摘要:

74 THE ANALYST, ORGANIC ANALYSIS. Emetine Octo-iodide and the Extraction and Estimation of Alkaloids generally. (Amer. Journ. Pharm., 1899, lxxi., 14-21.)-The authors consider that the simplest and quickest method of obtaining the alkaloidal solution sufficiently free from foreign matter for titration by their periodide method (ANALYST, xxiii., 324) is that of A. B. Lyons (ManuaZ of Pharm. Assaying, p. 20). This consists in macerating a weighed quantity of the powdered drug in a definite volume of Prollius’ fluid with frequent shaking for several hours, drawing off an aliquot portion of the clear liquid, evaporating and taking up the residue with acidulated water. To obviate the loss by evaporation of the volatile solvent, which often causes too high results, the authors prefer as a general method of extraction a process which in its main features is the same as that used by them in the assay of opium (ANALYST, this vol., 8).This method has given very good results with all the drugs examined, with the exception of ipecacuanha root. It was found to be almost impossible to extract free emetine completely from this root by percolation with the’ethereo-ammoniacal mixture. H. M. Gordin and A. B. Prescott.THE ANALYST. 75 Iodometric. Ether, chloroform, and acetone. were also tried as solvents, but all yielded results much lower than those obtained by Lyons’ process. Emetine appears to form two periodides, that produced when the iodine is added to the alkaloid differing from that formed when the alkaloid is added to the iodine.The higher periodide, which is the only one the authors have yet examined, is obtained in the latter way, It is a dark brown powder, hardly soluble in benzene, ether, or chloroform, readily soluble in alcohol, and very soluble in a mixture of 4 parts of alcohol and 1 part of chloroform, although chloroform by itself hardly dissolves it. From the results of their analysis they-conclude that it is emetine hydrio- dide hepta-iodide, C28H,,N20,.HI.17, and from this the iodine factor for emetine is calculated to be 0.5453. The following table gives the comparative results of the gravimetrical and iodo- metrical assay of various drugs, Except in the case of the ipecacuanha root, for which Lyons’ method was used, the alkaloids were extracted by the authors’ general method, and titrated as described in their former paper (ANALYST, xxiii., 324).For nux vomica the mean factor of strychnine and brucine (0-47845) was taken, and for atropine the factor 0.2849. Gravimetric. Drug. ~ Method. Iodometric 1 2 2 Iodometric 1 2 2 Belladonna root Iodometric 1 2 2 Iodometric I 2 ha root {! Gravbetric 1 2 --- Belladonna leaves Ipecacuan- , Grammes ~ Iodine Consumed. taken. i Gramme. 0.0526816 1 ’ 0.0526725 Alkaloids shaken out and weighed. ’ -- 2.5 1 0-0459179 2.5 0.0459263 %2} Alkaloids shaken out and weighed. 0 *095 7 7 6 4 0.0986635 C. A. M. The Separate Estimation of Strychnine and Brucine. H. M. Gordin and A. B. Prescott. (Amer. Journ. Pharm., 1899, lxxi., 18, 19.)-The periodide method of assaying nux vomica (ANALYST, xxiii., 324) may be used in conjunction with Dnnstan and Short’s method of separating strychnine from brucine (Pharm. J.Trans. (3), 14, 290) as a convenient method of separately estimating these alkaloids in the drug. The acidulated alkaloidal solution obtained from 4 grammes of nux vomica in76 THE ANALYST. any suitable way is made up to 100 C.C. Fifty C.C. of this are run into an Erlen- meyer flask, 10 C.C. of 2 per cent. sulphuric acid added, and water to about 200 C.C. After the addition of 25 C.C. of a 5 per cent. solution of potassium ferrocyanide, the flask is closed and shaken continuously for about thirty minutes. The liquid is filtered and the precipitate washed with water containing 1 per cent. of sulphuric acid, until the washings diluted with water have no bitter taste.The filter is then pierced, the precipitate washed into a second flask, where it ia mixed with 20 C.C. of a 5 per cent. solution of zinc sulphate, and the flask kept on a boiling water-bath for about fifteen minutes. The zinc sulphate decomposes the strychnine ferrocyanide, zinc ferrocyanide being precipitated and strychnine sulphate left in solution. Of this 50 c.c., representing 1 grarnme of nux vomica deprived of the brucine, are filtered off and run into a flask containing 20 C.C. of decinormal iodine solution and about 2 C.C. of dilute hydrochloric acid. The amount of iodine consumed multiplied by 43.9 (100 times the strychnine factor) gives the percentage of strychnine. The iodine consumed by the total alkaloids is determined in another portion of the alkaloidal extract in the same way, and the difference between the two amounts multiplied by 51.79 (100 times the brucine factor) gives the percentage of brucine in the drug.The following results were obtained by this method with a test-solution contain- ing 0.16 per cent. of strychnine and 0.22 per cent. of brucine (anhydrous) : Iodine consumed by 10 c.c., after the removal of Brucine. When completely cold the liquid is diluted to 100 C.C. Iodine consumed by 10 c.c., before the removal of Brucine. Found, per cent. Gramme. Gramme. Stiy-e, 0.0843130 0 -032 39 7 0.14 0.24 0.0843 132 0.032397 0.14 0.24 C. A. M. Melzer’s Picrotoxin Colour-Reaction as a Test for Cholesterin and Phyto- sterin. H. Kreis. (Chem. Zeit., 1899, xxiii., 21.)-Melzer has shown (Zeits. anal.Chem., 1898, xxxvii., 351 and 747) that when picrotoxin is treated with benzaldehyde and sulphuric acid a red colour is produced; the present author finds that choles- terin and phytosterin (indifferently) yield an analogous reaction. A few drops of a dilute ethereal solution are allowed to evaporate in a porcelain basin, when two drops of Melzer’s alcoholic solution of benzaldehyde and one drop of strong sulphuric acid are added. The mixture is made to spread itself over the surface of the basin and then left to rest. Cholesterin and phytosterin develop a reddish-violet colour, after- wards changing to a dark violet ; picrotoxin gives rather an ‘‘ eosin-red ’’ tint. When the colour disappears, it may be restored by more acid. The original tints shown by the fats resemble that produced in the Hager-Salkowsky test for choles- terin, for the colouring-matter is also soluble in chloroform, and may be the same substance.The latter reaction succeeds equally when Melzer’s benzaldehyde is replaced by chloroform. In view of this similarity, the author remarks that caution must be observed in toxicological analysis where picrotoxin has been apparently identified by its colour-THE ANALYST. 77 reactions ; in the ethereal extract of the acid liquor obtained after destruction of normal organic matter by the Stas-Otto method, cholesterin may well be present. F. H. L. On some Recent Methods for Examining Balsams and Resins. I(. Diete- rich. (Chem. Rev. Fett- ZL. Haw-Industrie, vol. v. [lo], 197-201.)-Reviewing his own method for determining the acetyl value, Kitt's " carbonyl number " method, and the Gregor - Bamberger " methoxyl value " method (ANALYST, 1898, 318j, the author expresses the opinion that none of them is capable of replacing the usual acid-, ester-, and saponification - value methods for the identification of, and the detection of adulteration in, the balsams and resins generally. He himself is engaged in perfecting a method based on the circumstance that the saponification- products of the ester-containing resins consist principally of alcohols-e.g., resino- tannol, resinol, etc., with merely small quantities of acids ; whilst the resins con- taining only resin acids, yield only acids and no alcohols under the same treatment.A table is given of the principal physical characteristics of the resins and the contained alcohols and acids. c.s. Notes on Colophony. R. Schick. (Zeits. angew. Chem., 1899, 27.)-This article is largely argumentative. The author does not agree with Dieterich's idea of determining the '' acid number " of resin by allowing it to stand for two hours in the cold with excess of seminormal alcoholic potash, and then titrating back with acid. The value so obtained is simply a number lying between the acid and the saponifica- tion values; for if the same process be continued longer, the results are practically the same as when the sample is boiled for twenty-five minutes. I n fact, the pro- portion of cold alkali absorbed rises steadily from the immediate and true acid number during twelve hours until it reaches a maximum agreeing with the hot absorption.The iodine number of resin varies in different grades between 137 and 173 ; the process is not complete in six hours, and is of little use in valuing the material. If the colophony be heated for thirty minutes in an open crucible to 300" C. the absorption falls some 44 points. Refractometer numbers, as determined with 20 per cent. solutions of resin in linseed oil at 40" C., range between 71.5 and 92.3, decreasing generally (in contrast with oils) as the iodine number rises. The refrac- tion does not appear very useful in estimating the quality of rosin itself, but is admirably adapted for detecting and estimating its presence when mixed with oils ; and the results so obtained agree fairly with the Twitchell process. The practical way of valuing resin depends rather on observations of colour and amount of impurity, such as sand and wood; but the market price depends mainly upon the colour, and therefore fixed grades have a moderately constant tint. Estimation of the matter insoluble in petroleum spirit seems of little use; for there is no evidence that such bodies as are insoluble in that solvent are objectionable to the consumer of the resin, F.H. L.78 THE ANALYST. A Colour Reaction of Lignin. A. Piutti. (Gaxxetta Chim. Ital., 1898, xxviii., 168-170.)-The hydrochloride of ortho-bromo-phenetidin, / OC,HS(1) C,H,-Br( 2) \ NH,.HCl(4) has the property of staining lignin yellow, while it has no action on cellulose, on ordinary textile fibres, such as linen, silk, cotton or wool, on chitin or on keratin.This reaction appears to be characteristic of lignin, since that substance is stained with the same intensity even after being repeatedly extracted with different solvents. By means of it, it is possible to make an approximate estimation of the amount of wood paste added to a given sample of paper, the colour obtained being compared with those of a standard scale prepared from paper containing known quantities of woody fibre. Lignin is coloured yellow by the other hydrochloride bodies of similar composition to o-Br-phenetidin, such as, for instance, the hydrochlorides o-Br-anisidin, of 0- and p-amido-phenol, of p-anisidin and of p-phenetidin, as well as by other salts of these bases, and the author considers it probable that the reaction is given by amido- phenols generally.Colorations given by lignin with other classes of compounds have been recorded, as, for example, the violet-rose colour with dimethyl-p-phenylene-diamine (Wurster), and with a hydrochloric acid solution of phloroglucinol (Wiesner, Ding. polyt., i., 227 and 397), the yellow colour with the hydrochlorides of naphthylamine and aniline, and the rose colour with pyrrol; but the nature of the coloured compounds formed, or on what group in the lignin molecule the reaction depends, has not yet been determined. The supposition that the reaction is due to the presence of an aldehydic group in the lignin receives some support from the facts that aldehydes combine very readily with the NH, group, and form yellow coloured compounds with amido-phenols. It is also noteworthy that the violet coloration which phloroglucinol in a hydro- chloric acid solution gives with lignin which has been thoroughly extracted with solvents is also obtained with aldehydes.C. A. M The Examination of Caoutchouc Milk. Girard and Lindet. (Bdz. xoc. Chim., 1898, xix., 812-815.)-1n whatever manner the incision is made in the bark of the tree, the caoutchouc milk has always the same appearance, being an opaque liquid with a great resemblance to animal milk. Under the microscope it appears as an emulsion of innumerable fine globules, from 3 to 5 p in diameter, in a (‘ serum.” As a rule the density of the milk is less than unity, with the exception of that from different species of the Algerian $cus. The density of the “serum” freed from caoutchouc varies from 1.037 to 1.040.I n order to determine the percentage of caoutchouc in the liquid, Girard modi- fied the nature of the (( serum ” by the addition of 95 per cent. alcohol, so that the globules collected on the surface and became united. The alcohol was added little by little, with constant stirring, until, when a volume about equal to that of the milk had been added, the whole of the rubber collected on the surface, leaving below a limpid, amber-coloured liquid.THE ANALYST. 79 The following table gives the percentage of caoutchouc thus obtained from Milk from Pernambuco (Haucornia) . . . ... 0.990 31.6 ,, ,, Africa ... ... ... ... .._ 0-987 33.4 ,, ,, Para (Siphonia elastica) ... ... 0.986 42.6 ,, ,, Nicaragua (Castilloa elastica) ...... 0.980 32.3 ,, ,, Algiers (Ficus macrophylla) ... . . . 1.000 37.5 9 , I , 2 , 9 , $ 3 ... . . . 1.005 37.1 ? # 9 , ,, (F. elastica) ... ... ... 1.001 17-3 ), 9 , ,, (F. nitida) . .. ... ,.. 0.971 31.3 9 , 9 ) ,, (3'. lmigata) ... ... . . . 1.005 28.0 ,, ,, New California (Kickxia Africana) ... 1.005 27.0 This similarity between caoutchouc milk and animal milk suggested to Girard the possibility of extracting the caoutchouc by churning the liquid previously heated to 50" C. This was succesvful on a small scale in the laboratory, and was then tried on a large scale on freshly collected milk in various parts of French Guiana by Bouery, who, after two years' experience, reported that the results were satis- factory. C. A. M. different caoutchouc milks : Density.Per cent. Caoutchouc. The Oxy-ferments of Milk and of Saliva. R. Dupouy. (Journ. Pharm. Chim,, 1898,551-553.) -In a former communication the author described the variation in the nature of different milks as regards the activity of the oxydases which they contain, and showed that they can be classified into two groups-those which contain an active oxydase, and those in which (like human milk) the oxy-ferment is very weak. Carnot (ANALYST, xxiii., 80) discovered the presence of an oxydase in saliva, but, as the author obtained negative results on repeating the experiments, he has made a further investigation of the subject, using exclusively a 1 per cent. solution of guaiacol as his reagent, this being very stable as compared with Carnot's reagents (tincture of guaiacum, solution of paraphenyl-diamine, 1 : 1,000, and paraphenyl-diamine with naphthol in alkaline solution). The presence of an oxydase in saliva can be demonstrated by adding an equal volume of the guaiacol solution and a drop of a solution of commercial hydrogen dioxide diluted with nine volumes of water, There is an immediate brown coloration, becoming more intense, and finally disappearing after a considerable time. On warming the saliva, the coloration with guaiacol appears readily until the temperature reaches 92" C ; above that temperature the colour appears very slowly, and is hardly perceptible. The author therefore regards 92" C. as the temperature at which the activity of the oxydase is destroyed. I t is also rendered completely inactive by an addition of a mineral acid, such as, for instance, a 0.2 per cent. solution of hydro- chloric acid. C. A. M. ~ - - ~ _ _ _ -

