ISSN:0003-2654    

DOI:10.1039/AN94772FX021

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772FP023

出版商:RSC    

年代:1947

数据来源: RSC

ISSN:0003-2654    

DOI:10.1039/AN94772BP027

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

JUNE, 1947 Vol. 72, No. 855 The THE ANALYST Fundamental Laws of Polarography BY J. HEYROVSKI? (Lecture delivered at a Meeting of the Society on October 31st, 1946) THE foundations of the polarographic method are closely connected both theoretically and experimentally with fundamental rese2rches on the significance of electrode potential and polarisation. In the seventies, G. Lippmann introduced the cell consisting of a mercury meniscus in a capillary, as one electrode, and a large mercury pool as the other. The capillary was connected by means of rubber tubing to a mercury reservoir, the height of which could regulate the position of the meniscus in the capillary. The r81e of the large mercury electrode was to ensure that, owing to its’ small current density, its potential would remain constant, so that the total external E.M.F.applied on the electrodes of this cell would produce changes of potential at the small electrode only. This provided a convenient system compris- ing a polarisable electrode (the capillary one) and an unpolarisable electrode (the bottom one). From Lippmann’s studies of electrocapillarity carried out with this cell Helmholtz was able to work out his theory of electrode potential being the potential of a double-layer condenser, of which one layer lies on the metal and the oppositely charged layer is in the surrounding solution. In 1903, B. KuEera developed Lippmann’s method further by raising the mercury reservoir so that mercury would drop slowly out of the capillary. He has shown that the drop-weight method is more convenient for the determination of the interfacial tension (y) of polarised mercury than Lippmann’s method of observations on the meniscus, since the drop-weight, w, is given by w = Z m y , r being the radius of the mouth of the capillary.How- ever, w is equal to m.t, m being the rate of outflow of mercury from the capillary and t the drop-time; hence, at a constant applied E.M.F., w = m.t = 2m-r~ = k is a constant. Since, however, m is proportional to the height, 12, of the mercury reservoir, t must be inversely proportional to 12. KuEera obtained with his method a number of electrocapillary parabolas, some of which, however, showed an anomalous maximum. In 1918 he suggested that the present writer should investigate the cause of such anomalies; in the course of these investigations it became evident that a much better insight into the processes occurring at the dropping electrode 229230 HEYROVSKY: THE FUNDAMENTAL LAWS OF POLAROGRAPHY [Vol.72 could be obtained by measuring the currents which pass through the cell at different voltages. In this respect the dropping mercury electrode was found to be especially suited to show a variety of exactly reproducible phenomena, as it offers the following advantages: (1) it develops always a fresh, regularly renewed surface of mercury and of the adjacent electrolyte solution, so that no time effects due to accumulating products of electrolysis are possible; (2) the large overvoltage on pure mercury prevents hydrogen deposition, so that even alkali metals may be deposited without decomposition of water taking place; (3) since the extent of electrolysis is small, changes in the concentration of the depolariser in solution are negligible, and consequently the measurements may be repeated with the same small amount of solution many times with identical results; (4) owing to the perfectly regular dropping, all processes repeat themselves at each fresh mercury drop with a high degree of exactitude, so that the current is a well-defined function of the dropping-electrode potential.From the regularity of conditions under which the surface of each drop is developed, IlkoviE, and, later, Rideal and MacGillavry, were able to deduce that the mean current, iE, due to electrolysis of a depolariser present at a concentration C in a concentrated solution of an indifferent electrolyte, is determined by the equation: where v is the electrovalency, F Faraday’s constant, D the diffusion coefficient and C, the concentration of the depolariser at the electrode surface, all quantities being expressed in absolute units; iE reaches its limit when C, = 0, at which condition the depolariser is completely exhausted at the electrode surface.This current is then called “diffusion current”; it gives the “height of the polarographic wave” and is proportional to the’ concentration C of the depolariser in the body of the solution, so that it serves as a measure of its concentration. From the relationships given above between m, t and h it follows that the “diffusion current” Is proportional to dz, i.e., it varies as the square root of the height of the mercury reservoir.The relationship between the current, i, and the potential, r, of the polarised mercury electrode* has been deduced by IlkoviC and the present writer from the formula of Peters i, = 0.627 V.F.D’~~~~~*~’~’(C-C,), where D and D’ denote the diffusion coefficients of the depolariser in its oxidised and reduced states respectively, the electrolytic process being ox. + u Q -+ red., e:g., 2%” + 2 0 it Pb. The curve, giving this dependence of the current, i, on the potential, OT, i.e., the current - voltage curve has the shape of curve 1 in Fig. 1. It has an inflexion for i = id/2, at which point the concentration of the depolariser at the electrode surface is half exhausted (C, = C/2) and also the con- centration of the lead amalgam reaches half of its final value.The potential,r+, at which this happens is a constant independent of the concentration of the depolariser, C, and of the properties of the capillary (m, t). This is the so-called “half-wave potential” charac- terising the quality of the depolariser. If we use instead of pure mercury in the dropping electrode a dilute, say, 0.001 per cent. amalgam of lead and polarise it in a pure solution of an indifferent electrolyte cathodically, starting with a large voltage, say, E = 1.0 v., the current is practically zero (Fig. 1, curve 2). On decreasing the voltage, i.e., imparting to the dropping electrode more positive potentials, we start anodic dksohtion of lead, viz., Pb + P b + 2 0 . At a potential at which half of the lead content from the surface dissolves, the “half-wave potential” of lead is reached and 4 i L!