摘要:

NOTE ON THE TESTS FOR DISTINGUISHING BOILED FROM UNBOILED MILK. BY H E N R Y L E F F M A N N . (Rend at the Meeting, Febrzmy 2, 1898.) IN the ANALYST for August, 1897, p. 211, is a brief note taken from the Jozcr. Phurm. e t China., giving several tests for distinguishing between raw and boiled milk. I have repeated these tests under varying conditions, and also tried other analogous reagents. As noted in the original article, the most striking reaction is with 1 : 4 .diamidobenzene. When a freshly prepared dilute solution of this substance is added to raw milk, and then a few drops of hydrogen dioxide solution, a deep blue colour at once appears. I have found that the colour is produced to a marked degree when the milk has been heated to 170" F. (76.5" C.), but after heating to 180" F.(82' C.) the property is lost. It seems possible, therefore, to distinguish between pasteurized and sterilized milk. Whole milk, ordinary skimmed and separator-skimmed milk, exhibit substantially the same colour. In addition to the reagents noted in the original report, I have found that the photographic developer, amidol, can be used,86 THE ANALYST. but eikonogen and various amido-, hydroxy-, and carboxy-derivatives of benzene and naphthalene were found to be inactive. Sour raw milk still shows the reaction, and even when more advanced decompo- sition has set in, but in the latter case it is less striking. Some experiments were made with a view to determining what ingredient in the milk causes the reaction. The temperature-about 175" F.-which destroys the effect is about that at which enzymes lose their activity. Various commercial enzymes, malt-diastase, taka-diastase, peptenzyme, pancreatic extract, papaw ferment, pine-apple ferment, and rennet ferment were used without effect. Solutions of blood- and egg-albumin also gave negative results. A sample of raw milk was treated with excess of magnesium sulphate, and the precipitate filtered off. The filtrate gave a deep blue colour with the 1 : 4 diamidobenzene, and a red tint with amidol, but no effect with the other reagents. A freshly-opened sample of Eagle condensed milk gave no colour. A piece of cheese rubbed up with water also failed to give the reaction. A solution of the diamidobenzene, after standing an hour or more, gives a slight blue colour with milk, boiled as well as raw, without the addition of hydrogen dioxide, consequently the solution for the test must be freshly made.

ISSN:0003-2654    

DOI:10.1039/AN898230085b

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

86 THE ANALYST. COPPER l C PURE FOR ANALYSIS.” BY JAMES W. WESTMORELAND, F.I.C., Associate of the Royul School of Miizes, London. (Read at the Meeting, February 2 , 1898.) SOME time ago circumstances which need not be detailed led me to examine a sample of copper-€oil, pure for analysis,” which had been obtained from a firm of wholesale chemists. The metal also contained *02 per cent. of lead, and some arsenic, but was not further examined. Later I called on the sellers, and found that their representative was by no means ready to admit the impurity of the metal; he stated that it had been supplied to many analysts, but none except myself had complained of the quality. Assuming this copper to be pure, and using it for standardizing volumetric solutions, it is evident that concordant yet very erroneous results might be obtained.For example, in testing material containing 5 per cent. of copper, the results would be 0.035 per cent. too high, with 70 per cent. material 049 per cent. too high, while metal con- taining over 99.3 per cent. would apparently contain over 100 per cent. copper. I next obtained some (‘ pure copper-foil ” from another dealer after requesting the assistant to be careful and give me the pure material. He pointed out the beautifully-planished surface of the metal as a guarantee of its purity, stating that such care would not be taken with ordinary copper-foil. The metal was well’ planished, but, as in many other cases, the outward appearance was no guarantee of inward purity. It is just possible that the vendor heard indirectly the result of this test, for mother sample purchased later was practically pure.I found it to contain copper, 99.30 per cent. It contained copper 99.10 per cent.THE ANALYST. 87 Another firm stated that their pure copper-foil was not electrolytic copper, but was probably nearly as pure, and this turned out to be the case. From another firm samples were obtained marked ‘‘ Copper-foil Opt,” which contained copper 99-81 per cent., and a sample of “ electrolytic copper,” prepared from purified sulphate of copper, which I have taken as one of my standard samples. From another London dealer I obtained some copper marked “Free from Arsenic ;” this is a specific1 statement of quality, but on examination I found the metal to contain : Copper ...... ... ... 99-23 per cent. Arsenic ... ... ... ... 0.67 ,, The following samples were obtained from a city in the North of Englend, marked Copper, pure for Analyses ” : ... ... ... ... 99-29 per cent. ... ... ... ... 99-64 ,, ... ... ... ... 99.87 ,, ... ... ... ... 99.03 per cent. ... ... ... ... 99.85 ,, ... ... ... ... 99.52 ,, ... ... ... .._ 99.65 ,, (4 Copper ( b ) ) 7 (4 7 7 (4 Copper ( e ) 7 8 (f> 2, (9) ), ( h ) 7 7 ... ... ... ... pure. 0 t her provincial samples gave Another sample, described I ‘ as pure as it is made,” contained copper 99.38 per cent, Another sample, marked ‘‘ Free from Arsenic,” contained copper 99.60 per cent., but was not further examined. I also obtained samples of metal which is sold as “ high conductivity copper,” and obtained the following results : (4 Copper ...... ... ... 99-86 per cent. ( b ) 9 ’ (4 9 7 ... ... ... ... 99.83 ,, ... ... ... ... 99.84 ,, I ’have used the electrolytic and iodide methods for determining the percentage of copper in the various samples. I t is evident that although samples which give 100 per cent. by the electrolytic test may possibly not be pure, samples which give lower results, say 99.5 per cent., cannot possibly be pure. The samples stated to be ‘‘ pure ” gave practically 100 per cent. by electrolytic test, and gave results agreeing within the error of experiment when used for standardizing thiosulphate solutions for the iodide test, in conjunction with copper obtained by the electrolysis of a solution of the pure sulphate, and of another sample of extremely pure copper, of which I obtained some quantity.Some of the impure samples were also used in this way (taking the percentage found by the electrolytic test)--and gave results agreeing within the limits of experimental error. ADDENDUM. Since my paper was read I have obtained two more samples of “electrolytic copper foil,” pure for analysis, from a London firm, whichcontained 99.00 and 99.09 per cent. of copper respectively.88 THE ANALYST. I have also obtained a sample of (‘ pure copper foil ” from a provincial dealer, which gave the following extraordinary results on analysis : Copper ... ... ... ... 94.42 Lead ... ... ... ... ... 0.39 Zinc ... ... ... ... ... 4.91 Iron ... ... ... ... ... 0.26 Arsenic traces ... ... ... ... 99 *98 I submitted a sample of this metal to a firm of London metal workers, who informed me that it was ‘‘pure Bright rolled copper.” The vendor, in answer to inquiries, stated that the metal was obtained some time ago from a London dealer, and that it was marked ‘‘ Electrolytic copper foil-pure for analysis-free from arsenic.” DISCUSSION. Mr. BLOUNT said that copper was a substance pre-eminently easy to obtain in a state of purity almost absolute. Nevertheless, the figures obtained by Mr. West- moreland showed a condition very far removed from purity. At the same time, although this indictment lay against copper sold as (‘ pure for analysis,” he could not help thinking that Mr. Westmoreland must have been a little unfortunate in his samples. Copper containing 99.1 or 99.3 per cent.of actual Cu, and sold as pure, was surely a somewhat unusual material, when it was considered that ordinary loco- motive firebox copper contained 99& per cent.-that was to say, it was not only specified to contain, but actually did contain, that quantity, and very often considerably more. He thought it would be interesting to know what was the balance of the impurities in each case. For instance, in the first sample referred to in the paper, containing 99.3 per cent., Mr. Westmoreland had found some arsenic, but had not said how much, or of what the balance consisted. Beside the arsenic, there was presumably something else. The percentage of arsenic found in the sample sold as ‘‘ free from arsenic,” viz., 0.67, was enormous in a refined tough copper, but even in this case a balance of 0.1 per cent.remained unaccounted for. I t seemed curious that so many of these arsenical coppers consisted mainly of copper and arsenic, being tolerably free from other impurities. Ordinary tough-pitch copper, containing 99.5 per cent. of actual Cu, and perhaps 0.2 per cent. of lead, would contain possibly 0.15 per cent. of arsenic, At the other end of the scale there might be 0.4 of arsenic, with 99.5 per cent. of Cu, all the other impurities being included in the remaining 0.1. It was just conceivable that some of the samples examined by Mr. Westmoreland were refined but not toughened coppers, and in such case they might very well have been free from most impurities save oxygen, It was impossible, however, to roll into foil copper containing much oxygen, so it seemed fair to assume that foil was not ‘( refined ” as distinct from ‘‘ tough-pitch.” The largest quantity of oxygen that could be contained by copper-foil would be about 0.15 or 0.2 per cent., so that the balance left from this and the actual Cu found by Mr.Westmoreland would probably be lead, arsenic, nickel (a common impurity in commercial copper), and the other odds and ends of things generally found. Touching the question of analysis, it was clearlyTHE; ANALYST. 89 evident that to obtain reliable results one must either be prepared to isolate the whole of the copper (and he knew of no process of doing this with any degree of accuracy except electrolysis), or one must have a standard for coinparison which was unexcep- tionable.He gathered that Mr. Westmoreland had followed both modes of pro- cedure, and in that case his figures would be gratefully received. He might mention, however, that in the electrolytic method it was necessary, in order to avoid serious errors, to isolate the copper as nearly as possible from a large quantity, e.g., 10 gramnies of the sample, and then to determine the residual copper in the solution. Mr. WESTMORELAND said in reply that, with the exception of one sample of electrolytic copper prepared from the pure sulphate and the three samples of L c high conductivity ” copper wire, all the samples were copper-foil. The samples were obtained from practically every dealer in the United Kingdom. His (Mr. Westmore- land’s) primary object was to obtain pure copper for standardizing volumetric solu- tions; consequently he had not troubled in most cases to further examine samples when he found they were impure. The absence of other impurities in arsenical coppers containing, as Mr. Blount suggested, 99.5 per cent. of copper and 0.4 per cent. of arsenic, may be explained on the assuniption that they are produced from very arsenical blister copper, and that, consequently, the other impurities present are eliminated before the arsenic is reduced to an allowable percentage. E e (Mr. West- moreland) had many years ago pointed out the necessity of determining the residual copper in the solutions from electrolytic assays.

