Lozenges containing liquorice give dark-coloured solutions on boiling with alkali, but the subsequent treatment with nitric acid and calcium carbonate decolourises the liquid. The average loss of chloroform in the manufacture of these lozenges appears to be about 50 per cent. A. R. T. Detection of Added Alkali in Cocoa. K. Farnsteiner. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 625-645.)-The addition of alkaline salts to cocoa, in order to increase its property of remaining in suspension in water, is very general on the Continent, and the results of analyses of cocoas so treated are given in this paper, together with methods of estimating the quantity of added alkali in the cocoa. I n order to render the results comparative, the figures are calculated for 100 grams of cocoa containing 55 per cent.of fat. If a sample of cocoa has an alkaline reaction, and yields an ash requiring more than 15 C.C. of acid for its neutrali- sation, and if, in addition, the amount of insoluble ash is less than 50 per cent. of the total ash, the sample must be considered as having been treated with either potassium or sodium carbonate. An analysis of the ash will show which salt is present, as normal cocoa ash contains but little sodium salt. On the other hand, if the alkalinity of the total ash exceeds 15 C.C. of acid, and the insoluble ash is more than 60 per cent. of the total ash, magnesium carbonate has been added to the cocoa.The addition of both potassium (or sodium) carbonate and magnesium carbonate is shown by the unusually high proportion of the insoluble ash to the total alkalinity. The addition of ammonium carbonate may be detected by mixing the cocoa with water and magnesium oxide and heating the mixture in a flask, in the neck of which is placed a piece of red litmus-paper. The quantity of ammonia may be estimated by distillation with magnesium oxide. w. P. s. The Quantity of Fat in Commercial Cocoa Powders. A. Beythien. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 679-682.)-Result.s are given of estimtt-THE ANALYST. 53 tions of the quantity of fat in 103 samples of cocoa powder manufactured by thirty- five different firme; of the latter, twenty-five had their works in Germany, eight in Holland, and two in Switzerland.Thirty-two of the samples contained less than 20 per cent. of fat and 65 less than 25 per cent. Of the cocoas manufactured in Germany, 28 contained less than 20 per cent., 30 less than 25 per cent., and 18 over 25 per cent. of fat. Four of the Dutch cocoas contained less than 20 per cent., 3 less than 25 per cent., and 13 over 25 per cent. All 7 of the Swiss cocoas con- tained over 25 per cent. of fat. w. P. s. The Chemical Analysis of Hops. C. J. Lintner. (Chem. Zeit., 1908, 32, 1068.)-The author, working in conjunction with Siller, has found that the per- centage of moisture expelled by heating 10 grams of the hops for four hours at 80° C. is practically identical with the result obtained by Hoffmann's method of distillation with oil of turpentine.Both methods can therefore be recommended as conventional means for the estimation of moisture in the sample. For the estimation of the tannin Chapman's cinchonine sulphate method (ANALYST, 1908, 33, 95) is approved, Testing for '' sulphuring " requires some caution, since with a very intense evolution of hydrogen almost any sample of hops will give off sulphuretted hydrogen. The author has investigated the bitter principles of hops. Two resins and two crystal- line bodies are known, the resins being probably derived from the latter by polymerisation and slight oxidation. The old designations of a- and ,@resins or a- and P-acids are no longer correct, since they are different bodies and not modifica- tions of the same body.Neither the a- nor the p-acid is a true acid. The author proposes the name of Zz~pzdiizic acid for the /3-acid (C25H3604), and that of hzmdone for the a-acid (C,,H,,O,) ; they behave as monobasic acids. No change of acidity occurs when they undergo resinification. The titration of the light petroleum extract with & alcoholic potassium hydroxide in presence of phenolphthalein gives results in good concordance with the method of weighing the bitter principles. If entire cones be extracted the petroleum extract is too low ; it is therefore necessary to powder the sample before extraction. The author has worked out a method for the separate estimation of the various bitter principles. The estimation of the a-resin is based on its precipitation as a lead salt; for this purpose it is necessary to adhere to certain conditions, since the humulone readily undergoes resinification.The scheme of analysis is as follow : (1) Extraction with ether for the estimation of the total resins and separation of the a-resin. The extraction is continued for ten hours ; the ether is then distilled off at a temperature of 40" C., and subsequently in vacuo ; the residue is dissolved in methyl alcohol and filtered. In one portion of this solution the u-resin is precipitated as lead salt, another portion is evaporated and dried at 80" to 90" C. until the weight is constant ; this gives the total a-, p-, and y-resins. (2) Extraction with light petroleum spirit, which dissolves only the U- and p-resins.The a-resin is precipitated in the same way as in the case of the ether extract, and the mixed a- and p-resins are determined by weighing the residue from another portion of the same solution. J. P. B.54 THE ANALYST. A Dutch Lard. C. Arragon. (Chem. Zeit., 1908, 32, l227.)-A lard of Dutch origin now being sold is stated to consist of lard freed from part of its lard oil by expression at a moderate temperature. Five samples of such lard obtained from different places gave the following analytical results : I. 11. 111. IV. V. Specific gravity at 100” C. 0-8585 0.8680 0.8575 0.8578 0.8588 Refractometer reading (tem- perature not stated) ... 48.5 48.3 47.7 47.5 48.7 Iodine value ... ... 50.7 50.9 48.9 49.6 54.3 Saponification value . . . - 195.5 195.5 195.5 194.5 Acid value ...... ... 1.9 1.8 0.8 3.2 1-3 I n each case the crystals obtained by slow crystallisation from ether had the characteristic form of those usually given by pure lard. None of the samples contained cocoanut or other vegetable oils. C. A. M. On the Composition of Liebig’s Meat Extract. R. Engeland. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 658-664.)-The author has separated the following bases from Liebig’s meat extract, the substances being identified chiefly by the composition of their gold or platinum double salts: Creatinine, neosine (C,H,,NO) ; carnitine (C7H,,N0,) ; vitiatine (C,H,,N,) ; histidine (C6H,N30,) ; methylgusnidine (C,H,N,) ; and alanine (C,H,NO,). w. P. s. The Detection of “Sugar-Lime” in Milk and Cream. K.Frerichs. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 682-683.)-The test described by Baier and Neumann (ANALYST, 1908, 33, 401) for the detection of sucrose in milk, when the latter has been treated with “sugar-lime,” is capable of detecting the presence of from 0.1 to 0.2 per cent. of sucrose in milk, a quantity much smaller than would be present if the prescribed directions for the use of ‘‘ sugar-lime ” were carried out. The blue coloration is easily distinguished from the apple-green colour given by pure milk. As regards the detection of the added lime in the milk the author considers that more work must be done on the subject before the limits given by Baier and Neumann can be applied in actual practice. w. P. s. The Typical Aromatic Substance Present in Jamaica Rum.K. Micko. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 433-451.)