摘要:

AUGUST 1908. Vol. XXXIII. No. 389. PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. STUDIES IN STEAM DISTILLATION. BY H. DROOP RICHMOND F . I . C . (Read at the Meeting June 3 1908.) PART III.-FoRMIc AND ACETIC ACIDS. THE rate of distillation of volatile acids of the series C,,H,,,+,COOH has been studied by Duclaux (Ann. Chim. Phys; [ 5 ] ii. 223) by J. A. Wilson (Jown. SOC. Chem. Ind. 1890 9 IS) by myself (ANALYST 1895 20 193) and by myself in conjunction with E. €3. Miller (ANALYST 1906 31 324). In Part I. of these studies (ANALYST 1908 209) I have shown the theoretical effect of condensation in the retort ; and as it is probableithat the discrepancies observed especially by Wilson are largely due to condensation I have thought that a repetition of previous experiments using an apparatus in which condensation is as far as possible eliminated would be of value.The apparatus used consisted of a 300 C.C. flask fitted with a tube bent over and connected with an upright condenser. The flask was supported on a piece of asbestos cardboard in which a circular hole was cut and both flask and tube were surrounded by a hollow cylindrical vessel in which water was boiled ; 100 C.C. of solution was placed in the flask and boiled by a small flame and fractions of approximately 10 C.C. were collected and titrated with alkali solution ; the fractions were measured to the nearest 0.05 C.C. In order to eliminate the effect of carbon dioxide in the solution, and that absorbed during titration a blank experiment with 100 C.C.of distilled water was made and all titrations corrected for the small figures obtained. All burettes and measuring vessels were carefully calibrated. The formic acid used was prepared by distilling pure oxalic acid with glycerol from a salt-bath; thi 306 THE ANALYST. was fractionated three times and the results of distillation proved it to be pure. The acetic acid was Kahlbaum’s 100 per cent. acid. Solutions of each acid were made up approximating to the following strengths : N/100 N/50 N/25 N/10 N / 5 ; 100 C.C. of each were distilled and after nine fractions of approximately 10 C.C. had been collected the distillation was stopped, moment to .-. 3 0 0 c.c 2 the flask and condenser washed out and the total acid estimated by titration. The totals always agreed very closely with the amount of acid taken.I n the tables below the amounts of water and of acid which have been distilled are calculated as percentages of the total water and acid in the still at the commencement of dis-tillation. For solutions of N/25 strength or weaker the percentage of total distillate has been taken as the percentage of water a8 the two are identical within the limits of experi-mental error. For stronger solutions the amount of acid as determined by titration has been eubtracted from the amount of distillate and from the amount of original solution taken and the digerence taken as water and the per-centages of water calculated. From the amounts of water and acid distilled over the quantities of each remaining in the still at any point have been deduced and for ease in calculation of the results these are expressed as fractions the total amount in the still before the commencement of distillation being taken as 1.These fractions are given in the tables in the columns headed x and y respectively. The rate of distillation of a substance in aqueous solution relative to that of water can be found from the ratio of the molecular composition of the vapour arising at any the molecular composition of the solution at that moment. The f~rmulae for the calculation of this ratio ( a ) have been derived in Part I. (loc. cit.), and are log y = a log x or a= log as a is the ratio of two logarithms it does not matter to what base these are taken and therefore common logarithms were used.As the rateof distillation of the acid relative to that of water (a) is really a ratio of molecules it should remain constant so long as no change in molecular association occurs; it is seen however that the value of a rises fairly constantly as the concentration increases. As both the acids examined have a smaller rate of distillation than that of water it is obvious that the concentration of the acid in the flask increases this being much more marked with formic acid with its low rate of distillation than with acetic acid. The rise of the va,lue of a during distillation i s log x THE ANALYST. 307 much more marked with formic acid than with acetic acid and it is evident that there is a connection between the strength of acid in the still and the rate of distillation ; this will be discussed later.On plotting out the results as curves (not given) it is apparent that there is a disturbing influence at the commencement of distillation ; although every endeavour was made to have the still-head hot before distillation commenced it was seen that condensation w&s taking place in the portion of the tube projecting from the steam jacket and it is evident that the rate of distillation deduced from the first fraction would be low owing tocondensation (Part I. Zoc. cit.). I n the calculation of the values of a this has been eliminated by subtracting the values for water and acid in the first fraction from the total and recalculating the results of the other fractions as percentages of the totals in the still at the commencement of the distill-&ion of the second fraction.The values given in the column headed a are all obtained in this way. The following results were obtained : 1. FORMIC Ac1~-N/95.1. X . Water distilled per cent. 10.15 0.8985 20.35 0,7965 30.35 0.6965 40.45 0.5955 50.2 0.498 60.1 0.399 70.25 0.2975 80.35 0-1965 90.5 0.095 2. FORMIC Ac1~-N/47.3. 9.7 0.903 19.6 0.804 29.6 0.704 39.2 0.608 49.5 0.505 59.4 0,406 69.1 0.309 79.0 0.210 88.8 0,112 3. FORMIC Ac1~-N/47.7. 10.1 0.899 20.0 0-800 30-0 0.700 39.9 0.601 49.5 0.505 59.7 0.403 69.3 0.307 79.2 0.208 89-3 0.107 Acid distilled per cent. 4-1 8.45 13.55 19.05 24.75 30-9 39.35 49.0 62.7 3.7 8.2 13.2 18.15 24% 31.1 38.7 47.7 60.1 4.1 8.5 134 18-85 24.45 31.4 38-7 48.05 60.85 Y.0.959 0.9155 0.8645 0.8095 0.7525 0.691 0.6065 0.510 0.373 0.963 0.918 0-868 0.8185 0-754 0.689 0.613 0.523 0.399 0.959 0.915 0.866 0.8115 0.7555 0.686 0.613 0.5195 0.3915 a. 0.386 0.408 0.412 0.4 11 0.402 0.415 0.415 0.420 0.413 0.41 7 0.412 0.421 0.419 0.421 0.419 0,422 -0.402 0.408 0.415 0413 0-418 0-417 0.419 0.421 Strength of acid in still. N/89-4 NJ82.8 N177.0 N/70*0 N/63*0 N/55.0 N/46-5 N/36-7 Nl24.2 N/46.3 N141.3 Nj38.5 N/35.2 N/31.8 Nj28.0 NJ23.9 Ni19.4 Nj13.3 N/44.9 Nj41.7 Nj38.7 Nl35.5 Nj31.9 Nj28.1 Nl23.9 N/19*5 Nl13. 308 THE ANALYST.4. FORMIC Ac1~-N/51*4. Water distilled per cent. 9.95 19.9 30 05 40.0 50.0 60.0 70.0 79.95 89.9 X . 0 -9005 0.801 0.6995 0.600 0-500 0.400 0.300 0.2005 0*101 5. FORMIC Acr~-N/50-8. 10.0 20.0 29.95 40.05 50.1 60.25 70.6 80.15 90.25 0.900 0.800 0.7005 0.5995 0.499 0.3975 0.294 0.1985 0.0975 6. FORMIC Ac1~-N/23*5. 9.95 20.0 30.0 40.1 50.1 60.1 70.05 80.25 90.45 0.9005 0.800 0.700 0.599 0.499 0.399 0.2995 0.1975 0.0955 7. lJORRIIC Ac1~-N/9-48. 9.85 20.75 29.5 39.75 50.75 60.45 70.7 80.4 89.35 0.9015 0.7935 0.705 0.6025 0.4925 0,3955 0.293 0.196 0.1065 8. FORNIC Ac1~-N/9*48. 9.85 0.9015 25.3 0.747 40.15 0.5985 59.9 0.401 698 0.302 82.1 0.179 93.75 0,0625 Acid distilled per cent.3-95 8-45 13-55 18.8 24-65 31.1 39.0 48.4 61.3 3.95 8-55 13.45 19.1 25.0 31.9 40.0 49.5 62.5 4-15 8-7 13.85 19.3 25.35 32.05 40.05 49.85 63.8 4.0 9.1 13.6 19.4 26-25 32.95 41.4 50.8 62.6 3.8 11.3 19.6 32.85 40.8 53.05 '71.45 Y. 0-9605 0.9155 0.3645 0.812 0.7535 0.689 0-610 0,516 0.387 0,9605 0.9145 0.8655 0,809 0.750 0-681 0-600 0.505 0.375 0.9585 0.913 0.8615 0.807 0.7465 0.6795 0,5995 0.5015 0.362 0.960 0.909 0.864 0.806 0.7375 0.6705 0,586 0.492 0.374 0.962 0.887 0.804 0.6715 0.592 0.4695 0.2855 a. 0.408 0.412 0.413 0.413 0.411 0.413 0.413 0.415 --0.417 0,416 0.422 0.420 0-421 0.421 0,425 0.423 __ 0.419 0-423 0.422 0,423 0.423 0.426 0.427 0.434 -0.430 0.433 0.436 0-437 0.437 0.434 0-439 0.441 -0-432 0.438 0.444 0.444 0.443 0,455 Strength of acid in still.N/48*8 Nj45.1 N/41.7 NJ38.1 NJ34.2 N/29-9 NJ25.3 Nj20.0 NJ13.4 N/47-i N144.4 N141.1 Nj37.6 NJ33.8 Nj29.6 Nj24.9 N120.0 N113.2 Nj22.1 Nj20.4 N /19-1 Nj17.5 Nj15.7 Nj13.8 NJll.7 Nl9.27 N16.20 N/W4 N/8*28 Nj7.75 Nl7.10 Nj6-33 Nj5-61 N/4-77 Nj3-82 N!2.66 N18.94 NJ8.00 NJ7-10 N/5-69 Nj4.85 NJ3-65 N 12.1 THE ANALYST. 309 9. $'OKMIC Ac1~-N/4*85. X . Water distilled per cent. 10.15 0.8985 20.3 0.797 30.3 0.697 40.3 0.597 50.5 0.495 60.6 0.394 70.6 0.294 80.45 0.1955 90.6 0.094 10.ACETIC BCID-N/95.5. 9-8 0.902 19.7 0.803 29.3 0.707 39.0 0.610 49.2 0.508 58.9 0.41 1 69.0 0.310 78.9 0.211 88.9 0.111 11. ACETIC Acr~-N/48-9. 9.8 0.902 19.6 0-804 29.5 0.705 39.3 0.607 49.3 0.507 59.1 0.409 68.8 0.312 78.8 0.212 88.8 0.112 12. ACETIC ~ I D - N / ~ ~ . I . 9.9 0.901 19.7 0.803 29.4 0.706 40.5 0.595 49.7 0.503 59.4 0.406 69.2 0.308 78.8 0.212 88.9 0.111 13. ACETIC Ac1~-N/9*64. 9-85 0.9015 20.15 0,7985 30.65 0,6935 49.95 0.5005 59.9 0.401 69.65 0,3935 79.85 0.2015 89.55 0.1045 Acid distilled per cent. 4.2 9.15 14.3 20.0 26.25 33.4 4 1.55 51.35 64.7 6.05 13.4 20.2 27-95 36.55 44.95 54.6 66-05 77.1 6.4 13.2 20-85 28.45 37.0 45.65 54.9 65.35 77.4 6.8 13.95 21.25 29.95 37.4 45.85 55.3 65.35 77.9 6-95 14.3 22.45 38.1 46.8 56.4 67.65 79.75 Y.0.958 0.9085 0.857 0.800 0.7375 0-666 0.5845 0.4865 0,353 0.9395 0.866 0.798 0.7205 0.6345 0.5505 0.454 0,3495 0.229 0.936 0.868 0.7915 0.7155 0.630 0.5435 0.451 0.3465 0.226 0.932 0.8605 0.7875 0.7005 0-626 0,5415 0.447 0.3465 0.221 0.9305 0.857 0.7755 0.619 0532 0.436 0,3235 0-2025 a. 0.434 0.439 0.441 0-438 0,440 0.443 0.443 0.442 --0.700 0.670 0.678 0.684 0.680 0-677 0.680 0.674 -0,657 0-680 0-678 0.687 0.688 0.688 0.687 0.682 -0.692 0,691 0.688 0.682 0-681 0.685 0.683 0.687 -0.675 0.693 0.692 0.690 0.695 0.705 0.708 Streugtli of ncid in still.NJ4.56 Nl4.25 NJ3.96 Nl3.62 NJ3.26 N/2*88 NJ2.44 N11.95 Nl1.30 N/92.0 N/88-5 Nl84.9 N180-8 Nl76.5 N/71-5 N165.4 N/57-8 N 146.3 NJ47.2 N/45-3 N/43*5 NJ41.5 N139.4 N136.8 N/33.8 Nl29.9 Nl24.2 NJ23.3 Nl22.5 N121.6 N/20*5 N/19-4 NJ16-6 Nl14.8 Nl11.8 Nj18.1 N/9*35 N/9.00 Nl8.64 N/7-82 N/7*30 Nl6.71 N 16 *03 N/5-0 310 THE ANALYST. 14. ACETIC Ac1~-N/4.81. Acid distilled per cent. X . Water distilled per cent. 9.85 0.90 15 6.9 19.7 0.803 13.95 29.65 0-7035 21.6 39-45 0 ~6055 29.4 49-4 0.506 37.85 59.3 0.407 46.6 69.1 0,309 55.95 79-1 0.209 66.5 89.15 0.1085 78.7 Y.0.931 0.8605 0.784 0.706 0.6215 0.534 0.4405 0.335 0.213 a. 0.680 0-694 0.695 0.700 0-699 0.699 0.700 0.703 -Strength of acid in still. Nl4.65 N14.49 N 14.32 Nl4.14 Nj3-92 N /3*67 N/3*38 N /3 BOO N12.45 The nature of the experimental error is best seen by a comparison of experiments 2 3 4 and 5 which were all made with solutions of nearly the same strength and which show that individual values for n may vary about 0.01 and for weaker solutions the error is perhaps slightly more By averaging a number oE results of solutions of nearly comparable strengths it is possible to compare strength of solution and rate of volatility with considerable accuracy.Owing to the large variation of con-centration during distillation a number of figures can be deduced for formic acid. The table below gives the average figures. FORMIC ACID. Strength of solution. Mean = S. N177.0 Nl58.9 Nl43.5 N/33-3 Nl24.4 N/20*0 N/16-7 Nl12.8 a. RIeaii. 0.402 0.4065 0.413 0.416 0.419 0.4205 0.4225 0.423 a. Calculated. 0.404 0.407 0.4105 0.4135 0.417 0.419 0.4215 0.424 Strength of solution. hl ean = S. N/9*27 Nj8.00 Nl6.25 N14.32 N13.71 N /2-92 N 12.44 N11.96 N/1*30 a. Mean. 0.427 0.432 0437 0.437 0.441 0.440 0.443 0.443 0.442 a. Calculated. 0.428 0.429 0.432 0.436 0.438 0.4405 0.4425 0445 0.4495 For acetic acid a8 the concentration does not change much only five points are calculated.ACETIC ACID. Stiwgth of solution. a. a. Mean = 8. Mean. Calculated. N/68*0 . . 0.680 . . 0.679 Nl35.4 . . 0.685 . . 0.683 N/17*5 . . . # 0.685 . . 0.687 N/6*90 . . 0.692 . . _ . 0-692 NJ3.54 . . 0-697 . . 0.696 The formuh used to calculate the values of the rate of distillation ( a ) were : For formic acid acetic acid . . . . 0.0256 log., 100 S + 0.4013 = a ; and 0-013 log., 100 S + 0.677 = a ; end it is seen that the agreement is fairly satisfactory. The formulae have probably no theoretical significance being merely approximations as they lead to the conclusio THE ANALYST. 311 that in infinitre dilutions the value of a is negative. sufficiently good to enable us to calculate the value of a for any strength of solution.distilled the total acidity being equal to that of a Nl23.8 solution. above equations were used. The approximation is however, A mixture of acetic and formic acids in nearly equimolecular proportions W ~ B For the purpose of calculating the results the values of a deduced from the The table below gives the results : FORMIC AND ACETIC ACIDS (MOLECULAR RATIO 0.495 0.505). Water distilled per cent. 10.0 20.05 30.05 40.25 50.4 60.45 70.55 80.4 90.3 Acid distilled per cent. 5-6 11.45 17.8 24-5 31.85 39.6 48.7 58-7 71.85 Acid distilled. Jalculated. 6.52 11-44 17.72 24.40 31.64 39.68 48-70 58.77 71.66 Strength of acid in still.N/22-8 N121.3 Nl20.3 N/18*9 Nl17.4 N/15*6 N113.7 Nlll.3 N/8-21 a. 2alculated. Formic. -0.4185 0.41 9 0.420 0.4205 0.422 0.4235 0.4255 0.429 >alculated per cent. Formic. 8.8 13.75 19.3 25.3 32.2 40.4 49 -9 63.1 a. 2alculated Acetic. -0.6855 0.686 0 -6865 0.687 0.6875 0.688 0.6895 0.691 Calculated per cent. Acetic. 14.05 21.6 29.4 37.85 47.0 56.8 67.4 79.95 Mean Ratio acetic. Total. -0.505 0.516 0.512 0.522 0.500 0.506 0-503 0.519 0.511 I t is seen that the agreement between the actual results and those calculated is very close and the mean ratio deduced is not far removed from the molecular ratio in which the acids were present. To obtain the actual ratios the molecular ratios must be multiplied by the molecular weights ; thus the actual quantities present were 0.1263 gram o€ acetic acid and 0.0958 gram of formic acid while the quantities deduced from the mean molecular ratio found were 0.1288 and 0.0945 gram respectively, It is seen that there is a tendency for the amount distilled to be slightly higher than that calculated and a repetition of the experiment confirmed this though the difference is hardly more than the known experimental error ; what the significance of this fact is is a matter which can only form the ground for speculation.The rise in the rate of distillation with increasing concentration is almost certainly due to association both formic and acetic acids being known to be highly associated in the pure state.Assuming that the vapour tension a t the boiling-point of the solution and the solubility in water do not change with molecular association the rate of distillation would be a direct index of the association. These assumptions are, however hardly justified. It may be that in the presence of another acid the degree of association is increased though there is no apparent reason why this should be so It is possible that in a mixed solution of acetic and formic acids mixed molecules are formed and that the rate of distillation of these is not exactly the mean of the rate of distillation of the corresponding associated molecules. A reason which, i n my opinion however has a greater probability is that in a mixed solution th 312 THE ANALYST.number of water molecules is less than in a formic acid solution of corresponding strength and greater than in an acetic solution. The amount of association will depend on the ratio of acid molecules to water molecules and therefore also the rate of distillation ; as formic acid is more highly asssociated than acetic acid and as the change in association and rate of distillation with concentration is greater with formic acid than with acetic acid it follows that there should be a greater increase of rate of distillation of formic acid in a mixed solution than decrease of rate of distillation of acetic acid or in other words the amount of acid distilled from a mixed solution should be greater than that calculated. The magnitude of the experimental error however prevents any definite conclusion on this point being drawn.I n a subsequent communiclttion I propose to give the results o€ distillation of aqueous solutions of the higher fatty acids and will postpone the discussion of the application of the results to the estimation of fatty acids in the presence of each other till then. DISCUSSION. The CHAIRMAN (Mr. THOMAS FAIRLEP) said that if there were equivalent quanti-ties of acetic and formic acids in the solution it would mean if he had understood rightly the meaning of Mr. Richmond’s experiments that equivalent quantities would appear in the distillate; or in othor words supposing the acids to be acetic and butyric the weights of these acids in the distillate would be in the proportion of their molecular weights.I n the specific gravity of dilute acetic acid certain abnormalities occurred which had been explained on the supposition that when the dilution passed a certain degree the molecular weight was not quite the same. The effect however of any such variations on Mr. Richmond’s experiments would be very small on account of the extreme dilution. The specific gravity and the boiling-point were not necessarily associated ; in fact the specific gravity taken at the ordinary temperature might represent a different state of matter from that existing at the boiling-point. Mr. F. W. RICHABDSON remarked that the author had said that the quantity of acetic acid tended to increase whereas as far as he (the speaker) could see from the table the percentage seemed to remain practically the same all through -namely 0.68.Mr. CHAPMAN said that this paper was of special interest because he believed that Mr. Richmond was the first worker to carry out an investigation of this kind under accurately defined experimental conditions. The value of the classical work of Duclaux was to some extent lessened owing to the fact that the exact mode of distillation Bad not been clearly defined. He (Mr. Chapman) should like to know whether Mr. Richmond had been able to effect any comparison between his own results and those of Duclaux. Mr. RICHMOND in reply said that the molecular weights of the acids did not affect the results because all these figures were expressed as percentages of the total acid present. They represented the rate of distillation of the acid compared with that of water. The formic asid which distilled less rapidly than water wa THE ANALYST. 313 concentrated in the flask and the acetic acid also was concentrated but to a much less extent. Since the acetic acid distilled faster than the formic acid a larger quantity of it was obtained and the ratio of acetic acid to formic acid was con-stantly altering. It was quite simple however to calculate what it was at any point. As regards the abnormality which occurred in the specific gravity of acetic acid his results were not quite comparable with those obtained by other workers, because this abnormality only occurred in the case of much stronger solutions than he had used. Sulphuric acid which had been shown by Ramsay and Shields to be very highly associated showed a similar decrease in specific gravity when the strength passed 97.5 per cent. The distillation to which Mr. Richardson had referred happened to be the most constant of all those he had made. The general results showed a tendency to increase. Absolute constancy could hardly be expected in any case as the experimental error was fairly large. He had examined Duclaux’s results very carefully and had found that they varied considerably owing in part to cooling of the still. He (Mr. Richmond) had repeated his experiments without the steam-jacket and had also found considerable variation in the results. Moreover Duclaux did not in all cases succeed in getting pure acids to work with