ISSN:0003-2654    

DOI:10.1039/AN8992400074

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

THE ANALYST. 79 INORGANIC ANALYSIS. Notes on the Electrolytic Determination of Iron, S. Avery and B. Dales. (Bey., 1899, xxxii., 64.)-Three processes were investigated : that recommended by Classen, in which the electrolyte is ammonium oxalate ; Smith’s method with acid sodium citrate ; and Moore’s with ammonium metaphosphate. Classen’s gives aTHE ANALYST. deposit of iron containing between 0.15 and 0.5 (mean 0.22) per cent. of carbon, and about the same amount of iron remains in solution. Smith’s iron contains between 1-54 and 5.0 per cent.. of carbon. Moore’s metal shows an excess in weight of 0.2 to 0-5 per cent., and the impurity consists wholly or in part of phosphorus and carbon. To ascertain whether carbon was the sole foreign ingredient in the metal thrown down from an oxalate bath, some of the iron was burnt in a current of air, passing the gas into baryta water; the amount of carbon calculated from the carbon dioxide was from 0.21 to 0-42 per cent.of the metal examined. The by-product in the Moore process is a heavy black substance, soluble in hot strong acids, but insoluble in dilute ones. F. H. L. - __ - - Impure Iron : A Possible Source of Error in Ulsch Nitrogen Estimations. L. Brandt. (Chem. Zeit., 1899, xxiii., 23.)-When a blank experiment was recently carried out to check the purity of the various reagents used in estimating nitrogen in Chili saltpetre by the Ulsch process, it was found that the acid distillate required too little caustic sodit for neutralization-the error amounting to 0.8 per cent. of nitrogen on the supposed sample.The impurity was traced to the iron, which evolved ammonia when it was dissolved in acid and boiled with caustic soda, but did not itself contain ammoniacal nitrogen. Boiled with alkali alone, nitrogen could not be detected in the filtrate either as nitrate, nitrite, or cyanide ; but after heating with metallic potassium, cyanide was discovered. By ignition in hydrogen the impurity was removed ; whereas neither extraction with water, alcohol, nor ether affected it. F. H. L. Volumetric Estimation of Alkalis and Acids by meaus of Iodine. C. F. Walker and D. N. H. Gillespie. (Zeits. anorg. Chem., 1899, xix., 194.)-When iodine acts upon a solution of a metallic hydroxide at a temperature high enough to destroy any trace of hypoiodite, a perfectly neutral liquid is produced which contains 1 molecule of iodate to 5 of iodide. On adding dilute acid, these two salts interact in the well-known way, evolving 6 atoms of iodine ; and by titration with thiosulphate or arsenious acid, the iodine-that is to say, the original hydroxide-may be estimated.Similarly, an acid may be neutralized by a known excess of alkali standardized as aforesaid, when determination of the surplus will give the strength of the acid. The process has been tested on the hydroxides of the alkalis and alkaline earths, on sulphuric and hydrochloric acids ; and although the precautions necessary to avoid loss of iodine and carbonation of the liquid perhaps render it somewhat complicated, the reaction proceeds so smoothly that it should be service- able for the indirect analysis of acids and probably for other suitable compounds. I t cannot, however, be employed on alkali-metal carbonates.The method outlined by Phelps (ANALYST, 1897, xxii., 55) may with advantage be slightly modified. A moderate excess of decinormal iodine is placed in a lightly-covered Erlenmeyer flask, the alkali is added (or, in determining acid, the acid is added, followed by a measured excess of standard alkali), and the whole is boiled till all free iodine is volatilized. The bulk of the liquid in d l tests should be uniform and as small as possible, starting with about 100 C.C. and boiling down to about 35 C.C. The vessel is cooled in aTHE ANALYST. 81 stream of water, 10 C.C. of 1 : 3 sulphuric acid (or hydrochloric acid, if barium be the metal) are introduced, and the liquid titrated with thiosulphate and starch. Blank experiments show that the error involved by conducting this titration in an acid solution is not apparent under the particular conditions referred to. F.H. L. Some Applications of Hydrogen Peroxide in Quantitative Analysis. P. H. Walker. (Jour. Arner. Chem. SOC., 1898, xx., 513-515.)-The Separation of Titanium f y o m Iron.-The cold slightly acid solution of the mixed sulphates (about 150 c.c.) is mixed with 100 C.C. of a solution of hydrogen peroxide (about 2.5 per cent.), and slowly run into a mixture of 100 C.C. of hydrogen peroxide and 30 C.C. of strong ammonia, with constant stirring. The precipitated ferric hydroxide is filtered off at once, and washed with cold dilute ammonia containing a little hydrogen per- oxide.The precipitate is dissolved off the paper with a mixture of hydrochloric acid and hydrogen peroxide, again treated with an excess of hydrogen peroxide, and reprecipitated as before. This treatment is repeated a third time, after which the ferric hydroxide can be dissolved, and the iron determined in the usual way. The filtrates containing the titanium are boiled down, and the titanium hydroxide (Ti(OH),) which precipitates is filtered off, washed with hot ammonium nitrate solution, ignited, and weighed as TiO,. An experimental mixture consisting of titanium dioxide fused with potassium bisulphate, and mixed with iron ammonium alum, gave the following results when analysed by this method :- Gramme.Titanium oxide found by first separation ... ... ... 0.0872 9 ) ,, second ,, ... ... ... 0.0104 ,, third ,, ... ... ... 0.0041 $ 7 Total found ... ... ... ... 0.1017 Titanium oxide taken ... ... ... 0.1016 The Separation of Uraiaium from I r o n . -The presence of a large excess of hydrogen peroxide prevents the precipitation of uranium by sodium hydroxide, but does not interfere with the precipitation of the iron. A slightly acid solution of the mixed salts is mixed with 50 C.C. of hydrogen peroxide, and run slowly, with constant stirring, into a solution of 5 grammes of sodium hydroxide in 50 C.C. of water, mixed with 50 C.C. of hydrogen peroxide. The liquid is diluted to 400 C.C. with hot water, and the iron filtered off and washed. The filtrate (which contains 811 the uranium) is acidified with hydrochloric acid, evaporated to dryness on the water-bath, the residue heated for an hour at 110" C.to separate any silica, dissolved in hydrochloric acid, filtered, and the uranium precipitated with ammonia, washed with ammonia, ammonicm nitrate solution and water, dried, ignited, and weighed as U,O,. In a solution containing about equal weights of Fe,O, and U,O, the following amounts of uranium oxide were found : U,O, Taken. (a) 0.1129 ( b ) 0.1056 U,08 Pound. 0.1124 0.1064 Difference. - 0.0005 + 0.000882 THE ANALYST. The Separation of Zirconium from Uranipim.--The solution of the mixed sul- phates is mixed with 50 C.C. of hydrogen peroxide, and run into a solution containing 5 grammes of sodium hydroxide in 50 C.C.of water, and 50 C.C. of hydrogen peroxide. No precipitateforms at first, but after heating on the water-bath for thirty minutes the zirconium oxide settles down as a heavy precipitate. This is collected, washed, and dissolved in a warm mixture of hydrochloric acid and hydrogen peroxide. The solution is boiled, the zirconium precipitated with ammonia, and the precipitate washed with ammonium nitrate solution and with water, dried, ignited, and weighed a s ZrO,. Zirconium Dioxide Taken. Zirconium Dioxide Found. Difference. 0.2150 0.2158 + 0.0008 C. A. M. Recognition of Ozone in Presence of Nit,rous Acid and Hydrogen Peroxide. G. Erlwein and T. Weyl. (Ber., 1898, xxxi., 3158.)--An alkaline solution of the hydrochloride of metaphenylenediamine, which is naturally colourless, is rapidly changed to wine-red by ozone; whereas nitrites and hydrogen peroxide do not affect it, and oxygen only causes a faint coloration after the lapse of some time.The ortho- and para-diamines behave similarly, but the meta-compound is the most useful. A solution containing 0.1 or 0.2 gramme of the hydrochloride in 90 C.C. of water and 10 C.C. of 5 per cent. caustic soda should be freshly prepared each time it is wanted; 25 C.C. of the reagent are tinted yellowish-brown in 5 seconds by 0.08 milligrainme of ozone. Conversely, liquids containing 6 milligrammes of diamine per litre of faintly alkaline water are yellowed by ozone, excess of gas destroying the colour. Twenty-five milligrammes of diamine yield a yellowish brown. Strong sulphuric acid changes the colour to a very dark red; nascent hydrogen (zinc and acid or alkali) bleaches it, but on agitation with air it returns to its original appearance.3'. H. L. Preparation of Starch-Zinc Iodide Solution. A. Seyda. (Chem. Zed., 1898, xxii., 1086.)-Two or three grammes of potato-starch are rubbed down most thoroughly with 50 or 100 C.C. of water, allowed to stand for one hour under cover, then heated in a strong flask for two to four hours at a temperature of 130" C. in a bath of rape oil. The liquid is diluted to about 750 C.C. with hot water, shaken, set aside for twenty-four hours, and filtered. Twenty grammes of zinc chloride and 2 grammes of zinc iodide (made from zinc dust and iodine) are introduced ; if neces- sary a few drops of centinormal thiosulphate are run in to destroy any blue colour, the whole is made up to 1 litre, well mixed, and finally filtered after twenty-four hours' standing into a bottle of brown glass.The solution keeps indefinitely. F. H. L. List of Atomic Weights for Analytical Purposes. (Chem. Zeit., 1898, xxii., 1031.)-A commission, consisting of Professors Landolt , Ostwald, and Seubert, appointed jointly by the German Chemical Society and the German '( Reichs-THE ANALYST . 83 gesundheitsamt. " has recently drawn up the following list of atomic weights. which it is hoped will be uniformly adopted for all commercial analytical purposes throughout Germany . For the sake of greater convenience. the table has been based on the unit 0=16000. and the figures are given to as many places of decimals (if any) as may insure the last being free from error .The weights of those '( elements '' marked with a point of interrogation are included under reserve . TABLE OF ATOMIC WEIGHTS . Aluminium Antimony Argon (?) ... Arsenic ... Barium ... Beryllium ... Bismuth ... Boron ... Bromine ... Cadmium ... Cmium ... Calcium ... Carbon ... Cerium ... Chlorine ... Chromium Cobalt ... Erbium (?) Fluorine ... Gallium ... Germanium Gold ... Helium (?) Hydrogen ... Indium ... Iodine ... Iridium ... Iron ... Lanthanum Lead ... Lithium ... Magnesium Manganese Mercury ... Molybdenum Copper ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . I . ... ... ... ... ... ... ... ... ... ... ... ... ... ... Atomic Symbol . Weieht .... "A1 ... Sb ... A ... As ... Ba ... Be ... Bi ... B ... Br ... Cd ... cs ... Ca. ... c ... Ce ... c1 ... Cr ... c o ... c u ... Er ... F ... Ga ... Ge ... Au ... He ... H ... In ... I ... Ir ... Fe ... La ... Pb ... Li ... Mg ... Mn ... Hg ... Mo 279 120 40 75 137.4 9.1 208.5 11 79.96 112 133 40 12.00 140 35.45 52 -1 59 63.6 166 19 70 72 197-2 4 1.01 114 126.85 193.0 56.0 138 206 -9 7-03 24.36 55.0 200.3 96-0 Rhodiu; ... Rubidium ... Ruthenium Samarium (?) Scandium ... Selenium ... Silicon ... Silver ... Sodium ... Strontium Tantalum ... Tellurium ... Thallium ... Thorium .. Tin ... Titanium ... Tungsten ... Uranium ... Vanadium Ytterbium Yttrium ... Zinc ... Zirconium Sulphur ... Neodymium (?) ... Nickel ... ... Niobium ... ... Nitrogen ... ... Osmium ...... OXY&CU ... Palladium ... Phosphorus ... Platinum ... ... Potassium ... Praseodvmium (?) ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... ... . . . ... ... Symbol . ... Nd ... Ni ... Nb ... N ... 0 s ... 0 ... Pd ... P ... Pt . . . K ... P r ... Rh ... Rb ... Ru ... Sa ... s c ... Se ... Si ... Na, ... Sr ... s ... Ta ... T0 ... T1 ... Th ... Sn ... Ti ... w ... u ... v ... Yb ... Y ... Zn ... Zr ... Ag Atomic Weight . 144 58.7 94 14.04 191 16-00 106 31-0 194-8 39-15 140 103.0 85-4 101-7 150 44.1 79.1 28.4 107-93 23.05 87.6 32.06 183 127 204 -1 232 118.5 48.1 184 239.5 51.2 173 89 65.4 90.6 F . H . L . A Soda Glass Unsuitable for Chemical Apparatus. E . Hoyer . (Chem . Zeit., 1898. xxii., 1033.)-Liebermann has already called attention to the fact that some chemical apparatus now on the market is made of such strongly alkaline glass that it is quite unfit for analytical purposes . A specimen of this material contained 66.5284 THE ANALYST. per cent. of SiO,, 24.52 Na20, 7-81 CaO, and 0.48 Fe,O, and A1,0,. On exposure to air in fine powder if gained 0% per cent. in weight in five weeks, and decreased very slightly when heated to 115" C. Treated even with cold water for twenty-four hours it lost 0.56 per cent, by weight or 2.3 per cent. of its content of alkali ; on boiling with water and cold or hot extraction with hydrochloric acid it lost more severely, eight hours' boiling with pure hot water causing B diminution of 11.80 per cent. in the total weight of the powder, F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8992400079