-The aroma of Jamaica rum is due to the presence of an aromatic substance which is not found in artificial rum, or in cognac, and which does not even appear to be present in rum prepared in Europe from molasses. By subjecting a mixture of 200 C.C. of Jamaica rum and 30 C.C. of water to fractional distillation, and collecting the distillate in seven separate fractions of 25 C.C. each, the aromatic substance is found in the fifth or sixth fraction, according to the alcoholic strength of the rum. It may be obtained in a concentrated form by redistilling these fractions, and the author has carried out an investigation with the purpose of ascertaining the nature or composition of the substance. I t is a colourless, not very volatile liquid, having a higher boiling- point than that of ethyl alcohol; it is not an ester, aldehyde, or ketone, but has theTHE ANALYST.55 character of an essential oil, and is possibly closely related to the terpenes. Whilst the substance is not soluble in dilute sodium hydroxide solution, long contact with the alkali changes its aroma. Jamaica rum, like cognac, also contains a terpene- like substance which is not present in artificial rum, but this substance has little to do with the characteristic aroma of rum. The residue remaining in the flask when Jamaica rum is distilled contains aromatic resinous substances which are, for the greater part, soluble in sodium hydroxide solution. The author considers that the separation and identification (by the smell) of the typical aromatic substance is of considerable help in distinguishing between Jamaica and artificial rum.w. P. s. Analyses of Colonial Oats, and the Determination of their Phosphorus Content. J. Lewis. (Cape of Good Hope, Department of Agriculture, Bull. No. 35, 1908.)-The percentage weight of kernel in the oat-grains from different districts in Cape Colony varied from 54.3 to 71.1, the highest figure being that given by a fine sample probably grown from Canadian seed. The author gives the following average results of his analyses of oats from various .districts of Cape Colony as specified in the table, together with the composition of oats from other countries for DurDoses of comparison : District. Piquetberg . . . Rlialmesbury Stellenbosch Caledon ...Bredasdorp . . . Robertson . . . Alexandria . . . King William’s Cathcart ... Queenstown.. . Cape . . . ... ... ... ... ... ... ... ... ... Town ... ... Average for Caps Colony ... ... Middle and North Germany ... South and West G&: many ... ... Austria-Hungary . . . France ... ... England and Scot- land ... ... America ... ... (Various sources j . . . Tumber of Samples. 6 6 2 1 6 6 5 3 2 10 5 52 103 44 34 196 16 22 (Large) Mois- tllrE. 10.37 9.50 10.13 10.35 9.78 LO048 9.66 10.05 8.98 9.59 9.69 9-85 12.45 13.39 11.83 13.50 13-74 10.67 13-30 Fat. 6.12 6-16 6-16 5.85 6.58 6.63 6.08 5.79 6.31 5.56 5.33 6.03 5-30 5.30 5-84 5.46 6-15 4.96 4.77 Pro- teins. 9-92 9.56 8-00 8.06 8-45 8-50 8-85 9-79 9.39 10.50 11.09 9.53 10.82 11.36 11.41 9.52 13-05 11-26 10.32 Digestible Carbo- hydrates.59.45 61.62 62.06 62.35 60.66 61.48 60-52 60.26 62-19 60.55 60.20 60.77 58.23 58.1 2 56.40 60.47 53-16 59.35 58.19 Crude Fibre. 10.80 9-92 10.00 10.05 10.81 9.43 10-94 10-59 9.71 10.09 9.51 10.20 10-25 9.93 11-01 9.18 11.89 9.33 10.32 P,O,. 0.57 0.48 0.46 0.50 0.46 0.47 0.67 0.57 0.48 0.62 0.76 CaO . )-093 )-091 1.108 1.118 1.095 3.102 1.112 3.107 1,086 3.104 3.12056 THE ANALYST, From these results it is evident that Colonial oats are equal in value as regards organic food material to those of other countries, but their content of phosphoric oxide is somewhat lower. The author has studied the question of the determination of the phosphoric acid in cereals, and finds the following method to give accurate results.To obtain an average sample of oats a large weight must be taken, and therefore 250 grams of the well-mixed product obtained by passing the oats through a coffee-mill are incinerated first over a Bunsen burner, and finally in the muffle-furnace at a dull red heat. The addition of calcium acetate is unnecessary. This ignition occupies several hours. The resulting ash is weighed, well mixed, and 1 gram boiled with dilute nitric acid, filtered, and the filtrate and washings evaporated at least six times with nitric acid, to ensure the complete conversion of meta- and pyro-phosphates into the ortho-phos- phate. The final residue is taken up with nitric acid, filtered, and the phosphoric acid in the filtrate precipitated with molybdic acid mixture, the precipitate being then dissolved in the usual way, and precipitated as magnesium ammonium phosphate.The author has proved that no loss of phosphorus occurs during the incineration, while the method proposed for the conversion of all the phosphorus into ortho-phos- phate is more convenient than a fusion, while being quite accurate. The method of repeated evaporation with hydrochloric acid gives low results. A. R. T. Simultaneous Estimation of Sulphuric Acid, Total Acidity and Tannin in Wine. P. Dutoit and M. Duboux. (Ann. Chim. anal., 1908, 13, 461-468.)- The method proposed consists in measuring the electrical conductivity of the wine while the latter is being neutralised by the addition of barium hydroxide solution. At first the conductivity diminishes until the whole of the sulphuric acid (as sulphate) has been precipitated ; it then rises until the total acidity of the wine has been neutralised and, finally, falls and again rises as the tannin is precipitated. In carrying out the process, 50 C.C.of the wine are placed in a small flask (provided with platinum electrodes and the necessary apparatus for measuring the conductivity) and heated to 25' C., which temperature is maintained during the estimation. After noting the initial conductivity of the wine, small quantities of barium hydroxide solution are then added successively from a burette until the conductivity ceases to diminish and commences to increase; this point gives the quantity of barium hydroxide required to precipitate the sulphates. The addition of the alkali is con- tinued as long as the conductivity rises; this additional quantity is a measure of the total acidity of the wine, On adding more barium hydroxide, the conductivity falls slightly, and then rises until it is equal to that at the point where the wine became neutral, showing that the tannin is precipitated.By plotting out a curve, using the C.C. of barium hydroxide solution as abscissae, and the conductivity as ordinates, the estimations may be made very exact. w. P. s. On the Treatment of Wine Barrels with Formaldehyde and the Detection and Estimation of Formaldehyde in Wine. F. Schaffer. (Zeits. Untersuch. Nahr. Genussm., 1908, 16, 674-675.)-Wine barrels are sometimes disinfected by means of formaldehyde (paraformaldehyde being volatilised in the barrels for thisTHE ANALYST. 57 purpose), and the formaldehyde is then removed by treating the barrels with sodium carbonate solution, water, and steam. The author has found. distinct traces of formaldehyde in a wine which had been stored in a barrel disinfected fourteen days previously with formaldehyde. The reaction described by Arnold and Mentzel (ANALYST, 1902, 27, 227) is recommended for the detection of formaldehyde, but, as wine frequently contains sulphurous acid, some preliminary treatment to decompose the formaldehyde-sulphurous acid compound is necessary before the test is applied to the distillate of the wine. The wine is distilled after the addition of phosphoric acid, and the distillate is rendered alkaline with potassium hydroxide. After the lapse of fifteen minutes the solution is neutralised with sulphuric acid, and the test is then applied. For the estimation of formaldehyde the method proposed by Legler may be used; it is based 011 the combination of the formaldehyde with ammonia according to the equation- 6CH,O + 4NH3 = N,(CH,), + GH,O. The distillate from a definite volume of the wine is treated with alkali and then neutralised with sulphuric acid, using rosolic acid or litmus as indicator. An excess of standardised ammonia is next added, the mixture is set aside for three hours, and the excess is then titreted with qc sulphuric acid. The quantity of formaldehyde present is then calculated from the amount of ammonia, used to combine with the aldehyde. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9093400049