ISSN:0003-2654    

DOI:10.1039/AN9083300305

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 313 OCHOCO FAT. BY J. LEWKOWITSCH, PH.D., F.I.C. (Read at the Meeting, June 3, 1908.) OCHOCO FAT is contained in the seeds of Scyphocephalium ochocoa, War., a tree found at the West Coast of Africa, and belonging to the Nzpisticacea. From a description published by Pierre (Bulletin de la SociStd linnienne de Paris, 1898, No. 5, Skance du premier mai, 1896), it appears that the nuts have no arillus, and that they are non-dehiscent. He therefore looked upon the plant as representing a new genus of Myristicacecz, and named the tree Ochocoa gabonii. Warburg (“ Identificierung der sogenannten Ochoconusse aus Gabun mit Scyphocephalium, einer neuen Muskatnuss-Gattung,” Notizblatt des K. Bot. Gart.), in 1895, described the tree as Scyphocephalium chrysothrix, wnd later, in 1897, as Scyphocephalzum ochocoa (Warburg, ‘( Monographie der Myristicaceen,” Acta Leopoldina, Halle a/S., lxviii., 1897). The statement he made in 1895--viz., that the nuts possess an arillus and are dehiscent-was corrected later on, in so far that the question whether the nute were possessed of an arillus or not was left open. A large number of nuts examined some years ago by Heckel (“ Les graines grasses nouvelles ou peu connues des Colonies franqaises,” Paris, 1902), as also those submitted to me, showed no sign of an arillus. This is important from a commercial point of view, as no ethereal oil can be obtained from the Ochocoa, whereas other species of Myristica, especially so Myristica oficinalis, yield sufficient quantities to render the prints on that account commercidly valuable.The specimens submitted to the author were identified by314 THE ANALYST. the Kew authorities as the kernels of Scyphocephalium ochocoa. The average weight of the kernels is 10 grams ; the smallest weighing 5 grams, and the largest 12-5 grams. The kernels, together with the thin husks surrounding the cndocarp, yield 58.8 per cent. of fat. By whatever process the fat is prepared, a dark-brown colouring matter is at the same time extracted, which is so tenaciously retained by the fat that I have been unable hitherto to remove it. Similar difficulties were met with by Heckel and his collaborators. This dark colouring matter is not only contained in the husks, but also in the membranous extension of the husk (spermoderm), which passes through the whole of the endosperm in the form of irregular lamelle radiating from the chalaza.As the examination of the dark fat offered some difficulties, the only way to obtain a fat free from colouring matter was to cut out carefully the white endosperm by hand. The amount of endosperm so obtained formed 84-7 per cent. of the kernels. The white endosperm was extracted in the usual manner, and yielded a perfectly white fat which had the following characteristics : These 84.7 per cent. contained 69.4 per cent. of fat. Specific gravity at 60" C. (water at 4" = 1) Saponification value ... ... ... Iodine value ... ... I . . ... Reichert-Meissl value ... ... ... Insoluble volatile acids required ... Me1 ting-poin t ... ... ... ... Unsaponifiable matter ...unsaponifiable matter ... ... ... Melting-point (capillary tube) ... ... ... ... Mean molecular weight of the fatty acids, The extracted fat had the acid vaiue ... ... ... 0.8899 ... -.. 238.5 ... ... 1.72 ... ... 0.65 ... 4.0 C.C. N/loKOH ... ... 45-48" C. ... ... 0.37 per cent. freed from ... ... 221.9 ... ... 4 7 9 O c. ... ... 1.42 These numbers lie so near those yielded by myristin, that the fat may be considered as consisting of practically pure myristin-or to be more precise, about 98 per cent. of myristin and about 2 per cent. of olein. The mixed fatty acids had the iodine value 1-47, and gave on separation by means of the lead-salt-ether method 12.82 per cent. of acids, the lead salts of which were dissolved by ether. The acids sbtained from these lead salts were, however, solid, melted at 31.7-32-2" C.in EL capillary tube, and absorbed no more than 9.9 per cent. of iodine. The somewhat low mean molecular weight of the insoluble fatty acids suggested that lower glycerides than myristin might be present. Hence the small amount of insoluble volatile acids was further examined. Their mean molecular weight was found to be 227.3 (myristic acid = 228) ; they melted at 43.3-48.9' C. The insoluble fatty acids were then washed with a considerable quantity of boiling water, but they lost thereby only 1.5 per cent. This shows that the insoluble acids consist practically of pure myristic acid, and inferentially that ochoco fat is free from laurin. The chemical constitution of the fat would thus appear to confirm the result of botanical diagnosis, that Ochocoa is a true Myristicucea.Up to the present, twelve fats have been obtained from Myristica species. The fat from Virola Venezicelensis consists to a large extent of rnyristin, and the pure triglyceride can be obtained from the crude fat by recrystallising it twice from ether,THE ANALYST. 315 The fat from Myristica suriizamensis is stated to consist of about 87 per cent. of myristin, 6.5 per cent, of free inyristic acid, and of a caoutchouc-like (resinous) substance. The present fat, ochoco fat, seems to be practically pure myristin without any resinous matter, and may therefore be looked upon as the best source for the preparation of myristin and myristic acid. I t seems convenient to form amongst the vegetable fats, as a separate group, a “Myristin Group” embracing all those fats which consist mainly or wholly of myristin just as I proposed grouping together, under the name of the Cocoanut Oil Group (‘( Chemical Technology and Analysis,” etc., p.738), a number of fats that seemed to be nearly related to each other on account of their high proportion of volatile acids. And under the name (‘ Chaulmoogra Group ” (Jahrbuch tie Chemie, xv. 420), three fats which are distinguished by the optical activity of their insoluble fatty acids. At this juncture it may be added that it might not be inconvenient to establish a, ‘ I Laurin Group,” to which would seem to belong dika fat, tangkallak fat, cay-cay fat (irvingia butter), and the recently described kusu oil. The natives apply the name ( I ochoco ” indiscriminately to several edible fruits, such as the fruits from Lophira alata, which yields Niam fat (Journ. SOC. Chem. Ind., 1907, 1265). DISCUSSION. Mr. L. M. NASH asked whether any appreciable quantity of the fat was obtainable Dr. LEWKOWITSCH said that the kernels contained about 59 per cent. of fat, and The only difficulty seemed to commercially. the nuts were readily obtainable in large quantities. be the extraction of the dark-brown colouring matter.