出版商:RSC    

年代:1899

数据来源: RSC

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84 THE ANALYST. APPARATUS. An Apparatus for Determining Melting-Points. L. N. Vandevyver. (Ann. de Chim. Anal. Appl., 1898, iii., 397-399.)-After describing the principal methods used for determining the meltingpints of substances, and pointing out the restric- tions of each, the author describes an apparatus which he considers to be of more general applicability. He takes as the melting-point that temperature at which a substance in passing from the solid to the liquid state leaves a sign of the change on an object with which it is in contact. His apparatus consists of a rod, A B (Fig. l), to which is attached a fixed ring, C , and a movable ring, D, which can slide down on to C. A piece of white filter- paper is fixed between the two rings, and a fragment of the substance of which the meltingpoint is to be determined is placed upon this.The rod terminates at B in a small mirror, M, placed at an angle of 135". A FIG. 1. The upper end of the rod is fixed in a cork which fits into a, large test-tube, and a thermo- meter, T, is placed with its bulb close to the sub- stance. The test-tube is immersed in a beaker, V (Fig. a), containing water, glycerin, or paraffin, etc., which is kept in motion during the warming by means of the agitator, R. When water is used it is advisable to have a small brush, S, attached to the end of R to dispel the air-bubbles which become attached to the glass and obscure the view. The moment the substance fuses a stain is produced on the paper, and this is reflected by the mirror. The author states that he has determined the melting-points of a large number of substances \---- - T . - - \- a FIG. 2. by this method, and has obtained a greater agreement in duplicate determinations than was possible by any other process. When a substance is being examined which stains paper in the solid state, a piece of ground or polished glass is substituted for the paper, and in this case also the change in the state of the substance is clearly shown in the mirror. For high temperatures the ordinary mirror is replaced by a metallic mirror, C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8992400084

出版商:RSC    

年代:1899

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THE ANALYST. APRIL, 1899. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS. THE monthly meeting of the Society was held on Wednesday evening, March 1, in the Chemical Society’s Rooms, Burlington House, the President, Mr. W. W. Fisher, MA., occupying the chair. The minutes of the previous meeting were read and confirmed. Certificates of proposal for election to membership in favour of the following candidates were read for the second time : Percy T. Adams, assistant to Dr. Matthew A. Bdams, Maidstone; Arthur French Angell, assistant to Mr. Arthur Angell, Southampton ; John B. Ashworth, assistant to Mr. Alfred Smetham, Liverpool ; Alfred Joseph Bull, assistant to Mr. Wm. Chattaway, and senior assistant in the Physical Laboratory, Birkbeck Institution, London ; Charles Crocker, assistant to Messrs.Morgan, Son and Seyler, Swansea; John S. Ford, analytical chemist, Edinburgh; C. A. Hackman, A.I.C., assistant to Mr. Alfred C. Chapman, London; Norman Leonard, B.Sc., F.I.C., assistant to Dr. Stevenson, Guy’s Hospital, London ; J. F. Liverseege, F.I.C., assistant analyst to the Corporation of Birmingham ; Richard Murray, chemist to Messrs. Brotherton and Go., Leeds; G. E. Scott- Smith, F.I.C., assistant to Mr. Alfred H. Allen, Sheffield ; W. P. Skertchly, assistant t o Mr. Otto Hehner, London; Harry Metcalfe Smith, F.I.C., assistant to Dr. Stevenson, Guy’s Hospital, London ; Lionel W. Stansell, assistant to Dr. Matthew A, Adams, Maidstone; and W. Northfield Yarrow, assistant to Mr. A. W. Stokes, London; and in favour of the following candidates for the first time: Julian L.Baker, F.I.C., chief chemist to the Beetroot Sugar Association, London ; Herbert Edward Burgess, chemist to the London Essence Co., London; Louis Charles Deverell, chief assistant to Mr. Benedict Kitto, London ; Julius Lewkowitsch, analytical and consulting chemist, London ; F. R. -O’Shaughnessy, Associate R.C.S., analytical chemist, London ; Arthur Marshall, A.I. C., analytical chemist and assayer, London; and Edward T. Shelbourn, A.I.C., assistant analyst to the London County Council, London. The following papers were read : ‘( Some Analyses of Ginger,” by E. G. Clayton ; L L Note on Boric Acid in Milk Samples,” by E. G. Clayton ; (‘ Caper Tea,” by John White ; and a “ Note on a Possible Source of Error in Modifications of the Leffmann and Beam Method of Fat Estimation in Milk,” by H. Droop Richmond and F. R. 0’ Shaughness y . Mr. Wm. Chattaway exhibited an apparatus for collecting samples of water in Winchester quart bottles at given depths.

ISSN:0003-2654    

DOI:10.1039/AN8992400085

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年代:1899

数据来源: RSC

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86 THE ANALYST, A NEW TEST FOR FORMALDEHYDE. B Y NORMAN LEONARD, B.Sc., F.I.C., AND H. METCALFE SMITH, F.I.C. (Rend at the Meetiiay, January 4, 1899.) IN the determination of the fat ( I hy the Werner-Schmid process ” in milk containing formaldehyde, we have occasionally noticed the production of a violet colour when the milk was heated with concentrated hydrochloric acid. This behaviour of formalized milk has also been observed by Fisher (ANALYST, xx., 156), whilst other experimenters have noted the production of a yellow colour (Zoc. cit., and ANALYST, xxi., 97). Further study of this reaction has enabled us to explain these discrepancies, and to show that it forms a most delicate test for formaldehyde in milk. The certain production of the violet colour requires the use of a, larger proportion of hydrochloric acid than is employed in the Werner-Schmid process.I n the case of milks containing such quantities of formaldehyde as are commonly added, little of the sample should be heated gently in a test-tube with from three to five times its volume of concentrated hydrochloric acid. Under these conditions, a fine violet colour quickly appears, even if the inilk contains so little as 0-0001 per cent. (1 per 1,000,000) of formaldehyde, whilst if much over 0.1 per cent. is present a yeZZoiv colour is produced. I n the latter case, however, the violet colour is readily obtained if a large excess of hydrochloric acid is used, so as to sufficiently dilute the liquid. So far as we have been able to ascertain, the reaction is not given by other aldehydes, or by any substance but formaldehyde.We may add that the reaction takes place, though less quickly, at the ordinary temperature, and by working in this way any confusion arising from the action of the acid on the milk itself is entirely avoided. Bearing in mind the fact, pointed out by one of us (ANALYST, xxi., 157), that the presence of a trace of some oxidizing agent is an essential condition in Hehner’s test, for formaldehyde, experiments were made to ascertain whether such was the case in the reaction described above. The “ pure redistilled ” hydrochloric acid used by us certainly contained a minute trace of a ferric salt, and gave a slight blue coloration when largely diluted and added to a solution of cadmium iodide and starch paste. When, however, the acid was digested for a short time with a little metallic zinc and then poured off, it gave these reactions no longer, and had also lost the power of producing the violet colour when heated with formalized milk.On adding a trace of ferric chloride, or of bromine, the reaction was readily obtained. I t seems probable, therefore, that the coloured products’forrned in Hehner’s test, and in the reaction we have described, are one and the same, the acid employed acting, perhaps, merely as a dehydrating agent. DISCUSSION. The PRESIDENT (Dr. Dyer) having invited discussion : Mr. W. W. FISHER said he remembered noticing, some years previously, in testing a sample of milk somewhat liberally treated with formaldehyde, that a colour was produced on boiling with hydrochloric acid.He did not investigate the cause o€ the reaction, but he now had a suspicion that it might not be due to formaldehyde only, as milk heavily treated with boracic acid showed a similar colour reaction.THE ANALYST. 87 When milk was treated with either formaldehyde or boracic acid, the curd was obtained in such a condition as to be very insoluble in hydrochloric acid, a fact which pointed to some change in the constitution of the casein itself, produced by the addition of the antiseptic ; and he thought it possible that the colour reaction referred to might arise from an alteration of the casein, and not simply from the presence of formaldehyde. Dr. RIDEAL thought that the presence of milk would be essential to the colour being obtained. Xr. Hehner, when describing his test with sulphuric acid, had noted that formaldehyde alone gave no reaction with sulphuric acid. Fritzmann (Chew. Centr., 1898, i., 218) has shown that the blue colour obtained with inilk and sulphuric acid is due to the presence of an oxidizing agent, usually nitric acid or nitrates in the milk or acid used. Mr. LEO TAYLOR remarked that when formalin had been added to milk which was being tested by the Leffmann-Beam or by the Werner-Schmid procew, the casein was always found to be difficult to dissolve. Mr. A. E. EKINS confirmed Mr. Taylor’s experience with regard to the insoluble condition of milk to which formalin had been added, as observed in the working of the Leffmann-Beam process.

ISSN:0003-2654    

DOI:10.1039/AN8992400086

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年代:1899

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THE ANALYST. 87 ADULTERATION OF SPIRITS OF NITRE WITH POTASSIUM NITRATE. BY W. F. LOWE, A.R.S.M., F.T.C. (Read ut the Meeting, January 4, 1899.) THE following short note on what appears to me to be an unusual form of adultera- tion of spirits of nitre will, I think, be of interest to the Society, as such a form of adulteration does not appear to have been recorded. A sample of ‘‘ spirits of nitre ” was received in the usual way from one of the food inspectors of my district. On examination I found that it yielded no gas whatever in the nitrometer when treated with potassium iodide and sulphuric acid, but with ferrous sulphate and sulphuric acid it gave a faint brown ring. The specific gravity at 15.5“ C. was 0.9073. I noticed a whitish deposit on the pipette used for transferring some of it to the nitrometer, and this led me to examine the sample for solid matter, when I found it to contain 1-12 per cent.of potassium nitrate. I have since had several similar samples, so that this was not an isolated case, and apparently a good deal of this stuff has been made up for sale, judging from the printed label which was put in (but unsuccessfully) by the defence when one of the caws was heard in court : SPIRITUOUS SOLUTION OF NITRE. N.B.-This is not the ordinary Sweet Spirit of Nitre, and must not be sold as such; for most purposes it is a much superior article. It contains an ingredient not in the Nitre of the Pharmacopaeia, making it much more effective on the Skin and Kidneys.’’ In spite of the label, I think it must certainly be considered a gross adulteration, as it is undoubtedly usually sold for spirits of nitre.88 THE ANALYST. Mr. JOHN WHITE said that he had been told by a firm of wholesale druggists that such an article a8 this was actually prepared and put on the market, and since receiving that information he had always determined the total solids in samples of sweet spirit of nitre that he had to examine, but he had never met with any such sample as that referred to by Mr. Lowe.