ISSN:0003-2654    

DOI:10.1039/AN8982300086

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE; ANALYST. 89 THE COMPOSITION OF MILK AND MILK PRODUCTS. BY H. DROOP RICHMOPU'D. (Read at the Jfeeti?zy, Mamh 16, 1598.) OF the 35,007 samples analysed during 1897 in the hylesbury Dairy Company's laboratory, 25,762 were samples of milk. The average composition of 12,907 of these, taken on arrival of the inilk from the farms at the depots, is given in Table I. TABLE I.-AVERAGE COMPOSITION OF MILK DURING 1897. January ... February ... March ... April ... June ... August . . . September . . . October ... November ... December ... May ... July ... Average ... Solids- Specific Total Gravity. Solids. Fat. not- Fat. 1-0327 1,0326 1.0325 1.0325 1.0328 1.0325 1.0318 1.0315 1.0321 1.0324 1.0324 1.0325 12-75 3-69 9.06 12.65 3-63 9-02 12.59 3-60 8.99 12.54 3.58 8.96 12.38 3.38 9.00 12-29 3.37 8-92 12.32 3.53 8.79 12.42 3.67 8.75 12.59 3.68 8.91 12.59 3-62 8.97 12.68 3.70 8.98 12-75 3-74 9.01 1-0324 12.54 3-60 8-94 EVENISG MILK.Solids- Specific Total Gravity. Solids. not- Fat. 1.0326 1.0325 1.0324 1.0323 1.0324 1.031.9 1.0314 1.0311 1.0316 1.0321 1.0320 1.0324 1.0320 13.16 1304 12.96 12 93 12-92 12.81 12.68 12.81 13-05 13.04 13.20 13-17 4.07 9.09 3-99 9.05 3-95 9-01 3.93 9.00 3-91 9.01 3.91 8-90 3-92 8-76 4.07 8-74 4.17 8.88 4.06 8-98 4.22 8-98 4.15 9-02 12-98 4.03 8.95 AVERAGE. Specific Gravity. 1.0327 1.0325, 1.0324 1.0324 1-0325 1.0322 1.0316 1.0313 1,0319 1.0323 1-0822 1-0323 Total Solids. 12-95 12.85 12-78 12-73 12-65 12-55 12.50 12.61 12-82 12-81 12.94 12.96 Solids- Fat. not- Fat. 3.88 9'07 3-82 9.03 3-78 9-00 3-75 8.98 3.65 9-00 3-64 8-91 3.73 8-75' 3-87 8.74 3.93 8.89 3.84 8.97 3.96 8.98 3.95 9.01 1.0322 12.76 3.82 8.9490 THE ANALYST.It is seen that the composition differs but very slightly from that found in 1896. As usual, the lowest fat was found in June, and the highest during the latter months of the year, and a marked depression of solids-not-fat was noticed in July and August. The methods used in 1896 have been employed without any modification ; in the few cases where the solids-not-fat fell below 8.5 per cent., milk-sugar, protaids, and ash have been determined. The following samples are the only ones showing any abnormality, and were passed as genuine, though not authenticated : I. 11. 111. Specific gravity ... 1.0294 ... 1.0288 ... 1:0355 Total solids ... 12-63 ... 12.34 .._ 13-63 Fat ...... ... 4.35 ... 4.20 ... 3.80 Sugar ... ... 4.14 ... 4-13 ... 4-67 Proteids ... ... 3-38 ... 3-29 ... 4-35 Ash ... ... 0.76 ... 0-71 ... 0.77 Solids-not-fat 8-28 8.14 ... 9.83 ... ... I have looked through the results of analyses for many years past, and have compiled the following table of the probable number of samples which will be found per 100, having solids-not-fat between the limits named. These figures only refer to the mixed milk of herds : Percentage of Solid s-not-Fat. 8-4 .to 8.5 8.3 ,, 8.4 8.2 ,, 8-3 8.1 ,, 8.2 8.0 f , 8.1 Below 8.0 ... ... ... ... ... Probable Number per 100. ... 1.092 ... 0.242 *.. 0.02'7 ... 0.022 ... 0.008 0.002 I t is seen that the proportion of samples appreciably below 8.5 per cent. i.4 excessively small ; the bulk of these occur during the months of July and August.I am not in possession of sufficient data to say definitely that the few genuine samples with solids-not-fat below 8 5 per cent. can be distinguished from adulterated milks ; but the whole of the samples low in solids-not-fat that I have examined, with whose genuineness I am satisfied (forty-six in all), have had an ash above 0.70 per cent., and nitrogen above 0.50 per cent. On the other hand, all samples to which I have added water have been below those limits, as well as below 895 per cent. of solids- not-f at. I would urge on public analysts the importance of determining the ash and proteids (or nitrogen) on every saniple which, from their preliminary results, they consider suspicious. The preparation of ether for milk analysis has received some attention; the occurrence in commercial ether of an acrid substance, which appears to be obstinately retained by fat, has probably been noticed by all.My first attempts at removing this were by distillation from oil, with a fair amount of success; I have, however, found that by distillation of the ether on a water-bath not exceeding 40" in temperature, from a flask fitted with Glynsky's bulbs, a product is obtained which is eminently satisfactory ; the last fraction (B.P. 34.6" to 34.8") can be used for thermo-regulatorsTHE ANALYST. 91 for incubators, as at 37" to 38" it has a vapour tension of about 24- inches of mercury above atmospheric pressure. I n the analysia of cream and clotted cream amyl alcohol has been substituted for ether to dissolve the f a t ; in this menstruum fat is easily soluble while hot, though it largely deposits on cooling; the other constituents of milk are almost insoluble. A series of comparative experiments showed that no appreciable difference was found between ether and amyl alcohol.Amyl alcohol is readily volatile at 100" in a current of air. The method used is as follows : 4 grammes of cream are weighed into a large platinum dish and evaporated in the water-oven ; after about one hour the solids-not- fat become adherent to the basin, and by inclining it the fat runs away to the lower portion, and the solids-not-fat are left comparatively free from fat. Under these circumstances drying is complete in about five to six hours. To extract the fat 25 C.C.of amyl alcohol are poured on, and the basin placed for a short time in the water- oven ; the amyl alcohol is then carefully decanted ; the solution of fat can be separated without loss of solids-not-fat if attention be paid to the slow decantation. This process is repeated about eight or nine times, the basin being usually allowed to stand overnight between the fourth and fifth treatments. The following experiment will show the results obtained with ether and amyl alcohol : Weight Weight after Four at 100". Hours' Drying. Weight Taken, after Drying Washings and Three Ether 3.9985 ... 2.898 ... 0.246 Amyl alcohol 3.998 ... 2.894 ... 0,2405 Amyl alcohoi ,.. 0.239 . . Weight after Four more Washings and Three Hours' Drying. ... 0.2385 Ether 0.240 ...Weight after Four more Washings and Three Hours' Drying. 0.238 The solids-not-fat are then dried for about three hours at 100" C. and weighed, the fat being found by difference. Determination of the fat by the Werner-Schmid or Leffmann-Beam methods gives results agreeing within the limits of experimental error : Fat bv Difference. 30.60 57-16 51.78 56.73 The solids-not-fat centage df ash. Werner - Schmid. Leff mann-Beam. ... 50.58 ... 50.14 ... 57.20 .. left in the basin on incineration at dull redness give the per- Clotted cream analysed by the method given above yielded the following results : Maximum. Minimum. Average. Total solids ... ... 75.50 ... 55.16 ... 66.64 Fat ... ... ... 67.69 ... 44-29 ... 58-22 Ash ... ... ... 1.11 ... 044 ... 0.70 Solids-not-fat .. ... 11-51 ... 5.68 ... 8.4292 THE ANALYST. The following percentages of water in butter have been found : Maximum. Minimum. Average. English fresh butter . .. 14.64 . . . 11.59 . . . 13.05 ,, salt ,, ... 15.44 ... . 11.50 .. 13.23 French fresh ,, (X) 1'7.82 ... 14-30 ... 15-73 ,, salt ,, . .. 14.84 . . . 9.09 ... 12.73 Danish ,, ,, ... 17.10 ... 8.90 ... 12.58 3 , Y 9 ,, (Y) 16.31 ... 13.08 ... 14.33 Tho English butters were examined within twenty-four hours of churning ; it is seen that there is no appreciable difference between fresh and salt butter. The most notable point is the high percentage of water in French fresh butters; these have been divided into two classes according to the district of origin. Of the X samples no less than 40 per cent.contained above 16 per cent. of water, which has been proposed as a limit, the maximum reaching 17.82, while the average is only just below 16 per cent. Only one sample of series Y contained above 16 per cent. of water, Two samples of Danish salt butter contained above 16 per cent. of water ; on microscopic examination the appearance described by Storch (ANALYST, vol. xxii., p. 197) as '( thick"-ie., the presence of enormous numbers of small water-globules- was noticed. They did not appear at all watery on casual examination, but seemed to be slightly (' overworked "; salt butters containing a lower percentage of water almost invariably look '' wet " if a short period after churning has elapsed. The French fresh butters did not appear '' thick," but had a tendency to break off short, or, in other words, had a low tensile strength. The manufacturers of the X butters have evidently worked out a method for retaining a somewhat large percentage of water, without in any way deteriorating the flavour or keeping qualities; seeing that the same thing occurred in 1895, and to a lesser extent in 1896, I believe I am justified in regarding the extra average per- centage of water (2 per cent.) as an addition.An interesting and difficult question is raised : Is this addition (which may be safely assumed to be commercially successful) to be regarded as an adulteration, seeing that the essential qualities of the butter (flavour, texture, etc.) are not only retained, but manifest themselves in a high degree? I may add that there was no suspicion of adulteration by margarine; the butyro-refractometer results usually fell between 45" and 46" at 35" C., and never appreciably exceeded 46". DISCUSSION. Mr. BEVAN inquired what was regarded as the particular advantage of amyl alcohol over ether in the determination of fat. Unless absolutely pure, it would contain substances boiling at a high temperature, which he doubted very much would be volatile at 100" C., even in a current of air. Mr. L. K. BOSELEY said that it was never suggested that amyl alcohol should be used in a Soxhlet, but merely for extracting the fat from quantities of, say, 100 grammes of butter, the advantage being that it could be boiled in a water-bath without loss. Amy1 alcohol would extract fat much better at a high temperature than ether would at a low one ; and any residual non-volatile substances could be afterwards washed out with ether,