ISSN:0003-2654    

DOI:10.1039/AN9083300313

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 315 THE ESTIMATION OF TARTARIC ACID IN THE PRESENCE OF MALIC AND SUCCINIC ACIDS.* BY L. GOWING-SCOPES. JOSEF VON FERENTZY has recently published a paper on this subject in the Chew,. Zed., 1907, 31, 1118 (cf. ANALYST, 1908, 27). His method, which depends on the insolubility of basic magnesium tartrate in 50 per cent. alcohol by volume, is as follows : 6 ‘ The solution containing the three acids is evaporated to i small volume, and alcohol is added until the solution contains 50 por cent. A sufficiency of magnesia mixture is added, and also more alcohol up to 50 per cent. After twelve hours the basic magnesium tartrate is collected, washed with 50 per cent. alcohol, and then ignited. “ As two molecules of magnesium oxide equals one molecule of tartaric acid, the weight of magnesium oxide found should be multiplied by 1.875 to convert it to tartaric acid.” * This iiiveutigttioii was ciiihd out under the Aiialyticsl Chcrnistry Iiivestigittion Scheme, t t ~ l d a portion of the expensc was tlefrayed by a grant from thc Society.316 THE ANALYST.I carefully tried this method and obtained the following results : Weight of Tartaiia Acid Taken. Weight of hlalic and Succinic Acids. Weight of Tart,ibl*ico Acid Foiiiid. Error. Grarn. 0.2000 0*3000 0*4000 Cram. 0.8000 0.7000 0*6000 Gram. 0.1965 0.3162 0-4005 Gram - 0.0035 + 0.0162 + 0*0005 In carrying out the method considerable difficulty was experienced in drying and igniting the precipitate without appreciable loss. Since the principle of the method depends on the separation of the tartaric acid as basic magnesium tartrate, and the final method by which the amount of tartaric acid is deduced is not an essential, I have obviated this difficulty by making the method a volumetric one, the basic magnesium tarcrate being finally titrated with potassium permanganate, in the manner described by Chapman for the titration of the bismuth salt (ANALYST, 1907, 32, 163). My experiments have shown that the adoption of the following details will give good results : 1.A quantity of the substance under examination is taken of such a weight or volume that the solution contains not less than 0.05 gram of tartaric acid, and not more than 0.10 gram. 2. If the bulk of the solution be large, or if alcohol be present (c.g., wines), the solution is evaporated to about one-half of the original volume.3. To the cool solution an equal volume of absolute alcohol is added; the precipitate which comes down in the case of fruit-juices and wines is filtered off and washed with 50 per cent. alcohol (by volume). 4. To the filtrate 10 C.C. ammonia and 10 C.C. absolute alcohol are added; any precipitate which forms is filtered off and washed as above. 5. To the filtrate 10 C.C. magnesia mixture, and finally 10 C.C. absolute alcohol, are added, stirring all the while. 6. The solution is allowed to stand overnight, and in the morning filtered through double filter-papers, washed with 50 per cent. alcohol, care being taken that no precipitate comes through. 7. The well-drained precipitate is dissolved off the filter with boiling water (about 400 0.0.).A dark-coloured insoluble precipitate of organic matter other than basic magnesium tartrate usually remains on the filter. 8. The filtrate is boiled down (preferably in a flask) to about 200 c.c., or until all alcohol is driven off, cooled, 10 C.C. strong sulphuric acid are added, and the solution diluted to 350-400 C.C. 9. The solution is heated to about 90" C. Potassium permanganate solution (6.9745 grams per litre ; 1 C.C. = 0-0050 gram tartaric acid) is run in, 8 C.C. at a time,THE ANALYST 317 shaking after each addition until the solution is deoolorised. When nearing the end of the titration, the permanganate is added drop by,drop until two or three drops have been added in excesB. 10. The solution is then titrated back with oxalic acid solution (1308793 grams per litre ; 1 C.C.= 1 C.C. permanganate). Nom.--The best results are obtained when the permanganate is added in very small quantities at a time. EXPERIMENTS MADR ON MIXTURES ON MALIC, SUCCINIC, AND TARTARIC ACIDS I N AQUEOUS SOLUTIONS. rVeight of Malic and Succinic Acid Taken. Weight of Tar- taric Acid Taken. Weight; of Tar- taric Acid Found. No. C.C. KMnO, used UP. No. of Experi- ment. Error. Grams. 4,9500 0.9900 0.4900 0.3233 0.2400 0.1900 0*1000 0.1000 0.0666 Gram. 0.0500 0*1000 0.1000 0.1000 0~1000 0~1000 0-1000 0~1000 0~1000 Gram. 0.0495 0,1032 0*1010 0*1010 0.1017 0*1010 0.1003 0.1007 0-0993 Gram. - 0.0005 + 0.0032 + 0.0010 + 0~0010 + 0.0017 + 0.0010 + 0.0003 + 0.0007 - 0.0007 1. 2. 3. 4. 5. G. 7. 8. 9. 6.90 14-40 14.10 14.10 14.20 14.10 14.00 14.05 13.85 10.11. 12. 13. 0~0500 0*0500 0.0500 0~0500 6.90 6.80 7-00 6.95 0.0495 0.0491 0.0501 0.0498 - 0*0005 - 0*0009 + 0*0001 - 0*0002 0.1005 0.0990 0.0997 0*1010 0.1010 0*1000 + 0.0005 - 0*0010 - 0.0003 $. 0.0010 + 0.0010 - 0~0000 14. 15. 16. 17. 18. 19. 0.1000 0~1000 0.1000 0*1000 0*1000 0.1000 20.10 19.80 19.95 20.20 20.20 20.00 0.0990 0.1025 0.1010 0.1005 0.1005 - 0~0010 + 0.0025 + 0.0010 + 0.0005 + 0.0005 20. 21. 22. 23. 24. 0~9000 0.4000 0.2333 0-1500 0.0428 0~1000 0.1000 0~1000 0.1000 0~1000 19.80 20.50 20.20 20.10 20.10 25. 26. 27. 28. 29. 0.0120 0:0200 0.0280 0*0400 0.0480 0.0100 0*0200 0.0300 0-0400 0.0500 2.00 3.90 5.85 7.80 10.10 0~0100 0,0195 0.0292 0-0390 0.0505 t_ 0~0000 - 0.0005 - 0.0008 - 0~0010 + 0.0005318 THE ANALYST.Grapc-Juice Taken. RESULTS. The separation is both clean and sharp, and the method has stood the test of over fifty trials made under various conditions. Nos. 1 to 13 were titrated with 1 per cent. potassium permanganate solution, while Nos. 14 to 23 were titrated with potassium permanganate Rolution of such a strength that 1 C.C. equalled 0*0050 gram tartaric acid. The figures in the second column are weights of a mixture of equal parts of malic and succinic acids. The mean of experiments 2 to 9 is 14-10, and it is worthy of note that this amount agrees almost exactly with that given by Chapman for 0.1 gram tartaric acid in combination as the bismuth salt. I t will be seen from the table on p. 316 that the errors in the first experiments are not due to the separation, but to the method of estimating the tartaric acid in the precipitate.Having thus made sure that malic and succinic acids do not come down, I tried the effect of apple-juice on the separation. Tartaric Acid in KO. of C . C . I<MllO, 100 U . C . nsecl Ill). No. of Experiment. 30 31 32 33 34 35 36 37 38 Apple-Juice used. Tartaric Acid T:Lken. Gram. 0*1000 0~1000 0~1000 0.1000 0~1000 0.0500 0.0500 0.0500 0~0500 Tart.aric Acid Found. Gram. 0.0997 0.0980 0.1007 0.0977 0.1007 0*0480 0.0487 0.0460 0*0480 Error. Gram. - 0.0003 - 0*0020 + 0*0007 - 0.0023 + 0.0007 - 0.0020 - 0.0013 - 0.0040 - 0.0020 Finding that substances usually present in fruit-juices did separation much, I determined the tartaric acid in grape-juice : not affect the No. of Exlieriment, 39 40 41 42 G ram.0437 0.425 0,425 0.435 8-75 8.50 8-50 8.70 As a final test of the applicability of the separation, I estimated the tartaric acid For this purpose a Mkdoc with a fairly high percentage of tartaric acid in wine, was used :THE ANALYST. 319 No. of Experiment. Wine Used in C.C. Tartaric Acid Found in 100 C.C. No. of C.C. KMnO, used up. 43 44 45 46 47 48 50 50 25 25 25 25 G la1 I I . 0.120 0.121 0.120 0*122 0.126 0.119 12.00 12.10 6.00 6.10 6.30 5.95 To check the"above figures the tartaric acid was estimated by the bi-tartrate method, and the result of 0.1000 gram per 100 C.C. obtained. I t is seen that the results for the estimation of tartaric acid in wine, although concordant by this method, are rather higher than that given by the bi-tartrate method. This is due to tannic aFid, which is precipitated with the magnesium tartrate. This substance should be separated by a suitable method before determining the tartaric acid. SUMMARY. 1. J. von Ferentzy's method of separating malic, succinic, and tartaric acids is clean and sharp. 3. More accurate results may be obtaimd by titrating the basic magnesium fartra t e with potassium permanganate. 3. Tartaric acid may be accurately estimated in fruit-juices by this method, and in wines if the tannic acid is first removed. In conclusion, I have to thank Mr. H. Droop Richmond, F.I.C., for the interest he has taken in the investigation, and Mr. F. W. Harbord, F.I.C., for allowing me to carry out the experiments in his laboratory and for useful advice.

ISSN:0003-2654    

DOI:10.1039/AN9083300315

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 319 ABSTRACTS Estimation OF PAPERS PUBLISHED IN OTHER JOURNALS. FOODS AND DRUGS ANALYSIS. of Alcohol and Extract in Spirits by Means of the Refracto- meter. J. Race. (Jouriz. SOC. Chem. Ind., 1908, 27, 547-548.) -The method described by Riegler (ANALYST, 1896, 21, 133) may be adapted to the examination of spirits. As, however, the increase in refractive index per unit of alcohol is not constant for all proportions of alcohol and water, the refractive index observed must be compared with a table of values, in order to ascertain the corresponding quantity of320 THE ANALYST. alcohol. The author gives a table showing the refractive indices corresponding with weights of alcohol ranging from 1 to 100 per cent. ; the readings were observed on mixtures of pure alcohol and water.The refractive index of the spirit is observed at a temperature of 15.5' C., and also that of the liquid obtained by the evaporation of 25 C.C. of the spirit almost to dryness, and then making the residue up to the original bulk. The difference between these results is due to alcohol and other volatile constituents, and the difference between the refractive index of the extract and that of water is due to the extractive matters contained in the spirit. w. P. s. Beer Analysis. J. Race. (Joz~rn. SOC. Chem. Ind., 1908, 27, 544-547.)- Estimation of Alcohol and Extract by Means of the Refractometey.-The alcohol and extract figures required for the calculation of the original specific gravity of the beer may be obtained by means of the immersion refractometer. For beers contain- ing over 4.5 per cent.of alcohol the following formuk give the best results : X = (0.00778r - 0*0029s)100 Y = (0.0035~ + 0*0013~)100 Where X and Y are the percentages of alcohol and extract required, r is the difference between the refractive index of the sample and that of water, and s the difference between the specific gravity of the sample and the specific gravity of water. In the estimation of chlorides, it is recommended that barium carbonate be added (0.5 gram to 500 C.C. of beer) before evaporating and igniting. The ash is then extracted with hot water, filtered, and titrated in the usual way. The author finds that it is necessary to add alkali to the sample in the estimation of sulphates, in order to prevent loss of sulphuric acid during the ignition.This loss is shown to be due to the action of the acid phosphates on the sulphates. (See also ANALYST, 1907, 32, 84.) w. P. s. New Method for the Estimation of Fat in Cocoa. A. Kreutz. (.&its. Untersuch. Nahr. Gemssnz., 1908, 15, 680-683.)-The method described is based on the fact that the fat is readily extracted from cocoa by means of ether if the cocoa be first fused with chloral alcoholate. In carrying out the process, from 1 to 1-5 gram of the cocoa is placed in a small flask, about 3 grams of solid chloral alcoholate are added, and the mixture is melted by heating on the water-bath. While still hot, the mass is treated with from 10 to 15 C.C. of ether, the mixture being well stirred, so that the cocoa powder is distributed evenly throughout the ether.A further quantity of about 35 C.C. of ether is now added, and, after being well shaken, the mixture is poured on a dry filter. The filtrate is passed again through the filter until it is quite clear, and the residue on the filter is then washed three times with ether. The ethereal extract and washings are evaporated in a weighed flask, and the residue of fat is dried at a temperature of 105O to 110" C., until constant in weight. w. P. s.THE ANALYST, 321 The Composition of the Eastern Food Products: Bosa, Halva, and Locoum. N. Petkoff. (Zeit. ofentl. Chcrn., 1908, 14, 205-208.)-The products known as bosa, haha, and locourn are in common use throughout Bulgaria and other Eastern countries, including Russia. Bosa, which is of Turkish origin, is a cooling summer drink, prepared by the limited fermentation with yeast of a decoc- tion of coarsely ground millet.Halva is a solid substance, prepared from t ( thaban ” (roasted sesame meal), boiled with water, sugar, citric or tartaric acid, and a, little saponine extract. Locourn is 8 gum-like mass, prepared from starch paste and sugar in varying proportions. The last mentioned contained unaltered starch, whilst saccharin is frequently present in bosa. The following results were obtained in the analysis of typical samples : Alcohol ... ... ... Water.. . ... ... ... Ash ... . . I ... ... Solid extract.. . ... ... Fixed acids (as lactic acid). . . Volatile acids (as acetic acid) Maltose ... ... Dextrin ... ... ... Sugars, total ... ... ... Cane-sugar .. . ... ... Nitrogenous substances . . . Phosphoric acid . . . ... Sesame oil ... ... ... Glycerin .. , ... Specific gravity ... ... Bosa. Per Cent. 0.738-0-831 0.236-0.305 7-31-11-24 0.0 15-0-03 8 2.44- 3-64 3.32- 4.05 - 0.30- 0040 - - 0.71- 0.98 0.056-0.1 15 - 0.065-0.090 1.030-1 -0425 Hdva. Per Cent. 0-50-1-98 - 0.95-1.35 - - I - 4.05- 5.13 46-85-59 *6 3 5.20-31.25 8.92-10.47 20.5- 29.68 0.455-0.631 - - Locoum. Per Cent. - 3.25 -7.7 0*034-0.08 - - - - - 56.7- 74.7 16-53-45.3 - - - - - C. A. hl. The Molecular Weight of the Dextrins occurring in Pine-honey. H. Barschall. (drbeit. Kaiserl. Gesundheitsarnte, 1908, 28, 405-419.)-As a result of a number of cryoscopic determinations, the author finds that the dextrin described by Hilger (ANALYST, 1904, 29, 306), as having an empirical of (CcHloO,)~,, is probably a trisaccharide with the formula (C6H1005)3.The latter is equivalent to a molecular weight of 486, whilst the mean of the values found was 473. w. P. s. Estimation of the Total Solids (Sugars) of Honey by Means of the Refractometer. Utz. (Zeit. nngew. Chem., 1908,21, 1319-1321.)-As the different carbohydrates, with the exception of dextrin, have practically the same refractive index, it is possible to calculate from the refractive index of a, sugar solution the amount of sugar therein. The following table has been compiled by the author, and322 THE ANALYST. shows the refractive indices corresponding with percentages of sugar varying from 70 to 90 : Sugar. Per Cent. 70 71 72 73 74 75 76 77 78 79 Refractive Index at 20” C .1.4635 14677 1.4701 1.4726 1.4751 1.4776 1.4801 1.4826 1.4851 1.4876 Sugtlr. Per Ceiit. Refractive Index at 20” C. 80 81 82 03 84 85 86 87 88 89 90 1.4903 1.4929 1.4955 1.4981 1.5007 1.5034 1.5061 1 *5088 1.5115 1.5142 1 51 76 In the case of honey the refractive index gives the total solidsof the sample. If the honey to be examined is in a crystallised condition, it should be warmed in a closed bottle until fluid, and then cooled to 20” C. I n taking the reading a few drops of the sample are placed between the prisms of the instrument. The results obtained in the examination of fifty-seven samples of honey are given : the highest refractive index observed was 1.4958, corresponding with 82.1 per cent. of total solids, whilst the lowest reading was 1.4780, or 75-5 per cent.total solids. w. P. s. Considerations affecting the ‘‘ Strength ” of Wheat Flours. J. L. Baker and H. F. E. Hulton. (Jo?wn. SOC. CILern. Ind., 1908, 27, 368-376.)-1t is im- probable that any one chemical or physical determination can be correlated with the 6 ‘ strength ” of flours, as the generally accepted definition of ‘‘ strength ” includes two distinct qualities-viz., size and shape of loaf. The authors were unable to show the presence in flour of a proteolytic enzyme capable of degrading the gluten, and so influencing the character of the loaf, but there are small quantities of an erepsin. Yeast can effect partial proteolysis of gluten, and it is probable that the physical character of the gluten may in this way be modified during the early stages of doughing.I t was found that the products of hydrolysis closely resemble those of the action of barley diastase on starch. As regards aqueous flour extracts, there is a considerable departure from Kjeldahl’s law of proportionality. In determining the diastatic power of wheats and flours by Lintner’s method, the reducing power of the solution in terms of maltose shouldnot exceed 20 per cent. No direct relation can be traced between the diastatic power of a flour and the bakers’ marks. Some flours improve on keeping. I n this connection it is noted that the diastatic powers of flours also change. Doughs have a greater diastatic capacity than either the aqueous extract of the flour or the dry flour itself, and this diastatic activity varies inversely with the amount of water The importance of amylolytic enzymes in flours is referred to.THE ANALYST.323 with which the flour is wetted. This activity increases on keeping the dough at a temperature of 40" C. The signification of gas production and its relation to 4 4 strength '' is considered, and in this connection the authors found that certain flours possessed a starch-lique- fying enzyme. The malt extract used by bakers is considered to have its main sig- nificance as furnishing this liquefying diastase. A trace of powdered malt added to flours increases the volume of gas liberated from the dough, and the percentage increase of gas from such malt-activated flours varies from 88, in the case of a flour giving without malt very little gas, to nil. The toxic action of flour and its aqueous extract on yeasts, in view of Lange's work, suggested that different flours might vary in their behaviour to yeast as regards their relative toxicity.The gliadin : glutenin ratio is discussed, and the formation of gluten from these two substances is shown to be independent of enzymic activity, as has sometimes been suggested. Gliadin separated from flour by alcohol was recombined with the residual gluten and starch, and from this the gluten was recovered by washing out. The diastatic activity of gluten is confirmed and considered, and is shown to reside in the glutenin moiety. Experiment did not confirm this. H. F. E. H. The Amylolytic and Proteolytic Ferments of Wheaten Flours and their Relation to Baking Value. J. S. Ford and J.M. Guthrie (Joziwz. SOC. Chem. Ind., 1908, 27, 389-393.)-The conditions of extraction of the flour with water affect the amylolytic activity to a considerable extent, destruction of the enzyme taking place with varying rapidity. Extraction in the presence of the alkaline phosphates, glycine, gelatine, and other substances, gives enhanced values, due, in the authors' opinion, to conservation of the enzyme by solution of protecting bodies. Digestion of the flour with an actively proteolytic preparation of papain (Jourtz. Inst. of Bmuing, 1908, 14, 60) showed a still higher amylolytic activity. The papain appears to influence the result in two ways : (1) by liberating diastase which would otherwise be, insoluble, and (2) by prevention of its destruction.The figure obtained in this manner the authors consider approaches the absolute value. From 20 to 60 per cent. of the total amylase present may be in the insoluble condition. .4nother method of obtaining diastatic value is by '' autodigestion," in which the flour is extracted at 30" C. for varying periods of time in presence of nitro-benzene to stop bacterial action. Prolonged autodigestion of one flour showed an increase in diastatic activity, and from this result is inferred the presence of a proteolytic enzyme. The protease in wheat flours, the presence of which can be deduced from an investigation of the amylase figures obtainable, may be detected by a modification of the ordinary gelatin method, the flour being digested for at least forty-eight hours at 35" C.in presence of nitro-benzene. This method the authors failed to make quantitative, though various modifications were tried. A preparation of the pro- teolytic enzyme from a flour containing it was incorporated in a high-class flour, and a baking trial with suitable controls was carried out, with the result that the loaf from the treated flour was unsatisfactory. The presence of this enzyme is held to524 THE ANALYST. be an important factor in explaining cases of (‘ rotten gluten ” and unsuitable malt extracts used as baking adjuncts. H. F. E. H. BACTERIOLOGICAL, PHYSIOLOGICAL, ETC. Activity of Pepsin, and a Simple Method for its Estimation. 0. Gross. (Bed. kZin. Wockenschr., 1908, 45, 643; through Chem. Zeit. Rep., 1908, 32, 310.)- The method is a modification of that described for trypsin (ANALYST, 1908, 130). Solutions of casein containing the necessary quantity of hydrochloric acid are mixed with increasing quantities of the pepsin under examination, and then heated for fifteen minutes at a temperature of 40" C. Sodium acetate, which precipitates casein but not caseose, is employed for determining the end-point of the digestion. The intensity of the digestion is proportional to the quantity of ferment added, whilst the time taken is inversely proportional to the quantity of ferment present. w. P. s.