= 1.0 v Fig.1. Current - voltage curves. ~~ ~ * m depends on the voltage V (Le., external applied E.M.F.) as T = - V + i. p, where p denotes the resistance in the circuit. Since both i and p are small, T is practically identical with V.230 HEYROVSKY: THE FUNDAMENTAL LAWS OF POLAROGRAPHY [Vol. 72 could be obtained by measuring the currents which pass through the cell at different voltages. In this respect the dropping mercury electrode was found to be especially suited to show a variety of exactly reproducible phenomena, as it offers the following advantages: (1) it develops always a fresh, regularly renewed surface of mercury and of the adjacent electrolyte solution, so that no time effects due to accumulating products of electrolysis are possible; (2) the large overvoltage on pure mercury prevents hydrogen deposition, so that even alkali metals may be deposited without decomposition of water taking place; (3) since the extent of electrolysis is small, changes in the concentration of the depolariser in solution are negligible, and consequently the measurements may be repeated with the same small amount of solution many times with identical results; (4) owing to the perfectly regular dropping, all processes repeat themselves at each fresh mercury drop with a high degree of exactitude, so that the current is a well-defined function of the dropping-electrode potential.From the regularity of conditions under which the surface of each drop is developed, IlkoviE, and, later, Rideal and MacGillavry, were able to deduce that the mean current, iE, due to electrolysis of a depolariser present at a concentration C in a concentrated solution of an indifferent electrolyte, is determined by the equation: where v is the electrovalency, F Faraday’s constant, D the diffusion coefficient and C, the concentration of the depolariser at the electrode surface, all quantities being expressed in absolute units; iE reaches its limit when C, = 0, at which condition the depolariser is completely exhausted at the electrode surface. This current is then called “diffusion current”; it gives the “height of the polarographic wave” and is proportional to the’ concentration C of the depolariser in the body of the solution, so that it serves as a measure of its concentration. From the relationships given above between m, t and h it follows that the “diffusion current” Is proportional to dz, i.e., it varies as the square root of the height of the mercury reservoir.The relationship between the current, i, and the potential, r, of the polarised mercury electrode* has been deduced by IlkoviC and the present writer from the formula of Peters i, = 0.627 V.F.D’~~~~~*~’~’(C-C,), where D and D’ denote the diffusion coefficients of the depolariser in its oxidised and reduced states respectively, the electrolytic process being ox. + u Q -+ red., e:g., 2%” + 2 0 it Pb. The curve, giving this dependence of the current, i, on the potential, OT, i.e., the current - voltage curve has the shape of curve 1 in Fig.1. It has an inflexion for i = id/2, at which point the concentration of the depolariser at the electrode surface is half exhausted (C, = C/2) and also the con- centration of the lead amalgam reaches half of its final value. The potential,r+, at which this happens is a constant independent of the concentration of the depolariser, C, and of the properties of the capillary (m, t). This is the so-called “half-wave potential” charac- terising the quality of the depolariser. If we use instead of pure mercury in the dropping electrode a dilute, say, 0.001 per cent. amalgam of lead and polarise it in a pure solution of an indifferent electrolyte cathodically, starting with a large voltage, say, E = 1.0 v., the current is practically zero (Fig.1, curve 2). On decreasing the voltage, i.e., imparting to the dropping electrode more positive potentials, we start anodic dksohtion of lead, viz., Pb + P b + 2 0 . At a potential at which half of the lead content from the surface dissolves, the “half-wave potential” of lead is reached and 4 i L!= 1.0 v Fig. 1. Current - voltage curves. ~~ ~ * m depends on the voltage V (Le., external applied E.M.F.) as T = - V + i. p, where p denotes the resistance in the circuit. Since both i and p are small, T is practically identical with V.230 HEYROVSKY: THE FUNDAMENTAL LAWS OF POLAROGRAPHY [Vol. 72 could be obtained by measuring the currents which pass through the cell at different voltages. In this respect the dropping mercury electrode was found to be especially suited to show a variety of exactly reproducible phenomena, as it offers the following advantages: (1) it develops always a fresh, regularly renewed surface of mercury and of the adjacent electrolyte solution, so that no time effects due to accumulating products of electrolysis are possible; (2) the large overvoltage on pure mercury prevents hydrogen deposition, so that even alkali metals may be deposited without decomposition of water taking place; (3) since the extent of electrolysis is small, changes in the concentration of the depolariser in solution are negligible, and consequently the measurements may be repeated with the same small amount of solution many times with identical results; (4) owing to the perfectly regular dropping, all processes repeat themselves at each fresh mercury drop with a high degree of exactitude, so that the current is a well-defined function of the dropping-electrode potential.From the regularity of conditions under which the surface of each drop is developed, IlkoviE, and, later, Rideal and MacGillavry, were able to deduce that the mean current, iE, due to electrolysis of a depolariser present at a concentration C in a concentrated solution of an indifferent electrolyte, is determined by the equation: where v is the electrovalency, F Faraday’s constant, D the diffusion coefficient and C, the concentration of the depolariser at the electrode surface, all quantities being expressed in absolute units; iE reaches its limit when C, = 0, at which condition the depolariser is completely exhausted at the electrode surface.This current is then called “diffusion current”; it gives the “height of the polarographic wave” and is proportional to the’ concentration C of the depolariser in the body of the solution, so that it serves as a measure of its concentration. From the relationships given above between m, t and h it follows that the “diffusion current” Is proportional to dz, i.e., it varies as the square root of the height of the mercury reservoir. The relationship between the current, i, and the potential, r, of the polarised mercury electrode* has been deduced by IlkoviC and the present writer from the formula of Peters i, = 0.627 V.F.D’~~~~~*~’~’(C-C,), where D and D’ denote the diffusion coefficients of the depolariser in its oxidised and reduced states respectively, the electrolytic process being ox.