ISSN:0003-2654    

DOI:10.1039/AN8982300089

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST. 93 ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. A Delicate Test for the Detection of a Yellow Azo Dye used for the Artificial Coloring of Fats, etc. J. F. Geisler. (Jozcrn. Anzer. Chem. Soc., 1898, xx., llO-l13.)-By the food laws of several of the American States, the addition of an artificial coloring matter to oleomargarine is forbidden. The author states that azo dyes have now largely replaced annatto ag the coloring substance, and calls attention to the fact that fuller’s earth gives a pink or red colour, with at least one, if fiat more, of these dyes. The dye can be precipitated from the clarified fat by the earth as a violet-red precipitate, which, when washed with naphtha to remove the fat, and dried, leaves a violet-red powder.This is immediately decolorized on contact with alcohol, the colour reappearing on evaporation of the latter. The coloring matter can be extracted with boiling alcohol, and as thus obtained is insoluble in cold and sparingly soluble in hot water. It dissolves in concentrated sulphuric acid with a yellow colour, which changes to red on the addition of water. Other strong mineral acids also produce a, violet or pink colour. In the latter particular it behaves like methyl orange, which, however, when pure does not give the fuller’s earth reaction. The reaction, with the help of the microscope, is exceedingly sensitive ; and whilst 14 grains of the coloring m&tter per ton of fat give a barely perceptible faint yellow tint, a strong pink tint is obtained on spreading $ gramme of the sample 011 a porcelain slab, and adding fuller’s earth. When the fat is dissolved in naphtha, and the earth added to the solution, the pink appears as a zone at the edge of the deposited reagent.I t is stated that commercially the yellow azo dye is used in combination with an orange dye, and that the latter does not give this reaction. C. A. M. The Determination of Antipyrine and of Iodine. J. Bougault. (Jozwn. Pharnz. Chim., 1898, vii., 161-163.)-0ne gramme of antipyrine combines quantita- tively with 1.351 gramme of iodine, and on this fact the author bases the following method of estimating these bodies by means of one another. To 20 C.C. of a solution of 1 gramme of antipyrine in 100 C.C. of 95 per cent. alcohol are added 20 C.C.of an alcoholic solution of mercuric chloride (2-5 grammes in 100 c.c.), and the solution of iodine (1.351 gramme in 100 C.C. alcohol) run in until the liquid becomes faintly yellow. The determination of iodine by means of a solution of antipyrine is made in a similar manner. The reaction is instantaneous, and antipyrine has the advantages over thiosulphate of readily being obtained in a pure and dry state, and of remaining unaltered in solution for an indefinite length of time (cf. ANALYST, xxii., 219). C. A. M.94 THE ANALYST. Opticity of Crystalline Digitalin. A. Petit. (BuZ. gdn. de Thdrap., 1897, ii., 748 ; through Chem. Zeit. Rep., 1898, 36.)-A 2 per cent. solution of absolutely pure crystallized digitalin in 95 per cent. alcohol has an opticity of + 11.6" at 18" C.; a solution of the same strength in chloroform rotates the beam +17.2". Inasmuch as well-crystallized (German) " digitoxin " has the same melting-point and chemical properties, and also exhibits the same rotatory power both in alcoholic and chloro- formic solution, the two bodies are manifestly identical. F. H. L. The Analysis of Liquorice Mass. A. Mellor. (Anze~. Jour. Pharnz., 1898, lxx., 36, 137,)-The following process has been adopted by the manufacturers and large consumers in the United States : Moisture.-Two grammes of the mass are dried in the water-oven until hard. The dry residue is then divided into small pieces and the drying repeated until the weight is constant. MineraZ Matter.-The dried mass is incinerated until the ash is white. Insoluble Substance.-Five grammes are dissolved in 100 C.C.of water, and after twelve hours the sediment is collected on a weighed filter, cold water being used in rinsing out the beaker. A further deposit occurs in the filtrate after another twelve hours, owing to traces of starch passing through the filter. This is collected on a second weighed filter. Gummy Matter.-Five grammes are dissolved in 50 c.c of boiling water and 100 C.C. of 95 per cent. alcohol added. The liquid is well stirred, and after standing all night the precipitate is collected on a weighed and dried filter and washed with alcohol (95 per cent.) 2 parts, and water 1 part, until the filtrate is colorless. The residue, dried in the water-oven, gives the combined weight of insoluble substances and gummy matter. GZycyrrhixin.-The alcoholic filtrate from the above is concentrated to a volume of 30 C.C. and transferred to a weighed beaker with the help of about 20 C.C. of water. The glycyrrhizin is precipitated by adding dilute sulphuric acid (12 drops of strong acid to 5 C.C. of water) with constant stirring. After standing all night, the liquid is poured off through a filter and the glycyrrhizin washed three times with ice-cold water, which is decanted each time. After adding 1 drop of concentrated ammonia- water to neutralize any acid, the beaker is dried in the water-oven to constant weight. Saccharke Matter.-The liquid decanted from the precipitated glycyrrhizin is neutralized with barium hydrate, the barium sulphate separated by filtration, and the amount of saccharine matter in the filtrate determined with Fehling's solution. Extractive Szibstance.-This is taken as the difference between 100 and the other constituents determined as above. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300093

出版商:RSC    

年代:1898

数据来源: RSC

摘要:

THE ANALYST 95 ORGANIC ANALYSIS. A Volumetric and Gas-volumetric method for the Determination of Hydroxylamine and Hydrazine. I(. A. Hofmann and F. KGspert. (Berichte, 1898 xxxi. 64-67.)-This is based on the oxidation of hydroxylamine or hydrazine, with a dilute solution of a vanadium salt in sulphuric acid the nitrogen evolved being collected and measured and the partially-reduced solution titrated back with per-m anganate . I. 2NH,O + 0 = N + 3H20. 11. N2H + 2 0 = N + 2H,O. Should other reducing substances be present a deduction is made based upon the amount of nitrogen calculated to hydroxylamine or hydrazine. The vanadium solution is prepared by dissolving 5 grammes of ammonium meta-vanadate in 50 C.C. of sulphuric acid kept cool and diluting to 1 litre. The substance to be analysed is dissolved in dilute sulphuric acid and the vanadium solution added slowly until a green coloration results.The nitrogen evolved at the ordinary temperature is collected which requires about twenty minutes. The flask is then warmed at about 60" C. for a few minutes at the end of wbich the green colour should still remain and finally the solution is transferred to a porcelain dish and titrated with standard permanganate until there is a permanent rose tint. The following results were obtained with hydrazine sulphate (15 grammes in 1,000 c.c.). The permanganate solution used contained 1.794 grammes of available oxygen per litre. Hydrazine Vanadium Permanganate. Oxygen Nitrogen at 0" C. Solution. Solution. consumed. and 760 mm. c. c. c. c.C.C. C.C. 10 50 20.51 0.03680 10 50 20.23 0.03630 10 50 20.20 0-03624 10 50 19.97 0,03583 19.85 = 22-09 per cent. The calculated amount of nitrogen =21*58 per cent. and the results were therefore in accordance with the equation N,H6S04 + 2 0 = N + 2H,O + H,S04. The results obtained with hydroxylamine sulphate hydroxylamine nitrate and hydrazine mercury sulphate showed a similar agreement with those required by theory. C. A. M. The Estimation of Phenylhydrazine. H. Causse. (BzLZZ. xoc. Chiin, 1898, xix. 147-149.)-This is based on ths fact that arsenic acid oxidizes phenylhydrazine, liberating nitrogen and leaving pheno€ and that a corresponding quantity of the arsenic acid is reduced to arsenious acid. As,O + C,H,N = N + H20 + C6H,0 + AS,^,. The reaction is quantitative in an acetic acid solution and the arsenious acid produced may be estimated either by titrating the standard arsenic acid solution with uranium before and after the reaction so as to obtainithe amount not reduced or by titrating the arsenious acid produced with iodine in the presence of sodium bicar-bonate (As,O + 21 + 2H,O = 4HI + As,O,) 96 THE ANALYST.About 0.20 gramme of phenylhydrazine or preferably of its hydrochloride are heated gently under a reflux condenser with 60 C.C. of an arsenic acid solution prepared by dissolving on the water-bath 125 grammes of arsenic acid in a mixture of 450 C.C. of water and 150 grammes of concentrated hydrochloric acid filtering when cold and making up to a litre with glacial acetic acid. When the bubbles of gas have ceased the liquid is boiled for about forty minutes and allowed to cool.After the addition of 200 C.C. of water a solution of caustic soda (free from sulphides) is added until the liquid is just alkaline. Hydrochloric acid is then added to acid reaction and when cold 60 C.C. of a cold saturated solution of sodium bicarbonate are added and the liquid titrated with decinormal iodine. If V be 'the volunie of iodine solution required the quantity of phenylhydrazine is obtained from the formula V x 00495 x 0.5454. The results given by the author agree well with theory and it is stated that the method is equally applicable to the analysis of compounds of aldehydes and phenyl-hydraxine although if the aldehyde belong to the fatty series it should be eliminated on account of its action on the arsenic acid; if however it belong to the aromatic series its presence is without effect and the estimation can be made on the compound itself.C. A. M. Examination of Wax with the Refractometer. J. Werder. (Clzenz. Zeit., 1898 xxii. 38 and 59.)-The author finds that the Zeiss butter refractometer may advantageously be employed in the examination of different kinds of wax especially whea the amount of material at disposal is very limited and that the indications obtained with it are quite as valuable as in the case of oils and fats. Owing to the high melting-point of the wax it is necessary to work at a higher temperature than usual preferably 66" to 72" C. and then to reduce the results to the normal tempera-ture 40" C. As shown in the annexed table the figures given by genuine beeswax vary from 42%" to 45*4" the great majorityof specimens falling between 44" and 45"; and it seems to make little or no difference to the refractive power whether they are tested before or after bleaching.Samples 19 to 24 had previously been examined chemically and had been rejected on the ground of their abnormal acid and ester numbers which were as follows : Number of Sample. Acid Yumber. Ester Number. 19 . 18.48 . 66.64 20 . 127.1 . 13-4 21 . 59.08 . 3.36 22 . 1045' . 14.3 23 . 41.0 . 57-0 24 . 106.9 " 48.1 No. 24 is a product called "glanzwachs," obtained by adding some of the mixture of stearic and palmitic acids as used in the manufacture of stearin eandles (No. 28) to a genuine wax this being a form of adulteration commonly employed in Switzerland THE ANALYST.97 REFRACTIVE POWER OF DIFFERENT KINDS OF WAX. Temperature of Refraction at Observation. 40" C. Sample. 1. Bleached from Egypt . . . 66.0 . 44.1 2. 1 1 , Turkey . . . 67.0 . 44-8 3. ,? , Moldavia . . 66.5 . 44.2 4. Yellow ) Egypt . . . 66.0 . 42.8 5. 3 9 , Monte Christ0 . . 71.0 . 44.8 6. 9 1 , France . . . 67.5 . 44.1 7. 1 ,) Savoy . . . 67.0 . 42.6 8. 91 ? California . L 69-5 45.2 ) ) North Bfrica . . 71.0 . 45.0 9. 9 , 10. 9 ) , Massowah . . . 71-5 . 44.3 70.0 . 44.9 70.0 . 44.0 68.5 . 44.6 69.5 , 44.2 $ 9 9 45 3 11. ) ) Y ) Italy 12. 7 , 13. 1 9 $ 9 14. , $ 9 Mexico}different samples { 67.0 . 15- 9 16. ) ? , Syria . . . 69.5 . 44-2 17. 9 7 , Casablanca _ .. 68.0 . 45.4 18. ,? , Smyrna . . . 70.0 . 44.7 19. Bleached in chips (professedly genuine) . 70.5 . 41.3 20. White Church candles . 67.5 32.0 21. . 68.0 32.5 22. 3 9 7 68.5 82-6 23. Yellow wax source unknown . . 66.0 . 38.3 24. Wax adulterated with No. 28 . . 65.5 . 38.8 25. Paraffin . . . . 65.0 22.5 26.- Ceresin . . . . . 77.0 . 41-0 27. Tallow . . I . . _ . 71.5 . 48.5 28. Stearin candle material . . . 70.0 . 30.0 29. Carnauba wax . . . . 91.0 . 66.0 30. Japan was . . . . . 71.0 . 47-0 . . ) ? 1 different samples . . 7 , 9 9 . . . . . F. H. L. On the Estimation of Unsaturated Fatty Acids. E. Twitchell. (Jour. SOC. Chena. Ind. 1897 1002-1004.)-The author bases a method for separating satura;t;ed from unsaturated fatty acids on the fact that the latter combine (in all probability quantitatively) with sulphuric acid forming addition compounds which are insoluble in petroleum spirit.As it was found that the saturated acids could not be extracted from a concentrated sulphnric acid solution by petroleum spirit and that the addition of water decomposed the sulpho-fatty acids experiments were made with sulphuric acid previously diluted and eventually 85 per cent. was fixed upon as the most satisfactory strength. The method of separation tentatively adopted is as follows From 0.5 to 1 gramme of the fatty acids are melted in a stoppered Erlenmeyer flask the flask chilled in ice-water 3 C.C. of 85 per cent. sulphuric acid added and the ternpersture allowed to rise. As soon as the action commences a clear solution is rapidly obtained, and the flask is again cooled.Fifty C.C. of petroleum spirit are then introduced th 98 THE ANALYST, flask well shaken the petroleum spirit decanted into a separator-funnel the flask rinsed out twice with 10 C.C. of petroleum spirit and the total extract washed with water the solvent evaporated and the residue consisting of saturated fatty acids, dried and weighed. Crude oleic acid solidifying at 12" C. when examined in this way gave a crystalline residue melting at 37" C. and the following results were obtained with the fatty acids from three different samples of oil : Origin of Fatty Acids, Lard . . Cotton-seed-oil . . . Ditto . . Solidifying Point, O c. 40.75 30.89 31.90 Amount used. Gramme. 0.7815 0.6150 0.5875 Petroleum Spirit Extract per cent.42-35 32-60 23.91 Melting-point of Saturated Acids "C. 53-5 53.0 . From the melting-points of the residues being somewhat low the author did not consider the saturated acids thus obtained qui,te pure although the impurity must have been slight. A second extraction of the sulphuric acid solution of the cotton-seed-oil fatty acids with 50 C.C. of ether yielded 0.019 gramme of residue which did not solidify at the ordinary temperature such residue being attributed to the dtlcomposition of a small amount of sulphostearic acid. The petroleum spirit used must first be tested to see whether any non-volatile substances are produced by treatment with sulphuric acid. If so it can be purified by being digested for an hour at 100" C.with about half its weight of concentrated sulphuric acid and then washed and distilled. C. A. M. Estimation of Phenol in Disinfectants in Presence of Soap. W. Spalteholz. (Chem. Zeit, 1898 xxii. 58.)-In the examination of neutral disinfectants such as creolin lysol and '( soluble cresol," where the phenols are not in a state of combina-tion there is no necessity to add any acid before distillation as recommended by Fresenius and Makin (ANALYST xxi. 301) since calcium phenolates are readily de-composed when heated in aqueous solutions. The sample is placed in an iron retort and distilled in a current of steam between 200" and 220" C. until the distillate no longer yields any oily matter. Bodies which contain soaps of oleic acid must not be heated above 210" lest the latter are decomposed ; but should 'this happen it will at once be rendered apparent by the presence of a layer of oil floating on the top of the water in the receiver.Alkali-rosin soaps easily resist a temperature of 220". The distillate consists of phenols alone in the case of lysol ; of phenols and tar hydro-carbons in the case of creolin mixed with the water ; and the simplest way of separating them is to extract the whole with benzene remove the aqueous portion and estimate the phenols themBelves with caustic soda. (Koppeschaar's process is not adapted for the analysis of mixed phenols of unknown composition.) Tried on a number of known products the author's method has given results usually 0.5 per cent. but occasionally 1.0 per cent.below the theoretical ; and it is therefore quite accurate enough for ordinary work THE ANALYST. 