102 THE ANALYST. ORGANIC ANALYSIS. Reactions of Formaldehyde. Romijn. (Nedei*l. Tijdsclw. COOT Pka.mz. ClLem. C ~ L Toz. jiiiiz, 1895 ; through licr. Intc?*. des FaZsq., ix., pp. 13, 14.)-The author converts forinaldehyde into hexamethylene-tetramine by ammonia. This body forms regular crystals, and gives well-defined reactions. The substance under examination is distilled with water, and a drop of the distillate mixed on a microscope-slide with a drop of aminonia ; after evaporation the crystalline residue is examined, and tested with the following reagents : 1. Mercuric Chloride i i ~ excess.-Formation of crystals ; hexahedral at once, octahedral after a time. The latter are easily obtained from a solution containing 1 : 10,000, and are still visible in 1 : 100,000.THE ANALYST.1.03 2. Platinic Chloride.-Octahedral crystals, perceptible in 1 : 1,000, but not in 3. Phosphomolybdic Acid.-Rhomboidal crystals from solutions of 1 : 10,000. 4. Potassium Iodide 01' .Bimuth Iodide i n Potussizun Iodide.--In slightly acid solutions yellow crystals are formed, which are plainly seen in solutions containing 1 : 1,000, also in 1 : 10,000 after a time. 5. Hydrochloric Acid Solutiou ?f Stannous Chloi.icZe.-Needle-like crystals from a solution containing 1 : 1,000. 6. Nei-curic Iodide in Potnssizm Iodide, sliyl~dly cLcidi$ed ~ v i t l ~ Hyd~oclilo~ic Acid. -Bright yellow hexagonal crystals from solutions containing 1 : 10,000. 7. Iodim iiz Potc~ssiz~?n Iodide.-Rhoin bic crystals easily seen in solutions of 1 : 1,000. 8. Picric Acid-Crystals from a solution of 1 : 1,000.Many other bodies, as silver nitrate, mercurous nitrate, gold chloride, glacial acetic acid, etc., also give crystalline bodies, but the reaction with mercuric chloride 1 : 10,000. is chiefly relied upon. TV. P. s. A New Method of analysing Alkaline Benzoates. G. Rebikre. (Jozwn. Phu~m. et Chim., 1896, 113-116.)--This is based on the fact that iiiost mineral acids liberate benzoic acid from its metallic compounds. A small quantity, 11, of the benzoate is treated with a sufficient quantity of hydrochloric acid, and the mixture evaporated to dryness. The benxoic acid and the excess of hydrochloric acid are volatilized, and the metal is left as chloride. The amount of chlorine is then deter- mined with decinormal silver nitrate solution, To determine the benzoic acid, the same weight 1) of the benzoate is dissolved in 50 to 60 C.C.of water, and n C.C. of decinormal sulphuric acid added. This exactly saturates the base, and the liberated benzoic acid is titrated with decinormal soda, phenol-phthalein being used as indicator. This method can be used with most metallic benzoates, but in the case of lithium benzoate care must be taken to add the smallest possible excess of hydrochloric acid, and to evaporate on the water-bath in order to avoid loss by volatilization. In the case of ammonium benzoate the process is modified as follows : A given weight, p (about 0-20 gramme), of the benzoate is dissolved in 20 C.C. of decinormal soda, and the mixture boiled until all ammonia is expelled. The excess of alkali is then determined with decinormal acid (72 c.c.).The ainount of ammonium will be (20 - n) x 0.0018. I t is necessary to prove that the benzoate itself does not contain free acid. For the estimation of the benzoic acid, the same weight, p , of ammonium benzoate is dissolved in 20 C.C. of water, and (20 - i z ) C.C. of decinormal sulphuric or hydrochloric acid added. C.C. being taken. The liberated acid is then titrated with decinormal soda. C. A. M. The Biuret Reaction. Hugo Schiff. (Bcrl. Bey., xxix., 298.)-It is shown that not only biuret and albuminous substances give a red coloration with cupric sulphatc and caustic soda, but all bodies which contain two CONI3, groups, corn-104 THE ANALYST. bined in the molecule with a single carbon or nitrogen atom, or joined by one or more CONH groups.Oxamide also gives the reaction. 0. H. A Method of Estimating Uric Acid. E. Riegler. (Zeit. anal. Chem., 1896, 31-34.)