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 57 BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Influence of Salt on the Micro-organisms of Butter. 0. Fettick. (Zent. Bakt., 1908 [ii.], 22,32; through Chenz. Zed. Rep., 1908, 32,674.)-The addition of salt to butter is a factor of great importance from the bacteriological point of view. I n unsalted butter the growth of micro-organisms is more vigorous, and continues for a longer time than in salted butter. I n unsalted butter the fission and budding fungi, which constitute the bulk of the micro-organisms present at the beginning, rapidly decrease, whilst the mycelial fungi (Oidium and PeiziciZZizirn) multiply strongly. I n salted butter the last-mentioned fungi decrease from the start and disappear entirely in the third month. Both in salted and unsalted butters the lactic acid bacteria are the principal forms which develop at first ; later, other species of fission and budding organisms come to the fore, but sooner in unsalted than in salted.‘The quantity of salt added should not be too large; an addition of 4 to 5 per cent. of salt destroys the lactic bacteria which impart the pleasant flavour and aroma to the butter, and allows the other organisms, which have an undesirable influence on the quality, to become predominant. The most favourable proportion of salt, in the case of butter containing 12 per cent. of water, has been found in practice to be 205-3 per cent. J. F. B. Observations on the so-called ‘‘ Bacillus Bulgaricus ” and on c c Lacto- bacilline.” S. A. Sewerin. (Zent. Bakt., 1908 [ii.], 22, 3 ; through Chem.Zeit. Rep,, 1908, 32, 668.)--“ Lactobacilline ” is the name given to dry and liquid prepara-58 THE ANALYST. tions supposed to contain B. Bulgaricus, which is reputed to be the specific acid producer of the Bulgarian beverage 4‘ yoghurt.” In the author’s opirion, this bacillus is undoubtedly identical with the Streptococcus Zebenis of Rist and Khoury. Experiments with pure cultures of this micro-organism showed that it not only brought about an energetic formation of lactic acid, but also had the pcjwer of trans- forming milk into a compact mucilaginous mass. From “ yoghurt,” also, were isolated races of this bacillus, some of which possessed this slime-forming property, whilst others mere devoid of it, though identical in all other respects. I t was not found possible to transform one species into the other.Simultaneous inoculation of milk with this micro-organism and with B. Zactis acidi led to a much more pronounced development of lactic acid during the first hours than in experiments in which the species were used by themselves. Various preparations of ( ( lactobacilline ” examined by the author did not produce Iactic acid fermentation to the required extent. Others were quite inactive, and contained no living micro-organisms, or only ordinary B. lactis acidi, yeast, etc. Many of the commercial samples were also defective in keeping qualities, and the time during which they were stated 00 be serviceable was found to be much too long. No dates of preparation were given by the manufacturers. C. A. N. Observations on Fermented Milk.4. Yoghurt and Mazun.W. Kuntze. (Zent. Baht., 1908 [ii.], 21, 737; through Chem. Zeit. Rep., 1908, 32, 668.)-The author’s experiments show that the B. Bzclgaricws of Luerssen and Kiihn is only a sporeless variety of B. rna,yun and of the lactic acid bacillus of Diiggeli. To the same group also belongs the Streptococcus Zebenis, the specific micro-organism of the Egyptian Zeben (see preceding abstract). These different varieties are also identical with those obtained from the stomachs of ruminants. Thus the author prepared from the stomach of a calf pure cuItivations of diplococci and bacilli, which, in conjunction with yoghurt yeast, transformed sterile milk into a product closely resembling the acid milk commonly met with in Turkey. C. A. M.The Negative Results of the Examination of Samples of Raw Thames, Lea, and New River Water for the Presence of the Typhoid Bacillus. A. C. Houston. (Second Repoyt to the Metropolitan Water Board, 1908, 1-33.)- The results of the examination of 156 samples of raw Thames, Lee, and New River water are given, from which it is seen that the most recent tests for B. typhosus, applied to a considerable number of samples of raw river water, at weekly intervals, during a period of twelve months, and involving the study of 7,329 microbes, failed to reveal the presence of a single typhoid bacillus. The writer points out that it has been maintained that primary conceptions as to the undesirable contamination of a water are best based on enumeration of the intestinal microbes contained in it, but that failure during a protracted period of time to discover the typhoid bacillus in a large number of samples of the water may perhaps be legitimately allowed to strengthen a favourable judgment as to the non-specific biological quality of the water.It is, however, considered by the writer to be altogether presumptuous to infer from the above-mentioned results that the typhoid bacillus is never present in the raw riverTHE ANALYST. 59 waters, or to conclude that any relaxation in the processes of purifying the waters before delivery to the consumer is justifiable, A full description of the conditions of experiment, methods, and composition of the media used, is given, A practical feature of the investigation was the comparative ease with which suspected typhoid microbes were excluded by means of simple tests.The most useful test for this purpose consisted in transferring portions of the suspected colonies-ie., those grown on neutral red-bile-salt-peptone-lactose-agar medium, which also contained sucrose, dulcite and salicin, and in some cases varying quantities of malachite green-to tubes containing separately dextrose (glucose), galactose, lEvulose, maltose, and mannite, and incubating the cultures at 37" C. for three hours; after cooling, the cultures were finally incubated at 20" to 22" C. for from twenty-one to forty-five hours. If in any of the five tubes there was gas-production, the microbe was rejected as not being typhoid. w. P. s. The Separation of Certain Enzymes by Means of Capillary Action.J. Griiss. (Ber. deut. botan. Ges., 1908, 620; Woch. fur Brau., 1908, 25, 841-842.)- The author has proposed a method for the separation of the different enzymes which may be present in a solution by taking advantage of their differential diffusion under capillary action on bibulous paper. In the present case he has examined the enzymes present in a glycerol infusion of barley embryos, the experiments being carried out in an atmosphere of hydrogen. Ten embryos were ground to a paste with 1 or 2 drops of glycerol, and the mass was then placed on a stretched Swedish filter-paper, on which 8 moist spot had previously been made by a few drops of water. When the liquid had ceased to spread, a strip, 1 mm. in width, was cut off from the edge of the zone, and small portions of this strip were piled up in two heaps on a cover-glass, with a small space between the heaps for the insertion of the object to be tested.The whole was then moistened with a few drops of thymol-water, and the cover-glass inverted over a hollow slide and enclosed withvaseline. In this case the test objects were thin sections of lupin seeds and some starch granules. After forty-eight hours, microscopic examination showed erosion of both the lupin hemicellulose and the starch, and the author concludes from this that the cyto-hydrolytic and diastatic actions are due to one and the same enzyme, since if two enzymes had been present in the infusion, they must have been separated by the capillary analysis. Many plant tissues secrete oxygenases and peroxydases, which form coloured products when the plant is wounded; these are sometimes protected in the iiving tissue by reducing substances, which resist boiling with alcohol.The author has been able to separate these various constituents by his capillary method in the case of potato- juice ; he has also obtained similar results by the capillary diffusion of an alcoholic extract of cacao-beans, and has studied the action of the enzymes of one kind of 6 ' diffusion field " on the constituents of another. J. F. B. Applieation of the Gasometric Method to the Exact Estimation of Urea. A. Ronchese. (Bull. SOC. Chim., 1908, 3, 1135-1141.)-Ten C.C. of the urine to be tested are added to 4 C.C. of a solution of basic lead acetate previously mixed with60 THE ANALYST.6 C.C. of water. The liquid is agitated and filtered from the precipitate, which contains most of the uric acid and creatinine. After diluting to 40 c.c., the liquid is treated as usual with sodium hypobromite solution, the result being corrected by means of that obtained in a similar way with a 2 per cent. solution of pure urea, to which 1 C.C. of a 5 per cent. solution of glucose is added if the original urine con- tained sugar. The result must be further corrected for the ammonia present in the urine. The quantity of this present is aecertained by diluting 10 C.C. of the urine to 100 C.C. with recently boiled distilled water, adding phenolphthalein, exactly neutralising with a dilute solution of sodium hydroxide, adding 20 C.C. of neutral formaldehyde solution, and titrating with TG sodium hydroxide solution until alkaline; for every 3 C.C.of sodium hydroxide solution used, 0.1 C.C. should be added as a correction. A. G. L. Bang’s Method of Estimating Sugar, and its Use in the Examination of Urine. (Biochern. Zeits., 1908, 15, 76-94.)-The accuracy of the method having been questioned ( c j . ANALYST, 1908,33,324), the author has subjected it to a critical examination, and finds that it is quite trustworthy for the estimation of dextrose. The method also gives satisfactory results in the estimation of sugars in urine. For all clinical purposes the method may be applied directly to the urine, but where special accuracy is desired, the urine may be clarified previously with lead acetate or mercuric nitrate, the latter by preference.The reducing substances (other than sugar) present in normal urine are almost, if not completely, removed by treat- ment with mercuric nitrate. Clarification with lead acetate is best attained by treating 100 C.C. of the urine with 5 grams of powdered lead acetate ; the mercuric nitrate solution which is recommended for the clarification is prepared by adding 220 grams of mercuric oxide, in small quantities at a time, to 160 C.C. of concentrated nitric acid, boiling the mixture, adding 60 C.C. of 5 per cent. sodium hydroxide solution (to neutralise some of the excess of nitric acid), and diluting the solution to 1 litre. Twenty-five C.C. of this solution are sufficient to clarify 50 C.C. of urine. The mercuric nitrate solution is also an excellent clarifier for molasses, when the sugar in the latter is to be estimated polarimetrically. About 10 C.C. are required for every 4 grams of molasses taken, but an excess of mercuric nitrate is with- out influence on the results. In order to prevent the possibility of inversion, the molasses solution, after the addition of the mercuric nitrate, is neutralised with sodium hydroxide solution, and a correction is made for the volume of the mercuric oxide pressnt. For instance, 25 C.C. of molasses solution and 10 C.C. of mercuric nitrate solution are, after neutralisation, diluted to a volume of 100.2 C.C. A. C. Andersen. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9093400057