ISSN:0003-2654    

DOI:10.1039/AN8992400087

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年代:1899

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88 THE ANALYST. ABSTRACTS OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. The Detection of Renovated Butter. C. B. Cochran. (Journ. Franklin. Instit., 1899, cxlvii., 94-97.)-Renovated or ‘‘ process ” butter is prepared from stale and unsaleable butter by melting out the fat, and either simply cooling it rapidly by means of ice, or (less frequently) mixing it with milk or butter-milk, and again churning it into butter. I n order to distinguish this product from fresh butter, the author recommends the following tests : (1) Microscopic examination of the sample by means of polarized light both with and without a selenite plate. (3) Jean’s modifica- tion of the valenta test. When examined under the microscope with polarized light with a selenite plate, fresh butter shows a uniformly coloured field in any position of the analyzer, whilst the field of renovated butter is mottled and of various colours.Without the selenite plate, renovated butter gives a dark field with white patches ; pure butter, a uniformly dark field. This difference is due to the state of incipient crystallization of the rapidly-cooled fat. When fresh butter is melted and allowed to cool slowly, the appearance is quite distinct from that of renovated butter, the large crystalline masses being globular in form and showing a distinct cross by polarized light. Old butter or butter which has been exposed to changes of temperature, some- times has a similar appearance under the microscope to that of renovated butter ; but although the author has obtained the variegated field with polarized light in the case of such butters, when using the selenite plate, he has never seen the white patches which renovated butter shows without the selenite plate.I n his opinion, ordinary butter does not readily assume the same crystalline form as ‘‘ process ” butter. The crystalline structure of oleomargarine is much more pronounced than that of renovated butter. The turbidity temperature of renovated butter in the Valenta test is lower than that of fresh butter, and more acetic acid is dissolved by it in Jean’s modification of the test. The following table gives the results of the examination of three samples of such butter and of a sample of fresh butter. Sample 4 was known to be renovated, and samples 2 and 3 judged to be so by the results of the analysis.(2) Valenta test. (4) Determination of free fatty acids. ( 5 ) Reichert value. The percentage of free fatty acid is also usually high.THE ANALYST. 89 Valenta Test. 1 98*7 per Cent. Nicroscopic Appearance. 1 Acetic Acid not crystalline 60" C. crystdline 1 48.5" C. f ~ 50" C. 9 ) i 49" C. Sample. Per Cent. of N-Alkali required Acetic Acid to neutralize 100 dissolved. Grammes of Fat. ---- 70 1.1 C.C. 100 6.5 C.C. 100 8.1 C.C. 100 , 9.4 C.C. 1. Fresh Butter 2. Renovated Butter 3. ?, 9 , 4. 9 1 I , The author also calls attention to the characteristic form in which butter crystallizes from arnyl alcohol. This is quite distinct from the form of oleomargarine or lard crystals, and has enabled him in many cases to detect the presence of a small quantity of foreign fat in butter.C. A. M. The Determination of Added Starch in Pressed Yeast. F. Dewalque. (137iZl. (7e Z'Ass. belge, 1898, xii., 264-269.)-The only method by which the author has been able to obtain good results is that of Maercker. Ten grarnmes of the yeast are mixed with 100 C.C. of water, and heated for twenty minutes at 60" to 70" C. The temperature is then brought to 60" C., ten C.C. of malt extract (prepared by extracting 100 grammes of green malt with 500 C.C. of water) added, and the temperature kept constant for half an hour. The saccharified liquid is brought to 250 c.c., filtered, 200 C.C. of the filtrate inverted with 15 C.C. of hydrochloric acid (specfk gravity 1.125), and diluted to 500 C.C. The reducing sugar in 25 C.C.of this is determined with Fehling's solution in. the usual manner, and a correction made for the amount of copper reduced by the malt extract added. The author prefers to calculate the quantity of starch on normal yeast, which, according to Hayduck, contains 74 per cent. of water, although he considers this estimate of the water too high. C. A. M. Notes on Cazeneuve's Method of Detecting Artificial Colour i n Wines. E. Comboni. (Stax. Speriment. Agrar. Ital., 1898, xxxi., 490-498.)-Cazeneuve's method consists in shaking 10 C.C. of the wine with 20 centigramrnes of yellow mercuric oxide and filtering, the filtrate being colourless (according to Cazeneuve) when the wine is pure. The author has made experiments with this test on different kinds of wine, from which he finds that this quantity of mercuric oxide is frequently insufficient to precipitate all the natural colouring matter, and that more certain results cazl be obtained by using 1.5 gramme to 10 C.C.of wine. But when the wine is of American origin or has been mixed with American wine the test is useless, and the colouring matter is not removed by the addition of as much as 8 grammes of the reagent to 10 C.C. I t is preferable to use the mercuric oxide in the freshly precipitated moist condition, and to add it to the cold wine. Treatment of the wine with amylic alcohol saturated with barium hydroxide also shows thi8 difference between Italian and American wines, the filtrate from the former being colourless, while that from the latter is invariably rose-coloured.The author considers that the method of Konig and Arata (no reference given), in which90 THE ANALYST. the wine is treated with fat-free wool, is the only certain test in dealing with American wine. C. A. M. The Composition and Characteristics of Sassafras Oil. C . Kleber. (Arne?.. Journ. Pham., 1899, lxxi., 27-32.)-Commercial oil of sassafras is distilled exclusively from the sassafras roots, and chiefly from the bark of the ro?t. L4t first it is nearly colourless, but on exposure to light and air gradually changes to yellow or brown. Its specific gravity lies between 1-07 and 1.08, and its optical rotation varies from +3" to +4". On exposure to cold crystals of saffrol gradually deposit, and by repeated treatment in a freezing mixture about 80 per cent.of that substance can be isolated. Pure saffrol is an optica,lly inactive colourless liquid, freezing at 8" C. and boiling at 232" C. Its formula is C,,H,,O,, and it appears to be the methylene ester of an ally1 catechol. CH, = CH.CH, I I C HC/ \CH 1 I HC, CO " I CO-CH,. The parts of sassafras oil which remain liquid even in a freezing mixture can be separated by fractional distillation into a fraction boiling between 155" and 175", and consisting chiefly of pinene, C1,H16, with a small amount of another terpene, phel- landrene, C,,H,,. The higher fractions contain about 0.5 per cent. of a substance which can be extracted by dilute alkali, and consists of eugenol C,,H,,O,. The fractions boiling about 200" C., yield, on cooling, colourless prisms of ordinary dextro - camphor, C,,H,,O, while the highest fractions contain a small quantity of a sesquiterpene C,,H,, which, from its colour reactions, the author believes to be cadinene.The percentage composition of oil of sassafras bark may thus be summarized : safrol, 80 ; pinene and phellandrene, 10 ; d-camphor, 6.8 ; eugenol, 0.5 ; cadinene (?) ; and residue, 2.7. The resemblance between oil of sassafras and oil of camphor has led to nianu- facturers substituting the oily by-products of the manufacture of camphor for sassafras. According to the author, many of the commercial sassafras oils are fractions of Japanese camphor oil of the same gravity (1.07) as the natural oil. They are largely used, especially by soap manufacturers, on account of their lower price. The oil of sassafras-leaves, which is not a commercial product, diBers greatly from the root oil.The yield obtained by steam distillation amounts to about 0.028 per cent. of the weight of the fresh 'leaves. The oil when fresh is greenish yellow, and turns to reddish brown on keeping. Its specific gravity is 0.873, its optical rota- tion + 6.25, and it has an agreeable odour recalling that of oil of lemon and oil of citronella. I t contains a considerable amount of citral, CloH160, of geraniol, CI0Hl80, and of the isomeric linalol, the acetic and valerianic esters of the two latter alcohols,THE ANALYST. 91 Code'ine. Nil Blood-red Pure blue and several terpenes, including pinene and phellandrene. In the highest boiling parts of the oil some cadinene also appears to be present, and a paraffin-like substance melting at 58" C.(Cj. ANALYST, xxiii., 212.) C. A. M. - Herdine. Nil Yellow, becoming blood - red on warming Greenish-blue Valuation of Phosphorated Oil. H. Ekroos. (Arch Pharm., 1898, 627 ; through Deutsclie Clzem. Z c i t . , 1899, xiv., 27.)- The author has unsuccessfully attempted to determine the proportion of element'al phosphorus in its solution in almond oil, which is known as Oleum phosplioratum. He tried treatment with bromine and iodine, followed by water, iu order to obtain phosphoric acid ; also the formation of silver phosphide by the aid of silver nitrate; also distillation of the phosphorus in carbon dioxide. None of the processes was accurate; and it would appear that, especially on keeping, the phosphorus enters into combination with the fatty acids of the oil, and is no longer amenable to ordinary analytical separations. F. H. L. ~~ ~~ - The Colour-Beactions of Heroi'ne. G. Wesenberg. ( c T ~ ~ ~ r i ~ . Pharvz. Clzinz , 1899, ix., 16-18.)-Hero'ine is the diacetic ester of morphine- /OOC.CH,\ and is prescribed in place of codeine phosphate. I t is precipitated by the usual alkaloidal reagents, the most sensitive being iodine in potassium iodide, which causes a turbidity in a solution containing 1 part in 100,000, The author gives the following table of its colour-reactions in comparison with those of morphine and C1:H1T\OOC.CH,/No7 codeine : __-~ - Reagent. -__p_--__ -~ Concentrated HISO, ... H,SO, + 1 drop of HNO, . .. H,SO, + 1 drop of ferric chloride in 100 C.C. On warming ... ... Potassium ferricyanide + ferric chloride ... ... Nitric acid ... ... ... Iodic acid . . . ... ... Morphine. Wil Blood-red Greenish-blue Immediate blue precipitate I time I Blood-red, be- , Yellowish-red i Yellow, becorning coining yellow ' red on warm- S e p a r a t i o n of ~ Nil 1 ing iodine