-This method is based on the property of uric acid of reducing Fehling's solution. On the assumption that one molecule of uric acid reduces two molecules of copper sulphate, one gramme of uric acid should correspond to 0.7556 gramme of copper. In the actual determinations made by the author using pure uric acid the ratio was higher than this, one gramme of uric acid giving 0.5000 grainme of copper as the inean of ten determinations. For the determination of uric acid in urine, it is necessary to first separate it in a form in which it can be used with Fehling's solution. This may be effected by the method of Ludwig-Salkowski (Zeit. m2nZ.Chcm., xxiv., 637) or more rapidly by that of Fokker (ihit7., xiv. 206). Two hundred C.C. of urine are mixed with 10 C.C. of a saturated solution of sodium carbonate, allowed to stand for half an hour, and filtered from the precipitated phosphates. The precipitate is washed with 50 C.C. of hot water, and to the filtrate and wash-water 20 C.C. of a saturated solution of animoniuin chloride added. The liquid is well stirred, and after five hours filtered, preferably through a Schleicher and Schiill filter, No. 597, 11 cm. The precipitate is washed with 50 C.C. of water, and then introduced by means of a jet from a washing-bottle into a 300 C.C. beaker. Several drops of potash are added to clear the liquid, then 60 C.C. of Fehling's solution, and the whole well stirred.The beaker is then heated on a wire gauze until the liquid boils, the boiling being continued for five minutes. When the precipitate has subsided, the liquid is filtered through a sinall tough filter (Schleicher and Schiill, No. 590, 9 cni.), the precipitate well washed, and dissolved in 30 C.C. of nitric acid (specific gravity, I-l), the filter being washed with 60 C.C. of water. To this solution dry powdered sodium carbonate is added little by little until there is a permanent tnrbidity. The liquid is then cleared by the cautious addition of sulphuric acid, and made up to 100 C.C. Twenty-five C.C. of this are placed in a 100 C.C. flask, one grainme of potassium iodide in 10 C.C. of water added, allowed to stand for ten minutes, and titrated with thiosulphate solution (1 C.C.= 0.002 gramme uric acid), using starch as the indicator. To the total amount of uric acid found in the 200 C.C. of urine, an additional 0.030 gramme should be added to allow for the solubility of the ammonium urate in urine. Thiosulphate solution of the right strength is readily obtained by diluting 126 C.C. of a decinormal solution to 500 C.C. The reaction employed is : 2Cu(NO3), + 4KI = CU$, + 4KN0, + I,. The reduced cuprous oxide may also be weighed directly or reduced to metallic copper, as in the estimation of sugar. I n the latter case the ainount of copper, multiplied by the factor ___ 'Oo0 = 1.25, gives the corresponding amount of uric acid. c. A. R!. 0.8000THE ANALYST. 105 Detection of Vegetable and Animal Oils in Mineral Oils.C. Halphen. ( A m . CJzim. Analyt., 1896, 29.)-The author finds that the reaction proposed for this purpose by De la RoyBre, and which consists of adding to a few drops of the sus- pected oil, contained in a porcelain dish, two drops of a solution of fuchsine just decolorized with alkali, is valueless. Many carefully prepared mineral oils have an acid reaction, and restore the colour of the fiichsine solution. Soaps are often added to mineral lubricating oils, and in such cases the free acid of any added vegetable oil is neutralized, and consequently they do not respond to the above test. The presence of soap in such oils may readily be detected by their action on a solution of Congo-red which has just been rendered violet by hydrochloric acid.Soaps, notwithstanding their alkaline reaction, change the colour of this indicator to red. (?) W. J. S. On the Determination of the Degree of Oxidation of Oils. W. Bishop. (Jount. Phnrm. ct CIiint., 1896, 55-61.)