ISSN:0003-2654    

DOI:10.1039/AN9083300319

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

524 THE ANALYST. ORGANIC ANALYSIS. Composition of Almond-Tree Gum. R. Huerre. (Joum. Pharm. Chinz., 1908, 27, 561-569.)-The following table embodies the results obtained in the analysis of almond-tree gum and of the closely similar gums from the apricot and plum trees : Gum froin Apricot-tree.. . ... Almond - tree (hard) ,, (elastic) Plum-tree . . . ... Soh blt i n Water calculated on Dry Substltn ce Per Cent. 91.17 21.06 8-90 79.16 Insolnlde iii Water. Pcr Cent. 8.83 713.94 91.10 20.84 Moist<nre. Per Cent. 16-14 15.76 25 15.48 Ash. Per CWt. 3.39 2 *34 2.52 Galactans Galactose. Per Ceiit. as 23.60 23.70 16.36 - Perit,osnns as Arnbiii ose. Per Cent. 48-75 54.60 76.35 - Total Sugars. 78.74 85 91 94.81 Notes on Bang’s Method of Estimating Sugar. H. Jessen-Hansen, (Biochenz. Zcit., 1908,10, 249-257.)-1t is shown that, in preparing the copper solution, it is not only necessary to keep within the limits of temperature prescribed by Bang (ANALYST, 1907, 32, ISO), but also to see that the liquids mixed together are of the exact concentration named, for it is not possible to dilute the solution subsequently without obtaining very different readings in the titration with the hydroxylamine solution.The speed of titration, the temperature, and the volume of the liquid titrated, have all some influence upon the results. I n standardising the solution, the end-point cannot be recognised with certainty with an excess of less than about 0.25 c.c., though in the presence of reducing sugars the change from blue to colourlessTHE ANALYST.325 can usually be seen after an excess of 0.1 C.C. In all cases a blank experiment under the conditions of analysis should be made. The influence of the conditions upon the results is to be attributed to the readiness with which the ratio between the nitrous oxide and nitrogen is affected by such conditions in the reaction which occurs : l O C U 0 + 8H,NO = 5Cu2O + NZO + 3N2 + 12HZO. I n the author’s opinion the method is sufficiently accurate for most technical purposes, and especially for comparative estimations, if these precautions are taken ; but for work of extreme accuracy Kjeldahl’s modification of Fehling’s process should be employed. C. A. M. Detection of Cane-Sugar in Seeds. E. Schulze. (Zeits. physiol. Chem., 1908, 52, 404 ; through Wochensch. Brau., 1908, 25, 371.)-Formerly the author extracted the finely powdered seeds with boiling 90-92 per cent.alcohol, and precipitated the sugar from the extract in the form of its strontia compound. The precipitate, which contained other carbohydrates besides cane-sugar, was decomposed by carbon dioxide, and the filtrate evaporated to a syrup ; the syrup was treated with 95 per cent. alcohol, and the cane-sugar was crystallised by allowing the solution to evaporate slowly over sulphuric acid. In order to avoid the extraction of other carbohydrates, the author now recommends the extraction of the seeds with absolute alcohol at a temperature of 50’ C. In most cases the cane-sugar may be crystallised directly from this extract without the intervention of strontia ; the seeds should previously be freed from fat by means of ether.Although cane-sugar is ordinarily very sparingly soluble in absolute alcohol, it would appear that the presence of certain other substances in the seed increases the solubility of the cane-sugar. By neither of the above methods is the recovery of the cane-sugar abRolutely complete. J. F. B. Colour and Spectrum Reactions of the Sugars with Naphtho-resorcinol and Hydrochloric Acid. B. Tollens and F. Rorive. (Ber. c h t . Chent. Ges., 1908, 41, 1783-1787.) - Naphtho-resorcinol (1.3 dihydroxynaphthalene), like other 1.3 phenols, gives characteristic colour reactions when warmed with carbohydrates in presence of hydrochloric acid. The test may be carried out in aqueous or alcoholic solutions. I n the former case there is a precipitate; in the latter there is none.The following procedure is recommended : A few crystals of the sugar and about the same quantity of naphtho-resorcinol are slowly heated to boiling with about 10 C.C. of a mixture of equal volumes of water and hydrochloric acid of specific gravity 1-19, The liquid is boiled very gently for one to three minutes; then placed aside for three to five minutes, and cooled under a tap. The deposit is filtered off, washed until the filtrate is nearly colourless, and dissolved in alcohol. The alcoholic solution is diluted with alcohol, if necessary, and examined spectroscopically. With lmulose and sorbose a fine purple-red coloration is developed, when the sugar is merely warmed with naphtho-resorcinol and hydro- chloric acid.The alcoholic solution of the deposit produced on boiling is yellowish-326 THE ANALYST. brown. With dextrose, mannose, and ali substances which yield these sugars on hydrolysis, the alcoholic solutions of the deposits show a band in the green portion of the spectrum. With galactose and carbohydrates which contain a galactose group the alcoholic solutions of the deposits show a band in the green and a band on the D line of the spectrum. If laevulose be present, this latter band does not show. I t is necessary, therefore, in such cases to destroy the lwulose by heating the sugar with the acid alone before adding the naphtho-resorcinol, and to filter the product and decolorise with blood charcoal. With the pentoses, and particularly with the methyl pentoses, the alcoholic solutions of the deposits show a strong green fluorescence.The solutions from the methyl pentoses are violet-blue, and show a band on the D line and another in the green. Glycuronic acid and its derivatives show colorations similar to those from the methyl pentoses. J. F. B. Simple Test for Glycuronic Acid by Means of Naphtho-resorcinol, Hydro- chloric Acid and Ether. B. Tollens. (Bey. dezd. Chem. Ges., 1908, 41, 1788-1790.) -Hitherto no reliable test for the detection of glycuronic acid in presence of pentoses has been available, but the author now describes the following reaction which affords a ready differentiation : A small fragment of the substance is dissolved in 5 to 6 C.C. of water in a test-tube 15 to 20 mm. in diameter, or else 5 to 6 C.C.of urine are taken, 0.5 to 1.0 C.C. of a 1 per cent. solution of naphtho-resorcinol in alcohol is added, and then a quantity of hydrochloric acid of specific gravity 1.19, equal in volume to the liquid already in the tube. Theliquid is slowly heated to boiling, and boiled gently for one minute ; it is put aside, for four minutes, and then cooled with agitation in a stream of water. An equal volume of ether is then added, the mixture is shaken, and, after the two layers have separated, the ethereal layer is examined spectroscopically. When the test is carried out in the above manner, a blue to red violet colouring matter, which is soluble in ether, is produced from glycuronic acid, whereas any coloration which may be produeed from pentoses or other sugars is not soluble in ether.I n the presence of urine the colour of the ethereal layer, which with pure glycuronic acid is blue, is violet or red, but in either case the ethereal solu- tion shows an absorption-band at, and slightly to the right of, the D line of the spec- trum. In the case of urine the separation of the ethereal layer sometimes presents a little difficulty, owing to the formation of a dark-coloured gelatinous emulsion ; in such cases the addition of a few drops of alcohol or of more ether assists the separation. J. F. B. Effect of Drying on the Dyeing Amnities of Ordinary and Mercerised Cotton. E. Knecht. (Jozmz. SOC. Dyers and Col., 1908, 24, 107 ; through Chew$. Zeit. Rep., 1908, 32, 327.)-If cotton be mercerised and dyed without drying, it absorbs a considerably greater proportion of dyestuff than if it be dried after mercerising and before dyeing.The author has studied this phenomenon quantitatively with benzo- purpurin, estimating the proportion of the dyestuff absorbed by the cotton by means of titanous chloride. Two hanks of bleached cotton were mercerised without tension in a lye of 1.225 specific gravity. After washing, one was dried at 100" to 110" C. and the other was kept moist; both were then dyed in the saine bath of benzo-THE ANALYST. 327 purpurin for fifteen minutes. The undried cotton absorbed 1.74 per cent. of the dyestuff, whilst the dried sample took up only 1.16 per cent. Ordinary bleached cotton shows no difference in dyeing aflinities with or without drying at 100" C. ; but this may be due to the drying of the cotton after bleaching.If cotton piece goods be mercerised, and if drying be prevented in certain portions by the local application of glycerol or other hygroscopic substance, and the piece be then dried and dyed, the places on which the glycerol is applied dye to a darker shade t,han the portions of the cloth which are fully dried. The action of drying after mercerisation on the dyeing affinities of the cotton is permanent, and is not destroyed by re-wetting. The absorption of iodine by mercerised cotton is modified by drying in the same manner as the dyeing affinity. J. F. B. Composition of Congo Copal and White Benguela Copal. A. Engel. (Archiu der Pharm., 1908, 246, 293-305.) - Congo CopaZ.-The sample examined became brownish-yellow at 90" to 92" C., began to melt at 105" C., and wag com- pletely liquid at 175",C.Its acid value (direct method) was 117.7 and (indirect method) 124.8, and its saponification value (one hour's heating) 152.6. Ether dissolved about 60 per cent. of the copal; alcohol, 48 per cent.; acetone, 28 per cent.; petroleum spirit, 15 per cent.; and alcohol-ether, 85 per cent. From the portion soluble in ether there was separated by treatment with alkali a monobasic acid, C,,H,,O, (coltgo-copalic acid), constituting from 48 to 50 per cent. of the original copal, whilst there remained in solution a resin (a-coitgo-copaZo~.esi~z) constituting 5 to 6 per cent. of the copal, and an ethereal oil distilling at 165" to 168" C. (3 to 4 per cent. of the copal). The portion insoluble in ether dissolved to the extent of 35 to 36 per cent.in a mixture of alcohol and ether, and the solution yielded an acid, C,2H,,03, termed coiigo-copalolic acid, which was soluble in ether, and a resin, P-congo-copalo- resin, insoluble in ether, the former constituting about 22 per cent., and the latter about 12 per cent., of the original substance. White Bengz~ela CopnL-The sample began to melt at 10Go to 108" C., and was completely fluid at 156" to 158" C. It had an acid value of 112 to 1148 (direct method) and 11'7.6 to 120.4 (indirect method), and a saponification value of 120.4 to 123-2. About 55 per cent. was soluble in ether, of which 43 to 45 per cent., consisted of bengucopalic acid, C,,H,,02, 3 to 4 per cent. of an ethereal oil, distilling at 148' to 155" C., and 4 to 5 per cent.of a-bengucopaloresin. The portion insoluble in ether (45 per cent.), treated with a mixture of alcohol and ether, gave a solution containing 22 per cent. (on the original substance) of bengucopalolic acid, C,,H,,O, (melting-point, 114" to 116" C.), which was soluble in ether, and 14 to 16 per cent. of P-bengucopnloresiu (melting-point, 192" to 196" C.), C22H3G02, insoluble in ether. C. A. 35. The Constituents of Cyprus Origanum Oil. Isolation of a New Terpene '' Origanene." S. S. Pickles. (PTOC. Chem. Soc., 1908, 24, 95.)-The essential oil yielded by the principal origanum plant of Cyprus has been examined and found to consist mainly of cmvacrol (84 per cent.). There were also present (1) a hydro-328 THE ANALYST.carbon, CIOHIG, apparently a new terpene, for which the name origalzene is proposed (2.5 per cent.) ; (2, cymene, which, together with associated terpenes (boiling-point 170" to 180" C.), constitutes 8.5 per cent.; (3) terpene alcohols (3-5 per cent.); and (4) high boiling residue (1-3 per cent.), besides very small quantities of a second phenol which gave a purple coloration with ferric chloride, and a volatile acid- probably isobutyric acid. Chemical Examination of Ipomcea Purpurea. F. B. Power and H. Rogerson. (Amer. Joz6rn. Pharnz., 1908, 80, 251-286.)-The authors have made an exhaustive examination of the aerial stems of Ipomaa pzqwrea, Roth (Comolcdzis pzcrpurezis, LinnB, the common '' morning glory ' l ) . The chief constituents are : (1) An essential oil, present to the extent of 0.018 per cent., and having the follow- ing characters: sp.gr. at 20°/20", 0,9085; optical rotation, -4.87" for 100 mm.; boiling-point, 90' to 180" C. under 35 mm. pressure. (2) A soft, dark greenish resin, present to the extent of 4.8 per cent., of which155 per cent. is soluble in ether. The alcoholic solution of the crude resin is optically active, the specific rotatory power being [aID = - 50.95". The aqueous liquid remaining after removing the volatile matters (oil, etc.) in steam contained potassium chloride and nitrate, together with tannin and colouring matters, and yielded glucose on heating with dilute mineral acid. The crude resin was treated with various solvents, and was found to be of very complex composition. The different fractions yielded the following results : (a) Petroleunz-ether extract (8 per cent.of the total resin) contained pentatriacontane, C:$,-,Hi2, melting at 74" to 75" C. ; a phytosterol, C,,H,,O, HzO, melting-point 132" to 133' C., and [a], = - 32.1" ; formic, butyric, and higher volatile acids ; stearic and pelmitic acids, with a small amount of an unsaturated oily acid. ( b ) Ethel. extract (7-3 per cent. of the resin) consisted chiefly of a resinous substance with formic, butyric, and higher volatile acids, a neutral oil of pleasant odour, and a crystalline acid, C9H,,0, (azelaic acid), melting at 103' to 104O C. (c) Chloroform extract (9.8 per cent. of the resin) yielded similar results to ( b ) , but no crystalline acid was obtained. (cl) Ethyl acetate extract (23 per.cent. of the resin) yielded a small quantity of a crystalline alcohol, ipuranol, C,:,H,,O,(OH),, melting at 285" to 290' C. ( e ) Alcohol extract (about one-half of the crude resin) consisted mainly of ipurolic acid, CI:,H2,(0H),.C0,H, cry stallising in fine colourless silky needles melting at 100" to 101" C. Other products obtained from this extract were the neutral oil and the volatile fatty acids previously mentioned, together with optically active valeric acid (d-methyl-ethyl-acetic acid), and a mixture of acids from which, after treatment with 5 per cent. sulphuric acid, a hydroxy-lauric acid, melting at 69" to 70" C., and ipoluric acid (see above) were isolated. The portions of the crude resin soluble in ether, ethyl acetate, and alcohol had a very marked purgative action.A. R. T. Oil of Lawsonia Alba. D. Hooper. (JOZWZ. and Proc. Asiatic Society of Bengal, 1908, 4, No. 2 ; through Pharrn. Jozmz., 1908, 80, 781.)--The seeds ofTHE ANALYST. 329 this plant are contained in a capsule of the size of a peppercorn, and are angular grains of 8, cinnamon-brown colour, 1.5 to 2.0 mm. long, and without appreciable taste or smell, One hundred seeds weighed 0.073 gram. On analysis, the seeds gave the following results : Moisture, 10.60 ; oil (ether extract), 10.48 ; albuminoids, 5.00 ; carbohydrates, 33-62 ; fibre, 35.55 ; ash, 4-75. The seeds are, therefore, not true oil- seeds, and cannot be considered nutritious. They were dry and fibrous, and con- tained some tannic acid. The thick, dark green oil slowly solidified to a jelly, and had the following characters : Solidifyiug-point, 25.5" C.; iodine value, 121.63 (of fatty acids, 127.45); slightly acid in reaction. I t is somewhat similar in nature to poppy-seed oil. A. R. T. Metanil Yellow : Its Use as a Selective Indicator. E. Linder. (Jo~LT?~.. Soc. Chem. Ind., 1908, 27, 485-489.)-The author prepares test-papers of inetanil yellow by steeping filter-paper in an aqueous solution of the dye-stuff' and drying in an air-bath at 90" C. These papers show a violet stain with acids ; the quality of paper and the depth of shade affect the sensitiveness of the indicator and the permanence of the violet stain in a marked degree. Schleicher and Schiill's paper, No. 589, black band, dyed to a medium shade of orange yellow, is recommended.The papers can be prepared so as to respond to solutions of sulphuric acid of Nj500 to NjlOOO strength. With the lower concentrations of acid the violet colour is not apparent unless the paper is dried ; water dissociates the violet coinpound, which, however, is re-formed on drying, unless the acid which had produced it be volatilised. The paper is extremely useful in detecting traces of acid in the atmosphere or gaseous effluents. The stabilities of the violet stains produced by the mineral acids also differ suffi- ciently to afford a meens for their identification : the violet compound of hydrofluoric acid, when placed in contact with sized paper, fades in two to three hours, the derivatives of nitric acid and hydrochloric acid fade in a week, and thn, stain produced by sulphuric acid lasts for months ; the permanence of the stains depends, however, on the quantity of acid.Sulphur dioxide and acetic acid have no action on the paper, which may therefore be used for the detection of sulphuric acid in the products of combustion of sulphur and as an adulteration in vinegars. I n the latter case a drop of the suspected liquid is placed on a dry test-paper, and the paper is dried at a temperature of 40" to 50" C. The presence of mineral acid is then indicated by a violet stain on the dried paper. J. F. B. Estimation of Mineral Oil in Rosin Spirit. J. Marcwsson. (Miitto K. ~~~ateria~~ri~~LIzgsa7nt, 1908, 26, 157 ; through Chenz. Zeit. Rep., 1908, 32, 325.)-The author shows that the Herzfeld sulphuric acid test for petroleum spirit in rosin spirit is not reliable.In the nitric acid test, originally proposed by Burton, small quantities of insoluble matters may be produced from the rosin oil itself. But in that case, if the portions of the sample boiling between 120" and 150" C. will mix with aniline or with acetic anhydride, the presence of benzin in technically appreciable quantities is excluded. The so-called German turpentine oils or pine-wood oils show a similar behaviour to rosin oil by the sulphuric acid test. Also for the testing of real oils of turpentine the nitric acid method is preferable, since at the low temperature at which330 THE ANALYST. it is carried out, according to the present procedure ( - 10' C.), losses of petroleum hydrocarbons of low boiling-point are avoided.J. F. B. The Fat of Mimusops Djave. J. Freundlieh. (Chem. Rev. Fett- zc. Harz- I d , 1908, 15, 78-79, 106-108.)-The seeds of the tree Mimusops Djave, which grows in the Cameroons, were found to contain 4.54 per cent. of a volatile oil and 64-42 per eelit. of a soft light brown fat of the consistency of lard. This fat contained 2.2 per cent. of yellow gelatinous unsaponifiable matter, and gave the following analytical values : Specific gravity at 36*5O/15' C., 0.9022 ; solidification-point, about 28" C. ; acid value, 13-8 ; saponification value, 182.45 ; iodine value, 56.0 ; Reichert-Meissl value, 0.7 ; acetyl value - Lewkomitsch's distillation method, 15.68, filtration method, 7.07. Fatty acids : Melting-point, 51" C. ; solidification-point, 46" C. ; neutralisation value, 190.52 ; and saponification value, 197.15.The difference between the neutralisation and saponification values of the fatty acids pointed to the presence of lactones or polyinerisation products. When a solution of the fat in hot alcoholic potassium hydroxide solution was mixed with ammonia solution and cooled it yielded a jelly-like mass which was readily filtered. On the addition of hydrochloric acid to the filtrate which contained the soluble potassium soaps the fatty acids separated, whilst the aqueous layer assumed a violet-pink coloration. This is probably a characteristic reaction of the fat of Jfimmops Djave. C. A. M. The Constituents of Olive Leaves. F. B. Power and F. Tutin. (Pm. Chm. SOC., 1908, 24, 117.)-Air-dried olive leaves were percolated with hot alcohol, when they gave about 30 per cent.of their weight of extracted material. This extract yielded, besides some amorphous matter, the following products : (1) A new mono- c~7.bozyZ~c acid, C,JH,,.CO,H (melting-point 68" to 69" C.); (2) a small amount of a mixture of fatty acids, containing oleic acid ; (3) hentriacontane, C3,HG, (melting- point 68" to 69O C.); (4) pentatriacontane, C3,H7, (melting-point 74.5" C . ) ; ( 5 ) olecisterol, C&,H3*0 (melting-point 174" C.), a new crystalline alcohol related to the phytosterols ; (6) a new Crystalline alcohol, olestraizol, C,,H,,O, (melting-point 217' to 218" C.), which appears to be a hydroxy-phytosterol ; (7) homo-olestrand, C,,H,,O, (melting - point 210" C., [aID + 71"), a compound similar to olestranol ; (8) an amount of d-mannitol equivalent to about 3-4 per cent.of the weight of air- dried Ieaves ; (9) a considerable amount of a, sugar which yields d-phenylglucosazone ; (10) a trace of an essential oil ; (11) oZeaizoZ, C31H4sO(OH),,H,0 (melting-point 303" to 304" C., [aID+78*3"), a new crystalline substance in an amount equivalent to nearly 3.4 per cent, of the weight of air-dried leaves. This compound contains one alcoholic and one phenolic hydroxyl group. The Constituents of Olive Bark. F. B. Power and F. Tutin. (Proc. Ckem SOC., 1908, 24, 117-118.)--Air-dried olive bark, on percolation with hot alcohol, yielded about 30 per cent. of its weight of extracted material. From this alcoholic extract the following crystalline compounds were obtained, together with sonie amorphous products : (1) A new ~~zo~zocu~~boxylic acid, C,,H67.COzH (melting-pointTHE ANALYST.331 69" to 70" C.) ; (2) a new nzonocarboxylic acid, C24H45.C0,H ng-point 79" Ca); (3) a new monocarboxylic acid, C,,H,,.CO,H (melting-point, YZ- C.); (4) a new ntoitocarboxylic acid, C,,H,,.CO,H (melting-point 84" C.) ; (5) a substance, probably a tertiary alcohol, C,,H,,O (melting-point 70' C.) ; (6) pentatriacontane, C,,H7, (melting- point 74" to 75" C.) ; (7) a phytosterol, C,?H,,O (melting-point 136" C., [aIn - 35.2"), which yields an acetyl derivative melting at 119.5" C. ; (8) a substance, C23H380,(0R), (melting-point 285' to 290" C.), which yields an acotyl derivative melting at 160" c., and is identical with ipuranol; (9) a new phenolic substance, olcnitol, C,,HIoO6 (melting - point 265" C.), dilute solutions of which show a blue fluorescence; (10) d-mannitol, in an amount equivalent to 1-9 per cent.of the weight of air-dried bark ; (11) a sugar which yields d-phenylglucosazone. -_ The Volumetric Estimation of Tartaric Acid in Tartar, Lees, and Wines. E. Pozzi-Escot. (Bull. SOC. Chim. Belg., 1'308, 22, 218-221.)-0ne gram of the sample of tartar, etc. (or 5 to 10 grams in the case of certain industrial products), is extracted with a boiling solution of potassium or sodium carbonate until exhausted, the sucoessive extracts being decanted on to a filter. The filtrate is made up to 100 C.C. (or 500 C.C. or 1,000 C.C. in the case of larger quantities having been taken), and 25 C.C.acidified with hydrochloric acid, boiled to expel all carbon dioxide, then made distinctly alkaline with ammonia, and treated with 40 C.C. of a iXG solution of barium bromide in strong alcohol, and with about 75 C.C. of 95 per cent. alcohol. The precipitated barium tartrate, which is almost completely insoluble, is filtered off and washed with small quantities of alcohol. I t may then be converted into carbonate by ignition, so as to give a gravimetric estimation of the tartaric acid, but the following volumetric method is simpler and more rapid: The filtrate and washings from the barium tartrate are treated with excem of ammonium oxalate, and the resulting barium oxalate separated, washed with ammoniacal water, and dissolved in very dilute hot sulphuric acid. The solution is treated with sulphuric acid in excess, and the oxalic acid estimated by titration with 2; permangauate solution. Each C.C. of the barium bromide solution used corresponds to 0.0075 gram of tartaric acid, and the amount of the latter is thus equivalent to the difference between the 40 C.C. of barium bromide solution and the amount of permanganate required. The method may be used for the direct estimation of tartaric acid in wines, but requires modification in the presence of a large quantity of sulphates or fluorides. Thus in the case of a strongly 6 ' sulphited" wine 50 to 100 C.C. are acidified with hydrochloric acid, and dilute barium chloride solution added drop by drop until a precipitate is produced, no barium tartrate being precipitated under these conditions. Ammonia, barium bromide solution, and excess of alcohol are then added, and the tartaric acid estimated as above described. C. A. M.