+ u Q -+ red., e:g., 2%” + 2 0 it Pb. The curve, giving this dependence of the current, i, on the potential, OT, i.e., the current - voltage curve has the shape of curve 1 in Fig. 1. It has an inflexion for i = id/2, at which point the concentration of the depolariser at the electrode surface is half exhausted (C, = C/2) and also the con- centration of the lead amalgam reaches half of its final value. The potential,r+, at which this happens is a constant independent of the concentration of the depolariser, C, and of the properties of the capillary (m, t). This is the so-called “half-wave potential” charac- terising the quality of the depolariser. If we use instead of pure mercury in the dropping electrode a dilute, say, 0.001 per cent. amalgam of lead and polarise it in a pure solution of an indifferent electrolyte cathodically, starting with a large voltage, say, E = 1.0 v., the current is practically zero (Fig.1, curve 2). On decreasing the voltage, i.e., imparting to the dropping electrode more positive potentials, we start anodic dksohtion of lead, viz., Pb + P b + 2 0 . At a potential at which half of the lead content from the surface dissolves, the “half-wave potential” of lead is reached and 4 i L!= 1.0 v Fig. 1. Current - voltage curves. ~~ ~ * m depends on the voltage V (Le., external applied E.M.F.) as T = - V + i. p, where p denotes the resistance in the circuit. Since both i and p are small, T is practically identical with V.June, 19471 HEYROVSKQ: THE FUNDAMENTAL LAWS OF POLAROGRAPHY 231 when all the lead from the surface of the amalgamated drop is dissolved, an anodic "diffusion current," i;, ensues.We thus obtain a curve of the same shape as when using pure mercury dropping into a lead salt in the solution. If the lead amalgam drops into a solution containing a lead salt, there is a cathodic diffusion current, id, as well as an anodic diffusion current, i;, the first indicating the concentration of lead in the solution, the second that in the mercury. In fact, in polarography we always deal with an electrode equilibrium of the depolariser in its oxidised (ox.) and reduced (red.) states, i.e., with redox potentials. The current - voltage curve for cases in which both the oxidised and the reduced forms are present is represented by the equation This formula is mostly applied to solutions of redox indicators and other systems containing in the solutions red.and ox. components, e.g., Fe" - Fe"', Cr" - Cr"', Sn" - Sn'", quinone - hydroquinone, lactoflavin - leuko-base, etc. The study of current - voltage curves gives us, indeed, the same information as the Michaelis "potentiometric titration curves." In these, increasing amounts of a reducing agent, say, Cr", are added to the depolariser, e.g., Fe"', whereby the ratio of ox. to red. is changed and the corresponding 7~ is noted (Fig. 24. In polarography the reduction of ox. to red. is effected by the current of electrons, which reduce the depolariser at the interphase, and the corresponding 7~ is shown on the abscissa (Fig.2b). To change diagram a into b one has first to turn a round through 90" and then turn its paper upside down to cover exactly deductions that are derived from Michaelis curves also follow from the polarographic semiquinones and dimers. Moreover, in polarography one of the components suffices, the second being formed at the electrode; this stable. Also the range of negative potentials at which the redox systems may be studied 1 N KCl calomel zero). When examining solutions containing more than one depolariser, we obtain the corre- sponding number of waves, which allow simultaneous qualitative and quantitative deter- mination of the depolarisers. If the half-wave potentials are near to each other, the waves coalesce so that the determination is uncertain; however, an addition, to the electrolyte, of a compound that makes complexes of different stability with the various depolarisers helps to resolve such coincidences into separated waves.Another difficulty arises when we have to determine accurately small quantities of a baser component in excess of nobler ones, e.g., traces of Zn or Cd in Cu. Then the noblest component (Cu") forms such a large wave at a positive potential that waves of the minor components, reducible at more negative potentials, are hardly distinguishable at the given sensitivity. This difficulty might be removed by applying a differential method described recently by Semerano and by Kanewsky, who use two solutions in separate vessels with exactly identical capillaries in each; the difference of currents flowing through the two capillaries is registered against the voltage.One of the vessels contains the sample to be analysed, the other only the indifferent electrolyte used in the first solution. Next, the noblest (most electro-positive) component is added to the in- different electrolyte in such an amount as to make its concentration equal to that in the vessel with the sample, so that the two diffusion currents balance each other. On increasing the voltage the diffusion currents of the baser components may be registered with a large sensitivity. The presence of air does not interfere, since the oxygen waves exactly balance each other. This differential method assumes equal drop-times and synchronous dropping for both electrodes, which is very difficult to maintain.Therefore the present author recom- mends here the use of two streaming electrodes instead of the dropping ones. One type of the streaming electrode is shown in Fig. 3. It consists of a thick-walled capillary with an inside diameter of 1 to 2 mm., drawn out at the tip to an internal diameter of about 0.1 mm. I the curve b. From this it is evident that all fee* -r waves, notably as regards the formation of i -7 a $ 4 is of special value if one of the forms is un- 3 t.ci cr .. is considerably extended (to -2.0 v. from the Fig. 2. (a) Potentiometric titration (b) Polarographic current - voltage curve.232 HEYROVSKQ : THE FUNDAMENTAL LAWS OF POLAROGRAPHY [Vol. 72 It is essential to keep the level of the solution in the vessel constant, so as to have always the same length of the electrode given by the jet of mercury.Two such electrodes, each surrounded by a solution in the same indifferent electrolyte, coupled according to the differential scheme, can be used to show slight differences between samples of similar com- position. In Figs. 4 and 5 curves obtained with two streaming electrodes are shown, the solutions being exposed open to the air; the sensitivity of the galvanometer was decreased 1:30. The method is very sensitive, but the consumption of mercury is large, amounting to 600 to 1000 g. per hour (under a pressure of about 50 cm. of Hg). One streaming electrode alone is not suitable for analytical purposes, since the charging (or “capacity,” i.e., “con- denser”) current is about 100 times larger than that of the dropping electrode.Fig. 4. Comparison of solutions: one Fig. 5. One solution contains Pb”, the other Cd” ions in a concentration 2.6.10-’M, both in N HCl. solution pure N HCl, the other containing Pb” and Cd” in a concentration 2-6.10-6M. Another method, which enables small quantities of baser constituents to be determined in presence of excess of nobler ones, and which at the same time gives new information on the shape of current - voltage curves, consists in obtaining the “derivative” curve, - T. Here again a double electrode is used (Fig. 6), but dipping into one solution only. Since syn- chronous dropping is difficult to attain, the drop-time is reduced (0.8 to 1 sec.) without synchronising the drops. Thus the curves in Figs. 7 and 8 were obtained. The equation of the current - voltage curves gives for the differential quotient at the half-wave potential .zd = 1Or. id, as a maximum. The advantage of this method for analytical di z=-- 4RT applications is due to the ease with which the half-wave potential and the height of the maximum, indicating the quantity required, are determined. The precision with which a component may be determined polarographically reaches in favourable case =t 1 per cent. of its absolute amount. Where greater exactness is required “polarometric titrations” may be used. In these the diffusion current of the component is followed at a certain constant voltage as it is diminished during precipitation with a suitable agent. The end-point of the titration is shown by the minimum value of the diffusion current; this minimum is best found graphically from a hand-drawn diagram, two measurements before and two after the end-point being necessary.By this method the precision is increased to 0.1 per cent. The com- ponent or the precipitating agent has to act as a depolariser. I t is best when both are polarographically active, because in this case a very sharp minimum of the diffusion Current is obtained (e.g., nickel with dimethyl- glyoxime). The school of I. M. Kolthoff has worked out many analytical applications of these polarometric ( d e d also “amperometricJJ) titrations. An interesting case is encountered in the polarometric titration of thorium salts with fluorides, neither of which is a depolariser, yet the presence of Th”” ions provokes a wave of nitrate ions added for that purpose.As soon as all thorium ions are precipitated the nitrate wave disappears. di v.F . - + Fig. 6, Scheme for obtaining the derivative curve.June, 19471 HEYROVSK~ : THE FUNDAMENTAL LAWS OF POLAROGRAPHY 233 In the last few years a new development of polarographic research has been started through the use of potential - time curves, obtained on the fluorescent screen of the cathode ray oscillograph.2 The voltage of the ordinary alternating current supply (of 50 cycles per sec.) acts on the dropping mercury electrode and the changes of its potential are recorded on the oscilloscope. The curve shown with pure indifferent electrolyte has the shape a (Fig. 9), and a trace of depolariser changes it into the shape b (Fig.9) with a time-lag at the depolarisation potential. I t Fig. 9 (a). Fig. 9 (b). Oscillographic potential - time curves. Increased frequency of the time base (to about 100,000 per sec.) changes curve b into Fig. 10, where the depolariser is characterised by a line at a certain potential. If more depolarisers are present, the corresponding number of lines appears as an “osdlographic spectrum” (Fig. 11). The quantity of the depolariser is deduced from the “derivative” curve (repre- dV senting - - t ) through the depth of the cut-in, shown on the curve in Fig. 12. To obtain a dt steady oscillogram the streaming mercury electrode has to be substituted for the dropping elect rode. REFERENCES 1. 2. HeyrovskB, J., “The Differential Method with the Streaming Electrode” (in Czech), Chaw.LisZy, Heyrovskf, J., and Forejt, J., “Oscillographische Polarographie,” 2. physih. Chem., 1943, 193, 1946, 40, 222-224. 77-96. PHYSICO-CHEMICAL DEPARTMENT CHARLES UNIVERSITY PRAGUE DISCUSSION The PRESIDENT, Dr. G. W. MONIER-WILLIAMS, expressed the cordial thanks of the Society to Professor Heyrovskf for enabling them to hear this authoritative account of the fundamental principles of polarography from one who was not only the originator but also the leading exponent of the subject. The Society was grateful also to the British Council, to whom they owed this opportunity of welcoming Professor Heyrovsw as their guest lecturer. Dr. J. E. PAGE said it was a great privilege for him to open the discussion on Professor Heyrovskf’s lecture.Few branches of analysis could have owed so much to one man as polarography owed to Professor Heyrovskf. A high percentage of the 1400 papers published on polarography had come from Professor Heyrovskf’s laboratory and the bulk of the remainder had been directly inspired by work initiated a t Prague. He (the speaker) was particularly interested in Professor Heyrovskf’s recent work with the cathode ray oscillograph and would like to know if he had used this technique to study (i) oxidation - reduction systems such as benzoquinone-hydroquinone and (ii) catalytic steps of the type formed by cysteine and cystine in ammoniacal cobalt buffer solutions. Mr. J. HASLAM said it