99 Lysol and ‘‘ soluble cresol” contain between 50 and 60 per cent. of phenols ; creolin from 0 to 28 per cent, although samples which emulsify well with water seldom have more than 18 per cent. The relative values of the two materials how-ever cannot be judged merely by the proportion of phenols found in them for if a creolin gives an oily precipitate on dilution with water that portion of the substance is wasted ; while on the other hand the neutral hydrocarbons present also exhibit distinct germicidal properties. F. H. L. A Reaction distinguishing between Creosotes and Guaiacols. H. Fonzes-Diacon. (BUZZ. SOC. Chim. 1898 xix. 191 192.)-A small quantity of the sample is dissolved in water 2 or 3 C.C.of a solution of copper sulphate (about 4 per cent.) added and 1 or 2 C.C. of a 4 per cent. solution of potassium cyanide. An immediate striated precipitate is produced which viewed by transmitted light is emerald-green in the case of creosote grayish-red with poor guaiacol and maroon-purple with rich guaiacol. I n this way it is possible to determine whether a product is a creosote containing 12 to 25 per cent., a guaiacol containing 65 to 70 per cent, or a guaiacol with 85 to 90 per cent. of crystallizable guaiacol without having recourse to a colour scale of typical solutions The emerald-green colour changes rapidly to yellow. in Adrian’s colorimetric method (ANALYST xxii. 162). C. A. M. Detection of Halogens in Organic Compounds.P. N. Raikow. (Chem. Zeit. 1598 xxii. 20.)-Some ten years ago Giinzburg recommended the use of an alcoholic solution of phloroglucinol and vanillin to detect free hydrochloric acid in the gastric juice; for the reagent gives an intense permanent red colour on warming therewith although it is unaffected by organic acids. If the same solution is heated with an organic body containing a halogen only in a few cases is the red colour pro-duced. If the substance is liquid and combustible it may be mixed with a few drops of the phloroglucinol-vanillin solution in a flat porcelain basin and the alcohol ignited. As the spirit burns away the red colour usually develops; but to render the test uni-versally applicable it is better to operate as follows A piece of porcelain is moistened with the reagent the solvent allowed to evaporate and the dried film (which is now colorless) is held over the flame of a spirit-lamp into which the suspected substance is introduced on the end of a platinum wire The test is roughly quantitative for according to the amount of halogen present more or less of the surface is turned red.If the organic substance is an inflammable gas it may be set light to and the porcelain dish held over the flame. F. H. L. Estimation of Carbon and Oxygen in Organic Bodies by Moist Combustion. J. K Phelps. Oxidation of Carbon with Potassium Permanganate.-Many organic substances are completely oxidized on warming with sulphuric acid and permanganate so that t;he evolved carbon dioxide may be absorbed in barium hydroxide and determined with iodine and arsenious acid as previously mentioned (ANALYST xxii.55). The apparatus consists of a wide-necked 75 C.C. flask fitted with a stoppered funnel and leading-tube for the gas the latter being expanded into a bulb immediately over the (Zeds. anorg. Chem. 1898 xvi. 85. I00 THE ANALYST. cork ; and a condensing-flask of 250 C.C. capacity provided with an inlet tube reaching to the bottom and an outlet closed by a screw clamp The two corks are of rubber, and so long as they do not come in contact with the liquids they willnot be attacked. The subatance is rinsed into the small flask with 10 or 15 C.C. of water ; 3 or 5 C.C. more of standardized caustic baryta solution than is necessary to absorb all the gas is introduced into the larger vessel the pressure reduced by means of a pump to 200 or 225 mm.the organic solution warmed excess of perrnanganate run in through the tube funnel and finally 10 C.C. of 1 4 sulphuric acid. The mixture is boiled for five minutes care being taken to maintain some vacuum while the receiver is well shaken and kept cold in a basin of water; pure air is then allowed to enter through the funnel to restore the atmospheric pressure and to drive the last traces of carbon dioxide into the baryta. The cork of the large flask is removed tha tubes washed another rubber cork carrying a funnel and a set of nitrogen bulbs put in its place; the liquid is heated decinormal iodine added till it becomes permanently red then cooled again and the excess of iodine titrated with decinormal arsenious acid.The permanganate solution should be boiled with sulphuric acid until all GO, is driven off; the water and acid must also be boiled till free from the gas. 0x;altltie~ may be decoinposed very smoothly in this way ; but in the case of formates and tartrates more than sufficient pure caustic soda (not ammonia) should be added a t first to neutralize the acid in the permangqtnate and then after the whole has been raised to the boil an excess of dilute sulphuric acid run in as before. The process was checked on ammonium oxalate barium formate and tartar emetic ; the figures show an average error of about 0.2 milligramme in estimating 0.15 to 0.6 gramme of GO,. Oxidation of Carbon with Clwonzic Acid.-Although a concentrated mixture of chromic and sulphuric acids is a much more powerful oxidizing agent than potassium permanganate there are many organic substances as Cross Higgin and Bevan have pointed out which yield some carbon monoxide on treatment therewith.The following arrangement ensures complete oxidation with-out the necessity for passing the gases over red-hot copper oxide The construction of the apparatus is explained by the annexed cut. The large flask is made of thick glass and holds 1 litre; the cone in the neck is of platinum and serves to protect the rubber cork from splashes when the vessel is shaken. The separating funnel holds 100 c.c.; the stopcock is well ground in, and moistened with strong metaphosphoric acid. The condensing flask holds 500 C.C. The substance to be analysed is weighed into a thin glass bulb the aperture thereof sealed the bulb dropped into the large flask and an excess of pure potassium bichromate added.A suitable amount of caustic baryta solution is poured into the condenser the apparatus put together 10 C.C. of pure sulphuric acid introduced into the generator and both flasks are boiled till about 2 or 3 C.C. of water have been evaporated from each and a vacuum is produced. The flames are removed the two clamps shut the little bulb is broken by a jerk and 20 C.C. of stron THE ANALYST. I01 sulphuric acid (previously freed from organic matter by heating with a few crystals of bichromate) run in through the funnel; The flask is well shaken heated to about 105” C. (the maximum temperature permissible if loss of oxygen is to be avoided), water added to dissolve the chromic acid crystals and the whole is again boiled (without allowing the pressure to exceed that of the atmosphere) for five minutes with constant agitation.By this time any CO will be oxidized; 60 or 70 C.C. of water are introduced the clamp between the two flasks is opened and the carbon dioxide is permitted to pass into the condenser which is kept cold and shaken as before. The contents of the generator are once more heated to the boil and a steady current of pure air is passed through the apparatus for fifteen minutes. Finally the CO is estimated in the manner already given. Estimation of Oxygen. -In the above process if a known amount of pure bichromate is employed and the excess of chromic acid remaining unreduced after the operation is determined it is evident that the quantity of oxygen required to burn the carbon may be calculated ; and from the total GO recovered by a simple sub-traction the oxygen in the original body may be deduced.The only special precaution necessary is that the sulphuric acid shall not become too strong lest it begin to act on the bichromate causing the evolution of oxygen instead of chlorine in the second distillation. Twenty C.C. of sulphuric acid are used in the C estimation, and the boiling is allowed to proceed-quietly. The volume of water added in the final dilution should be adjusted so as to leave 60 or 80 C.C. in the flask when the CO, has been driven off. This liquid is brought into a Voit flask connected wikh a Drexel washing apparatus containing an excess of sodium arsenite of known strength and a, set of nitrogen bulbs filled with dilute caustic soda.I t is treated with 35 C.C. of HCI (specific gravity 1*2) boiled in a gentle current of CO, which has been washed in a solution of iodine in potassium iodide and then in HI alone until some 30 or 40 C.C. have distilled off. Sometimes red vapours of chromyl chloride are produced during the boiling; but as this substance is reduced by the arsenious acid it is a matter of no consequence to the analysis. The latter liquid is acidified with sulphuric acid, made alkaline with potassium carbonate and titrated with decinormal iodine. The double method (for C and 0) was tested on ammonium oxalate phthalic acid pure sugar paper tartar emetic and barium formate.The results are exemplified in a table they are especially for the carbon eminently satisfactory ; the error in the oxygen determinations varies from 0-0 to 2.1 milligramines in 0.1 to 0.5 gramme. Organic substances which are volatile and yet difficult to oxidize cannot be subjected to this moist combustion ether is easily oxidized to acetic acid but it cannot be completely burnt up ; for although liquid acetic acid is very rapidly attacked by nascent chromic acid yet in the gaseous state (as it exists owing to the conditions of the reaction) it resists oxidation. Similarly naphthalene is not amenable to the author’s process. F. H. L. Separation of Ethylene from Benzene in Gas. E. Harbeck and G. Lunge (Zeits. anorg. Chem. 1898 xvi.26-50.)