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

60 THE ANALYST. ORGANIC ANALYSIS. Copal Resins from British West Africa. (Bull. Imperial Inst., 1908, 6, 245-252.)-Accra Copal.-The source of this resin has been identified as a tree of the Cyanothyrsus species. The resin, as obtained from the Ashanti district, is mostly in the form of yellowish-white, flattened tears, having a glassy fracture. Internally theTHE ANALYST. 61 resin is transparent. I t is almost entirely soluble in mixtures of equal parts of alcohol and benzene, and of alcohol and turpentine. About 75 per cent. dissolves in alcohol, but it is only sparingly soluble in turpentine, chloroform, or benzene. Two samples of the ‘ I mass ” variety were obtained from t;he Sekondi district (Gold Coast), and were found to be completely soluble in a mixture of turpentine and alcohol, almost conipletely soluble in alcohol and in ether, partially soluble (with swelling) in chloroform, sparingly soluble in turpentine, in benzene, and in a mixture of turpentine and benzene.The following figures were obtained by the analysis of these samples, the figures yielded by previous samples of Ashanti origin being also given : From Ashanti : Present Sample ..( Previous Sample 1 ..( 9 , ,, 2 . . I 9 , ,, 3 .., 1 ... ... ..< From Sekondi District : 2 ... ... .., Sierra Leone Copal : l ( First Grade ” l 6 Second Grade ” .. Appearance. Yellow ish-w hite tears. - Light brown clear mass. Very rough opaque mass. Transparen t, light yellow, tear shaped lumps. Sm aller tears. ~ Ash. Per Cent. ~ 0.1 2.21 0.12 0.5 0.2 0.2 0.04 0-20 p d Number ,Mgms. KOH per Gram).124 134 133 126 133 133 127 127 Moisture. Per Cent. Melting- Point, “C. 180 145 120 128 140-150 140-150 137 125 These last two samples of resin were found to be partly soluble in alcohol, ether, chloroform, carbon disulphide, and turpentine, and were completely soluble in a mixture of alcohol and benzene. Copal from Southern Nigeria.-This copal is derived from Cyanothyrsus Ogea, Harms. (Daniella obloizga, Oliv.), and is apparently identical with Ogea gum.” Both this Nigerian copal and Ogea gum are completely soluble in a mixture of alcohol and benzene, and in turpentine. I n addition, the copal was found to be completely soluble in a mixture of ether and benzene, partially soluble in chloroform, and almost insoluble in alcohol ; while ‘‘ Ogea gum ” was found to be completely soluble in a mixture of alcohol and turpentine, and partially soluble in alcohol.These differences in solubility are believed to be accounted for by the age of the Nigerian copal, which was obtained in 1902. The samples give the following figures on analysis :62 THE ANALYST. Nigerian Copal. Ogea Gum. Appearance ... ... ... Ash, per cent. ... ... Melting-point, "C. ... ... Acid number ... ... ... Resin of Daniella Thurifera from Northern Nigeria.-Daniella thurifera, Qliv., is the source of the so-called West African or Illorin '' balsam of copaiba " or '' wood oil." Two samples of naturally-exuded gum from the bark of this tree were examined, and were found to be quite different from the typical copals of commerce, both in their melting-point and in their ready and complete solubility in alcohol, turpentine, and in a mixture of alcohol and benzene.The following figures were yielded by the samples : A mass of glassy, pale Yellow, glassy fragments yellow resin. of copal-like resin. None. 0.5 110 116 180 (approx.) 120 (approx.) 1. ... Appearance ... ... Ash, per cent. ... ... Acid number ... ... Melting-point, "C. . . . . . . ... 2. Small, translucent, yellow- Small, yellowish-brown, 90" (approx.) 90" (approx.) ish fragments. granular fragments. Trace. 1.2 97 132 A. R. T. The Higher Melting-Point Constituents of Japanese Fish Oil. H. Okada. (Chem. Zeit., 1908, 32, 1199-1201.)-A specimen of Japanese fish oil derived from various species of herring was washed with dilute hydrochloric acid and water, and, after the addition of half its volume of ether, cooled for thirty minutes at -- 10" C.The solid deposit was purified by further treatment with ether at a low temperature, and fractionated by treatment at - 10" C. with a mixture of 40 parts of ether and 60 parts of alcohol, the successive deposits being treated with the solvent and chilled, until finally the melting-points of both soluble and insoluble portions were 34' to 35" C. The insoluble deposit melting at 34" to 35" C. contained no free acid, it had a saponification value of 195.9, an iodine value of 29.7, and a refractometer reading of 1.4545 a t 41" to 42" C. It was found to contain oleic acid and solid acids (melting-point 43" to 47' C.) which appeared to be a mixture of stearic and iso-cetic acids, and, in the author's opinion, consisted of the mixed glyceride- The absence of a fatty acid of the formula C17H3402 (margaric acid) was proved, and a fraction of the solid fatty acids melting at 5 7 O to 59" C.had quite a differentTHE ANALYST, 63 crystalline form from that of a mixture of stearic and palmitic acids of about the same me1 ting-point . C. A. M. Seeds of Lophira Alata. (BUZZ. Imperial Inst., 1908, 6, 243-245.)-The tree yielding these seeds is already well known o m of the sources of the so-called African oak, and is widely distributed in Sierra Leone and throughout the coastal districts of West Africa. The kernels were found to contain from 31.1 to 43.0 per cent. of a nearly white or pale yellow semi-solid fat having the following characters : Product ....,. ... ... Condition of kernels ... ... Yield of fat (per cent. calculated on the kernels) ... Specific gravity at 40” C.’ . . . Acid value ... ... .. . Saponification value . . . ... Iodine value ... ... ... Reichert-Meissl. value . . . ... Unsaponifiable matter . . . Titre test, “C. ... ... ... ... A. Fruits, Mostly sound. 31.19 18.54 195-5 68.4 0.9101 - 1.49 - B. Kernelf Good. 43.0 26.9 181-5 69.8 0.9 0.5 49.0 0.904 C. Fruits. Many partly decomposed. 39.6 33.2 194.6 70.3 0.9 47.0 0-9044 - D. Kernels Good. 41.1 47.5 180.7 72-1 0.8 0.901 47.5 E. Kernels. Fairly good. 41.76 48.0 183.3 72.5 0.8 0.86 48-5 0.9016 The variation in the fat content, which is highest in the case of the decorticated kernels, is due to the maturity and freshness of the fruits and to the dryness of the kernels.Samples D and E yielded a somewhat more rancid fat than the other seeds, as shown by the acid values. “ E ” had been stored for two months in the rainy season before shipment. The fat from the decorticated seeds has a uniformly lower saponification value than that from undecorticated seeds, but this difference does not appear to be of any importance. The “fat ” is suitable for soap-making. A. R. T. Detection of Savin Oil. A. Beythien and P. Atenstadt. (Zeits. Untersuch. Nahr. Genussm., 1908,16, 677-679.)-0f the few tests which have been described as being characteristic of savin oil, the authors find none that can be relied upon. The only test which appears to a certain extent satisfactory consists in heating 2 C.C.of the oil with 0.5 C.C. of stannous chloride solution for a short time in a boiling water-bath; the stannous chloride is coloured yellow, whilst the oily layer becomes brown or red-brown. Juniper oil and turpentine, however, also give similar colorations. The authors conclude that the characteristic smell of savin oil con- stitutes its best qualitative test, When sufficient oil can be obtained (yhich is unlikely in cases of poisoning) to enable some of its physical and chemical constants to be determined, it is to some extent possible to differentiate between savin oil (Oleurn sabina o$icinaZis) and64 THE ANALYST. the two kinds of juniper oils obtained from juniper berries and twigs. The following, figures bear this out : BGling-point . . ... Juniper Oil (from Twigs).Over 165" C. Juniper Oil (from Berries). [odine Value. Savin Oil. Yelting- Point OC. Specific gravity at 15" C. Specific rot a tion ... Refractometer value '25" C. Iodine value ... ... ... Saxlonification value . . . ... . . . c- r l . 3 91.8 545.95 13.6 0.8727 + 7.30 71.20 313.80 6-84 Below 165" C. 38-39 39-40 39 39-40 0.8571 + 5.95 64.00 329.44 6.00 Below 165" C. 0.9137 + 50.00 70.00 232-21 120.30 w. P. s. Charaeteristies of Ergot and Lyeopodium Oils and Areca-Nut Fat. A. Rathje. (Arch. Pharm., 1908, 246, 692-709.)-&got oil, as extracted from Secule corizutunz, is a pungent brown oil containing the glycerides of oleic acid (68 per cent.), hydroxyoleic acid (22 per cent.), and palmitic acid (5 per cent.). The sample examined also contained 0.36 per cent.of unsaponiiiable matter, 0.2 per cent. of mineral matter, and 0.6 per cent. of alkaloids. Lycopodaz~nz oil, obtained by extraction of the spores of lycopodium with a, solvent, is a yellowish-green oil, composed of glycerides of various fatty acids, including lycopodium acid (dihydroxy- stearic acid) (3.2 per cent.) ; lycopodic acid, C,,H,,O, (81 per cent.) ; stearic acid (1.13 per cent.) ; palmitic acid (0.85 per cent.) ; and myristic acid (2.0 per eent.). Arecu-nut fat, when obtained by extraction with ether, is a red-brown substance with an odour like that of nutmeg, whereas the substance extracted with ether is yellowish-white, and has but little odour. I t melts at 36" to 38" C., and consists chiefly of glycerides of lauric, myristic, and oleic acids, with smaller quantities of stearic, palmitic, and capric acids, and the proportion of these varies with the mode of extraction.About; 1 per cent. of unsaponifiable matter is present. The following analytical values were obtained with samples of the above-mentioned fats : Fatty Acids. Refrac ometei Read- ing. * 3aponi. Bcatioii Value. Reichert- Meissl Value. Specific Gravity. Acid Value Todir e Value. Hehnei Value. Acetyl Value. Fat. Ergot oil ... Lypocodinm oil Areca-nut fat : Extracted with ether Extracted with petro. leum spirit Mean Molecular Weight. 