was a privilege to have had the opportunity of listening to the lecture of Professor Heyrovsw, which was of fundamental value to the analyst.More and more they saw the fundamental nature of the work, which made possible the determination of reducible substances by clean and neat methods, and they saw also the selective nature of the polarographic method, as in the determination of nitrobenzene in aniline, for which the chemical method of reduction with titanous solution only gave a figure for total reducible matter calculated as nitrobenzene. He thought that in the future when they had more information about the correct ground solutions, the polarographic method would be of great value in that difficult problem for all organic chemists-the rapid quantitative determination of small amounts of various metals present in the sulphuric acid digestion products of organic materials.HEYROVSK? : THE FUNDAMENTAL LAWS OF POLAROGRAPHY [Vol.72 Mr. F. STEGHART, speaking of the IlkoviC equation, said that experiments by Maas and Kolthoff seemed to confirm its validity, but some experiments in the laboratory with which he was associated threw some doubt on it. In these experiments there was included in the polarographic circuit a high-speed high- precision amplifier designed in such a way that no interference with the current took place. The output from the amplifier was connected to two instruments, one representing the ordinary highly damped galvanometer and the other a high-speed high-precision recorder. Whilst the damped recorder, which for all practical purposes gave an exact replica of the ordinary galvanometer, confirmed the tests by Maas and Kolthoff, the high-speed recorder contradicted them.The curve obtained was practically never in agreement with one-sixth power of the time, but varied usually between two-thirds and one-third power. As the difference between such curves and the curve of one-sixth power is comparatively small and would only be shown by a highly accurate recorder, it appeared rather likely that the previous tests and those camed out by. IlkoviE to obtain confirmation of his theory were obtained only because of the inadequacy of the instruments used a t the time. The results of the experiments described above do not affect the practical usability of the polarograph in any way, but they make it appear very likely that the IlkoviE equation describes only part of the effect and that other factors, e.g., the turbulence near the surface of the drop, may play a part.Furthermore, it appeared from micro-photo- graphic experiments that the increase of the mass of the drop is not a linear function of the time, and if this is taken into account it increases the discrepancy between the actual record and the one-sixth power law. From all these tests it appeared that further investigation into the basic theory of the polaro- graph would be of great interest and might lead to further improvement in the usability and accuracy of the instrument. Professor HEYROVSKI?, in reply to Dr. Page's question concerning the oscillographic investigations with oxidation - reduction systems such as benzoquinone - hydroquinone, said that this particular case- as well as that of quinhydrone-shows perfect oscillographic reversibility and so does the system cystine - cysteine.Such red-ox electrode reactions must, therefore, come to the thermodynamically defined state of equilibrium with an extremely high rapidity. The catalytic reactions with cysteine were not yet investigated, but the reaction of blood-proteins in ammoniacal cobalt buffer solutions were found to show characteristic time-lags in the oscillographic potential-time curve, again proving the high rate of this cataiysed reaction. To Mr. Haslam's remark on the possibility of the determination of traces of metals in organic materials he expressed the opinion that such determinations, e.g., of iron, copper, bismuth, antimony, lead, thallium, cadmium, zinc, and so on, are possible without difficulties.In reply to Mr. Steghart, Professor Heyrovsky remarks that the validity of the one-sixth power law of IlkoviC has been firmly established experimentally by measurements with a torsion thread galvanometer of 0.01 sec. period of swing (Collection of Czechoslovak Ckpnical Communications, 8, 1936, p. 31), and also by the fact that the diffusion current, id, varies as the square root of the height of the reservoir, h, as was pointed out at the beginning of this paper (CoZZectim, 6, 1934, p. 510). Thus the one-sixth power holds equally for momentary currents and for the mean current. If a one-third power law held, then id would be proportional to the cube root of h (for id would equal R.mals.tllr = k'.ha/3.k-11s) : and if a two-thirds power law held, then id would be independent of h (for id would equal R.m2/3.ta/3 = k'.h21s.h-als). Experimentally the two latter cases are found only when a kinetic reaction takes place at the interphase (see e.g., Wiesner, CoZZection, 12, 1947, p.64), or when motion of the electrolyte occurs (as with maxima, when i = k.t113). Turbulence was never observed in the outflow of mercury, and as the rate of outflow is constant and given by the height of the mercury reservoir, the mass of the drop must be a linear function of time. There is a small capillary back-pressure at the beginning of the for- mation of each drop, amounting to a few per cent. of h and disappearing as the drop grows; this small effect, however, cannot account for the discrepancy referred to by Mr. Steghart. IlkoviE's law was derived on the assumption that each particle of the depolariser, say a cation, is deposited as soon as it touches the electrode. However, oscillographic investigations carried out by the present author (see e.g., Faraday SOC. Discussion on Electrode Reactions, April, 1947), show that the transfer of two or more electrons, e.g., in the deposition of Cu" or In"' ions, involves consecutive (dismu- tation) reactions ; in such instances-encountered in sulphate or nitrite solu tions--the electro-deposition is retarded and the assumption of Ilkovils does not hold ; consequently, also the one-sixth power relationship changes towards the one-third power. As soon as excess of chloride is added, the law of IlkoviE holds, just as it holds in the electro-deposition of any univalent cations (Tl., Na', K') in any solution. But such cases are anomalous.