-The process of Livache, which consists i l l determining the increase of weight in oils when exposed to the action of oxygen in contact with finely-divided lead, is only serviceable in the case of linseed-oil. I n other oils the oxidation proceeds too slowly. In order to obtain the most rapid oxidation, the main essential is to have the oil in as finely-divided state as possible by means of a porous neutral substance. The author found precipitated silica a suitable Sdividing agent, but the absorption was still too slow for practical purposes.The addition of manganese resinate to the silica gave the desired result. The commercial resinate is purified by treatment with ether or petroleum spirit, filtering, and evaporating the ether. The dry residue, which the author found to contain 9.80 per cent. of oxide, is powdered and kept in a stoppered bottle. The riiethod of determining the oxygen absorption of oils is as follows : From 5 to 10 grammes of the oil are weighed into a dish, and for 100 parts of oil exactly 2 parts of the resinate added; that is, for 10 grammes 0.2 gramme. The mixture is agitated on the water-bath until the resinate has dissolved, and then allowed to cool. One gramme of silica is weighed into a flat dish provided with a glass stirring-rod, and then drop by drop, by means of a pipette, 1.02 grammes of the resinated oil (1 grainme of oil + 0.2 grainme resinate) is added.The mass is intimately mixed, and spread aver the bottom of the dish, and is left at a temperature of from 17".to 25" C. for drying oils, and of 20" to 30" C. for other oils. The dish is weighed after six hours, and twice again in the twenty-four hours, and so on until the maximum is attained, the mhss being stirred up after each weighing. The inaxiinurn increase in weight, multiplied by 100, gives the degree of oxidation. The detailed results obtained with linseed, poppy, cotton seed, and earthnut oils are given in Tables I. and 11.106 THE ANALYST. I. Linseed-oil, Native. Density = 0.9357 a t 15" c. Linseed-oil, Native. Containing .5 per cent. iesin oil. 5 per cent.mineral oil. D=0.9323 at 15" C. Pure. I)=0%22 a t 15" C. Linseed-oil, La Plata. I) = 0.9304 a t 15" C. ? = 17"-23", 17" c. T = li"-14" C. r = 233-17" C. r-23"-17~ 0. 13.5 16.30 16.40 16.20 15.90 ... ... 14.80 ... . . . 1 i " C. c. 1243 16-10 16-60 16.50 15 -50 15.10 14-80 15.00 14-80 ... Hours. 6 22 24 30 48 72 96 120 144 216 4.95 16-70 17 -40 17.70 11.20 14-10 14-30 14-70 15-00 3.75 14-30 14-90 15.10 1.45 14-75 15-95 15.85 15-95 16.25 ... .., 16.65 11 -50 14.30 14-90 1-70 13-55 13-95 13.95 14.55 14-75 ... ... 15.35 14.80 14-60 .. . 13-80 ... ... 17.70 17 -70 17.30 ... ... 17-10 14.70 14.90 14-80 14-80 14-70 14-50 14.30 14.10 15-85 14-45 11. Cottonseed-oil, Containing cotton "stearin." 1) = 0.924 a t 15" C. Earthnut-oil, Mozambique. I)=0.916 a t 15" C.Poppy-oil. 1> = 0.9242 at 15" c. T= 28"-22" C, I!= 23"-17" C. T = 320-1 so, 34. 5"-14"C. Hours. 6 ... 22 ... 24 ... 30 ... 48 ... 72 ... 96 ... 120 ... 144 ... 4-8 13.60 13-90 14.50 0 -20 11.45 11.55 12-45 1-30 7.30 7 *60 8.20 0.10 5.70 6.20 7 -40 8 ~40 8-50 ... 0.80 3.50 3 30 4.70 5.30 6-10 6-70 - 0.20 - 0-20 - 0.10 0.80 3 -60 4-40 ... 4-80 14.10 13-00 12-50 12-00 10-40 14.30 13-35 8.20 6.50 6-50 12.75 8-00 ... I 7.80 ... 8.00 A general summary of results is given in the subjoined table. Earthnut-oil may be considered as intermediate bctween seirii-drying oils like cottonseed, and non- drjiag oils like colza and olive. For the latter it slightly more elevated temperatureTHE ANALYST. 107 Even then oxidation is not complete in a short should be employed (20' to 30" C,). time.111. Oils. Linseed, native ... ... ,, la Plata ... ... Hempseed ... ... ... Poppy, native ... ... Nut ... ... Cotton-seed with stearin . . . 9 , without stearin Sesame, Senegal ... . . . ,, Indian . .. ... Earthnut, African . . . ... ,, white ... ... Colza, native ... ... ,, Indian ... ... Olive ... ... ... ... $ 9 Density. 0,932 7 0.9304 0.9287 0.924 0.924 0.924 0-923 0.9215 0.921 0.916 0.916 0-9142 0-9137 0.9155 Degrees of Oxidation. 17*70-16.40 14.55-14.30 13-70 8-60 9.60-9.30 8-95-8.50 7-40 6.70 6-50 6.40 ? 5.90--5.80 ? 5-30 ? 15.45-15.00 14.50 - 13 -90 17.05 15.20 14.40 14.20 13.70 8-60 9.45 8.70 7.40 6.70 6-50 6-40 ? 5-85 ? 