0'9250 0 '936 17 0.884 0.973 1.468; 1'4671 - - 179.3 195-0 227'4 '234.6 11 -38 18.6 91.1 97'2 74.0 81-0 24.3 12.3 96-25 88.0 02.76 91-45 29.12 58.8 15.1 18'2 0'63 7'3 0.2 4-2 307.0 278 '0 244-6 238.5 a Tempratwe not recorded.C. A. M.THE ANALYST. 65 Rate of Hydrolysis of Soaps in Aqueous Solution. F. W. F. Ross. (C7zem. Trade Jozmz., 1908, 43, 540-541.)-The author emphasises the fact that the rate of hydrolysis of a soap in aqueous solution depends largely upon the nature of the fatty acids present, the sodium salts of different fatty acids having markedly different hydrolysis rates. The author has proved that this rate of hydrolysis is independent of the amount of combined alkali or of moisture, and of the presence or absence of free fatty acids or super-fatting. He bases upon these considerations a time-test of the rate of hydrolysis of a soap as a means of determining the alkalinity of any sample when in actual use. The freshly cut surface from the centre of a fair-sized piece of soap should be employed.Two C.C. of a 1 per cent. solution of phenolphthalein in absolute alcohol is gradually diluted with distilled water added in quantities of 0.1 C.C. at a time, and after each addition of water 1 drop of the solution is applied with a glass rod t o the freshly cut surface of the sample to be tested, and to a standard soap of known composition, and the time required for the appearance of a pink colour noted. If no colour be produced in five seconds after the addition of the first 0.1 C.C. of water, the second addition of water is made, and this is repeated until the time required in each case to produce a similar depth of tint is obtained. I t is convenient to find the dilution at which the standard soap reddens to the same extent as the sample soap in half a minute.The author’s standard soap showed only a faint flesh-pink colour in three and a half minutes when moistened with a drop of a mixture of 20 C.C. of absolute alcohol (containing 1 per cent. of phenolphthalein) and 25 C.C. of distilled water. Few soaps will resist this test for more than one minute. As a test of moderate severity for toilet soaps, 12 C.C. of absolute alcohol containing phenolphthztlein mixed with 9 C.C. of water should not give an immediate pink colour on a freshly-cut soap surface ; the author’s standard soap gave a slight reaction after three and a half minutes, It seems clear that a soap which hydrolyses rapidly under the above conditions cannot be regarded as being without action on the skin.A. R. T. Use of Sodium Peroxide in the Quantitative Analysis of Organic Compounds. H. Pringsheim. (Rer. d&. Chenz. Ges., 1908, 41, 4267-4271.) -The method proposed by the author (ANALYST, 1904, 29, 97, 220, 317) for the oxidation of organic gubstances by sodium peroxide for the estimation of halogens, sulphur, arsenic, and phosphorus has been modified and improved, and is particularly suitable for substances which are oxidised with difficulty. The combustion is effected in an iron crucible which contains a mixture of the organic substance and sodium peroxide. The mass is ignited by inserting a red-hot nail through a hole provided in the lid of the crucible, after having stood the latter in a basin containing sufficient water to cover about three-quarters of its height.Substances containing 75 per cent. and over of carbon, hydrogen, and sulphur are mixed with eighteen times their weight of peroxide; those containing from 50 to 75 per cent. of combustible elements are mixed with sixteen times their weight of peroxide. Substances containing 25 to 50 per cent. of these elements are previously mixed with half their weight of a substance rich in carbon and hydrogen, such as sugar, and those with less than 25 per cent. are mixed with an equal weight. The66 THE ANALYST, former mixtures require sixteen times their weight of peroxide, and the latter eighteen times their weight for combustion. If too much peroxide be taken, com- bustion does not proceed throughout the mass, and if too little, the reaction is too intense.For substances containing arsenic or phosphorus, half the above quantities of peroxide should be taken in excess. Combustion is complete if the whole mass fuses; small residues of carbon are of no account. The crucible is then overturned in the water in the basin, and the whole covered with a watch-glass until gas ceases to be evolved. For the estimation of sulphur, the liquid is acidified after removal of the crucible, filtered and treated with barium chloride, I n the case of halogens, products of a higher stage of oxidation must be reduced by adding to the alkaline solution about 3 C.C. of a saturated solution of sodium sulphite and sufficient dilute sulphuric acid to dissolve any iron oxide which may be present. After driving off the excess of sulphurous acid by heat, nitric acid and silver nitrate are added.Arsenic and phosphorus must be precipitated in alkaline solution, and in this case the presence of iron is objectionable. The combustion should, therefore, be effected in a silver crucible held in an inclined position, The solution of the melt is acidified with hydrochloric acid, filtered, made alkaline with ammonia, and treated with magnesia mixture. J. F. B. Fractionation of Crude Petroleum by Capillary Diffusion. J. E. Gilpin and M. P. Cram. (Amer. Chem. Jozmz., 1908, 40, 495-537.)-The observation has been made that when black vaseline is filtered through warm dry fuller’s earth, the first product is a liquid oil, while the succeeding portions are progressively more viscous, until quite hard vaseline is obtained.A similar fractionation occurs in the case of petroleum. The authors have shown that when crude petroleum is allowed to rise by capillary diffusion in a tube packed with fuller’s earth, there is a decided fractionation of the oil, that at the top of the tube having a lower specific gravity than that at the bottom. Moreover, when water is added to fuller’s earth containing petroleum, the oil first displaced differs in specific gravity from that which is after- wards freed by the addition of more water. Thus, by the addition of only a small quantity of water, the first fraction of oil liberated has a somewhat higher specific gravity than the immediately succeeding fractions, which, however, increase in density as more water is added, until at last the heavier portions are obtained.I n any case, however much water be added, about one-third of the oil remains in the fuller’s earth. The light fractions are shown by the authors to contain the paraffin hydro- carbons, which tend to collect in these fractions at the top of the tube, while the unsaturated hydrocarbons are found at the bottom of the tube. A. R. T. Use of Hydrofluoric Acid for the Hydrolysis of Proteins. L. Hugounenq and A. Morel. (Journ. Phurnz. Chim., 1908, 28, 486-493.)-The usual hydrolytic agents-alkalis, sulphuric acid, hydrochloric acid, eta.-when used for the hydrolysis of proteins, bring about destructive secondary changes before the hydrolysis proper is complete. The authors have found that this does not occur when hydrofluoric acid is employed, and that the hydrolysis may be carried out progressively to anyTHE ANALYST.67 desired stage without blackening of the liquid or the production of hydrogen sulphide or ammonia. Moreover, at the end of the hydrolysis there is no difficulty in eliminating the whole of the acid in the €orm of calcium salt. The hydrolysis is carried out in a copper boiler lined with sheet lead and heated in a water-bath. The boiler is closed by a leaden cover bolted to the flange of the shell, and is surmounted by a leaden worm-condenser. Samples may be withdrawn through a tubulure provided in the cover. The protein substance is placed in the boiler with four times its weight of water and three times its weight of the commercial 50 per cent. hydrofluoric acid. The mixture is heated in the boiling water-bath until a sample tested in a platinum dish shows the stage at which the hydrolysis should be stopped; complete hydrolysis may be attained after heating for thirty-six to forty-eight hours.When the contents of the boiler are cold, milk of lime is added cautiously, care being taken not to allow the temperature to rise above 40" C., nor the reaction to become alkaline. A slight degree of acidity is allowed to remain, and the liquor is then decanted off and the precipitate washed until free from drganic matters. The extract is concentrated in vac2~0 until it corresponds to 2 litres for every 100 grams of original protein. The usual systematic precipitations may then be efYected as follows : (1) Separation of insoluble phosphotungstates, €ollowed by the isolation of the di-amino acids, and the purin and pyrimine bodies; (2) elimina- tion of the excess of phosphotungstic acid, followed by the separation of the tyrosine and most of the mono-amino acids by crystallisation; (3) esterification of the residual amino acids by Fischer's method and separation of the esters; (4) another portion of the original liquid is examined for carbohydrates. Both with proteins and carbohydrates, hydrolysis may be carried out by hydrofluoric acid to a full extent without humification and without, in the case of proteins, the formation of bodies yielding flocculent phosphotungstic precipitates or syrupy polypeptides ; consequently maximum yields of crystalline derivatives are obtained. J. F. B.