ISSN:0003-2654    

DOI:10.1039/AN9083300324

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 331 INORGANIC ANALYSIS. A Delicate Test for Bromides alone or in Solution with Chlorides. J. S. Jamieson. (Proc. Chem. SOC., 1908, 24, 144.)-The solution to be tested is heated to boiling with 1 or 2 C.C. of dilute sulphuric acid and 1 or 2 C.C. of a solution333 THE ANALYST. of potassium dichromate (strength not mentioned). I t is then cooled, and shaken with chloroform. The chloroform layer is separated, washed two or three times with water, and finally shaken with a little dilute potassium iodide solution. I n the presence of a bromide,. the chloroform is coloured violet, due to the liberated iodine. 6NaBr + K2Cr,0, + 7H2S0, = 3Na,SO, + K,SO, + Cr,( SO,):, + 7H,O + 3Br,. The following equation probably represents the reaction : The above reaction will detect 0.5 mgm.of sodium or potassium bromide, either free or in presence of sodium chloride. The Estimation of Halogens in Organic Compounds. H. Baubigny. (Bzd1. SOC. Chim., 1908 [iv.], 3, 630-633.) - I n former communications (ANALwr, 1903,28,276 ; 1904, 29, 198) the author has described a method of separating iodine from chlorine and bromine by means of sulphuric acid and potassium dichromate, the former yielding iodic acid, whilst the two others are evolved in the free state without any trace of chromyl chloride if a silver salt be added to the oxidising mixture. Bromine compounds do not yield any product analogous to chromyl chloride, even in the absence of a silver salt, whereas chroniyl chloride is invariably formed under those conditions. Since, however, the chromyl chloride is always accompanied by free chlorine, it is not possible to effect a separation by absorbing the chromyl chloride in water and the bromine in alkali sodium sulphite solution.For a separate estimation of chlorine and bromine in an organic compound, all the gaseous products of the oxidation (in the presence of silver sulphate) should be absorbed in the alkaline sulphite solution. The latter is then concentrated on the water-bath in a flask, through which is passed a, current of air until the volume is reduced to a few C.C. The bromine and chlorine may then be separated by a method previously described (ANALYST, 1898, 23, 22), in which both halogens are converted into copper salts, and the bromine then liberated by the action of potassium permanganate. Or the alkaline solution of the bromine and chlorine may be divided into two parts, in one of which both halogens are estimated together by means of silver nitrate.The other portion is rendered slightly acid with sulphuric acid, to reduce (by the sulphurous acid formed) any oxidation products of the halogens. It is then neutralised, concentrated on the water-bath in a current of air to 20 or 25 c.c., and any sulphite destroyed by the addition of potassium permanganate. The liquid is now treated with crystalline potassium permanganate and copper sulphate in the proportion of, say, 0.3 to 0.4 gram of the former and 4 to 8 grams of the latter for a quantity of 0.1 to 0.4 gram of bromine, and after these have completely dissolved is left to crystallise in a wide vessel i'i~ vacuo over potassium hydroxide.The copper bromide formed in the reaction is alone attacked by the permanganate, and when the mass has become absolutely dry, a11 bromine will have disappeared. The chlorine in the residue may then be estimated in the usual way, whilst the difference between the amount and that obtained in the estimation of the combined halogens is a measure of the bromine. C. A. M. The Separation of Silver Chloride, Bromide, and Iodide. H. Baubigny. (Bull. SOC. Clzirn., 1908 [iv.], 3, 629-630.)-An approximate separation of silverTHE ANALYST- 333 chloride, bromide, and iodide is effected by Hager's method (Zeit. anal. Chem., 1871, lo, 341) of treating the salts with a boiling 10 per cent. solution of ammonium bicarbonate, which dissolves chiefly the chloride, and then separating the residual bromide and iodide by treatment with a 5 per cent.solution of ammonia. Although this method is far from quantitative when the three salts are present, good results may be obtained by applying it to a mixture of only the chloride and iodide. The precipitate of the two salts.is heated on the water-bath at 70" to 80" C. with 70 to 100 C.C. of a solution containing per litre 100 grams of commercial ammonium bicarbonate and 20 C.C. of a 20 per cent. solution of ammonia (specific gravity, 0.925). After some minutes the liquid is allowed to cool and decanted on to the original filter, and the residue again digested with the ammoniacal solution. Finally, the residual silver iodide is washed with the reagent diluted with its own volume of water, and dried and weighed.The dissolved chloride is precipitated by the addition of nitric acid, and estimated in the usual way. C. A. M. Simple and Rapid Estimation of Nickel in Presence of Cobalt. M. E. Pozzi-Eseot. (Ann. C l z h . Anal., 1908, 13,217-218.)-The solution containing nickel and cobalt is made up to a known volume, and an aliquot part precipitated with a hot saturated solution of ammonium molybdate. The whole is placed in a special graduated tube and spun in a centrifuge for a few minutes, after which the volume of the precipitate is read, and compared with that given by a solution, containing a, known amount of nickel, treated in the same way (cf. ANALYST, 1907, 32, 432). A. (3. L. Rapid Estimation of Nickel in Presence of Cobalt, Iron, Zinc, Manganese, Aluminium, Chromium, Uranium, Magnesium, and the Alkaline-earth Metals. M.E. Pozzi-Escot. (Ann. Chinz. Anal., 1908, 13, 215-217.)--To the slightly acid and highly concentrated solution of nickel and other metals there are added a large excess of a hot saturated solution of ammonium molybdate and a small quantity of ammonium chloride. The solution is kept at 60" to 70" C. for oneortwo minutes and well stirred, and then cooled to the ordinary temperature. The precipi- tate, which contains the whole of the nickel, practically all the iron and aluminium, a large part of the chromium and alkaline-earth metals, and a little manganese, uranium, and zinc, is filtered off, washed with a cold saturated solution of ammonium chloride, and treated with boiling water and ammonia, when only the nickel dis- solves.The solution is filtered off, and the precipitate, if considerable, is dissolved in acid and reprecipitated with ammonia. From the filtrate, nickel is precipitated by boiling with sodium hydroxide and bromine, and finally determined electrolytically. The results are satisfactory (cf. ANALYST, 1907, 32, 432). A. G. L. Estimation of Iron by Means of Permanganate after Reduction with Titanous Sulphate. H. D. Newton. (Zeits. Anorg. Chem., 1908, 58, 378-380.)- The iron, which must be in sulphuric acid solution, is reduced by the addition of an excess of titanous sulphate solution, the excess of the latter is oxidised by the addition of bismuth oxide, which is without action on the ferrous sulphate, and, after the334 THE ANALYST, bismuth oxide and reduced bismuth have been removed by filtration, the solution is titrated with & potassium perrnanganate solution.The titanous sulphate solution is prepared by fusing together in a platinum crucible 20 grams of commercial titanic acid and 60 grams of sodium-potassium carbonate ; when cold, the mass is powdered and dissolved in hot, concentrated sulphuric acid, and the solution is then cooled, diluted, and filtered. The filtrate is treated with an excess of zinc, and the solution is filtered quickly into a flask containing about 2 litres of freshly distilled water. The flask should be fitted with a device so that an atmosphere of hydrogen can be maintained in the flask above the solution.The solution to be titrated must not contain hydrochloric acid, and a correction should be made for the amount of iron which is nearly always present in commercial titanic acid. w. P. s. Winkler’s Method for the Volumetric Estimation of Alkali Hydroxides in the Presence of Carbonates. S. P. L. Sorensen and A. C. Andersen. (Zeit. and. Chem., 1908, 47, 279-294.)-It is shown that this method only gives trustworthy results if the precipitation with barium chloride be carried out in the warmed solution, and when the latter contains only normal carbonates. If the solution contains hydroxide or bicarbonate it must be treated with hydrochloric acid or sodium hydroxide before heating and precipitating. The quantity of acid or hydroxide required is ascertained by a previous estimation.When a solution of R pure normal carbonate is treated, while hot, with an excess of barium chloride, only normal barium carbonate is precipitated ; if, however, the precipitation be performed a t the ordinary temperature, more or less acid carbonate is thrown down, and the supernatant liquid becomes distinctly alkaline. Further, if the solution of the alkali carbonate contains hydroxide, a, greater or less quantity of basic barium car- bonate is precipitated on treating the hot solution with barium chloride. w. P. s. The Separation of Magnesium from the Alkalis by Alcoholic Ammonium Carbonate. F. A. Gooch and E. A. Eddy. (Zeits. Anorg. Cltent., 1908, 58, 427-432.)-The method described is a modification of Schaffgotsch’s ammonium carbonate method (,4n?t.Phys., 1858, 104, 483). I t consists in concentrating the solution containing magnesium and alkalis to a volume of 50 c.c., adding 50 C.C. of absolute alcohol, and 50 C.C. of a reagent prepared by saturating 180 C.C. of strong ammonia and 800 C.C. of water with ammonium carbonate, adding 900 c c. of absolute alcohol and filtering. The whole is stirred for Eve minutes, allowed to stand for fifteen minutes, and filtered, the precipitate being washed with the above reagent, dried, and ignited to magnesium oxide. If large quantities of alkalis are present, the precipitate is dissolved in a small quantity of hydrochloric acid and reprecipi- fated. The results are accurate. A. G. L. Simultaneous Qualitative Detection of Nickel and Cobalt. H. Grossmann and W.Heilborn. (Her. dezit. Chem. Ges., 1908, 41, 1878-1880.)-By a slight modification of the dicyandiamidine test for nickel, described by Grossmann and Schiick (ANALYS~T, 1907, 32, 273), the same reagent can be made to show theTHE ANALYST. 335 100 grams soil in 1000 c.c., 7 days ... ... 2 , ) ? ,, 1000 c.c., 5 hours .. . ... 9 , 7 ) ,, 500 c.c., 7 days ... ... t , ) ? ,, 500 c.c., 5 hours ... ... simultaneous presence of cobalt. The solution containing the two metals, suitably concentrated and freed from a large excess of acid, is treated with ammonia until it smells strongly of it, 10 to 20 C.C. of a 10 per cent. solution of cane-sugar are added, then a sufficient amount of dicyandiamidine sulphate, and finally sodium hydroxide. With large quantities of nickel there is a change in colour to yellow or reddish-yellow ; in presence of large quantities of cobalt an intense red to red-violet coloration is produced, The yellow nickel dicyandiamidine compound then separates in brilliant crystals at the ordinary temperature, either at once or after standing, according to the quantity of nickel present, and the presence of minute quantities of cobalt may then be readily detected by the reddish-violet colour of the solution.J. F. B. 0.02287 0.03818 0.5320 0.01807 0.03958 0.5210 0.01999 0.03355 0.2718 0.01599 0.03089 0.2285 Note on the Dyer Method for the Determination of Plant Food in Soils. F. T. Shutt and A. T. Charron. (Journ. Amer. Chem. SOC., 1908, 30, 1020-1023.) -Working with a rich black loam in which sand predominated, and typical of large areas in the Canadian North-Western wheat belt, and using a I per cent. solution of citric acid as solvent, the authors obtained the following results by varying the time of extraction and quantity of solution used : They conclude that the conditions given in the original method should be rigidly adhered to.A. G. L. A Scheme for the Separation of the Rare Earths. C. James. (Joz~r?~. Amcr. Cham SOC., 1908,30,979-992.)-The mixed oxalates of the rare earths, obtained as usual, are converted into sulphates by ignition with sulphuric acid. The sulphates are dissolved in ice-cold water, and the solution saturated with solid sodium sulphate. The precipitate, consisting chiefly of cerium earths (fraction A4), is filtered off and washed with a solution of sodium sulphate. I n the filtrate the small quantity of thorium remaining in solution is precipitated wit-h potassium sulphate and added to fraction A ; the filtrate is precipitated with oxalic acid to obtain the yttrium earths (fraction B).Fraction A is converted into hydroxides by treatment with hot sodium hydroxide, the washed hydroxides are dissolved in nitric acid, the solution is neutralised, stirred rapidly by an electrical device, and an excess of zinc oxide added. A solution of potassium permanganate is then added until a permanent red colour is obtained. The precipitate (fraction C) contains the whole of the cerium and thorium, together with manganese and a little of the other cerium earths. Froin the filtrate the remainder of the cerium earths is precipitated by means of sodium sulphate (fraction D), small amounts of yttrium earths being recovered as oxalates from the336 THE ANALYST.final filtrate, and added to fraction B. Fraction C is freed from manganese by solution in hydrochloric acid and precipitation with sodium sulphate, the small quantity of thorium remaining in the filtrate being precipitated with potassium sulphate or oxalic acid. The double sulphates are then converted into hydroxides, which are dissolved in nitric acid. From the neutralised solution impure thorium is obtained by boiling with hydrogen peroxide, Th,O,N,O, being precipitated. Thorium free from cerium is prepared by repeatedly dissolving thorium oxalate in ammonium oxalate, or in ammonium acetate, or by distillation in vacz~o of thorium acetylacetonate.I n the filtrate from the hydrogen peroxide treatment, cerium is precipitated by means of zinc oxide and potassium permanganate, after adding sufficient ammonium nitrate to form the double salt ; the quantity of zinc oxide used should be such that some of the cerium, together with the traces of other cerium earths present, is left in solution Pure cerium is finally obtained by dissolving the anhydrous sulphate