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DOI:10.1039/AN8992400088

出版商:RSC    

年代:1899

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93 THE ANALYST, ORGANIC ANALYSIS. Estimation of Formaldehyde. 0. Blank and H. Finkenbeiner. ( B e y . , 1898, xxxi., 2979.)-The authors find that Legler’s method of titrating formaldehyde with ammonia gives results some 1.5 per. cent. below other methods of estimation (cf. ANALYST, 1897, xxii., 221). The following process for oxidizing it to formic acid by means of hydrogen peroxide in the presence of an alkali is preferable and quite accurate : 3 grammes of the solution or 1 grarnme of the solid are introduced into 25 C.C. of 2N sodium hydroxide solution contained in a tall flask ; 50 C.C. of 2.5 or 3-0 per cent. pure hydrogen peroxide are then cautiously and slowly dropped i u , the addition lasting about three minutes. After standing from two to three minutes longer, the alkali is titrated with 2N sulphuric acid and litmus.In the case of formalins stronger than 45 per cent. 30 C.C. of sodium hydroxide solution should be used; samples weaker than 30 per cent.. should be allowed to stand ten minutes before titration. The volume of standard alkali used, multiplied by six, gives the formaldehyde in 1 gramme of the solid, or multiplied by two in 3 grammes of the solution. A similar reaction occurs, but much more slowly, with benzaldehyde, especially in presence of a trace of ferrous sulphate ; acetaldehyde is also oxidized, but it is doubt-ful whether the decomposition is complete. Paraldehyde is very slowly atLacked, and even ferrous salts do not greatly quicken the action, F. H. L. Note on Testing Formaldehyde. L. F. Kebler. (Airier. Jozwn.Plzamz., 1898, lxx., 432-433.)-1n estimating the strength of a solution of formaldehyde by Legler’s method (Berichte, xvi., 1333), in which the formaldehyde is shaken with a standard solution of ammonia and the uncombined ammonia distilled over and titrated with standard acid, the author finds that, as a rule, the reaction between the aldehyde and ammonia is rather slow, and that if they are left in contact for less than six hours, the results will probably be considerably too low. Thus, a commercial sample of formalin showed a strength of 16 per cent. when the ammonia was distilled after a fifteen minutes’ reaction, but by increasing the time of contact the percentage gradually increased up to 37.5 per cent. after six hours. This result was also obtained when the mixed solutions were left overnight.The results obtained at different times under six hours were not constant in duplicate determinations of the same sample. C. E. Smith, who was delegated by the Pharmacopceial Research Committee to investigate the efficiency of various methods proposed for the determination of formaldehyde, found that by making a suitable correction the strength could be estimated by leaving it for about fifteen iiiinutes in contact with normal ammonia solution (i4ine~. Jozwn. Pliniwz., lxx., 86). The author’s explanation of Smith’s obtaining such results is that the number of samples of formalin exsmined by him was too limited, and evidently not representative of the commercial article. C. A. M. A New Method of Detecting and Estimating Acetone.G. Denighs. (Joz,mz. Plmm. Chinz., 1899, iu., 7-14.)-1n a recent communication (Comptes Reizd.,THE ANALYST. 93 1898, cxxvi., 1868) the author described certain insoluble or but slightly soluble compounds which mercuric sulphate forms with acetones of the fatty series. When dried at a temperature not exceeding 100" C. those compounds which are formed without secondary reactions have a composition corresponding to the formula [(SO4Hg),.3Hg0],.4[CO.R,~. The readiness with which ordinary acetone forms the insoluble compound, [(S0,Hg),.3Hg0],4[C0.(CH3),], and the high molecular weight of that compound (3,952) as compared with that of the acetone which produced it (4 x 58), enable the formation of this substance to be used as a ready means of detecting and estimating traces of acetone.The mercuric reagent required is prepared by dissolving 5 grammes of mercuric oxide in a hot mixture of 20 C.C. of sulphuric acid and 100 C.C. of water. For the detection of acetone in aqueous solution, which should not contain more than 10 grammes per litre, 2 C.C. of the solution are mixed with 2 C.C. of the reagent and the tube immersed ill a lioiling-water bath, a turbidity or precipitate being formed within ten minutes. The lowest limit of the reaction is reached with a solution containing 2 centigrammes per litre, but the smallest traces can lie detected by distilling the acetone solution and testing the first tenth of the distillate. When the acetone is dissolved in methylic alcohol, 2 C.C. of the solution are mixed with 2 C.C.of water, and 4 C.C. of the mercuric reagent added, the dilution being necessary to prevent the precipitation of the mercuric sulphate on boiling the liquid. I t is possible to detect 3 centigramines per litre after the tube has been left for ten minutes in the boiling water. I n the case of solutions in ordinary alcohol, it is necessary to dilute so that the liquid to be tested does not contain more than 2 per cent of alcohol, since otherwise mercurous sulphate is precipitated on boiling. The limit of sensibility is thus less than with aqueous solutions, and may be taken as 1 gramiiie per litre. I n the quantitative determination of acetone by this method, 25 C.C. of the mercuric reagent are mixed with 25 C.C. of the acetone solution, care being taken that the amount of acetone present does not exceed 50 milligrammes and that the percentage of alcohol in methylic alcohol solutions is not more than 10 or that of ordinary alcohol solutions more than 1 per cent.The flask, with its stopper tied down, is immersed in boiling water for ten minutes. After cooling, the precipitate is collected on a weighed filter, washed with from 75 to 100 C.C. of cold water, dried a t 100" C., and weighed. The aeight of the precipitate, multiplied by 0.06 (the coefficient experimentally determined), gives the weight of acetone in the 25 C.C. of the solution examined. The determination may also be made more rapidly by the author's volumetric lllethod of estimating mercury (ANALYST, xxi., 303), the ainoiint of that metal being determined after the precipitation, the amount precipitated being obtained from the difference between the quantity found and that originally present, and the acetone calculated from the result.The liquid containing the precipitated acetone is diluted to 100 C.C. and filtered. Twenty C.C. of the filtrate are mixed with 15 C.C. of ammonium hydroxide, 50 to 60 C.C. of water, and 10 C.C. of a solution of potassium cyanide, equivalent to a94 THE ANALYST. decinormal solution of silver nitrate. After the addition of a few drops of a solution of potassium iodide (1 : 5) the liquid is titrated with decinormal silver nitrate. As it is necessary that the solution to be examined should not contain more than a certain amount of acetone, a preliminary approximate estimation of the quantity present may be made by observing the time required for a precipitate or turbidity to form when the mixed liquids are heated in boiling water.Two C.C. of the mercuric reagent and 2 C.C. of the acetone solution, diluted with 9 volumes of water, are mixed in a test-tube 16 to 18 cm. long and 18 mm. in diameter, which is kept in boiling water. The time required for the appearance of turbidity in the liquid is shown in the following table : Acetone Grarnrries per Litre. I Time. Acetone Grammes per Litre. I Time. 60 seconds . . . 10 grammes. 1 2+ minutes . . . 0.20 gramnies. 90 2 9 , ~ 4 to 5 minutes ... 0.05 ,, 75 9 , ... 5 9 ) I 3 7 7 ... 0.10 7 , 100 to YO5 seconds 1 ,, I 10 minutes . 0.02 ,, 2 minutes ... 0.5 ,) C. A. M. - ~ _ - - - - - The Purity of Ether used as a Fat Solvent.T. Mathner. (Chern. Zeit., 1899, xxiii., 37.)-The Verband lnndzoirthschaftlic3zer Verszcchsstationen stipulates that the ether employed to estimate the proportion of fat in food-stuffs shall be free from alcohol and water. Even the purest ethers of commerce contain about 0.5 per cent. of alcohol; and this can only be removed entirely by repeated agitation with fresh clean sodium extended over several days. The author has prepared such ether, and has investigated the yields of fat from various materials in comparison with the same solvent mixed with known quantities (1 to 10 per cent.) of alcohol; also using ordinary ethers of the specific gravities 0.720 and 0,722. His results go to prove that extreme freedom from alcohol is not required; the fat increases slightly as the ether becomes more dilute; but in no case, save where the solvent was damp, did the error exceed 0.25 per cent.calculated on the sample, or 9 per cent. calculated on the fat itself, even when 10 per cent. of alcohol was present in the ether. Consider- ing that food-stuffs do not contain a very large proportion of fat, and that they are not specially rich in substances soluble in alcohol, he holds that commercial ether (specific gravity, 0.720) suffices for all industrial analyses, provided it be thoroughly dried by means of powdered quicklime. F. H. 1,. A Comparison of the Methods of Iodine Absorption i n the Analysis of Fats. J. J. A. Wijs. (Chen2. Rev. Fett. 21. Haw. Ind., 1899, vi., 5-11.)-1n a recent com- munication (ANALYST, xxiii., 238) the author showed that in the Hiibl process the main reaction is an addition of hypoiodous acid to the fat.He has now made a comparative examination of Hubl’s method, of Waller’s method (AKALYST, xx., 280). and of his own recently described iodine chloride method (ANALYST, xxiii., 240). He finds that in the Hub1 process the absorption of iodine takes place with great rapidity in the first few moments, and but slowly afterwards. I n addition to the length of time, the stage at which the blank determination is titrated has aTHE ANALYST. 95 considerable influence on the result, as is shown in t h e following table of iodine values obtained with a freshly prepared solution : EARTHNUT OIL. LINSEED OIL. Time of Blank Determination. Blank Determination. 7- Absorption.,- * \ 3, hours ... 87.02 - 173.74 - 7 ?, . . . 88-23 85.38 177.65 170.39 24 9 , ... 90.21 82.32 181.89 163.16 Before .t4bsorption. After -4bsorption. Before Absorption. After Absorption. In the author’s opinion the results obtained by titrating the blank before the absorption are probably the more correct. For the decrease in the amount of thio- sulphate required by Hiibl’s solution on keeping depends on the oxidation of the alcohol by the hypoiodous acid, and thus on the concentration of that acid. When a fat is present this concentration is somewhat reduced by the addition of part of the hypoiodous acid to the fat, but chiefly by the splitting off of acid (HCl) from the addition compound. Practically the whole of the changes brought about by these reactions occur in the first few moments of the absorption, and thus the oxidation of alcohol by hypoiodous acid in the presence of the fat is very much less than in the blank determination.With regard to the time allowed for the absorption, the author prefers the iodine value obtained after seven hours, since he finds that the rapidity with which the iodine disappears (as shown by titration) reaches’its lowest limit after that time, and then commences to rise again. With a Hub1 solution, five days old, it was found that the absorption occurred more rapidly during the first few moments than was the case with the fresh solution, but that the rapidity of the disappearance of iodine (b., I + IC1+ HIO) did not reach its lowest limit until after twenty-four hours. The iodine values obtained for the same linseed oil as before with this solution were : Blank Determination.Before Sbsorption. After Absorption. Time of Absorption. A- - 2 hours ... ... 163.82 7 ?, ... ... 172.20 169.00 24 I j ... ... 177.60 167.03 I n this case the author regards the value 177.60 as the most probable. Similar determinations were made with Waller’s solution. Here it was found that the rapidity of disappearance of iodine (I + IC1+ HIO) was considerably less, reaching its lowest point in the case of earthnut oil after twenty-four hours, and aTith linseed oil only after forty-eight hours. The iodine values thus obtained with the same oils were : EARTHNUT OIL. LINSEEl) OIL. Time of Blank Determination. Blank Determination. Absorption.-A- -’- 24 hours ... 86.98 86.85 170.67 170.11 48 ?, ... - - 171.45 170.37 With a strongly acid solution, like that of Waller, the splitting off of hydro- chloric acid from the addition compound does not take place, or at most does so to Before Ak)ssorption. After Absorption. Before Absorption. After Absorption.96 THE ANALYST. a trifling extent. Hence the concentration of the hypoiodous acid in the solution remains about the same throughout the absorption, and the author therefore considers the iodine values obtained when the blank is titrated after the absorption as probably the more correct, although the difference is small. As the results obtained by Waller's method are usually somewhat lower than the Riibl value, it is possible that the absorption is not quite complete, even after the twenty-four and forty-eight hours given in the above experiments.The statement frequently made, that the values given by the Waller solution are higher than those of the Hiibl process, is to be attributed to the blank determination having been titrated at the end of the absorption. With the author's solution of iodine chloride in glacial acetic acid (ANALYST, xxiii., 240) the experiments showed that the absorption was complete after fifteen minutes with earthnut oil and after an hour with linseed oil, the further absorption in each case being practically nil. The following table gives the amount of iodine absorbed by the oils in one minute and its percentage of the actual iodine value in the case of the different solutions ; EARTHNCT OIL.LINSEED OIL. of I. A'bsorbed in Per cencof 1 Minute. Iodine Value. 1 Minute. Iodine Value. Iodine chloride in acetic acid 86.91 98.9 174.07 98.1 Hiibl solution, 16 hours old 82-54 93.9 152.46 85 -9 9 , 128.90 72.6 ,, 5 days old ... - - Waller's solution . . . ... 