-1n the ordinary analysis of coal or coke-oven gas it is usual to estimate the “heavy hydrocarbons” by absorption with fuming sulphuric acid or bromine making no distinction between the benzene an 102 THE ANALYST. the ethylene in spite of the fact that these substances are of very different value either for illuminating or heating purposes. The authors have investigated two methods of separating these hydrocarbons the first depending upon the conversion of ethylene into ethane in presence of hydrogen and platinum black the second on the nitration of the benzene. A full description of the preliminary experiments the apparatus necessary and the final calculations is given in the original article ; but it is too lengthy and replete with detail to be properly abstracted; the following cursory account however explains the principles underlying the two processes, Conversion of EthyZene into Et7zaizeL-A U-shaped tube about 10 cm.long and 3 mm. in internal diameter with capillary ends is filled with 0.5 gramme of platinized asbestos ( = 0.11 gramme of Pt) through an aperture in the base which is afterwards sealed up. I t is hung within a glass or metal beaker full of water or copper turnings, according to the temperature at which it is to be employed. A current of pure hydrogen is next passed through it for two hours at 100" C. and two hours in the cold to saturate the platinum black; and the apparatus is then ready for use. I n one sample of the gas to be analysed which must obviously contain an excess of hydrogen the total amount of ethylene and benzene is determined by absorption in fuming sulphuric acid the other constituents being estimated in the usual way.A second sample is freed from oxygen with alkaline pyrogallol and led two or three times over the platinized asbestos at 100" C. The residue is treated with funling sulphuric acid as before which now absorbs the benzene only the difference between the volume taken up before and after condensation thus giving the percentage of ethylene. As I volume of ethylene unites with 1 volume of hydrogen to form 1 volume of ethane the proportion of the former ingredient may be more simply deduced from the contraction; but by operating in this manner it is impossible to determine also the hydrogen and the methane. Unfortunately the process is not available for those many cases in which carbon monoxide is present in the original gas.Diyect Estimation of the Benzene by Nitration.-The sample of gas is passed through a 10-bulbed tube containing a mixture of equal parts by weight of pure strong sulphuric acid and fuming nitric acid (specific gravity 1-52) which converts the benzene into metadinitrobenzene and removes the whole of the ethylene The acid liquor is diluted with ice-cold water neutralized with caustic soda (also in presence of ice) the bulk of the dinitrobenzene collected on a filter-paper (if there be sufficient of it precipitated to be worth filtering) and washed till free from acid. The filtrate and washings are made up to some convenient volume and an aliquot portion is extracted twice with ether.The solvent is distilled off the residue dried in a current of air dissolved in fresh anhydrous ether mixed with the rest of the product the solution filtered again evaporated and the solid matter dried at 70" or 80" C. (or over sulphuric acid in vacuo) and weighed. The precipitate thrown down on neutralization is quite pure and without odour ; that extracted by means of the ether is apt to be contaminated with inononitrobenzene ; but the melting-point of the whole is generally about 86.5" C. (instead of 90" C.). The reaction is perfectly quantitative ; the products formed by the action of the acids on ethylene remain in the aqueous liquid and do not affect the purity of the dinitrobenzene. Nevertheless as the process is somewhat tedious and requires THE ANALYST.103 complicated apparatus it should only be resorted to for specially important analyses as a check on the former method. To convert the weight (N) of dry dinitrobenzene in grammes into the percentage by volume (V) of moist benzene vapour in moist gas at the temperature to and pressure b mm. the following formula may be used s is the proportion of benzene plus ethylene W that of the hydrogen in the original gas and e the tension of aqueous vapour at to C. N(1+ 0*00367t)(100- S) V = 98.50564 x - W(b - 2; e) F. H. L. Use of Lead Carbonate in Analysis. G. Morpurgo. (Giorn. di Farm. di Trieste 1897 ii. 355; through Chem. Zeit. Rep. 1898 19.)-The author recom-mends the use of freshly-precipitated lead carbonate in all cases where the acetate is usually employed e.g.for the removal of coloring-matter acids tannins etc., from complex solutions. The moist carbonate only requires shaking with the liquid, does not dilute it while the minute trace of lead which passes into solution can be easily removed by a small crystal of sodium sulphate. F. H. L. Oil of Basil. J. Dupont and Guerlain. (Bull. Soc. Chim. 1898 xix. 151-154.) -Two essences are known by the name of basil-one collected in the South of France and in Germany having 8 sweet characteristic odour; the other imported from Reunion being marked by a strong smell of camphor which partly masks the characteristic odour. Moreover the former is lmo-rotatory the latter dextro-rotatory. Dumas and Peligot (Ann. Chim. Phys. lvii. 334) extracted from oil of basil a crystalline inodorous product which they considered to be a hydrate of terebenthine CloH,,+3H,0.The authors however have not been able to find any trace of this substance in two samples of the French essence. The French oil examined by them was an oily yellow liquid with a specific gravity of 0.9154 at 15" C. and a rotation in a 100 mm. tube of -7.40". Four-fifths of the oil distilled over between 190" C. and 220" C. and the distillate was further fractionated into two main portions boiling at 195" C. to 200" C. and 205" C. to 215" C. respectively. The former constituting nearly 60 per cent. of the essence was an oily liquid which was identified as linalol (C,,R,,O) by its composition and chemical and physical properties. The fraction boiling at 205" to 215" had the odour chemical and physical characteristics of p-methoxy-allyl-benzene the chief constituent of oil of tarragon.A sample of Reunion oil examined by the authors was also found to contain p-methoxy-allyl-benzene but no linalol a fact confirnied by Bertram and Walbaum (Arch. der Pharnz. February 1897) who found their sample to contain 60 per cent. of that compound and a small quantity of a dextro-rotatory camphor. The results of their analysis of a specimen of German oil showed a close agreement with those obtained by the authors in the case of French oils and confirmed their conclusions as to the presence of linalol in the European essences and of camphor in the Reunion oil. C. A. M 104 THE ANALYST. Solidi-fying point. 22.5 20.5 22.5 18-5 22.5 14-5 27.2 24.3 ~-Examination of Rose-Oil.P. N. Raikow. (Chew,. Zeit. 1898 xxii. 149,)-The present author is unable to corroborate the figures previously quoted (ANALYST, xxiii. 12) as characteristic of true rose-oil and he does not consider Dietze's specifi-cation of much value. The samples are undoubtedly genuine many of them having been extracted by himself from different varieties of the plants cultivated in different parts of the rose-growing districts. Nos. 1 2 and. 3 are mixed oils made from red and white roses (as it is the custom to do with marketable specimens); 4 is from red roses alone (22. centi-folin) ; 5 from inferior. kinds of red flowers ; 6 and 7 are the favourite and expensive '' green rose-oils 77; 8 is from Seraphimoff and Go.of Kazanlik said to be the same as that examined by Dietze who gave it an acid number of 1-2 and a saponification number of 9.2. The two samples of geranium-oil are from Konig and Co. of Leipzig-Plagwitz ; the first is called '( 01. Geranii Turkicum rect. alb.," the second " 01. Geranii Gallic. lA." The specific gravities of the rose oils were determined at 15.00- except No 8 which was at "5" '* ; those of the geranium-oils were observed both at 27.5" and at 15" C. The optical examination of the rose-oils was carried out in a 100 mm. tube at 25" C. ; that of the geranium-oils at 19" C. The solidifying-point is the tempcra-ture at which the first crystals of stearoptene were deposited. The acid and saponi-fication numbers are nearly all the mean of two or more tests; the ratio in the last column is that between the acid and the ester number.ROSE-OILS. His own results are shown in the subjoined table. 27.5" C. 17.5" No. 1 No. 2 No. 3 No. 4 No. 5 No. 6 No. 7 No. 8 Specific Gravity. 0.8531 0.8583 0.8659 ----0.845 Rotatory Power. Acid Number. -2" 12' 15" - 2" 6' 50" -2" 38' 40" -2" 35' - 2" 45' -1" 43' 40" -3" 28' 30'' -3" 3' 50" Saponifi-cation Number. 17.7 16.5 16.9 13.1 (16-8) 17.8 21.1 10.8 GERANIUN-OILS. Ester Number. 16.1 14.2 15.4 12.3 14.3 18.4 9 5 -Ester Specific Rotatory Acid Saponification Gravity. Power. Number. Number. Number. 1.0 39.6 38.6 7.7 62-8 55.1 Turkish 0-8867 (27.5") 41' 20,t French 0.8869 (27-5") -70 52' 9 1 0.8960 (15") ) 9 9 0.8971 (15") } -Ratio.1 10.1 1 6.1 1 10.2 1 15.4 1 5.7 1 6.8 1 7-3 -Ratio. 1 38.6 1 7.2 h'. H. L. The author concludes that the " constants " relied on by Dietze are not sufficiently precise to allow of the certain detection of adulteration. On the Precipitation of Proteids. H. Schjerning. (Zed. aizal. Chem. 1897, xxxvi. 643-6G3.)-The fact that ash-free proteids behave in a different manner fro THE ANALYST. 105 those containing ash led the author to make experiments on the effect of adding salts to different precipitating reagents. It was found that the addition of various quantities of a 10 per cent. solution of calcium chloride did not interfere with the precipitation of proteid matter by stannous chloride.On the other hand the precipitates obtained with lead iron or aluminium acetates gradually decreased as more of a 10 per cent. solution of calcium acetate was added. From this the conclusion was arrived at that in the case of the tin precipitate a sort of double salt with two basic radicles but only one acid was probably produced, To determine the influence of salts containing a different acid radicle to that of the precipitating salts a similar series of experiments was made with a 0.4 per cent. solution of disodium phosphate. Up to a certain point the addition favoured the precipitation but when added in excess had a disturbing effect. The reactions taking place were probably as in the equations : 291b.Pb.CH3CO0 + Na,HPO = (Alb.Pb),HPO + 2CH,COONa or 2Alb.Pb.CH,C00 + Na,HPO = (Alb),Pb + PbHPO + 2CH,COONa.In applying this to the method of separating proteids the solutions of the pre-cipitants were of the same strength as given in the Zed. anal. Clzem. xxxv. 286, and whenever the proteid solution contained little or no phosphate the phosphate solution was added in the proportion of 20 C.C. to 6 C.C. of the lead acetate solution or to 0.8 gramme of ferric acetate and 40 C.C. of dilute acetic acid (15 C.C. of 40 per cent. in 1 litre). Care was taken that the proteid solution did not contain in 10 C.C. more nitrogen than corresponded to about 5 C.C. of decinormal acid. The following table gives the results obtained with various proteid solutions. A cross indicahs that the determination could not be made on account of the liquid not filtering clear or in the case of the ferric acetate owing to the iron not completdy precipitating on boiling : Malt I.. . . . . . ) ) 11. . . . . . . Egg-albumen I. . I1 .