in ice-cold water and heating on a water-bath, when the hydrated sulphate separates. From the filtrate the rest of the cerium is precipitated in an impure state by adding excess of zinc oxide and permanganate, and is worked in with the next lot. From the final filtrate, a fraction H of other cerium earths is obtained by adding oxalic acid, which is added to fraction D.The oxides obtained from fraction D are dissolved in nitric acid; an equal quantity of nitric acid is saturated with magnesium oxide, and the mixed solutions are repeatsdly fractionally crystallised. If at any stage the liquid refuses to crjstallise or a precipitate forms, owing to the accumulation of yttrium earths, the lanthanum earths are precipitated as sodium double sulphates and reconverted into magnesium double nitrates, the yttrium earths in the filtrate being precipitated as oxalates, and added to fraction B. Commencing with the least soluble, the lanthanum earths crystallise in the following fractions : Lanthanum and praseodymium ; praseodymium and neodymium ; neodymium ; samarium, europium, gadolinium with small amounts of terbium, dysprosium, etc.From these fractions lanthanum and praseodymium are separated by fractional crystallisation of the ammonium double nitrates from a solution containing free nitric acid to the extent of one-tenth the weight of dissolved solid, 3 equivalents of oxides being used for 2 of ammonia. Pure lanthanum is finally obtained by slowly heating the saturated solution of the anhydrous sulphate in ice-cold water to 32' C. Neodymium is separated from praseodymium by fractional crystallisa- tion of the double manganese nitrate (equivalent for equivalent) from nitric acid of specific gravity 1-3 ; the colour of the oxide should be blue. Pyaseodymium is obtained in the two last fractionations, and must be freed from traces of cerium, preferably by precipitating the latter with hydrogen peroxide in sodium acetate solution.Samarium, europium, and gadoliniim are separated by fractional crystallisation of the magnesium double nitrates from nitric acid of specific gravity 1.3, after adding some bismuth nitrate. Samarium is the most insoluble, followed by bismuth, europium, gadolinium, dysprosium (terbium) in the order named. I n fraction B the yttrium earths are separated by fractional crystallisation of the bromates obtained from the sulphates by double decomposition with barium bromate at 100" C. The earths crystallise in the following order: Samarium and gadolinium, terbium, dysprosium and holmium, yttrium, erbium. Terbium is obtainedTHE ANALYST. 337 by further fractionation of the simple nitrates, after adding bismuth, from concentrated nitric acid.Terbium and bismuth are found in the intermediate fractions. Dysprosizim is obtained by fractionating the ethyl sulphates. Pure holmium has not yet been obtained. Yttyizm is obtained according to Muthmann snd Rijlig’s method (Ber. deut. Chem. Ges., 1898, 31, 1718) by precipitation with magnesium oxide. From the most soluble bromate fraction, scandium is precipitated as potassium double sulphate, erbium, gtterbzzim, and thzdizmz remaining in solution. A. G. L. A New Test for Silver. A. W. Gregory. (Proc. Chem. Soc., 1908,24, 125.)- When a solution of silver salt is added to a mixture of 20 C.C. of aqueous ammonium salicylate (20 grams of salicylic acid neutralised with ammonium hydroxide, a slight excess of the latter added, and the solution made up to 1 litre) and 20 C.C.of ammonium persulphate solution (50 grams in 1 litre), an intense brown colour is produced. By this reaction, 0.01 mgm. of silver can be detected. As lead does not give this reaction, silver may be tested for in presence of this element ; 1.1 mgm. of silver may be detected in this manner in the presence of 0.2 gram of lead. It was found that the brown substance formed in this reaction did not contain silver, and it is probable that the silver salt acts as a catalyst, since on boiling a solution of ammonium salicylate with ammonium persulphate a similar brown colour is produced. Volumetric Estimation of Silver. W. R. Lang and J. 0. Woodhouse. (Tyans. Chem. SOC., 1908, 93, 1037-1040.)-The authors make use of the apparatus previously described by Lang and ,411en (see ANALYST, 1907, 32, 308) for this determination, the method being based on the rapid clearing of turbid solutions in narrow tubes.Some modification of the apparatus was necessary, the principal differences from the former one being the use of fine sand to retain the silver chloride precipitate, and the permanent attachment to an exhaust for washing the precipitate and solution down the tube. No excessive shaking of the mixture of solution and reagent is required beyond that sufficient to ensure proper mixing after each fresh addition of the precipitant. The results are obtained in half an hour with an average error of less than 0.1 per cent. A. R. T. Decomposition of Certain Materials and Industrial Products by Means of Sodium Peroxide and Metallic Sulphides.J. H. Walton, Jr., and H. A. Scholz. (Amer. Chem. Jozwn., 1908, 39, 771-789.)-The authors show that such substances as galena, lead glazes, bauxite, chrome iron ore, etc., are readily decom- posed by mixing 0.5 gram of substance with about 8 grams of sodium peroxide, 0.5 to 1.2 gramsof zinc sulphide, and 0.3 gram of potassium persulphate in a covered nickel crucible placed in a, dish of water, the mixture being ignited by means of a short piece of magnesium wire, or string soaked in alcohol. The substance should be finely powdered; the ingredients must be thoroughly mixed and should be perfectly dry. The nickel crucible used only loses about 0.02 gram in weight at each fusion. A. G. L.338 THE ANALYST. The Use Fig.I . of Sodium Peroxide in Certain Quantitative Processes, S. W. Pam. ( J o z m . Amer. Chem. Soc., 1908, 30, 764-770.)-The author has applied the bomb devised by him for use with sodium peroxide to a number of quantitative determinations. The bomb is shown in the figure, and consists essentially of a small steel cylinder, A, closed at one end by a narrow steel tube, L, fitted with the valve M at the other by a steel plate, C, both tube and plate being screwed to the cylinder by the collars F, E, which are made tight by rubber washers. The bomb is immersed in cold water during the reaction ; the water circulates through the holes shown in the collars and keeps the washers cool. The substance to be decomposed is added to a mixture which will react vigorously, placed in the bomb, and the mixture ignited by dropping in a piece of red-hot iron or nickel wire through the tube L, the valve M being pushed down at 0 to admit the wire to the interior of the bomb.Thus, sulphur and arsenic iiiay be determined in pyrites by mixing 0.25 gram of the ore with 10 grams of sodium peroxide, 0.5 gram of potassium chlorate, and 0.5 gram of benzoic acid. If the liquid be diluted to 200 or 300 c.c., silica need not be filtered off before precipitating the sulphur with barium chloride. The results obtained are considerably higher than those given by Lunge’s method. Sulphur in coal, coke, and rubber may be determined in a simiIar manner, but using only 0.3 gram of benzoic acid. For halogens in organic compounds, 0.3 to 0.5 gram of the substance is mixed with 10 grams of sodium peroxide and 1 to 2 grams of a mixture containing 50 per cent.of boric acid, 40 of potassium nitrate, and 10 of magnesium powder. Liquids are weighed out in closed thin glass bulbs, which are broken after the bomb is shut. Carborundum also is readily decomposed by this mixture. A. G. L. A New Reaction of Thallous Salts. F. Ephraim. (Zeits. Anorg. CILCV~., 1908, 58, 353-355.)-1f a neutral or acid solution of a thallous salt be treated with a solution of antimony trichloride containing potassium iodide, a voluminous orange- red precipitate is formed. The reaction can be obtained with solutions of thallous salts containing not more than 1 part in 20,000. The solution of antimony trichloride is prepared by dissolving antimony trioxide in dilute hydrochloric acid, adding water so long as no oxychloride is precipitated, and then adding solid potassium iodide to the solution.The orange-red precipitate has a composition corresponding with the formula 3T11.2Sb13.; it is only stable in solutions containing potassium iodide or hydriodic acid, and cannot, therefore, be used for the direct estimation of either thallium or antimony, as any attempt to wash it with water, alcohol, hydrochloric acid, etc., results in its decomposition. The compound may, however, be collected, treated with dilute tartaric acid solution, and filtered. Yellow thallous iodide remains insoluble, whilst the whole of the antimony goes into solution in the filtrate, and may be estimated in the usual way.w. P. s.THE ANALYST. 339 Some Observations on the Assay of Telluride Ores. G. Borrowman. ( J o z i m . Anzcr. CILem. SOC., 1908, 30, 1023-1027.)-Working on an ore containing 10.5 per cent. of tellurium and 161.8 ounces of gold per ton, the author finds that the loss in gold is only about 0.24 per cent. if the ore is assayed without previously removing the tellurium. The addition of even very large quantities of litharge to the assay does not prevent some tellurium from passing into the lead button. Hence, if silver also is to be estimated, it is best to extract the ore with nitric acid, precipitate the dissolved silver as chloride, and assay this together with the insoluble residue. The most favourable temperature for the assay is 1,200" C. The author ascribes the unsatisfactory results often obtained. with telluride ores to want of homogeneity of the ore.A. G. L. The Volumetric Estimation of Alkali Vanadates by Means of Stannous Chloride. T. Warynski and B. Mdivani. (BdZ. SOC. Chiin., 1908, [iv.], 3, 626-628.)-A solution of an alkali vanadate is quantitatively reduced by stannous chloride solution, the oxide V,O, being converted into V,O,. The reduction takes place either in a cold or hot solution, and in the presence of either hydrochloric or sulphuric acid. The best concentration for the stannous chloride solution is about 2 per cent., and it should be standardised upon a standard solution of iodine. A 3 per cent. aqueous solution of ammonium molybdate is used as indicator, a blue coloration being given in a spotting test as soon as the stannous chloride is present in excess.A distinct blue colour is given by 0.000015 C.C. of the stannouschloride solu- tion acting upon 0.5 C.C. of the indicator. The results of test estimations quoted show that the method is extremely accurate. C. A. M. Estimation of Vanadic and Molybdic Acids in Presence of One Another. G. Edgar. (Amer. JOZLVZ. Science, 25, 332; through Chem. News, 1908, 97, 245.)- Vanadic acid may be reduced to the tetroxide by means of sulphurous acid without affecting the molybdic acid, provided the concentrat'ion of the latter be not more than 0.2 gram MOO, in 50 C.C. of solution, the same volume containing also at least 1 C.C. of strong sulphuric acid ; while, if the proportion of sulphuric acid be increased to 5 c.c., no reduction of molybdic-acid occurs in solutions four times the above concentration.After determining the reduced vanadium, the molybdic acid may be estimated by reduction with amalgainaiied zinc, the reduced vanadium simultaneously produced being duly allowed for. To carry out the method, 75 C.C. of a solution of the mixed components, containing not more than the specified proportion of molybdic acid, and acidified with 2 to 3 C.C. of strong sulphuric acid, is heated to boiling and a, current of sulphur dioxide passed for a few minutes, until the clear blue colour indicates the complete reduction of the vanadium to the tetroxide. The boiling is continued, and a current of carbon dioxide passed into the liquid until all the sulphurous acid is removed.The vanadium is then determined by titration with decinormal potassium permanganate, the following equation expressing the reaction- 5V,O, + 2KMn0, + 3H,SO,= 5V,O,+ K,SO, + 2MnS0, + 3H,O. This titrated liquid is then slowly passed through & column of amalgamated zinc in a Jones's reductor, being preceded by 100 C.C. of hot water and 125 C.C. of 29 per340 THE ANALYST, cent. sulphuric acid, and followed by 100 C.C. of sulphuric acid (24 per cent.) and 200 C.C. of hot water. The hot solution thus reduced is again titrated with standa,rd permanganate, a little phosphoric acid being added to decolorise the ferric salt. Since the final reduction of the vanadium is to the dioxide, V20,, if the C.C. of permanganate used in titration (1) be multiplied by 3, and the product subtracted from the result of titration (2), the number obtained is the amount of permanganate required to oxidise the MoZO3 to molybdic acid, MOO,. The test-analyses show the method to be capable of con- siderable accuracy if carefully carried out. The receiver contains a solution of ferric alum. A. R. T. Estimation of Vanadium. A. M. Wilson, (Ertg. and Min. Journ.? 1908, 85, 962 ; through Chem. Zeit. Bcp., 1908, 32, 335.)-One gram of the ore is evaporated on a water-bath with 20 C.C. of nitric acid (1 : l), 20 C.C. of nitric acid and 3 C.C. of sulphuric acid are added and evaporated to fuming, and the residue boiled with 30 C.C. of water until the vanadium is completely dissolved, dilute sulphuric acid being added if necessary. The solution is filtered from silica, the filtrate evaporated to 30 c.c., and oxidised with hydrogen peroxide until the liquid becomes dark red in colour. Iron is next precipitated by adding sodium hydroxide? the whole is diluted to 300 C.C. with hot water, boiled, and filtered. The filtrate is heated to boiling and treated with sulphur dioxide until it turns blue, after which the excess of sulphur dioxide is removed by twenty minutes’ boiling in a current of carbon dioxide. The hot filtrate is titrated with potassium permanganate solution. The presence of uranium does not interfere with the results, as it is precipitated with the iron. AS a check, 1 gram of the sample may also be fused, first with 3 or 4 grams of sodium hydroxide, and then for another five minutes after adding 0.25 gram of potassium nitrate. The melt is treated with water, the solution filtered and evaporated with sulphuric acid. After filtering off the silica, the liquid is reduced and titratad as above. A. G. L.