73.52 83.6 102.64 57.8 summarized : The different final values obtained in the experiments described above are thus EARTHNUT OIL. LINSEED OIL. F- 'P -- Value. Value. Hiibl solution, 16 hours old 82.32 90.21 88.23 163.16 181.89 177.65 Hub1 solution, 5 days old ... - - - 163.82 177.60 177.60 Waller's solution 86.85 86.98 86.85 170.11 171.45 170.35 Iodine chloride in glacial acetic acid ... ... - - 87.93 - - 177.37 I n order to determine to what extent the iodine value serves as a measure of the compounds with two unsaturated bonds which occur in fats, the iodine values of a number of unsaturated fatty acids were determined by means of the iodine chloride solution with the following results : Solution.Minimum. Most Probable Minimum. R/Iaximum. Most Probable Melting-point, Acid Value. Iodine Value. "C. -7 - Calculated. Found. Calculated. Found. Erucic acid ... 32 165.7 165.2 75-15 749 Brassidic acid ... GO 165.7 165.0 75.15 75-0 Elaidic acid ... 44 198-6 198.4 90.0'7 90.0 Oleic acid* ... - 198.6 184.3 90.07 87.6 Undecylic acid.. . - 304.3 292.9 136.6 133.1 c. A. nir. * Bought as free from linolic acid.THE ANALYST. 97 Per cent. 174-7 169.7 178.0 167.5 168.0 178.8 The Heat of Bromination Test for Oils. A. H. Gill and J. Hatch. (Joum. Amey. Chem. Soc., 1899, xxi., 27-29.)-1n order to render the results obtained with different calorimeters comparable, the authors propose to refer the rises in tempera- ture to a standard, as in the Maumeni! test, They find that sublimed camphor can be obtained in a sufficient state of purity to serve as the standard material.The rise of temperature on brominating the camphor is determined in the apparatus and by the method chosen, and the rises in temperature of the various oils are divided by this number, thus giving a '' specific temperature reaction." The following results were thus obtained by a method which was substantially the same as the modification proposed by Wiley (ANALYST, xxi., 210). The factor 17.18 was obtained by dividing several of the Hubl values by this specific temDer a ture .Per cent. -- 180 180 178 178 168 178.8 I Oil. Neat 's-fGot Tallow. . Prime lard Sperm ... No. 1 lard Olive ... Cotton-seed Corn ... Cod ... Linseed 0-938 59.5 101 169.5 0.934 , 52.5 103 160.0 0.932 60 105 162.0 0.934 1 73.5 I 135 ' 157.0 0.931-0-937 1 57-74 103-126 - 0.934 t - 111 I -__I___- ---- Specific Temperature Reaction. ... ... 3.286 ... ... 3.348 . . I ... 3.715 ... ... 4.191 ... ... 4.096 ... ... 4.762 ... ... 5.667 1 . . ... 6.381 ... ... 8.002 ... ... 9.049 171 160 162 181 170-18E I76 Iodine Value. Calculited. 56.5 57.4 63.8 72.1 70.3 81.8 97.3 109.5 137.4 155.6 Determined (Hubl). 59.1 57.2 63.8 73.2 73.9 82.0 103.0 107.8 135.0 160.0 C. A. M. The Analytical Constants of American Linseed Oil. A. H. Gill and A. C. Lamb. (Journ. Anzer.Chern. SOC., 1899, xxi., 29, 30.)-The following results were obtained by the authors with samples of linseed oil representative of all the principal brauds in the market. I n applying the Maumeni! test the oil was mixed with a heavy petroleum and allowed to stand for an hour or two before adding the sulphuric acid, a correction being made for the addition. All the results are stated to be the mean of two closely agreeing determinations. .- _-- - - _ _ _ -- I I I Iodine 1 Iodine ' Specific Gravity I Valenta i Maurnen4 abeorbed ~ absorbed 1 at 15" C. , Test, "C. I Test, "C. I Brand. I 1 ----- I I Western raw.. . ... i 0.933 ~ 79 I 97 Old 'balcutta ... ... i 0.931 . 71.5 . 106 9 , 0.932 70 90 * . . I 73 105 Eastern oil ... ... 1 0-931 73 1 105 ?, -.. ,, special , 0.934 Western boiled ...Eastern ... Acid bleaciid Bleached without acid Menhaden oil ... Usual constants ... Average ... ... -. - _____~____ 0.936 I 74 ~ 100 - ~ _ Drying Test. Holm required. --- 72 72 72 72 72 18 IS 84 84 84 --98 THE ANALYST. It is pointed out that these results differ from the usually accepted values in the Maumen6 figure being about 10 per cent. higher and the iodine value about 4 per cent. lower. Menhaden oil was examined because it is frequently used to adulterate linseed oil. C. A. 35. The Deteotion and Estimation of Earthnut Oil in other Oils. J. Bellier. ( A m . tZe C'hina. nnnl., 1899, iv., 4-9.)-0ne C.C. of the oil under examination is saponified in a tube with 5 C.C. of an alcoholic solution containing about 85 grammes of potassium hydroxide per litre.1.5 C.C. of dilute acetic acid, exactly neutralizing the 5 C.C. of the alkali, is then added, and the whole well shaken. The solution of potassium acetate and fatty acids in 70 per cent. alcohol is now cooled rapidly by shaking the tube in water having a temperature below 20" C, Owing to the presence of the potassium acetate the arachidic acid and other solid fatty acids are precipitated in a very short time. When the precipitate ceases to increase, 50 C.C. of 70 per cent. alcohol containing 1 per cent. by volume of hydrochloric acid are added, the tube shaken and placed in water at 17" to 19' C. When the oil contains more than 10 per cent. of earthnut oil, the alcohol leaves a more or less abundant precipitate of arachidic acid. If the quantity is less than 10 per cent., the liquid in the tube remains clear, or nearly so, at first, but after being left for thirty minutes in the water a cloudiness, which masks the bottom of the tube, can be observed.With pure oils, the liquid remains perfectly transparent throughout the whole time. In this test, the majority of olive oils give a solution which remains absolutely clear even below 16" C. But with certain rare specimens of Tunis olive oil which contain a large amount of solid fatty acids, with cotton-seed oil, and with sesame oil, the liquid may be turbid after the addition of the 70 per cent. alcohol. To distinguish these oils from earthnut oil the temperature is slowly raised until the liquid just becomes clear, and the tube is then placed in water at 17" to 19" C.After thirty minutes, olive, cotton-seed, or sesame oils remain transparent, while in the case of earthnut oil the turbidity is reproduced. The author states that no mistake is possible with an oil containing more than 5 or 6 per cent. of earthnut oil. For the quantitative determination of earthnut oil, 5 grammes of the oil are saponified with 25 C.C. of the alcoholic potassium hydroxide solution and a volume of dilute acetic acid, exactly neutralizing the alkali taken, is added. The liquid is then rapidly cooled by immersing the vessel in water. After an hour the precipitate is collected on a filter, washed with 70 per cent. alcohol containing 1 per cent. of hydro- chloric acid, the temperature being maintained between 15" and 20" C., and the washing continued until the filtrate does not become perceptibly turbid on the addition of water. The precipitate, which contains other acids besides arachidic acid, is dissolved off the filter with 25 to 50 C.C.of boiling alcohol (92 to 93 per cent.), From 8 to 16 C.C. of water are added to the solution in order to reduce the strength of the alcohol to about 'TO per cent., and the liquid is then cooled for an hour in water at a temperature below 20" C. The arachidic acid which precipitates is collected on a dried and weighed filter, washed with 70 per cent. alcohol (free from hydrochloric acid) untilTHE ANALYST. 99 0.030 ~ 0.030 0.71 Sesame oil (Jaffa) 0.71 ICotton-seed oil (purified) the filtrate remains clear- on the addition of water, dried at 100" C.and weighed. The melting-point of the acid thus obtained is usually about 72" C. From the weight of the acid obtained from pure Bordeaux earthnut oil (021 gramme), the coefficient of the oil is o m ~ = 2 3 81. This figure is higher than Renard's coefficient (22). The author considers that this method is capable of rapidly estimating earthnut oil when present in greater proportion than 2 per cent. Of all the oils (other than earthnut oil) examined, only one (Tunis olive oil) gave a pre- cipitate corresponding to about 1.5 per cent. of earthnut oil, as is shown in the 100 0.030 0.020 0.48 following table : -. - . . . . Oil. Bordeaux Earthlzut oil Marseilles Olive oil +5% Earthiut oil 0l;;e oil (Nice) 9 , 7 , +lo% ,? 9 , 9 9 +go% ,, 9 9 9 , ,, (superfine) 2 , 9 , 9 , 9 , u s I 4.20 100*00 Olive oil, Tunis (Sousse) I 0.020 0.21 1 5.00 ,, ,, ,, I 0.060 0.84 20.00 I ), ,, 9 7 I 0.040 -- _-- I- -- 4.17 ~ 99.28 ~ ,, ,, ,, (Sfax) 0.010 0.42 I 10.00 I ,, ,, African lO.010 - 0.4s 0.24 1.44 0-24 0.95 0.72 The following specimens of olive oil gave only a slight turbidity : Calabrian, Nice superfine, Tunis (Sousse), St.Denis, and Algerian. With olive oils of the following origin the liquid remained perfectly clear : Var olive oil (recent), Var (old), Corsican, Spanish, Italian, Italian (Bari), Nice (fine and superfine) and a sample of unknown origin. C. A. M. A Method of Separating Citronella1 and Citral. J. Flateau and H. Labb6. (BzdZ. SOC. Chim., 1898, xix., 1012-1013.)-The aldehydes citral or geranial (C,,H,,O) and citronella1 (C,,H,,O) are found together in the different essential oils of andropogon and in oil of lemon-grass.They can be prepared by the oxidation of their correspond- ing alcohols, but the yield is small, and in manufacturing processes they are invariably obtained from the essential oils in the form of their bisulphite compounds, and freed more or less completely from other substances by pressure. The only method of differentiating the two aldehydes hitherto known is that of Doebner, which consists in converting them into the respective citryl- and citronnellyl- P-naphtho-cinchonic acids, which have different melting points, but according to the authors this is only applicable to qualitative work, and cannot be used as a practical means of separation. They have found that on treating an aqueous solution of the bisulphite compounds (prepared by treating the aldehydes for two or three hours with a solution of sodium bisulphite containing a third of its volume of ether, while the temperature is kept low) with a solution of barium chloride, the citryl suiphite100 THE ANALYST.remains in solution, while the citronellyl sulphite is precipitated quantitatively as a barium salt with the composition C,,H,,O,S,Ba. This salt is insoluble in hot alcohol, ether, benzene, and petroleum spirit. It does not dissolve in cold water, but is partially decomposed in boiling water. The citronellal can be recovered by saponifying the salt with a 10 per cent. alcoholic solution of potassium hydroxide, removing the insoluble barium salt by filtration, passing a current of carbon dioxide through the filtrate to remove the excess of alkali, filtering again, precipitating the aldehyde by water, washing it, extracting it with ether, and purifying it by fractional distillation.By this process the authors found from 5 to 6 per cent. of citronellal in various oils of lemon-grass. The whole of the citral (which is employed commercially as the crude material in the manufacture of ionone) could be recovered from the filtrate from the barium precipitation. C. A. M. The Characteristics of Essence of Neroli and Essence of Petit-grain. E. Charabot and L. Pillet. (BUZZ. Xoc. Chim., 1898, xix., 853-857.)-The essential oil of petit-grain contains limonene, C,,H,, ; linalol, C,,H,, OH (in the free state and as an acetic ester), a terpene, C,,H,, ; and, according t o Passy (BzcZZ.SOC. Chim., xvii., 519), geraniol, geranyl acetate, and other oxygenated substances. According to Tiemann and Semmler (Berichte, xxvi., 271) essence of neroli contains about 20 per cent. of limonene, 30 per cent. of lmo-rotatory linalol, and 40 per cent. of linalol acetate. The saponification value given by Schimmel and Co. is 38, but the authors point out that this does not agree with the percentage of ester found by Tiemann and Sernrnler. As petit-grain is the oil most frequently employed for the adulteration of oil of neroli, the authors have examined a number of authentic samples which they had themselves distilled. They find that the specific gravity of neroli varies from 0.8720 to 0.8760 at 15" C., and that of petit-grain from 0.8910 to 0.8940.Other characteristics of the two oils are shown in the subjoined table : Refractive index 71 I) 1 ' +3-12 I 2 +3.57 3 +2-15 4 +3*18 5 +4*03 6 +3.42 7 +1*42 8 + 3 5 4 ~ 9 + 4-06 1-474 at 18" 1.475 ,, 18" 1.473 ,, 20" 1.473 ,, 20" 1.473 ,, 20.5" 1.473 ,, 20" 1.470 ,, 21" 1-472 ,, 20" 1.474 ,, 19.5" -~ - _ _ -~ Solubility in 80 per Essence I cent. alcohol a t of Petit- I I 20" c. 2 in 3.1 1 1 2 ,, 2-9 2 1 2 ,, 2-6 1 3 1 2 ), 2.9 4 1 2 ,, 3.1 6 ; I 2 ,, 2.7 ~ 8 1 insoluble I I 2 ) ) 2.9 ' 5 1 2 , 9 2 6 7 i I Rotatory power a t 15" C. - 5.54 -'5*12 - 6.15 - 5.57 - 5.33 - 4.45 -- 6.00 - - 5.45 . Solubility in 80 per cent. alcohol. 2 in 2 2 ,, 2.0 2 ,, 2.1 2 ,, 2.2 2 ,, 2.1 2 ,, 2.1 2 ), 2.1 2 ,, 2.2 The rotatory power which, contrary to what might be expected from Tiemann and Semmler's researches, is dextro-rotatory, can.thus afiord a valuable indication of the purity of neroli oil, the dextro-rotation being increased by an addition of oil ofTHE ANALYST. 101 lemon, orange, or bergamot, and reduced by essence of petit-grain. The solubility in alcohol increases with the age of the oil. The insoluble sample (9) was a mixture of different specimens distilled in 1897. A further difference between the two oils is that neroli contains a large proportion of a dextro-rotatory fraction distilling at about 179" C., whereas in the first distillation of petit-grain no fraction is obtained near that temperature. For a determination of the esters, from 2 to 3 grammes of the oils were heated on the water- bath for thirty minutes with semi-normal alcoholic potassium hydroxide. the residual alkali titrated, and the amount corresponding to the esters expressed as linalol acetate, C,,H,70C0.CH,.PERCENTAGE OF ESTERS AS LINALOL ACETATE. No. of sample ... ... 1. 2. 3. 4. 5. 6. 7. 8. 9. Essence of neroli 14.4 10.1 18.0 16% 13.4 15.1 16.7 12.1 14.5 Essence of petit-grain 54.9 55.9 60.7 59.2 69.6 51.5 61-1 63.7 - The following results were thus obtained : Oil of bergamot contains about 38 per cent. of esters, and an addition of it to neroli would also be shown by the increase in the quantity thus determined. Since both the oils lost their odour on saponification and acquired that of linalol, the authors consider that their characteristic perfumes are due to the different natures of the esters, the alcoholic constituents of each being apparently identical.C. A. M. The Composition of Oil of Thyme. H. Labbe. (Bull. SOC. Chim,, 1898, xix., 1009-1011 .)