ISSN:0003-2654    

DOI:10.1039/AN947720229b

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C.Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner.He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction June, 19471 STUART: THE DETERMINATION OF ACETYL GROUPS 235 The Determination of Acetyl Groups by Trans-Esterif ication BY R.G. STUART THE method of assay of acetyl groups by catalysed trans-esterification to ethyl acetate was investigated by Matchett and Levine.l They used absolute alcohol as a solvent, concentrated hydrochloric acid as a catalyst, fractionation through a column packed with glass helices, and intermittent small-volume take-offs into a receiver charged with excess of alcoholic alkali. The take-off device resembled that shown at E in Figure 1. The efficiency of the method depended on the difference in boiling-points between the ternary mixture, water, alcohol and ester, and the binary, alcohol and water.0-Acetyl compounds were given about two hours fractionation, from 2ml. of acid in 50ml. of alcohol, with a 2-ml. take-off every 15 min. N-Acetyl compounds, reacting more slowly, received four hours treatment, with 3 ml. of catalyst and similar take-offs, at half-hour intervals. In these laboratories, the first attempt to use this method was made on N-acetyl- phenetidine, which is used as an “analytical standard” for acetyl groups. For quantitative recovery, it was found necessary to distil a large volume of alcohol (more than 100 ml.) and in doing so to refill the still-pot several times. The subsequent titrations had an unduly large possible error, and the time of distillatioa exceeded 8 hours. To reduce inaccuracy and running costs, an apparatus was designed (Fig.1) to allow the redistillation of the alcohol from the receiver into the still-head at the same rate as that from the still-pot into the receiver. It was then possible to examine rates of recovery of ethyl acetate under standardised conditions, the volume in the two flasks remaining constant. At this stage it was found that introduction of a few per cent. of water or of methyl alcohol caused no significant change in rates of recovery, but anhydrous ethanol was retained as a reagent because of greater ease of purification. APPARATUS (Fig. 1) The still-pot A (100-ml. round-bottomed Pyrex flask, B24 neck, with lugs) is attached by springs to the fractionating column C, which has an effective length of 90 cm., an effective bore of 14 mm., a vacuum jacket (pressure about 1 micron Hg), a working hold-up of 7 ml., a static hold-up of 3 ml., a through-put, just before flooding, of about 20 ml. per minute, and a filling of 4mm.of Fenske single-turn glass helices2s3 The still-head includes a total reflux condenser D into the U-tube E. This U-tube has a variable constant-ratio take-off through tap F into a visual drip-feed into con- denser R, which cools the take-off and refluxes the reagent alcoholic potash in flask B (a replica of flask A). The tube between condenser R and flask B is connected by a 10-mm. bore vertical lagged air tube to a small reservoir P, above tap G, which controls a visual drip- feed into the top of condenser D. Condenser H is a total reflux into reservoir P, and con- denser K cools the pressure outlet to flask A and the fractionating column.The two outlets to the whole system, the tops of condensers H and K, are capped by soda-lime tubes L, attached via B10 joints. For strength, the four condensers are jointed by 10-mm. bore water-carrying tubes, the whole still-head assembly being of glass blown in one piece, with its centre of gravity near enough to that of the fractionating column to allow it to be rested in and supported by the B34 joint which tops the column. The column is clamped at two symmetrical points to the bench framework, and the stillhead is lightly clamped round the jacket of the air-tube at X. Flasks A and B are heated by small electric heaters, each of about 500 watts, and the upper halves of the glass joints are lightly greased with petroleum jelly.METHOD OF OPERATION MACRO ANALYSIS REAGENTS- (1) Anhydrous ethanol 99.5 per cent.-This is freed from aldehyde by distillation in vacuum from 1 per cent. of sodium metal and subsequent fractionation through column C (Fig. l), using 250-ml. flasks and charging the still-pot with 200 ml. The first 50 ml. contain all the remaining aldehyde bodies, and the bulked first fractions are re-fractionated, separating236 STUART: THE DETERMINATION OF ACETYL GROUPS BY [vol. 72 the first 50ml. The bulked main fractions, 140ml. each, are stored in rubber-stoppered amber bottles. f C ) A C D I L n Water t F +-Water x Front Elevation. Side Elevation. Fig. I. (2) Potassium hydroxide, 0.8 Pev cent. solzction in the pzlra$ed aZcohZ-This solution, which is about 0.11 N , is colourless and remains so indefinitely when exposed to daylight.It is stored in a rubber-stoppered white glass bottle, allowed to starid two days for carbonateJune, 19471 TRANS-ESTEFUFICATION 237 to precipitate and settle, and then pipetted as required from the supernatant clear layer. The temperature correction is about 0-1 per cent. per degree, and the titre changes very slowly, a new standardisation being required monthly. (3) Hydrochloric acid, concentrated ArtalaR-35 per cent. of HCl in water. PROCEDURE- Charge flask A with 45 ml. of the alcohol, 3 ml. of concentrated hydrochloric