*. Milk . 'I. . . ) ) 11. . . . . . . Witte's peptone . Liebig's flesh pep-tone . . . . . . Liebig's meat ex-tract . . . . . . . . . . . . Diastase (Merckj . Urine . . . . . . Solution. 100 graiiiiiies } in a litre 2 gamines in I 400 C.C. 75 c.cdiluted J } to 500c.c. I 2.5 gramrnes in 500 C.C. . 5 grainmes i n 800 C.C. . 5 graiiiiiies i n 800 C.C. 0 . . 12 grammes in 500 C.C. 50 C.C. diluted;; 500 C.C. . Stannous Chloiide. Vithout ! With CaCI2. 8.6 8.7 5.8 + + + 1.2 + 8.4 15.8 0-6 8.9 9.9 89.2 91.5 82.6 80-1 2.7 13'9 10.7 36.9 1.4 Lead Acetate.Vithout 1 With Na2HPOd. 18.0 18.5 90.3 88.8 S8-2 + + + + 2.0 -20.6 20.1 92.3 92.2 91.9 -+ + 19.2 + 2.4 Ferric Acetate. Yithout I With N%HPO+ -1- + + .+ + + + + + + + 31.9 33.0 97.2 94.2 93'8 93.0 59.2 56.4 25.3 80.4 3.1 Vormal Ura-nium Solu-tiun. 41.8 44.8 99.9 94.2 92-9 92.2 59.2 53.4 36.7 85.9 1'9 'recipi-tation with I- Acetic Acid. ?ulgso.$ 19.9 21.3 96.0 93.0 92.1 92.2 51.2 47'2 15.1 59.7 1.4 A very old sample 106 THE ANALYST. 1.7 7’9 1.6 0-0 From comparison with the results obtained with the malt-extract the author considers that them are two kinds of “ albumin ” present in milk.He divides the pre-cipitated proteids in the following way and adds in a subsequent note that the names 4 ‘ albumin,’’ etc. are only to be regarded as a provisional nomenclature, indicating to some extent the characteristics of hhe substances. a = Albumin I. = the tin precipitate. b = , + albumin 11. + denuclein = the lead precipitate. c = 2 + 7 + , + propeptone =the iron precipitate a= , + , + , + , +peptone=theuranium pre-e = , + , +propeptone = the magnesium sulphate precipitate. Calculating the results from this the substances were found to have the following cipitate. composition : 0-8 11-0 1-1 0.0 Witte’s Pep-tone. Liebig’s Pep-tone. Liebig’e Meat Extract. 10.7 10.2 0.0 6.1 11.4 38.4 Dia-stase.Malt Extract. Egg-Albumin. Milk. Urine. I. 8 -9 11.7 11.3 9 9 -11. 9.9 10.2 12.9 11.1 -I. 89-2 1.2 1.9 3.9 2.7 11.” 91.5 1.2 1-5 0.0 Albumin I. . Denuclein . . . Albumin 11. . Propeptone . . . Peptone . 2.7 8.0 148.5 0.0 13.9 9.2 33.2 0.0 36.9 20-7 5 22.8 5.5 1.4 1:7 0.0 0.7 0.0 Total . 41-8 44.1 98.8 94.2 93.8 I 93.0 59.2 56.3 85.9 3.8 The author remarks i iat the fact that he finds no true peptone but only’ propeptones in either Witte’s or Liebig’s peptones is in accordance with the results of Konig and Bomer ; but on the other hand he differs from them in finding a large quantity of peptone in Liebig’s meat extract ( c j . ANALYST xxi. 17). C. A. M. The Classification of Proteids.A. Wroblewski. (Berichte 1898 xix., 3045-3052.)-The author defines proteids as bodies which on complete decomposition with acids yield as final products ammonia nitrogenous organic bases (such as lysine arginine etc.) and amido acids (such as leucine tyrosine etc.). Hence pro-tamines which yield no amido acids on decomposition cannot be classed with the proteids although closely allied to them. Probably peptones also do not comply with the definition though for want of more definite knowledge they may be grouped with their mother-substances the albumoses. I n the subjoined scheme of classification the proteids are divided into three main groups I. Albuminous bodies (Eiweissstoffe) ; 11. Compound albuminous bodies (Zusammengesetzte Eiweissstoffe) ; and 111.Albuminoid bodies (Eiweiss-a hnlic he Subs t anzen). To the first group belong proteids which a?e closely related to fresh or coagulated white of egg ; they contain sulphur in their molecule. Albumi7zs are .soluble in water. Globulins are insoluble in water but soluble in dilute saline solutions, AEbumiizs soZubZe in alcohol all dissolve in dilute spirit of wine and many of theni in strong spirit. Albz~rniizatcs are formed by the action of alkalies on. albumins. They are insoluble in water but readily soluble in alkalies. Acid albumins are produced by the action of acids on albumins and are soluble in very dilute acids o THE ANALYST. 107 alkalies. Coagulated albumiizs are the products of the coagulation of albumins by heat or by enzymes and are marked by their great insolubility.The second group comprises proteids whose molecule consists of an albumin group and another group often of a non-proteid nature. Thus in hanzoglobins there is a coloring-matter group ; in glyco-proteids a carbohydrate group ; in n z d e o -albumim a nuclein group; and in nucleins a nucleic acid group. The third group is subdivided into three classes (1) Structural substances (Gerustsubstanzen) ; (2) Alburnoses and peptones ; ( 3 ) Enzymes. In the first class are keratins constituents of horn. They contain much sulphur, are only with difficulty attacked by pepsin and trypsin and on decomposition yield much tyrosin. They are hardly soluble in reagents contain little sulphur and on deoomposition yield but little tyrosin. Collagenes contain very little sulphur and do not give aromatic amido-acids as decomposition products.Alburnoses and peptoizes constituting the second class have much smaller mole-cules than the albuminous bodies. By virtue of their toxic properties some of the albumoses are closely related to the enzymes. The enzymes grouped in the third class might be further divided in accordance with the conditions of their greatest activity. Thus some work best in acid solution others in alkaline solution. Among the former are pepsin ptyalin, diastase invertin myrosin and emulsin ; whilst representatives of the latter are trypsin steapsin and urase. PROTEIDS. EZnstim are contained in the cartilaginous tissues. GROUP I. Albuminous Sub-stances. 1. Albumins: Egg albumin Serum albumin Lact-a1 bumin iMuscle albumin Plant albumin Etc.2. Globulins : Egg globulin Seruni globulin Lacto-globulin Fibrinogen Myosin Plant globulins Vitellin (?) Etc. 3. Albuminous sub-stances soluble in alcohol chiefly of vegetable origin. 4. Albuminates. 5. Acid albumins : like. Syntonia and the 6 Coagulated albumin-ous substances : Fibrin Paracasein Coagulated white of egg. GROUP 11. Compound Albuminou: Substances. 1. Glyco-proteids : Mucins Mucoids. 2. Haenloglobin. 3. Nucleo-albumins. 4. Caseins: Of CO~VS’ milk Of human milk. 5. NuclBios. 6. Amyloids. 7. Histones ( 1 ) GROUP 111. Albuminoid Substances. Class 1. Structural substances. (Geriistsubstanzen). Keratins. !. Ela-tins.i. Collagenes : Collsgene, Glue and the like. Class 2. 91 bumoses and Peptones. Class 3. Enzymes. 1. Proteolytic : Pepsin Trypsin Papayotin and the like. 2. Amylolytic : Diastase Invertin and the like. 3. F a t - decomposing enzymes : like. Steapsin and the 4. Glucosidedecompos-ing enzymes. 5 . Amide decomposing Urase and the 6. Coagulating enzymes and the like : Rennet and the like. enzymes : like. C. A. M 108 THE ANALYST. Taka Diastase. J. Takamine. (Amel JOZWIZ. Phnim. 1898 lxx. 137-141.)-I n Japan and other Asiatic countries certain fungi are used for the production of diastase. That used in Japan belongs to the genus Aspergillus and is termeif Noyashi. This is specially cultivated on sterilized wheat bran or other suitable material and when mature is dtied and the spores separated by shaking or sifting ; the product thus obtained is called Taka-moyashi and can be preserved indefinitely.For the manufacture of diastase for commercial purposes wheat bran is moistened with water steamed and after cooling to below 40" C. is mixed with a little Taka-moyashi and spread in a layer in a room similar to a malt-floor where the tem-perature is maintained at about 25" C. and the humidity at about 80 per cent. Within forty to fifty hours the diastatic power of the mass reaches its maximum, and further growth is checked. The mass is known as Tuka-Koji and can be used in the green or dried state. The diastase it contains is soluble in water and an aqueous extract of the Taka-Koji concentrated in vacuo to a syrup has from eight to ten times the diastatic power of malt extract of similar consistency.The diastase can be precipitated from this aqueous extract by the addition of alcohol and when separated by means of centrifugal force and air dried is a non-hygroscopic j ellowish-white powder readily soluble in water and capable of converting over one hundred times its weight oE starch in ten minutes. By further purification by re-precipitation or otherwise its diastatic power which is exceedingly stable can be st ill further increased. C. A. M. A Simplo and Accurate Method of Testing Diastatic Substances. J. Taka-mine. (Amer. JozL'I'~. Pham. 1898 lxx. 141-143.)-This is based on the great stability of Taka-diastase (see preceding abstract) which does not lose its diastatic power with keeping as the author finds to be the case in the diastase isolated from malt. The exact diastatic capacity of a quantity of Taka-diastase is determined once for all by Lintner's or Junk's method (ANALYST xxi. 122) and that of any substance under examination compared with the standardized sample and expressed in any terms desired. Eight glass cylinders holding about 150 c.c. are placed in water warmed to about 40" C. and into each is poured 100 C.C. of 5 per cent. starch paste. I n the first glass is placed 1 C.C. of the saliva or other liquid to be tested whilst the other seven cylinders receive successively increasing quantities of a freshly-prepared 1 per cent. solution of the standard Taka-diastase commencing with I C.C. in the second cylinder and ending with 7 C.C. in the eighth. The contents are stirred until the starch becomes liquid and a drop from each is then removed to a white tile where it; is mixed with 1 drop of a solution of iodine prepared by dissolving 1 gramme of iodine and 2 grainmes of potassium iodide in a little water and making up to 120 C.C. The drops when spread out on the tile with the finger form a colorimetric scale, ranging from blue to purple and reddish-brown and the colour given by the substance in the first tube is readily matched. C. A. M