ISSN:0003-2654    

DOI:10.1039/AN9083300331

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

340 THE ANALYST, APPARATUS, ETC. New Gas Analysis Apparatus. R. Ross and J. P. Leather. ( J o u m Sot. Chem. Incl., 1908, 27,49l.)-The apparatus which the authors have designed consists of a measuring bulb, surrounded by water, provided with a three-way stopcock, and connected by flexible tubing to a mercury reservoir and an 800-mm. graduated tube. The measuring bulb communicates with eight absorption pipettes by means of a capillary tube provided with specially designed stopcocks (see diagram). The method of work- ing is as follows : By raising the mercury reservoir, the measuring bulb and the whole of the connec- tions are filled with mercury, which is allowed to flow through each stopcock in turn I;I Rhr&THE ANALYST. 341 until the small glass cups are about half filled.The reservoir is then lowered till the mercury falls to the mark on the measuring bulb. The barometric pressure is now read off in millimetres, including the tension of aqueous vapour, sufficient water for this purpose being introduced with the mercury. The barometer tube is then shut off and the measuring bulb refilled with mercury ; the gas to be analysed is then introduced into the bulb and adjusted to the mark at atmospheric pressure. To transfer the gas to the absorption pipette, the mercury in the capillary tubes is driven forward by the gas into the cups till the gas just reaches the three-bored stop- cock ; the small stopcock is then closed. The absorbent is driven up till it fills the bore of the tap. The stopcock is then reversed, allowing the gas to enter the pipette.When absorption is complete, the process is reversed and the gas is finally swept out of the capillary tubes by means of the mercury from the cup. The mercury is again brought to the mark in the measuring bulb, connection with the niillimetre barometer tube having been re-established. The reading, multiplied by 100 and divided by the first (barometric) reading, gives the percentage absorption. J. F. B. Simple Apparatus for Continuous Extraction with Solvents of Variable Boiling-point. E. Warner. (Chem. Zeit., 1908, 32, 608.)-The extraction thimble is placed in a spiral of nickel wire in a Soxhlet-Zunz extractor. The vapours from the boiling liquid (petroleum ether, etc.) below pass around the thimble into the condenser, whence the condensed liquid drops into the thimble, penetrating the substance to be ex- tracted, which is mixed with sand, asbestos, etc., before it passes back into the flask.By using this apparatus in place of the ordinary Soxhlet extractor, it is claimed that separation of the liquid into more . and less volatile constituents is avoided. A. G. L. An Apparatus for Simultaneously Extract- ing a Solid and Filtering the Solution so Obtained. F. Record. (C7zem News, 1908, 97, 280.)-In the apparatus shown in the figure, the sub- stance to be extracted is placed on a layer of asbestos, F, supported by a filter-paper on the filter-disc E in the inner tube A, which is sealed into an outer con- centric tube B. The vapour of the solvent rises through the holes D and C into the condenser, whence it drops back into the inner tube and percolates the substance.A. G. L. \ \ F’ A New Gas-Burner. P. Engler. (Chem. h i t . , 1908, 32, 519.)-An improved Bunsen burner is described in which the proportions of air and gas can be regulated a t will to any degree between a full blue flame and a full white flame, according to indications on a divided scale. The foot of the burner is slightly raised from the bench, and the air enters underneath through a central hole coinciding with the342 THE ANALYSTc stem of the burner. The gas enters the foot at the side in the usual manner, and the stem of the burner has two holes bored in its side for the admission of gas to the central tube. One of these gas-channels is directed upwards in a slanting direction, so that the gas passing through draws air with it from the central orifice in the foot of the burner. The other gas-channel is directed horizontally, so that the gas- supply impinges against the side of the tube and passes up without drawing air with it.The two gas-channels are connected by a smaller channel, so that the flame is noh extinguished on passing from one gas-supply to the other. The regulation of the flame as regards air-supply is effected by turning the stem by means of a handle, by which any desired combination of the two kinds of gas supply may be obtained. On turning the handle to its extreme position a very small flame is obtained. Since the central tube of the burner is open from top to bottom and the gas is admitted only from the side, there is no possibility of the gas-jet becoming clogged by substances falling down the tube.J. F. B. A Combined Stopcock and Capillary Connecting Tube for a Gas Burette. (Proc. Chenz. SOC., 1908, 24, 95-96.)-The combination indicated in the A. G. Hill. c. figure is sealed to the top of the measuring burette B. The three-way stopcock C, in addition to controlling the flow of gas from the burette, also affords a means of connecting the pipette with the outside air through the bottom outlet E when it is attached to the burette. The burette is connected to the pipette by a short piece of thick rubber tube. To expel the air entrapped in the capillary tubes and rubber connection, a piece of rubber tube is slipped over the bottom outlet E of the stopcock C, and the stopcock is turned to make con- nection between the pipette and the outside air; the air is then sucked out through the tube, and the absorbent fills the vacant space.The stopcock is closed by giving it a half-turn, so that the handle is in a plane at right angles to that of the connecting tube. I n order to connect the burette with the pipette, the stopcock is given another half-turn in the same direction as before. The barrel of the stopcock is pierced in a way which makes it impossible to connect the burette with the outside air through the bottom outlet E, a source of accidental error being thereby eliminated. When absorption is complete and the gas is returned to the burette, the absorbent is allowed to flow back as far as the stopcock C, which is quickly closed to prevent it from flowing m y farther.The bulb D facilitates this adjustment by retarding the advance of the absorbent before it reaches the stopcock ; it also prevents the drops of absorbent, which often lodge in the rubber connection, from passing over with the gas into the burette. Before the pipette is disconnected from the burette, the stopcock is turned backTHE ANALYST. 343 to the position which will connect the pipette with the outside air, and the thread of absorbent is allowed to flow back into the pipette. Arrangement to Faeilitate the Use of Hempel’s Pipettes. J. S. Studer. (Joum. SOC. Chem. I d . , 1908, 27, 483.)-For the full analysis of producer gas Hempel’s apparatus is essentia,l, and the author has devised an arrangement for manipulating the pipettes with 8 minimum of trouble and a maximum of accuracy.This arrangement consists of a disc, C, which rests horizontally on a central support, D. This support is hollow from the top to the point e, on which point rests the small piston which projects from the centre of C. In this way ;I horizontal rotation can be given , to the disc C, and the - various K U J absorption vessels and explosion pipette which are supported radially can be brought consecutively into connection with the gas burette. When it is necessary to agitate the contents of one of the pipettes, the bolt b is released, and the board carrying the pipette may ther? be swung to and fro on the fulcrum a. The fact that the burette is a fixture enables a water-jacket to be more easily placed around it ; leakage or fracture at the point d, where the connection is made, is practically impossible.The pipettes, five in number, contain in order : sodium hydroxide, bromine water or fuming sulphuric acid, alkaline pyrogallol, ammoniacal cuprous chloride, and an explosion arrange- ment. The explosion pipette is not swung on a fulcrum, and is filled with mercury; it is connected with a battery and induction coil. The absorption of ethylene by bromine water, which is frequently omitted, is regarded by the author as essential, since the omission may introduce a large error in the estimation of calorific value. J. F. B. Polarimetrie Observations with Small Quantities of Liquid. J. Donau.. (Monatsh. Chem., 1908, 29, 333-336.)-The author has extended the use of capillary tubes, which he had previously adopted for colorimetric observations, to polarimetric work.The capillary tubes, 0.4 to 0.5 mm. in diameter and 5 and 10 cm. in length, are made by Zeiss and by Schott of Jena, of black glass (No. 1312 111.). The ends are ground and closed by cover-glasses ; the capillary tubes are fixed by rubber stoppers in wider glass tubes which themselves fit inside the ordinary metal tubes of the polarimeter. The tubes are filled by holding them in a clamp in a slightly inclined position, allowing the liquid to flow down them and closing the ends with the cover- glasses. Small air-bubbles are easily removed by means of a very fine platinum wire. For the 5-cm. tubes an ordinary sodium flame may be used, but for the 10-cm.344 THE ANALYST.tubes a 6-ampBre arc lamp is necessary, the light being filtered through red glass or else coloured by steeping the carbons in a concentrated solution of salt and drying. The 10-cm. tubes can be filled with 12 to 17 cub. mm. of liquid. J. F. €3. Apparatus for the Automatic Extinction of a Gas-Flame. L. L. de Koninck. (Bull. SOC. Chem. Belg., 1908, 22, 192-195.)-The apparatus shown in the figure is based upon that devised by Michaelis (Chem. Zeit., 1897, 21, 194), for the automatic extinction of a gas- burner in case of the failure of the water-supply to a hot-water oven, condenser, etc. It con- sists of a stand supporting a horizontal oscillating brass arm, one end of which holds a metal funnel, whilst the other termi- nates in a spindle carrying a movable counterpoise. On this side of the arm is also attached a pear-shaped glass vessel, with inlet and outlet tube for the gas, and in which is a little mercury.The movable water- funnel is pierced at the point of the cone by an opening about 1 mm. in diameter, and opens into a large fixed glass funnel, whence the water is conducted to the hot- water oven, etc. ; whilst a curved brass tube connected with the water-supply by means of an indiarubber tube is also attached to the oscillating arni. When in use, the counterpoise is regulated so that the movable funnel takes the position shown in the figure when the gas and water are both on. Should the water then cease to flow, the movable funnel empties itself, and the extremity of the pear-shaped vessel fells, with the result that the mercury falls into the curve of the tube and extinguishes the gas.It is essential to arrange that the bent tube connected with the water-supply should open outside the funnel when the latter is in this position; otherwise an unexpected renewal of the water-supply would fill the funnel again, and once more allow the gas to pass. C . A. M. A New Arrangement of Apparatus for the Estimation of Sulphur in Cast Iron and Steel. E. Raymond. (Bull. SOC. Chiwz. Belg., 1908, 22, 181-183.) -The flask in which the metal is decomposed is fitted with a thistle funnel for the introduction of the hydrochloric acid and for the passage of the current of carbon dioxide, and has a side tubulure through which the liberated hydrogen sulphide escapes. After leaving the flask, the gas traverses a small bulb to retain acid mechanically carried over, and then passes into two serpentine tubes contained in,THE ANALYST.345 and opening into, cylinders oontaining hydrochloric acid charged with bromine, where the hydrogen sulphide is oxidised in the usual way. C. A. 11. New Instrument for Reducing Gas Volumes to Standard Conditions. G. T. Davis. (Journ. Amer. Chem. SOC., 1908, 30, intended for use only with gases which can be collected over water, and consists of a vertical iron pipe about 2 metres long, fitted with a T near the top and an elbow at the lower end. The elbow is closed by a rubber stopper carrying a glass T, one arm of which is connected with the bottom of an aspirator bottle containing distilled water, whilst the other arm is connected by a piece of rubber tubing with a glass tube carrying a tap and a rubber stopper. The neck of the aspirator bottle is fitted with a stopper carrying a tap-funnel and a piece of glass tubing con- nected with the top of a second aspirator bottle, into which tap-water can be run in from below, thus causing the distilled water in the first bottle to rise in the iron tube to a height at which it meets the very short inner arm of a glass siphon-tube inserted through the T at the top of the iron tube.The long arm of the siphon delivers the water into the tap- funnel on the top of the distilled-water bottle. The other limb of the T is connected to a small reservoir, to prevent overflow if the tube is filled too rapidly. The iron tube is fitted below the siphon with a fixed 971-973.)-The apparatus is f scale reading directly in degrees C.slides a second scale, each division of which is and 760 mm. pressure, the bottom of the burette On this scale at,, 13.6 mm. long. To reduce the volume of a gas to O O C . L S ' n k containing the gas is connected with the tapped glass tube by means of the stopper on the latter, care being taken that no air-bubbles are introduced, the mark 760 on the sliding scale is brought opposite to the graduation on the temperature scale which represents the observed temperature, and the meniscus in the burette is levelled with the graduation on the sliding scale which represents the observed barometic pressure (corrected for vapour tension of water). The corrected volume of the gas is then read off on the burette. The distances in cms. of the temperature graduations from the inner arm of the siphon are as follows: 15", 73.9; 16", 79.2; 17O, 84.0; 18O, 83.2; lga, 94.2; 20°, 99.5; %lo, 104.8; 22O, 110.2; 23*, 115.8; 24O, 121.2; 2 5 O , 126.9; 26O, 132.7; 27O, 138.7 ; 28O, 144-4 ; 29", 150.7 ; 30°, 157.0. The temperature graduations of course increase downwarda, whilst the pressure graduations increase upwards. A. G. L.346 THE ANALYST. A New Form of Potash Bulb. A. E. Hill. (proc. Chein. SOC., 1908, 24, 182-183.)-The potash bulb shown in the figure has the advantage of being compact and strong, while its chief feature is the introduction of the domes C and D through holes in the walls of which the gases bubble into the concentrated caustic potash solution contained in each compartment. Sufficient potassium hydroxide solution is placed in the bulb to cover the top of the dome D when the gases are bubbling through the solution. The vessel F is three parts filled with soda-lime, the remaining portion containing granulated, calcium chloride as a drying agent, This vessel F then 8erves for about twenty experiments without renewal, the caustic potash being renewed each time as usual. A. R. T.