acid, a few carborundum chips, and enough of the sample under test to yield 0.043 to 0-086 g. of CH,CO, Le., requiring 10 to 20 ml. of 0.1 N potassium hydroxide.Charge flask B with 20 ml. of 0.1 N potassium hydroxide and 16 ml. of alcohol. Boil the contents of both A and B until U-tube E and reservoir P are filled with alcohol, and adjust both drip-feeds to about one drop per second. The relative drop sizes of the two feeds have been previously found by experiment to have the ratio 6 : 5, and the rates can be adjusted sufficiently accurately by eye to keep the volumes in the flasks constant, that is, about 35ml. in each. Distil from both flasks for one hour from the initial time of boiling of flask A, turn off the taps, and titrate the contents of flask B with 0.1 N sulphuric acid, using phenolphthalein as indicator. Titrate a “blank” on the 0.1 N potassium hydroxide alone. Deduct 0015ml. from the net reading to allow for carbon dioxide in the alcohol (0.1 ml.), and for alkali ab- sorbed by the glass of flask B (0.05 ml.).Carbomdum chips are not used in flask B because they are susceptible to attack by alkali. The carbon dioxide in the system becomes concen- trated in flask B, and the correction is found from a blank titration on a portion of the alcohol, which does not change in this respect on storage. It is unnecessary to boil flask B for longer than one hour, because, when the rate of re- action has been found from the first hour’s run, the time required to reach a quantitative yield is read off graphically (see Fig. 3 and p. 238); flask B is charged with excess of 0.1 N potassium hydroxide, plus alcohol to make up to 35 ml., and distillation from it is resumed for an hour after flask A has been boiling for an hour less than the total time.For the final back-titration the correction is 0-05;ml. of 0.1 N potassium hydroxide. It is unnecessary to clean the apparatus internally, and it is mounted semi-permanently. No hydrochloric acid remains in the column after draining, and if necessary alcohol can be removed from the column by aspirating a stream of air downwards through it after removal of the soda-lime tubes. (This is sometimes advisable, to remove stale alcohol before an assay.) With known O-acetyl compounds, one distillation, over a time of two hours, is sufficient. RE s ULTS- To check the efficiency of fractionation, ethyl acetate itself was distilled in the apparatus, with the quantities of reagents as specified, 92 per cent.was recovered in 30 minutes, and 99.5 per cent. in the first hour. From sodium acetate the equivalent of 99.8 per cent. was recovered, as ethyl acetate, in one hour. For many O-acetyl compounds and N-acetyl compounds curves were drawn of the rates of acetyl recovery (Fig. 2). For all O-acetyl bodies, 99.9 per cent. was recovered in the first two hours; but for N-acetyl compounds the rate varied considerably with the molecular structure, although it was remarkably constant for each compound. Compound (1) Ethyl acetate . . .. .. .. .. .. (2) Acetylsalicylic acid . . .. .. .. .. (3) Acetanilide . . .. .. .. .. .. (4) N-Acetylphenetidine . . .. .. .. .. (6) N-Methylacetanilide . . .. .. .. .. (7) N-Ethylacetanilide . . .. .. .. .. (8) Diacetyl-9-phenylene-diamine .. .. .. (9) Triacetoxybenzene, 1 : 2 : 3 . . .. .. .. (10) Triacetoxybenzene, 1 : 2 : 4 . . .. .. .. (5) Toluene-azo-diacetylaminotoluene, 2 : 1 : 1 : 4 : 3 . . yo Recovered 30 &., 92.6; 1 hr., 99.5. 1 hr., 98-0; 2 hr., 99.9. 1 hr., 59.5; 2 hr., 82.9; 3 hr., 93.1; 7 hr., 1 hr., 40-5; 2 hr., 65.0; 5 hr., 93.2; 12 hr., 1 hr., 79.2; 3-6hr., 97.8; 12 hr., 100-2. 1 hr., 10.4; 4 hr., 33.2; 8 hr., .69*1. 2hr., 9.6; 9 hr., 33.3. 1 hr., 70-6; 2hr., 914; 3h., 97.6; 6h., 99.8. 99.9. 99.8. 2 hr., 100.0. 2hr., 100.1. Other O-acetyl compounds tested included acetic esters of higher alcohols, phenols and sugars; without exception, all the ethyl acetate was recovered in two hours. The same wasf IJune, 19471 TRANS-ESTERIFICATION 239 From this percentage, the time required to reach, say, 99.9 per cent.is read off on the graph, and the distillation completed. These methods have been used in the analysis of research intermediates, and the rate of reaction can be used to suggest the location of the acetyl group, although the possibilityof more than one type being present must be borne in mind. TIME (HOURS) Fig. 3. Rates of Recovery of Ethyl Acetate from Acetyl Compounds. (1) Ethyl acetate (5) 2: 1 : 1 :4:3-Toluene-azo-diaetylaminotoluene (2) Acetylsalicylic acid (6) N-Methylacetanilide (3) Acetanilide (7) N-Ethylacetanilide (4) N-Acetylphenetidine (8) Diacetyl+phenylenediamine are given in parenthesis at the bottom of the graph. N.B.-Dotted lines (6) and (7) indicate a reduced time-scale for 6 and 7 ; the corresponding time figures REVERSIBILITY OF REACTION (on cooling)- The necessity of sometimes allowing the still-pot to stand overnight, and to continue its heating next day, made advisable a check on the effect of this.Using acetanilide, refluxing two hours, standing overnight and then distilling one hour, 93.5 per cent. was recovered. From the exponential curve for this compound (measured in one day, without cooling) the theoretical recovery is 93 per cent. in 3 hours. It follows that the reversibility of the reaction under these conditions is not significant and that probably a small amount of trans-estedica- tion occurs during cooling and re-warming. The rapid removal of ethyl acetate from the reaction chamber into the U-tube will reduce the reverse reaction, if any occurs.0-Acetyl compounds were not considered. EFFECT OF CONCENTRATION OF CATALYST- amounts of hydrochloric acid were used. Following are results obtained with acetanilide and acetylsalicylic acid when different (1) Acetanilide : 1 hour’s distillation and trans-esterification. 