ISSN:0003-2654    

DOI:10.1039/AN8982300095

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年代:1898

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THE ANALYST. 109 I N 0 RGAN IC AN A LY S I S. Estimation of Tin in Stannic Salts, A. Fraenkel and J. Fasal. (Nitth. k.k. Tech. Gew. MZLS., 1897, 227 ; through Chem. Zed. Rep., 1898, 11.)-An amount of the stannic salt containing 0.2 to 0.4 gramme of tin is treated with a few drops of strong hydrochloric acid, and 0.5 to 1 gramme of aluminium wire is added. The whole is warmed gently for about half an hour, or until hydrogen is given off briskly, and a fresh piece of wire does not become coated with tin, thus showing that decomposi- tion is complete. Ten C.C. of strong hydrochloric acid are next introduced, and the flask is heated for fifteen minutes till all the metal is dissolved and no more gas is evolved, The solution of stannous chloride is then mixed with Rochelle salt, made faintly alkaline with sodium bicarbonate, and titrated with iodine ; or if the greater part of the free acid only is neutralized, Fraenkel's potassium bichromate method may be adopted.The results are slightly too low. F. H. L. Separation of Beryllium from Aluminium. F. S . Havens. (Zeits. anorg. Chem., 1898, xvi., I5.)-This process is identical in principle with that already described by Gooch and Havens for the separation of iron from aluminium by means of ether and hydrochloric acid (ANALYST, xxii., 194) ; but the details of the operation have been slightly modified, and it is now preferably carried out in the following manner: Fifteen C.C. of the aqueous solution of the mixed chlorides of aluminium and beryllium, containing about 0.2 gramme of the corresponding oxides, are placed in a covered platinum basin, and suspended within a larger vessel through which a current of cold water is constantly passing.The liquid is saturated at 15" C. with gaseous hydrochloric acid, 15 C.C. of ether are added, and the whole is saturated with gas once more. The insoluble aluminium chloride is collected and treated exactly as before; the filtrate, which is allowed to run directly into a platinurn crucible, is slowly and cautiously evaporated till all free acid is driven off, then mixed with a little nitric acid to convert it into nitrate, evaporated again, and finally ignited, first at ti low temperature and afterwards over the blowpipe. The author states that if the beryllium chloride contains no free HC1 when the nitric acid is dropped in, the platinum will not be attacked ; but the residue must not be heated more than necessary, lest part of the chloride volatilise.The beryllium can also be determined by removing the excess of HC1 and then precipitating with ammonia. The results are sufficiently accurate : calculated as A1203, the aluminium is from 0.1 to 0.8 per cent. too low ; the Be0 from 0.4 to 0-8 per cent. too high. F. H. L. Use of Metallic Sodium, Magnesium and Aluminium in Blowpipe Analysis. W. Hempel. (Zeits. amrg. Clzem., 1898, xvi., 22.)-The utility of ordinary blow- pipe analysis is somewhat restricted by the difficulty of exposing the substance under examination to a satisfactory reducing flame. This may be overcome in the following manner. A very small, clean fragment of sodium (the size of a grain of millet) is laid on a piece of filter-paper about 4 square centimetres in area, and pressed out with an oily knife until it is quite thin and pliable.The110 THE ANALYST. powdered sample is placed in the middle, and the whole rolled up into a cylinder so that the paper forms a double layer all round. The cylinder is wrapped round with a close spiral of iron binding-wire, the excess of paper cut off, and the cartridge approached to the edge of a Bunsen giving a reducing flame till the paper catches fire. Immediately the reaction is over, the wire is thrust into the centre of the flame to protect the mass from oxidation, and gradually lowered towards the orifice of the burner until it is cooled by the current of gas. The residue is shaken out of the wire and extracted with water in an agate mortar to dissolve the caustic soda. When this has been removed, the insoluble portion can be examined as usual, any reducible metals which the original body contained being present in considerable amount.Silicon and boron will also be found in the elemental state mixed with some carbon from the paper ; the residue should then be treated with hydrochloric acid, washed with water, ignited on foil till the carbon is burnt off, when a sufficient proportion of the silicon and boron will still be left unoxidized to respond to the ordinary tests. The metallic sodium should be kept in an air-tight battle rather than under petroleum; and if care be taken not to employ too much of it, there is no danger of an explosion.If it be desired to recover a larger quantity of the reduced matter, the mixture may be diluted with common salt, and the reaction effected in an iron crucible. As the presence of sodium salts hinders the recognition of other metals by their flame tests, a further portion of the sample may be mixed with powdered aluminium or magnesium, wrapped in paper and treated as above ; but owing to the infusibility of the earths the reduction is not so complete as with sodium. (Silicates may quickly be opened up in this way.) F. H. I;. The Analysis of Crude Sodium Sulphide. F. Jean. (Jour. Pharm. chh., 1898, vii., 170-172.)-Ten grammes of the sulphide rapidly broken into large pieces, in order to obtain an average sample, are dissolved in a little water, and the solution after removing the insoluble matter by filtration, made up to a litre.Ten C.C. of this solution are titrated with decinormal iodine with starch as indicator. The volume used corresponds to the sulphide, sulphur in excess, and thiosulphate. To a second portion of 10 C.C. a solution of ammonium sulphate (607 grammes per litre), is added, the saiiie volume being taken as was used of the iodine solution in the preceding titration. After the addition of 30 C.C. of water the liquid is dis- tilled, and the ammonia liberated by the sodium monosulphide received in 20 c . ~ . of decinormal acid. This is subsequently boiled to remove sulphuretted hydrogen, and titrated with decinornial alkali with turmeric as indicator. Each C.C. of decinormal acid neutralized by the ammonia corresponds to 0.0039 gramme of sodium mono- sulphide.The residual liquid in the distilling-flask is titrated with decinormal iodine when cold, each C.C. used corresponding to 0.0079 grarnme of sodium thiosulphate. The difference between the amount of iodine solution required here and that used in the first titration corresponds with the sulphur of the sulphides and polysulphides, which may be expressed as sodium monosulphide by multiplying the number of C.C. by 0.0039. The quantity thus calculated is always in excesss of that obtained by theTHE ANALYST. 111 distillation with ammonium sulphate, owing to the excess of sulphur in the poly- sulphides being included in the monosulphide. This excess is therefore calculated into sulphur (100 of sodium sulphide = 41 sulphur). If the sample contained only monosulphide the results obtained by the distilla- tion with ammonium sulphate and by the titration with iodine would agree. The result obtained by titrating the sulphide with an ammoniacal solution of zinc is the same as that obtained in the iodine titration (making a deduction for the thiosulphate) since the sulphur of the polysulphides acts upon the zinc like the monosulphide. In the courfie of their experiments on this method the authors have established the following facts : (1) When a solution of sodium monosulphide is boiled with an excess of ammonia, part of *the sulphur is volatilized in the form of ammonium sulphide ; and (2j when a solution of sodium thiosulphate is boiled with an excess of ammonium sulphate there is a liberation of ammonium sulphide and a, deposit of sulphur ; but this decomposition does not take place in an alkaline liquid, or under the conditions described above. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8982300109

出版商:RSC    

年代:1898

数据来源: RSC

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THE ANALYST. APPARATUS. Apparatus for the Valuation of Manganese Peroxide. M. Nothomb. (Chenz. Zed., 1898, xxii., 80.)-This apparatus may either be used for the purpose indicated or for the estimation of carbon dioxide. I t is comparatively small, and when fully charged weighs only about 80 gramines. The glass stopper of the flask serves also as a stopcock, opening or closing communication between R and R1 according as it is revolved in the neck of the flask. The latter contains a small quantity of dilute sulphuric acid, but not enough to touch the perforated receptacle carried by the tube E. Into the acid is put a weighed amount of manganese peroxide, and a few crystals of oxalic acid are laid in the basket. The stopper is then inserted in such a position that R and R1 are not connected, strong sulphuric acid is poured into the bulb to the height shown, and the whole weighed.Connection is next made between R and R1 till the oxalic acid is covered with liquid; and when the reaction has ceased, dry air is blown in through E to drive out the carbon dioxide. 111 The lower part of the tube F1 inside the bulb is of course not joined to R, as inight be imagined from the illustration given herewith. F. H. L. A New Measuring Pipet,te. 0. Bleier. (Chenz. .&it., 1898, xxii., 59.)-With reference to the illustration of his pipette on p. 55 of this volume, the author notes that for convenience sake the distance between each bulb should be a trifle greater112 THE ANALYST, than there shown-in fact, that each constriction should be a short tube-as other- wise, although the capacity of the apparatus between each graduation may easily be determined, it will probably work out to some uneven number of cc.s, thus depriving the pipette of much of its practical simplicity.A modified form of the arrangement, which will be found very useful, especially for measuring large volumes of water, as in diluting liquids or making up standard solutions, may be prepared by constructing the bulbs of different sizes. For instance, the graduated portion a--b may contain 25 C.C. ; b-c, 25 C.C. ; c-d, 50 C.C. ; d-e 100 C.C. ; e-f, 200 C.C. ; so that by suitable manipulation any quantity of water can be measured with perfect accuracy. In this manner the use of graduated flasks, which are of necessity marked high up in the neck, can be avoided ; and a standard solution may be prepared in a much larger vessel by weighing the solid, calculating the proper amount of water, and adding it by means of the measuring burette, when, as the vessel need only be halE full, the liquid can be shaken satisfactorily till solution is effected.F. H. L. A Convenient Filter - stand. H. Faber. (Chem. Zeit., 1898, xxii., 39.)-The construction of this stand is sufliciently explained by the dia- gram. The tables A and B are either fastened rigidly together so that they revolve simultaneously on the ver- tical axis C, or B may be carried by a shoulder on the socket rising from A, in order that by the insertior of a suitable number of washers under- neath B, the distance between the two tables may be adjusted to suit diflerent sized funnels and beakers. F. H. L. An Improved As- bestos Filter. A. Goske. (Chenz. Zeit., 1898, xxii,, 12.)-The object of this improvement is to reduce the amount of asbestos necessary to ensure efficient filtration, so that while the filtrate is perfectly clear, yet the operation is not unduly prolonged. As will be seen in the accompanying cut, the hollow glass ball has two small holes in its upper part. It is covered with a layer of dry asbestos fibre about 5 mm. thick, then connected with the pump, and a sufficient quantity of asbestos powder previously suspended ,in water is poured over it in the same way as is done in preparing a Gooc!i crucible. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8982300111

出版商:RSC    

年代:1898

数据来源: RSC