ISSN:0003-2654    

DOI:10.1039/AN9093400060

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年代:1909

数据来源: RSC

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THE ANALYST. 67 INORGANIC ANALYSIS. Simplified Methods for the Estimation of Gaseous Impurities in Factory Air. M. Kahn. (Gesundheits. Ingeniezw, 1908, 31, 693-697 ; through Chem. Zeits. Rep., 1908, 32, 631.)-The estimation of the usual impurities of air is rendered automatic as far as possible by drawing the air through measured volumes of reagents in which a colour change is produced. The air is aspirated and measured by means of a small pump driven electrically by accumulators. Carbon dioxide is estimated by means of & sodium hydroxide solution, coloured with phenolphthalein ; sulphur dioxide by H&a iodine solution ; chlorine with 9&G sodium thiosulphate solution [? containing potassium iodide and starch] ; and ammonia by TG sulphuric acid, with subsequent estimation of the ammonia absorbed by means of Nessler solution.The results obtained are reliable. A. G. L. Researches on Aluminium. Analysis of Aluminium Powder. E. Kohn- Abrest. (Conqtes rendw, 1908, 147, 1293.)-The author had previously shown that aluminium powder, even when made from the purest leaf, contains considerable68 THE ANALYST. quantities of oxide. (1) by the reduction of ferric sulphate and titration with permanganate : and (2) by weighing as water the hydrogen disengaged from hydrochloric acid. The results agreed satisfactorily. The following is a full analysis, after allowing for the effect of impurities, such as iron and silicon, upon the quantity of hydrogen evolved : He determines the aluminium present in the metallic state-- 3Fe,(S04), +2A1=A12(S04), +6FeSO, ...Aluminium , metallic ... ... Silicon ... ... ... ... ... Silica ... ... ... ... ... Iron ... ... ... ... ... Nitrogen ... ... ... ... 0 . . Carbon ... ... ... ... ... Sodium ... ... ... ... ... Aluminium insoluble in acids ... ... 92.499 0.418 0.259 0.613 0.152 0.310 0.006 0.024 Tot a1 ... ..* ... 94.281 Aluminium oxide by difference ... 5.719 The powder was separately found to contain 3.430 grams of combined aluminium, united with 2.288 grams of oxygen to form 5.718 grams of aluminium oxide-a satisfactory agreement. 0. E. M. The Use of the Rotating Anode in Electrolytic Separations. M. E. Holmes. (Jourm. Amer. Clzem. SOC., 1908, 30, 1865-1874.)-The deposition of cadmium and its separation from other metals were studied, using, in conjunction with a rotating dish anode (300 to 400 revolutions per minute) and a stationary dish cathode, low-current densities (0.3 to 0.4 ampere per 100 sq.cm., at about 2.75 volts), instead of the high-current densities hitherto used. Working in sulphate solutions containing 1 C.C. of free sulphuric acid (specific gravity 1.09) in 60 C.C. total volume, at room temperature, it was found that 0.2 gram cadmium was completely deposited in forty-five to sixty minutes, and that, under the same condi- tions, it could be successfully separated from aluminium, cobalt, nickel, zinc, and magnesium, but not from iron or manganese. In the presence of chromium the results were satisfactory only if the deposit was well washed with hot water to remove occluded liquid. I n a solution containing 5 C.C. of formic acid in place of the sulphuric acid, cadmium was successfully separated from manganese.I n solutions containing 1 C.C. of 25 per cent. acetic acid and 1 gram of ammonium acetate, heated to nearly boiling before the electrolysis commenced, cadmium could be successfully separated from aluminium and magnesium, but not from the other metals mentioned above. A. G. L. The Mixed Barium-Strontium Chromate Precipitate. L. H. Dusehak. (Journ. Amer. Chem. SOC., 1908, 30, 1827-1833.)-The author shows that when barium is precipitated as chromate by the Fresenius method in the presence of strontium, the precipitate of barium chromate obtained always contains strontium in quantity depending on the relative concentrations. The fact that double precipitation by this method yields results satisfactory from an analytical standpoint is supposed to be dueTHE ANALYST, 69 to the variations in the composition of the final precipitate obtained being within the limits of experimental error of the method (cj.ANALYST, 1908, 34, 12). A. G. L. Impurities in Commercial Chlorates. G. Ponndorf. (Chenz. Zeit., 1908, 32, 1151.)-B. Carlson and J. Gelhaar (Chem. Zeit., 1908, 32, 604) proved that the blue coloration observed by Gartenmeister (ibid., 1907, 31, 174; 1908, 32, 677) on adding potassium iodide starch and sulphuric acid to a cold saturated solution of electrolyticslly prepared chlorate was not, as he supposed, a proof of the contamina- tion by hypochlorite and chlorite, and showed that the samples of which he complained were free from these compounds.Gartenmeister then attributed the coloration, and also the spontaneous ignition of explosives containing these chlorates, to an acid of intermediate composition, at present unknown. The author investigated five samples of chlorate. To 1 gram of the sample dissolved in 25 C.C. of water were added a small crystal of potassium iodide, a few drops of starch solution, and 0.5 C.C. of 1 in 4 sulphuric acid. All the samples had previously been found by the method of Carlson and Gelhaar to be free from chlorite and hypochlorite. No 1 obtained from Gartenmeister, and described as free from active chlorine-containing acids, gave a blue colour in two and a half minutes; Nos. 2 and 4 (Swedish electrolytic chlorates) immediately; No.3 (German electro- lytic chlorate) immediately a very strong coloration ; and No. 5 (German) immediately a strong coloration. Mixtures containing 70 per cent. chlorate, 10 per cent. ammonium nitrate, and 20 per cent. resin, were made from the five samples, and numbered correspondingly I. to V. Portions of 1 gram, at least two for each sample, were heated slowly in the oil-bath, in test-tubes of 15 cm. internal diameter. Nos. I., II., and IV. decomposed, fired, and puffed off vigorously : No. I. at 127", 132", 130" and 130" C., No. 11. at 134O and 134.5' C., and No. IV. at 126", 145", 133" and 136" C. respectively. No. 111. did not fire at 172" and 172" C., nor did No. V. at 170" and 170" C., though a brown coloration, caused by the decomposition of individual particles, was observed in each case.I t thus appears that a chlorate which does not pass the Gartenmeister test is not therefore more dangerous than one that does. The author regards the self- ignition of a mixture of chlorate, sugar, and sulphur, described by Gartenmeister, as due to some cause other than the contamination of the chlorate. He has never had a case of self-ignition of explosives prepared from electrolytic chlorates. 0. E. M. Detection and Colorimetric Estimation of Chlorates and Other Oxidising Agents. J. F. Virgili. (Chenz. Zeit., 1908, 32, 1254-1255.)--For the detection of chlorates and oxidising agents generally, the author recommends the aniline test, which gives an intense blue coloration. Two reagents may be used, according to the requirements of the case : (a) A solution of 50 grams of chemically pure aniline hydrochloride in 1 litre of hydrochloric acid of specific gravity 1.12; (b) a solution of the same quantity of aniline salt in 1 litre of hydrochloric acid of specific gravity 1.145.When 4 C.C. of the reagent ( a ) are added to 1 C.C. of the liquid to be tested,70 THE ANALYST. the mixture, if chlorates be present, assumes a mulberry colour, which rapidly changes to dark blue. The test is very delicate ; a quantity of 0-02 mgm. of potas- sium chlorate is easily detected, and even 0.007 mgm. gives a slight coloration. Reagent ( b ) is still more sensitive, but the coloration disappears more rapidly than in the case of (a), and its use requires greater care. This test is not characteristic for chlorates ; any substance which liberates chlorine from the reagent will give the same coloration-for instance, hypochlorites, hypobromites, bromates, iodates, the peroxides of hydrogen, sodium, barium, manganese and lead, chromates, bichromates, manganates, permanganates, vanadates, ferricyanides, and the salts of per-acids.The presence of reducing substances which are oxidised or chlorinated more readily than aniline interfere with the test-for instance, certain phenols, the chromogens of urine, certain putrefaction products, bromides, iodides, and a large excess of nitrites. Perchlorates, ferric and auric salts, nitrates, small quantities of nitrites, nitric acid below 1.2 specific gravity, arsenates, tungstates, and molybdates do not interfere. The reaction is more delicate for the detection of traces of hydrogen peroxide than the chromic acid-ether test, but the coloration may not appear until after about half an hour.Bromides and iodides may be removed by preliminary treatment with silver nitrate. In applying the test for colorimetric estimations, the solutions are mixed in the proportions mentioned above, and the colorations developed after half an hour are compared with those of standard solutions ; any subsequent darkening of the liquid after that time is not to be taken into account. When reagent ( b ) is used the colours must be compared after ten to fifteen minutes. If 5 C.C. of the liquid to be tested contain 0.1 mgm. to 2.2 mgms. of potassium chlorate, 20 C.C. of reagent (a) are used; if 5 C.C. contain 0.5 mgm.to 7.0 mgms. of chlorate, 20 C.C. of solution ( b ) may be used ; solutions containing larger quantities of chlorate should be diluted. J. F. B. Volumetric Estimation of Chromic Acid. J. A. Muller. (Bull. SOC. Chim., 1908, 3, 1133-1135.)-Fairly good results are obtained by titrating chromic acid solutions with standard leal! nitrate solution, in the presence of a large excess of sodium acetate, using silver nitrate as indicator. The method is applicable in the presence of other oxidising agents which do not precipitate lead. Sulphuric acid should not be present. A. G. L. The Oxydimetrie Estimation of Chromium by Potassium Ferricyanide. H. Bollenbach and E. Luchmann. (Zeits. anorg. Chenz., 1908, 60, 44645.)- The chromic salt solution is added to a mixture of a freshly prepared solution, containing 4 to 12 grams of potassium ferricyanide, and 50 C.C.of a 2N sodium hydroxide solution. After thorough stirring, barium hydroxide solution is added until the chromate produced is completely precipitated. The solution is filtered through a double filter-paper, acidified with hydrochloric acid, and the ferrocyanide formed titrated with potassium permanganate solution in the cold, preferably by adding an excess of the permanganate and titrating back with standard ferrocyanide solution. The chromic salt solution to be titrated must be free from all metals of the hydrogen sulphide group, as well as from cobalt, nickel manganese, and allTHE ANALYST. 71 reducing substances. Aluminium and moderate quantities of ammonium salts do not interfere; the quantity of ferric iron present must not be more than twice that of the chromium.Three molecules of potassium permanganate correspond to five atoms of chromium. The test results quoted are satisfactory. A. G. L. Volumetric Estimation of Manganese, Iron, and Chromium. E. Luch- mann. (Berg- u. huttenm. Rundsch., 1908, 5, 1 and 17; through Chem. Zeit. Rep., 1908, 32, GSO.)-Manganous or ferrous salts are oxidised by treatment with a freshly prepared solution of potassium ferricyanide, made alkaline with sodium hydroxide. The manganese dioxide or ferric hydroxide formed is filtered off, the solution made acid with sulphuric, hydrochloric, or nitric acid, and the ferrocyanide formed titrated as usual with potassium permanganate solution.If both iron and manganese are present, iron is first estimated with acid potassium permanganate solution, and the two metals then estimated together as above. For chromic salts see preceding abstract. A. G. L. New Reactions of Hydrazoic Acid. F. Raschig. (Chem zeit., 1908, 32, 1203; cf. Ber. deut. Chem. Ges., 1908, 41, 4194.)