ISSN:0003-2654    

DOI:10.1039/AN9083300340

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

346 THE ANALYST. JOINT COMMUNICATION FROM THE COUNCILS OF THE INSTITUTE OF CHEMISTRY AND SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. To THE RIGHT HON. JOHN BURNS, M.P., PRESIDENT OF THE LOCAL GOVERNMENT BOARD, WHITEHALL, S.W. July 15, 1908. SIR, In reply to a recent communication from the Council of the Society of Public Analysts and other Analytical Chemists, asking you to receive a, deputation on the subject of the present unsatisfactory position of Public Analysts, you mentioned (April 27, 1908) that the matter had already received consideration, and that, while you did not think it necessary to trouble a deputation to attend at the Board, you would be prepared to consider suggestions submitted to you in writing. The Council of the Institute of Chemistry have also had under consideration the same subject, which is of vital consequence to many members of the chemical profes- sion, and now join with the Council of the Society of Public Analysts in this communication.The Sale of Food and Drugs Act, 1875, in Section 10, provides that the appoint- ments and removals of Pubic Analysts by local authorities shall at all times be subject to the approval of the Local Government Board. This provision, so far as it relates to removals, was obviously intended for the protection of the Public Analyst against arbitrary or capricious dismissal, and against attempts to alter unfairly theTHE ANALYST. 347 conditions of his appointment, and the Local Government Board has, in virtue of this, been able, on several occasicns, to intervene on behalf of the Public Analyst.Unfortunately, however, some local authorities have ‘‘ contracted themselves out” of the Act by appointing their Public Snalyst only from year to year, thus avoiding the necessity of seeking the consent of the Board to his removal by refraining from renewing his appointment. This proceeding, if not contrary to the letter, is, obviously, contrary to the spirit and intention of the Act. In such cases the Board has hitherto held that it is unable to interfere. Even in the case of permanent appointments, the security intenled to be afforded to the analyst by the Act of 1875 has been in some cases rendered inefiective through the provision whereby local authorities may appoint more than one Public Analyst. This provision has been occasionally so abused that the local authority, although unable to dismiss its permanently appointed Public Analyst without the consent of the Board, has, nevertheless, contrived to transfer practically the whole of his work and emoluments to another analyst.Further, a local authority, having a Public Analyst whom it is unable to dismiss without the consent of the Board, may yet render his position untenable either by reducing his remuneration, or by enlarging his duties without equitably increasing his remuneration. Attempts to decrease the remuneration of Public Analysts arise, no doubt, in most cases from the natural difficulty on the part of those who are not possessed of the requisite special technical knowledge to appreciate the time and skill involved in the carrying out of analytical investigations, which necessarily tend to become more complex as the methods of food sophistication grow more subtle, On the question of the remuneration of Public Analysts, the Local Government Board has hitherto taken the view that, under the Acts at present in force, it has no power to intervene. This is the more regrettable inasmuch as the Public Analyst is in effect an officer of the Board.I t may be pointed out that the Board, recognising the special training required for the position of the Medical O h e r of Health, has, on several occasions, felt able to intervene on the question of his remuneration. The position of the Public Analyst, though not in every respect analogous to that of the Medical OEcer, demands a training equally severe, and it is suggested, therefore, that the Board should be able t o take similar steps to sateguard his interests.Quite apart from the point of view of the analyst, there are public reasons for urging that the condition of insscurity which at present attaches to his appointment should not longer continue. Public Analysts are placed in a position of trust in con- nection with the administration of Acts of Parliament the contravention of which involves liability to criminal prosecution, and cases have not infrequently occurred in which the Public Analyst has had to issue certificates condemning goods sold by members of the local authority from whom he derives his appointments. It, is of the utmost importance in public interests that an officer who is placed by the Legisla- ture in a judicial position should have security of tenure on his appointment, so that he may be enabled to perform his duties impartially and independently. We venture to suggest that the Board should introduce into Parliament a Bill providing :348 THE ANALYST.(a) That not merely the appointment and removal, but also the terms and conditions of the appointment (including specifically the terms of remuneration), of a Public Analyst shall be subject to the approval of the Local Government Board. ( b ) That notwithstanding any provision relating to thatduration of appoint- ment under which any Public Analyst may have been heretofore, or shall be hereafter, appointed, his tenure of of€ice shall not terminate nor be determinable,, nor shall the terms of his remuneration be alter- able, without the approval of the Local Government Board.( c ) That Public Analysts be entitled to appeal to the Local Government Board on all matters relat?ing to their office ; and, (d) That, when fresh legislation has the effect of increasing the work of the Public Analyst, some arrangement be made for the adequate readjust- ment of his emoluments. A joint deputation from the Institute of Chemistry and the Society of Public Analysts has already been accorded an interview by Sir Thomas Elliott, on behalf of the President of the Board of Agriculture, and has made representation on the analogous position of;official Agricultural Analysts appointed under the Fertilisers and Feeding Stuffs Act, 1907. The suggestions of the deputation were very sympatheti- cally received, and Sir Thomas Elliott, in the course of his remarks, said that the Board realised the advantages of continuity in the service of such officers ; that the analysts had to be trained, that they had to maintain expensive laboratories, and to keep their knowledge up-to-date for the benefit of the public. If they held office only for a year or two, their experience was wasted, whereas by continuous service they became every year more eflicient and better acquainted with local condibions.We venture to hope that, by the joint action of yourself and the President of the Board of Agriculture, it may be possible to deal with the position of both Public Analysts and of3cial Agricultural Analysts in one measure, simultaneously amending both the Sale of Food and Drugs Act, 1875, and the Fertilisers and Feeding Stuffs Act, 1906, in the directions indicated. We have the honour to remain, Sir, Yours faithfully, PERCY F. FRANKLAND, President of the Institute of Chemistry o j Great Britain and Ireland. R. R. TATLOCK,] President of the Society of Public Analysts and other Analytical Chemists.

ISSN:0003-2654    

DOI:10.1039/AN9083300346

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

THE ANALYST. 349 PARLIAMENTARY REPORTS. REPORT OF THE PRINCIPAL CHEMIST UPON THE WORK OF THE GOVERNMENT LABORATORY FOR THE YEAR ENDING MARCH 3 1 s ~ , 1908, WITH APPENDICES. (ISSUED AS A PARLIAMENTARY PAPER, pp. 1-32.) THE business of the Government Laboratory may be divided into three classes, viz. : (1) Work in connection.with the Revenue Departments, (A) Customs, (B) Excise; (2) work in connection with other Government Departments; and (3) work in connection with the administration of the Food and Drugs Act, and Fertilisers and Feeding Stuffs Act. In all, 191,304 analyses and examinations were made as compared with 173,606 for the preceding year. One thousand four hundred and eighty-six samples of imported butter were examined in accordance with the provisions of the Sale of Food and Drugs Act, 1899, and the Butter and Margarine Act, 1907.Of these 43.7 per cent. contained boron preservetive and 22.3 per cent. added colouring matter. There has also been a decrease in the number of samples found to contain water in excess of the legal limit. Owing to the Butter and Margarine Act, 1907, coming into force in January of this year, there was considerable increase in the number of samples examined. In 200 samples only 4 exceeded the legal limit for water. Of the 61 samples of imported cream 45 contained boron preservative, 36 of these containing in addition salicylic acid. The fat varied from 24 to 50 per cent. Of 87 reference samples under the Sale of Food and Drugs Act and the Fertilisers and Feeding Stuffs Act, 67 agreed wholly or partially with the analyses of the Public Analysts, whilst 19 disagreed.Six thousand one hundred and twelve samples of beer were collected from public houses, and of these 12.1 per cent. were found to be diluted, being nearly 2 per cent. more than last year. There was no evidence of the use of saccharin or of saponin. One thousand and eleven samples of beer, wort, and materials used by brewers were tested for the presence of arsenic; 48 contained it in excess oi the limits laid down by the RDyal Commission on Arsenical Poisoning. I n 121 samples of malt 9 exceeded the limit, the highest amount being :G grain per lb. None of the samples of glucose, invert sugar, or caramel exceeded the limit. The Board of Agriculture and Fisheries, in pursuance of the power to make regulations by which analyses are to be made, conferred upon them by the Fertilisers and Feeding Stuffs Act, asked the assistance of a committee of representatil-e chemical experts to advise in the framing of such regulations.The Committee held several meetings, and ultiinately submitted to the Board a series of methods of analysis for their consideration and approval. I n connection with this Committee, analyses of various materials were carried out for the purpose of testing the validity of the suggested methods. No samples of milk-blended butter were received. In several samples "hydroxyl " was used as a praservative.350 THE ANALYST. REPORT OF THE SELECT COMMITTEE ON THE HOP INDUSTRY, TOGETHER WITH THE PROCEEDINGS OF THE COMMITTEE. The Select Committee of the House of Commons appointed to inquire into the past and present condition of the hop industry have presented a report in which they deal very fully with the various causes which, in their opinion, have led to the present depressed condition of the hop industry in this country.The recommendations of the Committee are not of a startling or far-reaching character, and can at the best have very little effect in improving the prospects of the English hop-grower. Thus the Committee recommend the prohibition of the use of hop substitutes, although the quantities of such substances used in brewing are shown by the Annual Returns to be quite insignificant. I t is further recommended that foreign hops imported into this country should be marked as to their place of origin in accordance with the provisions of the Marking Act of 1866, and that brewers should be required to enter in their brewing books the proportions of foreign hops they employ, and to indicate on the cask or bottle in which any beer is sold the extent to which foreign hops have been employed in the brewing of such beer.Apart from the fact that such a regulation would be very irksome and vexatious to the brewer, it would be exceedingly difficult, if not impossible, to make it effective. Seeing that it is an impossibility by any means at present known to chemical science to ascertain by the examination of a sample of beer the nature of the hops employed in its production, it would be interesting to know what provisions would be made by the authorities for checking the accuracy of the statutory declarations. On the whole, it is to be feared that the report will bring but little comfort to the grower, for the recommendations, even if made effective, could not inaterially improve the condition of the hop industry in this country, whilst they mould be exceedingly harassing to the brewer. A. C. C.

ISSN:0003-2654    

DOI:10.1039/AN9083300349

出版商:RSC    

年代:1908

数据来源: RSC

摘要:

350 THE ANALYST. REVIEW. LEATHER TRADES CHEMISTRY. By S. R. Trotman, M.A., F.I.C. 8vo. 290 pp. This work, which is the latest addition to Messrs. Griffin’s by now well-known scientific and technical series, is another welcome addition to leather trades biblio- graphy. The author modestly explains in his preface that several valuable works already exist treating upon the same subject, but that, owing to the general lack of knowledge of analytical details of modern processes, he has been tempted to write the present volume in the hope of filling a long-felt want in this department. He also recalls that the International Association of Leather Trades Chemists has carried out such an infinite amount of work on tannin analysis that to publish all would be impossible, so that the book has been limited to those problems which most often arise in actual practice; and we judge, from the way the subject is treated, that the author has succeeded in his object.London : Charles Griffin and Co., Ltd. Price 18s. net.THE ANALYST. 351 The book is composed of twenty-four chapters, and embodies several distinctly novel ideas. The opening chapter treats on fuel analysis, the importance of which seems to have been entirely disregarded in other books on the leather industries. The next chapter deals with the estimation of nitrogen by both Dumas’ and Xjeldahl’s methods, followed by a lucid explanation of the principles and praotice of volumetric analysis. Water analysis is then treated very fully, and it is evident that the author has spent much time in research upon the effect of the various impurities in the operations consequent to leather manufacture.The insertion of the chapter on effluents is also very welcome, as this has had so little attention heretofore in leather trades literature. The subjects of depilation, deliming, and the qualitative recognition of the tannins are then dilated upon in an efficient manner, followed by a very clear chapter on the eternal question of tannin analysis, which contribution reveals a very thorough knowledge of the subject, and is in itself an excellent recommendation for the work, as is also the next chapter on the oommon vegetable tannins, which contains some very fine photo-micrographs of sumach and its adulterants. There are several chapters, which should prove especially valuable to tanners and curriers, on oils, ~oaps, varnishes, fleshings, and glue, which are written in such a manner as to prove that the author is well acquainted with his subject.Light leather manufacturers will also be very interested in the chapters upon mineral tannages, degreasing with benzene, and the dye-stuffs, which last subject is supplemented with tables showing the chemical reactions of the most important classes of dyes. Disinfectants and antiseptics are also given a, place, and the pages dealing with the analysis of leather, containing much valuable information and many figures bearing on the adulteration of tanned leather, and the methods employed in the determination of adulterants, alone justify the publication of the work. Lastly, but not least--and, moreover, quite a, distinct novelty-is a glossary of technical terms used in the trade. This might very con- veniently have been enlarged upon, but even in its present incomplete form will still no doubt prove of considerable value to the uninitiated. Summarising, the result of Mr. Trotman’s years of practical laboratory ex- perience and industrial research should be highly appreciated by his readers, and although the volume is primarily scientific, the language used is such that any tanner with an elementary knowledge of science can easily follow the text. J. G. P.

ISSN:0003-2654    

DOI:10.1039/AN9083300350

出版商:RSC    

年代:1908

数据来源: RSC