-On treating 500 grammes of essential oil of thyme with aqueous solution of potassium hydroxide, the author obtained 160 grammes of thymol. The substances insoluble in the above solution were washed, dried, and fractionally distilled, the following fractions being obtained : Between 155" and 158" C., about 83 grammes ; 165"-169", about 67 grammes ; 174"-177" about 70 grammes ; 180"-184", about 30 grammes ; 195"-200", about 15 grarnmes ; 200"-215", about 28 grammes. The portion distilling between 155" and 158" was a hydrocarbon, which from the melting-point of its nitroso-chloride (106.5") was proved to be distinct from pinene, the presence of which was noted by Schimmel and Co.in thyme oil. The second fraction (165"-169") had the same boiling-point as menthene, with which substance it was identified by the melting-point of its nitroso-chloride (113"-113*5"), and by the fact that on oxidation with permanganate it yielded cymene. The fraction which distilled over between 174" and 177" had the characteristic odour of cymene, and like that substance yielded terephthalic acid on oxidation. The fourth fraction (180"-184" C.) also had the odour of cymene, and yielded the same oxidation products. Hence, the author considered it probable that the third and fourth fractions consisted of a mixture of different cymenes boiling at from The next fraction (195"-200") was identified as linalol by its odour, and by being converted into geraniol on heating in a sealed tube at 150" C.with an equal volume of acetic anhydride. 174"-184" C.102 THE ANALYST. In the fraction boiling between 200" and 215" C. borneol was identified by Schimmel and Co's. method of oxidizing it to camphor by means of bichromate. The nature of the residue was not determined. From the results of his determinations the author gives the following as the percentage composition of oil of thyme : Thymol, 30 ; hydrocarbon (156"-158"), 17 ; nienthene, 15 ; cymene, 21 ; linalol, 5 ; borneol, 8 ; residue, 4. He points out that the valuation of the oil should not, as is customary, be based solely on the proportion of phenols which it contains, since the other compounds, such as linalol and borneol, have also pronounced odours, which contribute to and modify the perfume of the essential oil.C. A. M. On the Estimation of Glucose. Msquenne. (Bd. SOC. Chim,, 1898, xix. 926.)-The author simplifies Lehmann's method of determining glucose by titrating the unreduced copper, and by having a large excess of sulphuric acid in the liquid which obviates the filtration. Ten C.C. of Fehling's solution (Pasteur's formula) are mixed with a quantity of the glucose solution containing less than 50 milligrammes, and water added so that the total volume of the liquid is exactly 30 C.C. The whole is then rapidly heated, boiled for two minutes, cooled, and after the addition of 20 C.C. of dilute sulphuric acid (1 : 1) and 10 C.C.of a 10 per cent. solution of potassium iodide, titrated with 2 per cent. thiosulphate, using starch as indicator. The difference between the number of C.C. required by the original Fehling's solution and by the liquid after titration gives tho amount corresponding to the glucose. The following table gives the volume of the thiosulphate solution corresponding t o known quantities of saccharose inverted by the ordinary method. 2.5 ... 0.90 , 30 .., 10.95 5 ... 1-80 1 35 ... 12.70 40 ... 14.45 5-65 45 ... 16-15 50 ... 17.80 Sugar, milligrammes. Thiosulphate, C.C. ' Sugar, milligrsmmes. Thiosulphate, C.C. 3.75 i 10 ... 15 ... 20 ... 7-45 25 * * I 9.20 ! c. A. M. Test for Albumin in Urine. W. C. Alpers. (Amer. Jozirn. Pharm., 1898, lxx. 449-451.)-The test for albumin consists in acidifying the urine with hydrochloric acid, and adding an equal volume of a 1 per cent.solution of mercury succinimide. In the presence of as little as 1 part of albumin in 150,000, a white cloudiness is obtained. C. A. M. - - Tho Influence of Food Preservatives on Digestive Enzymes. H. Lefienn. ( J02~t-n. FrankZin lizstit., 1899, cxlvii., 97-108.)-The enzymes used in the author's experiments, which had reference principally to the digestion of starch, were : Malt diastase (Merck) ; pancreatic extract (Parke, Davis and Co.); peptenzyme, a preparation containing all the digestive ferments of the alimentary tract (Read and Csmick);THE ANALYST. 103 and papaln, the enzyme of papaw sold under the name of “caroid.” I n each experiment 50 C.C.of a freshly-prepared solution of arrowroot-starch (10 grammes per litre) were used. The following results were obtained in a series of experiments with taka-diastase 11 milligramrnes of the enzyme and 50 milligramines of the preservatives being used in each case, and the solutions diluted to 150 C.C. after the digestion : 1. Salicylic Acid : Showed starch reaction strongly, and only traces of sugar ; 133 C.C. of the solution did not reduce 10 C.C. of copper solution (equivalent to 0.046 gramme of dextrose). 2. Sodium Benzoate : No starch present ; much sugar formed. 3. Saccharin : Much starch present ; traces of sugar. 4. Boric Acid : No starch present ; much sugar formed. With pancreatic extract solution the results were : Salicylic acid.. . Sodium benzoate Saccharin .. . Boric acid ... Salicylic acid.. . Sodium benzoate Saccharin . . . Boric acid ... Milligranimes. ... 50 ... 50 ... 50 ... 50 ... 50 ... 50 ... 50 ... 50 Pancreatic Solution, C.C. 1 1 1 1 3 3 3 3 30 sugar formed. Much sugar formed. No sugar formed. Much sugar formed. No sugar formed. Much sugar formed. Trace of sugar formed. Much sugar formed. Saccharin in small quantities (10 milligramrnes) interfered with the digestion of starch by taka-diastase (10 milligrammes), by papain (20 milligrammes), and to a lesser extent by peptenzyme. Formalin ( 3 c.c.) did not affect taka-diastase (I1 milli- grammes), but 1 C.C. had an injurious effect on pancreatic extract (1 c.c.). From the results of these and similar experiments which are given in tabular form, the author has arrived at the following general conclusions : Beta-naphthol is injurious to malt diastase, but does not seriously affect the starch-converting capacity of the taka-diastase or pancreatic extract.Boric acid, borax and boroglyceride, interfere but little with either starch or proteid digestion. Salicylic acid interferes with the action of most of the enzymes, especially those that convert starch, but does not seriously affect proteid digestion. Sodium benzoate has no appreciably injurious influence on any of the enzymes. Sodium fluoride interferes but little with the digestion of starch, but sodium silicofluoride has a considerable influence on pancreatic extract. In the author’s opinion, if the use of any preservative is to be permitted in food, boric acid and sodium benzoate are the least objectionable, since they appear to have less tendency to disturb the digestive functions than the other preservatives commonly employed.C. A. &I. Estimation of Humus in Soil. C. Aschmann and H. Faber. ( C h m Z c i t . , 1899, xxiii., 61.)-This process depends on dissolving the humic acid in alkali, and titrating the liquid with permanganate. Solutions required : Sodium hydroxide104 THE ANALYST. 50 grainmes per litre ; perrnanganate, 0.32 granime of the potassium salt per litre ; oxalic acid, 0.63 gramme per litre ; 1 : 5 sulphuric acid. To standardize the reagent, the strength of the oxalic acid must first be ascertained in terms of the perman- ganate. 0.125 grarnme of pure humic acid (Merck) is dissolved in 500 C.C.of water with the aid of sodium hydroxide. To 5 C.C. of the solution and 100 C.C. of water pernianganate is added until the colour remains constant ; after five minutes 10 C.C. of oxalic acid are added, and the end-point of the reaction is determined in the usual manner by titrating the excess with permanganate. In carrying out the actual analysis, 25 grainmes of air-dried, finely sieved earth are heated for an hour on the water-bath with 100 C.C. of the sodium hydroxide solution. The solution is removed by decantation and the insoluble matter treated similarly several times. The liquid is finally diluted to 510 C.C. (allowing 10 C.C. for the deposit), and after standing some days to clarify (filtration is to be avoided), is ready €or titration, 5 C.C.being manipulated exactly as above. In order to obtain accurate results, the proportion of huinic acid present in the extract should not greatly exceed that employed during the standardization of the permanganate, a point which can be settled by comparison of their respective colours, and adjustment of the volume of the solution obtained from the soil. As examples of the amount of humic acid in various soils, the following may be quoted : Good garden mould ... I . . ... . . . Highly manured hotbed ... ... ... Forest earth, upper layer . . . ... ... ,, subsoil ... ... ... Soil from tan-pit, upper layer ... ... ,, under ground ... ... Field earth, extremes ... ... ... ,, ,, average ... ... ... ... 9 , 9 , Per cent. 1-87 5 *5-11.5 0.88 0.3 1.25 0.44 0 *05-1.7 0.5-0.7 F.H. L. Combustion of Mixed Gases containing Carbon Monoxide, Methane, and Hydrogen. (Zeits. anoyg. CImz., 1899, xix., 179.)-The authors remark that there are objections to all processes for the analysis of gaseous mixtures which depend on absorption of hydrogen with palladium or of carbon monoxide with cuprous chloride; and they fall back on the old explosion methods, so modified by the aid of suitable apparatus as to avoid liability to exces- sive pressure, which may cause the formation of oxides of nitrogen, if not actual danger to the operator. The apparatus which they have adopted resembles that of Winkler, and is shown in the acconipanying illustrations. The rubber cork u (Fig. 1) carries a glass tube b open at both ends, in which a copper wire c, 3 mtn.thick, is held air-tight by a rubber ring. The second copper wire, 1.5 inm. in diameter, is pushed through the cork and twisted round the glass tube till it reaches the top of c ; and a platinum spiral d, of twenty or thirty coils, 2 mm. in diameter, made of wire 0.25 inm. thick, the ends of which are wrapped round the copper conductors, forms the source of heat. The general arrsngenient of the apparatus is L. M. Dennis and C. G. Hopkins,THE ANALYST. 105 explained by Fig. 2 : 0, o are clips ; ZG is a screw clamp. ordinary Hempel burette fitted with a water-jacket. The measuring vessel is an F is a means of varying the resistance, so that d may be kept at the desired temperature. is mercury which bears a drop of water on its surface to insure perfect saturation.The volume tfl The 9 of gas operated on is selected so that neither it, nor the neces- sary oxygen, nor the residue after explosion, shall exceed 100 C.C. The pipette is filled with mercury by opening 9 and raising the reservoir, then closing 9 and applying a vacuum pump to t till the air in b is extracted. A measured quantity of the sample is intro- duced, and a known excess of oxygen brought into the burette, which are both kept ~~ sealing liquid 0 FIGURE 1. at about atmospheric pressure k is closed, the burette-reservoir is raised to such a position that the mercury shall eventually fill the burette entirely without passing over into the pipette. Electrical connections are then made, the spiral FIGU1:E 2. heated t.0 redness, 0 , o are opened, and k is cautiously unscrewed till the oxygen flows into the pipette at about 10 or 20 C.C.per minute. The exact F speed is chosen so that the spiral re- m a i n s incandes- cent, and it heeds to be increased in - inverse proportioii to the molecular weight of the ma- t e r i a1 examined. The combustion proceeds quietly without flame or explosion ; but if pure hydrogen be under treat- ment, it is necessary, owing to the excessive contraction, to employ a mixture of oxygen and air, and also to diminish the force of the current as the operation proceeds, lest the platinum melt in the final atmosphere of oxygen and nitrogen.106 THE ANALYST. Mixtures of hydrogen, methane, and nitrogen were prepared from ordinary coal- gas by absorbing the heavy hydrocarbons in fuming sulphuric acid, the oxygen in alkaline pyrogallol, and the carbon monoxide by double treatment with cuprous chloride. A known volume (60 to 67 c.c.) of the gas was then burnt with a known amount of oxygen, the residual volume was noted, the carbon dioxide absorbed by potassium hydroxide, and the final residue measured.Five successive tests showed from 56.4 to 56.6 (mean 56.44) per cent. by volume of hydrogen, and 39.9 to 40.0 (mean 39.94) of methane; corresponding experiments with 12 C.C. in a Hempel pipette giving 55.85 of hydrogen and 41-10 methane. Mixtures of hydrogen, carbon monoxide, methane, and nitrogen similarly prepared yielded equally satisfactory results, the greatest variation froin the average proportion of hydrogen being 0.37 per cent. when analysing a mixture containing 53.7 per cent. In the latter case the process is carried out as follows : A measured volume of the gas is burnt with a measured excess of oxygen, the residue is driven over into the burette and measured, the carbon dioxide is removed by potassium hydroxide, and the volume again noted. A known amount of hydrogen is introduced into the pipette, the current is again started, and the remaining mixture of nitrogen and oxygen forced back gradually until all the gas is in the combustion pipette once more. From the amount of contraction which then occurs the excess of oxygen can be calculated, and the difference between this figure and the original quantity of oxygen employed gives the volume of oxygen actually used in the first com- bustion. By means of these data ’the composition of the gaseous-mixture may be deduced thus : V = the original volume of the sample ; K = the contraction during the (first) explosion ”; 0 =the volume of oxygen required to oxidize V ; GO, = the volume of carbon dioxide already determined : 1. H = K - 0 . 4CO t H - 2 0 2. co= ... 3 3. CH,= CO, - CO. 4. N=V-(H+CO+CH,), or, 5. CO = CO, - CH,. 2K - CO-- 3H 3 6. CH,= . - 2 I n the absence of nitrogen, these formuke may be substituted : 7. 8. 9. H = V - GO,. 2c0, + 2K - 3v 3- CH,= ~ F. H. L.THE ANALYST. 107 ,It = 14,000 for ill’= 2 to 12 =12,000 ,, =12 to 17 =11,000 ,, -17 to 24 = 10,200 ,, =24 to 30 d = 9,400 for M’ = 30 to 35 -8,000 ,, = 3 5 to 38 =7,900 ,, =38 to 40 =7,600 ,, =40 to 50 Calorific Power 1 Calorific Power , calculated by Goutal’s modified i formula. Coal. I 1. New Pitsburgh, A 1 6,288 2. New Pitsburgh, B ~ 6,502 3. Lancaster 1 6,694 4. Brazil , 6,721 5 . Shelburn 6,492 6. Shop 1 5,823 ~ ~ _ _ _ determined with ifferenee. , Percentage Hempel’s calori- Difference. meter. ,- ~ 6,175 + 113 + 1-85 6,415 + 87 6,703 -7 6,846 -125 6,532 -40 5,806 + 17 - - - - + 1.35 -0-10 -1.90 -0.60 + 0.30 .- - C. ,4. M.