-Sodium nitride does not react with iodine solution in neutral or acetic acid solution. If a solution of sodium thiosulphate is added drop by drop to the mixed solutions, or if a crystal of sodium thiosulphate is introduced, and the whole vigorously shaken, the sodium nitride is converted quantitatively into iodide, with evolution of nitrogen, which may be collected and measured. The thiosulphate is converted as usual to tetrathionate, but acts on the nitride only as a catalytic agent.Sodium sulphide acts in the same way, whereas arsenious acid, bisulphites, and ferrous sulphate are without action on the nitride. On treating sodium nitride with sodium hypochlorite, no reaction occurs in alkaline solution. On the addition of acid, a colourlesa gas is evolved, which explodes violently on contact with a burning splinter of wood. The gas appears to be chlorine nitride, N,Cl, as it yields sodium nitride and sodium hypochlorite in equi-molecular proportions on passing it into sodium hydrate solution. A. G. L. Volumetric Estimation of Lead in Minerals. J. A. Muller. (BUZZ. SOC. Chim., 1908, 3,1131 -1133.)-Fairly satisfactory results are obtained by titrating lead in sodium acetate solution, containing a little free acetic acid, with potassium bi- chromate solution, using silver nitrate as indicator.A considerable excess of sodium acetate must be used, especially if sulphuric acid is present, as is the case when ores are assayed, for should the excess be insufficient, the precipitated lead chromate carries down with it lead sulphate, and low results are obtained. A. G. L. Free Lime in Portland Cement. A. H. White. (Journ. Industrial and Engineering Chenz., 1908, 1, 5.)-This is a description of a microscopic test for free lime in Portland cement, based on the formation of crystalline calcium phenolate which has a characteristic appearance when examined in polarised light. The reagent used consists of 5 grams of crystallized phenol dissolved in 5 C.C. of nitro- benzene and 2 drops of water added.The test is made by placing 2 or 3 mgms. of72 THE ANALYST. the finely powdered cement on a slide, adding a drop of the reagent, pressing down with a cover-glass, and placing at once under the microscope with crossed nicols at a magnification of about 80. Cement is only feebly refracting, but within a few minutes, if any free lime be present, brilliant points begin to show, which develop in fifteen minutes into clusters of radiating needles, and at the end of two hours the needles may be 0.1 mm. long. The formation of crystals of phenol is prevented by the moisture present in the reagent, and also that absorbed from the air as the solvent on the slide evaporates. Calcium hydroxide responds to the test as well as calcium oxide, but no other substance has been found to do so.Phenolphthalein may be added to the reagent, when pink spots appear round the particles of lime; but in this case magnesia also will react. Comparison of this test with the boiling test showed a good agreement, the former being the more delicate. Cements which do not give the crystals within an hour contain no more than a negligible trace of lime. Experiments with this test on unsound cements showed the cause of the unsoundness to be free lime, brought about in most instances by coarse grinding. I n certain methods of ageing cements it is possible that hydrate of lime may remain permanent, and under these conditions the microscope test, alone might condemn .a sound cement. J. H. J. Solubility of Lime in Water. G.T. Moody and L. T. Leyson. (Trans. Clzem. Xoc., 1908, 93, 1767-1772.)-The authors’ observations are the outcome of an attempt to adapt for use in volumetric analysis a solution of lime saturated at a known temperature, but it was found that, as stated by previous observers, the solubility varied considerably, even when the lime-water was prepared under exactly similar conditions. Further experiments were then made to check the statement of Lamy (1878) that the solubility of lime varies according to the method of prepara- tion, and it was found that a volume of acid capable of neutralising 100 C.C. of saturated lime-water prepared from calcite neutralised 92.2 C.C. of lime-water from white chalk, 100.9 C.C. of lime-water from precipitated lime (by calcium chloride and caustic soda), and 99.09 C.C.of lime-water from white marble. These variations have been found to be due not to any peculiarity of the lime itself, but to impurities present in the lime other than that obtained from calcite. The precipitated lime obstinately holds chlorine (as basic chloride ?) which it is impossible to remove by washing with water, and this impurity probably reduces the solubility of the lime. The greater ‘‘ strength ’’ of the lime-water prepared from white chalk was found to be due to its containing small quantities of alkalis other than lime, and also silica, which, on ignition, is partially converted into soluble silicates, which themselves neutralise a certain proportion of acid. This effect of the presence of silica was experimentally confirmed by adding silica to some powdered pure calcite and igniting the mixture, which yielded a lime-water much “stronger” than that from pure calcite.The authors have also found that (1) lime-water is only fully saturated after a long contact with excess of lime ; (2) saturated lime-water becomes supersaturated when its temperature is raised, and this excess of lime is only given up very slowly; (3) lime-water is appreciably weakened when filtered through paper or other fibrous materials ; (4) precipitated lime containing chlorine, strongly ignited to drive off thisTHE ANALYST. 73 impurity, gives a lime-water practically identical in strength with that obtained from pure ignited calcite; (5) lime prepared by heating calcium carbonate obtained by precipitation with sodium carbonate gives a lime-water slightly stronger than that prepared from calcite, due to the fact that the former contains a minute quantity of sodium carbonate carried down with the precipitate.Determinations of the exact solubility of lime, prepared by igniting purest calcite, were made by the authors, using an apparatus specially designed to avoid all the above-mentioned sources of error as far as possible. The following table shows the solubility of pure lime in water at the temperature stated : Temperature. "C. Weight of Water in Grams required t o Dissolve 1 Gram CaO. 2 10 15 20 25 30 768.5 786.8 804.3 826.4 868.7 908.2 Temperature, "C. 40 988.1 50 1083.0 60 11'79.0 70 1274.8 80 1368.1 Weight of Water in Grams required to Dissolve 1 Gram CaO.A. R. T. The Precipitation of Magnesium as Ammonium Magnesium Phosphate. E. Raffa. (Gazz. Chim. Itnl., 1908, 38, 556-566.)-Experiments described in detail show that magnesium is quantitatively precipitated by means of a slight excess of disodium ammonium phosphate, the reagent being prepared by adding to a solution of disodium phosphate the exact quantity of ammonia required to form the double salt. For a gravimetric estimation, an excess of the reagent (20 to 25 C.C. of a solution) is placed in a beaker, and 10 C.C. of the solution of the magnesium salt (magnesium chloride), which should contain from 0.3 to 0.5 per cent. of magnesium, rapidly introduced. On stirring the liquid, without touching the side of the beaker, the precipitate subsides completely. It is then collected on a tared filter or in a Gooch's crucible, washed with a 2.5 per cent.solution of ammonia until free from chlorine, and treated in the usual way. It becomes perfectly white after being heated for about fifteen minutes over a Tech's burner. Voluinet~ic Estimation of Magnesium.-Ten C.C. of the solution of the magnesium salt are run rapidly into 40 C.C. of the neutral reagent in a stoppered cylinder, and the mixture shaken and allowed to stand until the precipitate has completely subsided. An aliquot portion of the clear liquid is then withdrawn, treated with 1 to 2 C.C. of strong acetic acid, and the excess of phosphate titrated with a standard solution of uranyl acetate. In six test estimations of a solution con- taining 0.368 per cent. of magnesium the results thus obtained ranged from 0.351 to 0-378 per cent.In using this method for the analysis of cements, etc., the calcium is first eliminated, ammoniacal salts expelled in a muffle, the residue taken up in water, and the magnesium estimated in the solution. C. A. M. Volumetric Estimation of Mercuric Salts. H. Morawitz. (Zeits. A9zorg. Chem., 1908, 60, 456-?158.)-Dilute solutions of mercuric chloride may be titrated74 THE ANALYST. with potassium cyanide solution, using p-nitrophenol as indicator, as though they contained the corresponding quantity of free acid, provided that a little free acid is added as catalytic agent. For this purpose 10 drops of TG hydrochloric acid saturated with p-nitrophenol are added to the mercuric solution to be titrated ; the correction to be made is ascertained by titrating 100 drops of the acid-indicator with the same potassium cyanide solution.The latter should be freed from carbonate by treatment with barium hydroxide solution. The results obtained are good. A. G. L. Estimation of Nickel in Nickel-Steel by Means of Dimethylglyoxime. A. Iwanicki. (Chem. Zeit. Rep., 1908, 32, 644.)-The following method is stated to be rapid and trustworthy for the estimation of nickel in nickel-steel. Five grams of the drillings are dissolved in 50 C.C. of hydrochloric acid (specific gravity 1.125), the mixture being gently heated to aid the solution, Concentrated nitric acid is then added, drop by drop, until the solution is clear and dark red in colour, and the whole s concentrated to a volume of about 25 C.C. The residual solution is rinsed into a separating fume1 with hydrochloric acid (specific gravity 1.125), and shaken with 100 C.C.of anhydrous ether, which removes the greater part of the iron, the solution being then shaken with three successive quantities of 5 C.C. of ether containing hydrochloric acid. The acid solution containing the nickel is heated until most of the ether remaining in solution has been evaporated, filtered, the filter washed with hot water, and the filtrate diluted to a volume of about 500 C.C. After the addition of a little tartaric acid, the solution is neutralised with ammonia, then rendered slightly acid with hydrochloric acid, and dimethylglyoxime, in the form of a 1 per cent. alcoholic solution, is added. On heating the mixture and adding ammonia, scarlet-red nickel oxime is precipitated. The precipitate is collected on a weighed filter, and the clear filtrate is passed through a filter of equal weight to the first ; both filters are washed with hot water, dried, and weighed together in a weighing-bottle. The empty filter is now removed, the bottle and full filter are reweighed, and, after removing this filter, the bottle is weighed empty. The weight of the precipitate thus obtained, multiplied by 0.2031, gives the quantity of nickel. w. P. s. Volumetric Estimation of Water-Soluble Phosphoric Acid in Super- phosphates. L. Schucht. (Chem. Zeit., 1908, 32, 1201-1202.)-Twenty grams of the superphosphate are extracted with 1 litre of water. On a part of the solution obtained, a preliminary test is made to determine the quantity of normal potassium oxalate solution necessary for the complete precipitation of the lime present, by adding an excess of the oxalate solution, filtering, and titrating with potassium permanganate solution. To 500 C.C. of the solution the exact quantity of normal potassium oxalate solution so found is then added, the whole is heated to 70' C., cooled, made up to 550 c.c., and filtered; 110 C.C. of the filtrate are titrated with sodium hydrate solution, using methyl-orange or indigo-methyl-orange as indicator; and another 110 C.C. are titrated with the same sodium hydrate solution, using phenolphthalein as indicator. The first titration gives the quantity of free acid present ; the difference between the two titrations that of water-soluble phosphoric acid. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400067