5.30 ? The degree of oxidation can be controlled by the Hiibl number, and in the author's opinion is in many cases more complete than the latter, since it shows at once the absorption power and the rapidity of oxidation.I n applying the method to the detection of vegetable oils in lard, it is preferable to employ the liquid fatty acids, for the separation of which the author recommends Halphen's process (ANALYST, xix., 282). C. A. M. The Bromine Heat-Value of Fats and Oils. J. A. Wilson. (Chem. News, 1896, 87.) - The author has examined Hehner and Mitchell's thermal process (ANALYST, xx., 146), and considers it in the main accurate and convenient. Using a test-tube packed in cotton-wool as his calorimeter, he found that with cocoanut-oil the rise of temperature multiplied by 5.5 gave at once the correct iodine value. With tallow, lard, butter, etc., it was necessary to add 1 before multiplying by that factor.This was shown in the following table : Rise of Temperature Calculated Observed with Bromine. Iodine Value. Iodine Value. Oil or Pat. Cocoanut-oil . . . ... 1.5 8.2 8.4 S.A. tallow . . . ... 7-0 43.2 44.0 Olive-oil (pure) . . . ... 14.0 82.5 82.0 Rape-oil ... ... ... 18.0 104.5 103 -4 W. J. S. The Use of the Calorimeter in Butter and Lard Analyses. E. de Schweinitz and J. A. Emery. (Jour. Anzer. Chem. Soc., xviii., 1896, 174-179.)- The samples of lard and butter which the authors were examining by the usual methods were prepared by washing, melting, filtering and drying at 100" C., and108 THE ANALYST. 9 1 12 14 16 18 19 22 26 27 2S 29 sent to Professor Attwater for combustion, without any information being given except that they were fats.The results of the analyses of butters and oleo- margarines are given in the following table : I. 1 i Original substance. Oakdale Manufac- turing Co., oleo- margarine Oakdale Manufac- turing Co., oleo- margarine Vermont Mann- facturing Co., oleomargarine Vermont Manu- facturing Co., oleomargarine Swift 8: Go., oleo- margarine Hammond Manu- facturing Co., oleomargarine Woodlawn oleo- margarine Elgin Creamery Butter Plains Va. Butter Armour 8: Co.'s Armour tc Co.'s best butter oleomargarine - I----- I-I- 0.8835 8'53 0,8906 8-00 0'8828 9.47 0.8874 9-00 0.8830 8-32 O'ti891 9.15 0.8880 9-23 0.8925 8-32 0.S979 11-43 023984 12-98 - - 0.42 0.35 0 -35 0.30 0 '22 0-22 0.35 11.10 8 ..5G 10'82 - 5.17 3.i6 5-31 3 $8 2.12 6.69 3 .SO 3-81 4-05 4.04 - .3 C 7 - i p v k -__ 1-36 2.59 1.33 1 -66 0.81 1-43 1-52 1.27 1'84 1-30 - ~ 5 -95 - 5 -67 3.68 2'19 6-21 3.68 3-64 4.93 3 -94 - ~ 23'0" 25.0" 25'0" 22.5" 24.0' 25.0" 22.5" 35.3" 36-1" 33.5" - Fat.al $ 6 CZ H 52.80 54-49 66.50 66.59 60.67 60.53 61.80 37.i5 36-86 41'20 49.91 9.599 9.620 9.795 9.649 9 -644 9.607 9.670 9-32i 9-362 9-320 9.601 5 i s Y ; alz g q s$ ~- Purple brown Purple brown Purple brown Purple brown No change No change No reaction No reaction Highly coloured Very highly coloured Highly coloured The figures obtained for butter-fat differ slightly from those given by Stohman, who found the heat equivalent, as determined by the potassium chlorate method, to be 9.192 small calories per gramme, while by the oxygen method it was 9.231 calories. The increase in the calories of mixtures of butter and oleomargarine was in proportion to the amount of the latter added. I n Table 11. the results were obtained by mixing Elgin butter (26) with Woodlawn Oleomargarine (22). 11. T,,eoretical I. Actual Combus- Theoretical Combus- tion Calories, tion Calories, per gramme. per gramme. Actual I. NO. NO. Sample. 2 E. and & W. ... 43-90 43.76 9-391 9.412 8 E. and 4 W. ... 48-01 49.77 9-416 9-498 I n the case of lards taken from different sources, the results are not so distinc- E. and 2 W. ... 54-40 55.78 9.491 9.584 tive, but, taken in conjunction with the iodine absorption, will be of use.THE ANALYST. 109 111. ANALYSIS OF LARDS FROM ARMOUR AND Co. Quality. Lard, leaf ... ... ... ,, caul fat ... ... ,, intestinal fat ... ... ,, head ... ... ,, trimmings . .. .-. ,, mixture of all fats ... ,, compound, 1st grade . 9 , , t 2nd grade ,, shield . . . ... ,, special pure ... ... Melting-point. Iodine No. _- 56.85 40.0" 58-61 40.7" 54.74 29.5" 68.79 - 65.57 - 63.86 __ 86.18 - 86-57 - 61.01 37.5" 63-63 Combustion Calories, per gmmme. 9-621 9.573 9.581 9.503 9.606 9.654 9.583 9.530 9.598 9.617 Cottonseed-oil, Becchi's Teat. None. Slightly darker. None. 9 9 9 9 9 , Purple brown. I , 9 9 None. C. A. M.