ISSN:0003-2654    

DOI:10.1039/AN8992400092

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

3 08 THE ANALYST. I NO RGAN I C AN A LYS IS. Electrolytic Estimation of Tin in Tin Ores. E. D. Campbell and E. C. Champion. (Joum. Amer. Chem. Xoc., 1898, xx., 687-690.)-0ne gramme of the finely-powdered ore is treated with sodium carbonate and sulphur, in the usual manner. When cold the mass is dissolved in 40 to 50 C.C. of water, and filtered from the insoluble oxides and sulphides. The solution contains nearly all the tin in the form of sodium sulphostannate, and the small quantity left in the residue is fused as before and brought into aolution. The united solutions are made weakly acid with hydrochloric acid, and the tin precipitated as tin sulphide. The liquid which contains the stannic sulphide in suspension is then boiled to expel the excess of hydrogen sulphide, and concentrated to about 75 to 80 C.C.Ten C.C. of hydrochloric acid (specific gravity 1-20> are added to the hot solution, and small quantities of sodium peroxide stirred in until the tin sulphide is com- pletely converted into oxide and the solution has become clear. The liquid is boiled two or three minutes, filtered from the sulphur into a large platinum dish, and the residue washed with hot water. Ammonia is added to the solution until a permanent precipitate results, and then 50 C.C. of a 10 per cent. solution of ammonium oxalate, and the clear liquid is electrolyzed over night with a current of N D,,, = 0.10 A and 4 V. When the tin has been completely precipitated the deposit is washed with water and alcohol and dried at 80 to 90" C., and the dish weighed. The deposit is finally dissolved off the basin with dilute hydrochloric acid, and the weight of the washed and dried platinum basin determined.C. A. M. Iodometric Estimation of Gold and Platinum. H. Peterson. (Zeits. anorg. Clzem., 1899, xix., 59.)-The De Haen process for the determination of copper (Fresenius, Quant. Anal., i., 335), which depends on the addition of an excess of potassium iodide to a solution of copper free from any substances capable of decom- posing the reagent, and titrating the liberated halogen by means of thiosulphate, is equally available in the case of gold and platinum. With the latter, the dark reddish-brown liquid produced when a strong solution of iodide in excess is mixed with the double platinic chloride should be treated with standard thiosulphate (without starch) till the colour changes to a pale lemon yellow ; 1 atom of platinum corresponding to 2 molecules of thiosulphate.Gold is similarly treated in the presence of starch ; but, as an intermediate reaction takes place between the aurous iodide and part of the reagent yielding the compound NaAuS,O,, 1 atom of gold corresponds to 3 of thiosulphate. Both methods should be useful where only small amounts of the respective metals have to be estimated; and in many instances cupellation of gold samples may thus be avoided. F. H. L. Qualitative Separat,ion of the Platinum Metals. F. Mylius and R. Dietz, (Bey., 1898, xxxi., 3191.)-The following process is published as an appendix to an article on the characteristics and purity of the _several platinum metals now metTHE ANALYST.109 with in commerce ; it does not profess to give absolutely complete separations, but is the simplest that can be devised. The amount of material operated upon should contain about one gramme of the platinum metals; and beside gold and mercury, the common metals may be present in the neutral or acid solution as chlorides. Platinum alloys may be run down with lead, which converts iridium and ruthenium into an insoluble form, leaving the others soluble. The solution, mixes with nitric acid, is distilled in a retort and the vapours led into caustic soda. If the liquid becomes yellow, osmium may be present, and can be identified by the odour of its tetroxide on addition of hydrochloric acid, or by the production of its brown sulphide when the acid liquor is warmed with thiosulphate.The cold residue from the retort is extracted, three times if necessary, with a little ether. Should this become yellow, gold is indicated (chromic acid also gives a colour varying from yellow to blue, and ferric chloride may equally tint the ether), and may be tested for with ferrous sulphate, etc. The residual solution is treated with amnionium acetate, and boiled for several hours with formic acid under an inverted condenser in order to throw down the noble metals. The precipitate is filtered off, washed with acetate solution, dried and ignited in a porcelain boat in a stream of hydrogen. Mercury yields the well-known metallic sublimate. The residue is extracted with warm HC1 (to remove traces of tin and other heavy metals not reduced by the formic acid), dried, mixed with common salt, heated as before to dull redness in a current of damp chlorine, and the product leached with water.Any insoluble matter must be repeatedly submitted to the same process ; should any portion resist the chlorine, it k u s t be further examined for iridium and ruthenium. To the aqueous solution from the ignition in chlorine, saturated ammonium chloride is added as long as a precipitate (B) falls, which should consist of Pt, Ir, and Ru ; Rh and Pd remaining theoretically in solution (A). If dark in colour, (B) is dissolved in warm water, treated with hydroxylamine hydrochloride, cooled, and precipitated again with ammonium chloride. The deposit is recrystallized twice, if necessary, and identified as pZatirz.zm under the microscope.The hydroxylamine converts the bichlorides of I r and Ru into sesqui- chlorides ; their solution is evaporated to dryness, ignited in hydrogen, and fused with nitre and potash in a silver crucible. The melt is attacked with water and separated by decantation into a blue-black residue (C) and a solution (D). (D) is saturated with chlorine, and distilled from a retort as long as the vapours are coloured into weak alcohol containing HC1. A yellowish-brown colour indicates ruthenium, which, volatilizing as tetroxide, now exists as chloride. Its presence may be corroborated by rendering the liquid ammoniacal and adding thiosulphate : a strong red-violet colour is produced. (C) is washed, dried, ignited with salt and chlorine, and taken up in water ; iridium yields a dark-brown solution, from which ammonium chloride precipitates the double salt.(A) is slowly evaporated with excess of ammonia, and the residue crystallized from weak cold ammonia; any insoluble matter, consisting generally of Ru, is removed by filtration. Rhodium separates as yellowish crystals of Rh(NH,),Cl,, soluble in hot, strong sulphuric acid with a yellow colour. (It should be noted that ignition with salt and chlorine gives a pink aqueous extract, from which Rh is not thrown down by NH,C1 in dilute solution, cf. A and B above.) The ammoniacal filtrate is acidified with strong HCl110 THE ANALYST. when palladium falls as Pd(NH,),Cl,. It is purified by ignition in hydrogen, solution in nitric acid, evaporation, dissolution in water, and precipitation with mercuric cyanide.F. H. L. Estimation of Manganese by means of Potassium Permanganate. F. W. Daw. (Chemical News, vol. lxxix. [2043], p. 25.)-To obviate the sources of error usually present-non-elimination of organic matter, excessive use of zinc oxide, and standard- izing the reagent against iron instead of manganese-the author proposes the following method : 0.5 gramme of spiegel or ferro-manganese-together, in the latter case, with 0.4 gramme of pure iron wire-is dissolved in 30 C.C. of hydrochloric acid (the iron being oxidized with a little nitric acid), and 15 C.C. of 50 per cent. sulphuric acid added. After evaporation until a copious disengagement of acid fumes ensues, the sulphates are taken up with water and the solution made up to about 500 C.C. The acid is then partly neutralized with sodium carbonate, and the iron thrown down by a gradual addition of zinc oxide, a large excess being avoided.The whole is boiled up, and, without filtering, titrated with permanganate solution (10 grammes per litre, stand- ardised against ferro-manganese of known composition). I n estimating the manganese in the standard sample, the author precipitates with bromine and ammonia, and weighs as mangano-manganic oxide. Silica and metallic oxides are removed by dissolving in hydrochloric acid, adding ammonium acetate, and passing hydrogen sulphide, the weight of the resulting precipitate, after ignition, being deducted from the result of the first weighing. c. s. Separation of Cerium from Lanthanum and ‘‘ Didymium.” P.Mengel. (Zeits. anol-g. Chem., 1899, xix., 67.)-The author has investigated the reactions of the cerium group of metals singly and in combination? studying their behaviour when ignited in the air, and using specially prepared and purified specimens of cerium salts or artificially made mixtures of cerium oxides with those of lanthanum and ‘‘ didymium.” He finds that of all the oxidizing agents hitherto proposed for the isolation of cerium, sodium peroxide is the most convenient; it is available in all cases, and gives the largest yields. When the various oxalates of this group of metals are strongly ignited together, the whole of the cerium is converted into dioxide. When a mixture of the pxides of lanthanum and didymium is heated to 400” or 500” C., it takes up oxygen and becomes brown in colour ; at a white-heat the surplus oxygen is expelled, and the colour changes to gray.But if cerium be present simultaneously, this decolorization does not occur ; for a definite brown compound of cerium dioxide and praseodymium peroxide ( Pr,07) is produced which is permanent at high temperatures. For this reason processes for the deter- mination of cerium that depend on oxidation followed by ignition are incorrect, and only give approximate results when but little praseodyniium occurs in the sample. F. H. L. _ . ._ The Separation of Rubidium and Cesium. A. Lemoine. (Bull. de l’Ass. helge, 1898, xii., 344-347.)-A usual method of separating these metals consists inTHE ANALYST.111 treating the iiiixed carbonates with absolute alcohol, which dissolves czsium carbonate, leaving rubidium carbonate, which is nearly insoluble. Various methods have been proposed for converting the chlorides into carbonates, but the author finds the following the most simple and rapid : The residue of chlorides is warmed for some time on the water-bath, with frequent stirring, with an excess of silver carbonate suspended in water. The liquid is filtered, the precipitate washed with cold water, and the filtrate containing the rubidium and czsium as carbonates evaporated to dryness and treated with alcohol in the usual manner. C. A. M. Copper as a Reagent for Polysulphides i n Ammonium Sulphide. T. Chan- delon. (BUZZ. de Z’Ass. belge, 1898, xii., 277.)-On introducing a strip of bright copper into a solution of ammonium sulphide free from polysulphides, the metal remains bright for several days, whereas if only a minute quantity of a polysulphide be present it becomes black within a few hours. By means of this reaction the guthor has found that traces of polysulphides are formed when a dilute solution of ammonia is saturated with hydrogen sulphide. He has proved that the blacken- ing of the copper is not due to any excess of hydrogen sulphide in the liquid, % saturated aqueous solution having no action on the metal, at least during the first hours of contact. C. A. M. ._ ~ - __ - - - Copper as a Reagent for Tetrat4ionates in Sodium Thiosulphate. T. Chandelon. (BzdZ. de Z’Ass. belge, 1898, xii., 277-279.)-On treating metallic copper with a solution of a tetrathionate there is an immediate abundant deposit of copper sulphide, with the formation (probably) of tri- or penta-thionate, or perhaps a, mixture of the two. By means of this reaction it is possible to detect traces of tetrathionate in a solution of thiosulphate. From an 8 per cent. aqueous solution of sodium thiosulphate sold as ‘‘ chemically pure ” the author obtained a very adherent deposit on the copper within twenty-four hours. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN8992400108

出版商:RSC    

年代:1899

数据来源: RSC

摘要:

THE ANALYST. 111 APPARATUS. Apparatus for the Employment of Sulphuretted Hydro- gen. C. Graebe. (Bw., 1898, xxsi., 2981.)-Attention is called to the advantages, both on the score of purity of the laboratory atmosphere and economy in raw material, accruing from the adoption of closed vessels for the treatment of liquids with this reagent. A convenient form of flask is shown in the annexed sketch; it is constructed of such dimensions that the solution only fills it about half-way. The supernatant air is driven out before the stopper is fully inserted, and then the gas simply passes into the vessel at the rate it is absorbed; the operation may thus be left over night, or can be hastened by periodical agitation. F. H. r,,112 THE ANALYST, Apparatus for Distil€ation in High Vacua.L. T. C. Schey. (Chem. Zeit., 1899, xxiii., 61.)-This apparatus, illustrated in the accompanying sketch, is designed for distillations in vacz~o with the aid of a water and mercury pump. As will be seen, it has only one rubber connection. The long-necked flask is charged through a tube funnel, and the opening is then sealed; at the end of the distillation a piece of rubber tubing is slipped over the point, which is broken to allow dry air to enter. The flask is heated in an air-bath, the temperature of which alone is noted, The receiver is cooled with an ice-jacket. When the distillate has been collected, the lower bulb is cut off or removed by fusion. By joining a fresh bulb in the same place, the whole apparatus is ready for use again, and can be employed as long as sufficient neck remains to the distilling flask. It is convecient to use twc similar apparatus, one being at work while the other is mended and filled. F. H. L. An Automatic Reservoir Pipette. H. Gockel. (Zeits. angezo. Chenz., 1899, 10.) The construction of this apparatus is shown by the annexed diagram. The stopcock b has two parallel holes, and also a groove c, which serves for the admission of air when the pipette B is being emptied. Care must be taken that no liquid (or water when the pipette is washed) passes into a ; otherwise the pipette works quickly and accurately. , I t is made in various sizes by Rlt, Eberhardt, and Jiiger, of Ilrnenau. F. H. L.

ISSN:0003-2654    

DOI:10.1039/AN8992400111

出版商:RSC    

年代:1899

数据来源: RSC