出版商:RSC    

年代:1909

数据来源: RSC

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THE ANALYST 75 APPARATUS, ETC. A Nitrometer provided with Means for correcting the Barometrical Pressure. Herman. (BUZZ. SOC. Chim. Belg., 1908, 22, 440-444.)-The apparatus shown in the figure consists of a mixing vessel, M, attached by means of rubber tubing to the top of the burette, B, which has a side-tubulure, T, and a three-way cock, R. The lower end of the burette is connected with the bottom of a movable water-bulb, A, and this has two tubulures at the top, one of which is connected with the inner tube of a gasometer, G, and the other with the bulb of a siphon barometer. The gasometer tube is immersed in a vessel of water, and has a tap at the top communicating with the air. On the support of the thermometer, t, tables of correction for the tempere- ture and the tension of water vapour are printed.In using this apparatus, the tap, R, is turned so that the interior of the burette communicates both with the outside air at T and with the mixing v~ssel, M, whilst the tap, r, of the gasometer is also opened. The level of the water in the burette is now brought to the zero point by raising the water bulb, and the tap, R, turned so as to close the tubulure, T, while still leaving the burette in communication with the mixing vessel. The substance to be analysed and the reagent are next brought into contact in the mixing vessel, and when all the gas has been evolved the water bulb is lowered until its contents are at the same level as the water in the burette. To apply the barometrical correction, the tap, R, is turned so as to close the top of the burette, 4 Then, if the atmospheric pressure is in excess of 760 mm., the tube of the gasometer is raised (after closing the tap, r ) until the mercury of the barometer scale stands76 THE ANALYST.Cold water. - a - - -*--.) exactly at 760 mm., whilst if the pressure is less than the normal figure this process is reversed. The volume of the gas in the burette will thus be simultaneously increased or reduced to what it would be at the normal pressure. C. A. M. An Apparatus for the Distillation of Mercury. J. Wetzel. (Chem. Zed., 1908, 32, 1228.)-By means of the apparatus here illustrated it is possible to purify by dis- tillation about 23 kilos. of mercury in ten hours. The impure mercury is placed in the open vessel a, the end of the tube c immersed in a basin of pure mercury, and a vacuum created by means of a water-pump at b.This causes the mercury to ascend the capillary tube d, and simul- taneously to rise through the space between the outer and the middle tube e into the bulb i. The level of the mercury in this bulb should be so regulated (by pouring mercury into the vessel a) that it stands about 2 cm. below the opening of the tube e. Heat is now applied by means of the ring-burner g and the condenser h connected with the water-supply. After thirty to forty minutes the tap b is closed and the water-pump disconnected. The mercury vapour condenses on the point of the condenser h, and falls into the upper part of the tube e, where the glass float f closes the opening of the capillary tube until the liquid reaches a certain height, when it rises and allows the mercury to pass and leave the apparatus by the tube c.The vacuum in the apparatus is stated to be nearly perfect. C. A. M. Stirrer for Use in Vacuum Distillation Flasks. H. Suchting. (Zeits. anal. Clzem., 1908, 47, 755, 756.)-The piece of apparatus described is intended for stirring the contents of a flask while undergoing distillation at a reduced pressure. As a result of the stirring the liquid boils more steadily, and the frothing which usually occurs at the end of the operation is prevented. The stirrer is constructed as follows : The neck of the flask is closed by means of a rubber stopper through which passes a glass tube about 5 mm. in diameter; the tube projects 5 cm. below, and about 84 cm.above, the stopper. On this tube, and immediately above the stopper, is fused a wide glass tube about 10 cm. in height, a quantity of mercury being placed in the cup thus formed. A second long glass tube is placed over the first with its lower end dipping into the mercury, whilst its upper end is fixed, above the inner tube, by means of a rubber joint, to a glass rod passing down the inner tube and into the flask. ,4 pulley is fitted on the outer long tube, andTHE ANALYST. 77 when the latter is rotated it carries the rod with it, a stirring device being fitted at the bottom of the rod, so that the contents of the flask are agitated as the rod rotates. The whole is held upright by means of short pieces of glass tube fitted round the outer long tube ; these pieces of tube are held in clamps, and act as bearings.The top of the mercury cup may be fitted with a rubber stopper carrying another piece of wide tubing which acts as an additional bearing. When the air is exhausted from the flask, the mercury in the cup rises in the space between the two long tubes until the height of the barometer is reached. An air-tight joint is thus formed without interfering with the movement of the stirrer. w. P. s. New Form of Gas-Burette. A. E. Hill. (Tralzs. Chem. Soc., 1908, 93, 1857-1859.)-This apparatus, whilst being compact, is claimed to be more accurately graduated than the ordinary form. I t consists of the graduated bulbed tube AB, each bulb having a capacity of (I 10 C.C. This vessel is sealed at the top to the 3-way capillary tap C, which is specially adapted for controlling the flow of gas between the burette and the absorption pipette (cf.ANALYST, 1903, 33, 342). The double tube EFG consists of (1) the measuring tube EF, of a capacity of 10 c.c., graduated into twentieths of a C.C. (each twentieth being represented by a length of 1.5 mm.), and (2) the levelling tube FG, by which the pressure of the gas inside can be adjusted to that of the outer atmosphere. The vessel AB and the side-tube EFG join at the three-way tap H, which controls the flow of water between the burette and the levelling reservoir connected to H by the tubing K, but not shown in the figure. The burette is filled with water by opening the tap C, and turning H into position (1) in figure, which makes con- nection with all parts of the burette.The reservoir is next raised until the water fills the burette and reaches the tap C, which is then closed. Before a sample of gas is drawn into the burette, H is turned into position (3), thus disconnecting the tube EFG from the reservoir. At this point it is advisable to close the top opening of the tube FG, to prevent its con- tents being disturbed by the partial vacuum in AB. The tap H is now turned into position (2), connecting the tube EFG to the reservoir, and a part of the gas compressed in AB is allowed to pass over into EF. The pressure of the gas in this tube is adjusted by raising or lowering the reservoir, and the volume of the gas is then read off in 2c C.C. from the combined readings of AB and EF, both of which are equally accurate.The burette is then connected to an absorption pipette, the tap H turned into position (l), and the gas driven over from the burette to the pipette by opening C and raising the reservoir. After absorption is complete, the tap H78 THE ANALYST. is turned into position (3), and the gas returned to the tube AB by lowering the reservoir, when its volume can be measured as before. A. R. T. Pressure-Equalising Attachment for Desiccators. E. Dowzard. (Amer. Journ. Pharnz., 1908, 80, 588.)-When a hot crucible or other vessel is placed in the ordinary form of desiccator, an expansion of the contained air causes the lid of the desiccator to rise and become displaced, while a partial vacuum is produced, rendering the removal of the lid somewhat difficult.The author's device obviates the incon- venience, and consists of a filled calcium chloride U-tube to which has been fused a piece of glass tubing bent to fit against the inside wall of the desiccator. This U-tube thus fits inside the lower part of the desiccator, under the tray on which rest the articles to be weighed, and it communicates with the outside air at the end of the glass tube fused to it, which fits into a rubber stopper placed in an opening in the side of the upper part of the desiccator. The expanded air thus escapes, and dry air enters, through the U-tube. A. R. T. New Mercury Nitrometer. C. A. Garcia. (Bull. SOC. C7zim., 1908, 3, llll-l114.)-The novelty of the apparatus shown in the figure is that one measuring vessel is provided with both a mercury and a water-levelling vessel. The gas - burette proper, T, has a capacity of 20 c.c., and is graduated into & C.C. Its upper part is joined by a tap, A, to the usual cup, F. I t s lower part widens into a vessel, G, of 40 C.C. capacity. The upper part of this vessel is connected by a side-tube provided with a tap, B, to the water-reservoir D whilst its lower end is connected by a tap, C, and a long piece of india-rubber tubing to the mercury reservoir E. I n using the nitrometer the burette T is first filled with mercury from the reservoir E, the tap B being closed. The tap A is then also closed, and E lowered until the mercury in G falls below the level of the side-tube. The tap C is shut, and the reacting liquids (e.g., urea and sodium hypobromite solution) are sucked into T from F by opening A. At the end of the reaction the gas generated is readily placed under atmospheric pressure by admitting water from D through B, thus avoiding the troublesome levelling of mercury. The apparatus is made by Stroehlein, of Dusseldorf. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9093400075

出版商:RSC    

年代:1909

数据来源: RSC

摘要:

THE ANALYST. 79 BOARD OF AGRICULTURE AND FISHERIES. ANNUAL REPORT OF THE INTELLIGENCE DIVISION, Part I. : Proeeedings under the Sale of Food and Drugs Acts, the Merchandise Marks Acts, the Fertilisers and Feeding Stuffs Act, and the Board of Agriculture Act, for the Year 1907.-The total number of samples taken during 1907 in England and Wales under the Sale of Food and Drugs Acts was 93,088, including 43,794 samples of milk and 17,845 samples of butter; of these, 4,041 samples of milk and 1,046 samples of butter were adulterated. Tables are given showing the number of both genuine and adulterated samples analysed in each county and borough during the year. I n Scotland the total number of samples analysed was 6,842, including 3,455 samples of milk (of which 450 were adulterated) and 1,108 samples of butter (of which 87 were adulterated).The report also deals with methods of sampling, value of test samples, standard of quality for milk (cf. ANALYST, 1901, 26, 251), etc. Over 3,000 fancy names for margarine were submitted for the Board’s approval, and of these about 1,000 were approved. Nine applications for name9 for milk-blended butters were also received. The number of samples of fertilisers analysed in Great Britain under the Act was 1,210, and of feeding stuffs, 1,597 ; 183 samples of fertilisers and 267 samples of feeding stuffs were reported as being of unsatisfactory quality, etc., and in twenty cases applications were made either for the Board’s consent to the institution of prosecutions or for the Board’s advice. Proceedings were taken in two instances : (1) A sample taken from a consignment of sugar-meal showed a deficiency of 50 per cent.in oils and 38 per cent. in albuminoids, but the summons was dismissed on technical grounds. (2) A feeding stuff, described on the invoice as ‘cdecorticated cotton cake,” was found on analysis to contain over 15 per cent. of husk and woolly matter; the magistrate, however, dismissed the case on the ground that there was no standard for husk and woolly matter in decorticated cotton cake. With regard to criminal proceedings, the Board are of opinion that they would not be justified in concurring in a, proposal to prosecute, in any case in which their consent is required, unless there was reason to believe that the offence wag wilful or due to gross negligence. The inquiries and correspondence conducted in the division in connection with the Fertilisers and Feeding Stuffs Act also had reference to the appointment of agricultural analysts and official samplers, the methods of executing the Act, and proposed prosecutions.Several inquiries were undertaken during the year as to alleged offences under the Merchandise Marks Act, 1887. Two samples of so-called cider were found to be composed entirely of sugar in solution, with chemicals, flavouring essences, and80 THE ANALYST. colouring matter, and to be free from apple-juice. Proceedings were instituted, and resulted in the manufacturers being fined $5 and $20 respectively. Successful pro- ceedings were also taken against a trader for consigning margarine in unmarked packages. The packages were sent to a railway-station in the vicinity of a dairy, the owners of which were strongly suspected of adulterating their butter, but sufficient evidence could not be obtained against them to warrant a summons being issued.The same dairy company were later convicted and fined for mixing con- densed milk with butter. w. P. s. INSTITUTE OF CHEMISTRY. PASS LIST : JANUARY EXAMINATIONS, 1909. OF nineteen candidates who presented themselves for the Intermediate Examination, the following eleven passed: M. S. Baker, R. Boyd, B.Sc. (Glas.), W. G. Carey, H. S. Coupland, B.Sc. (Lond.), S. E. Crook, H. R. Lyell, A. Marcan, G. S. McKee, F. J. L. Petri, J. Shelton, and N. Garrett Smith. Eight candidates presented them- selves for the Final ilssociateship Examination in the Branch of Mineral Chemistry, and three passed: T. W. Harrison, B.Sc. (Lond.), J. R. Hill, B.A. (Cantab.), and N. M. Hyslop. I n the Branch of Metallurgical Chemistry, of two examined, one passed : Charles Salter, Assoc.R.C.Sc., A.R. S.M. Of eight candidates who presented themselves in the Branch of Organic Chemistry, the following six passed: H. T. Clarke, B.Sc. (Lond.), H. Davies, J. G. Hay, V. J. Harding, B.Sc. (Manc.), G. Hogan, and J. H. Ryffel, M.A. (Cantab.), B.Sc. (Lond.). I n the Examination in the Chemistry of Food and Drugs and of Water, of nine who presented themselves, four passed : W. Bacon, B.Sc. (Lond.), B. S. Evans, B.Sc. (Lond.), 0. J. Patrick, and V. J. Tilley. W. Bacon and J. H. Ryffel were examined for the Fellowship.

ISSN:0003-2654    

DOI:10.1039/AN9093400079

出版商:RSC    

年代:1909

数据来源: RSC