1.5 ml. of hydrochloric acid; 45 ml. of alcohol; acetyl recovery 38-5 per cent. 3.0 , Y 9 , 9 ) 9 ) ; 45 #P P9 > Y ; J > J # 59a5 P J ) # J J 75*0 P t ) J 6.0 9 , >, 9 , 9 ) ; 45 P J 9 ) J Y ; 9 ) (2) Acetyl-salicylic acid: 1 hour. 1-5 ml. of hydrochloric acid; 45 mi. of alcohol; acetyl recovery 96.8 per cent. 9 9 9 ) ; 45 9 9 8 9 9 ) ; J > ,, 99.0 P J 3, 3.0 , Y ,Y 6.0 ,2 #, J , 3, ; 45 3, 8 , 9 9 ; ,, J S 98*8 # # J J 3.0 I Y ,, ## 97*8 J ) # # J J J P ; 45 # t # ) ? # ; 3 9240 STUART: THE DETERMINATION OF ACETYL GROUPS BY [Vol.72 From these figures it appears that an 0-acetyl trans-esterification is not significantly affected by alteration of the concentration of hydrochloric acid, which appears to act as a true catalyst. With N-acetyl compounds, the rate plotted against the concentration of acid appears to follow a curve similar in shape to the’trans-esterification curves. The application of this to the speeding of reactions is limited by the capacity of the column to retain hydro- chloric acid vapour under the working conditions. When 3 ml. of concentrated hydrochloric acid were used, the quantity of chloride in the distillate was not significant, even when, on one occasion, flask A was accidentally allowed to run dry; but with 6 ml.of the acid its rate of distillation was equivalent to 0.15 ml. of 0-1 N per hour. The column could be lengthened to increase retention. For convenience, the volume of hydrochloric acid used in all determinations was kept a t 3 ml. METHOD- MICRO ANALYSIS The distillation rates are left unchanged, but the total volume of alcohol used is reduced from 80 ml. to 60 ml. In flask A are 35 ml. of alcohol and 3 ml. of concentrated hydrochloric acid, and in flask B, 20 ml. of 0.01 N alcoholic potassium hydroxide plus 5 mi. of alcohol. Enough sample is weighed to give a net titration of less than 10 ml., the back titration being carried out with 0.01 N sulphuric acid, and neutralised phenolphthalein as indicator. As before the only significant errors are due to carbon dioxide in the alcohol (usually = 0.4ml.of 0.01 N per 20 ml.), and to the effect of boiling 0.01 N alkali in a glass flask (usually = 0.2 ml. of 0-01 N per 20ml. per hour). In practice, only a blank titration on 20ml. of alcohol is necessary. There is less margin of error for variations in rate of distillation and re-distilla- tion; but the rate of trans-esterification of M-acetyl compounds is increased about 10 per cent. The relatively larger excess of 0.01 N potassium hydroxide in flask B is to ensure that hydrolysis of the distilled ethyl acetate will be rapid enough to prevent its remaining in circulation. RESULTS- With known compounds the curves obtained were, as expected, similar to those obtained on the macro scale, with an approximately 10 per cent.increase in the rates of reaction of N-acetyl compounds. The method has been applied in the analysis of a number of research intermediates, both for percentages and for identification. DISCUSSION A trans-esterification under these conditions is essentially a hydrolysis of the acetyl compound, followed by an esterification of the acetic acid. This esterification is in all cases at a uniform rate, not significantly affected by the concentration of catalyst. The wide differences in the rates of recovery depend solely on the rates of initial hydrolysis. This rate is fast and uniform throughout a wide range of 0-acetyl compounds, and is of the same order as the rate of esterification, because the two together give a rate of recovery not far below that for ethyl acetate.(The exponential form of the straight distillation is due to the mechanism of fractionation, including the slight washing-out effect of the distillate from flask B crossing the Mowing distillate from flask A). It follows that for 0-acetyl compounds the reaction at the boiling-point is almost in- stantaneous and ionic and depends on the hydrogen ion concentration, which itself has a maximum not affected by a large excess of strong acid. With N-acetyl compounds, the rate of hydrolysis depends on the concentration of hy- drogen chloride, in accordance with Dawson’s “Dual Theory of Acid Catalysts,” which ascribes the catalytic effect to the concentration of HCI molecules, in addition to that of H and C1 ions. This leaves a wide field of investigation into other causes of variation, namely, the shape of the molecule and the effect of substitution, especially of the spare H atom of the acetylamino group.A recent experiment points to the molecular shape as the prime influence ; because N-acetyl-diphenylamine reacts more rapidly than methyl acetanilide, and this more rapidly than the ethyl derivative. The difficulty of dislodging the strongly held N-acetyl by collision with hydrochloric acid molecules or ions is increased by a protective effect of substituted groups and by the sub- sequent decrease in polarity, which probably more than counterbalances the decreased strength of the bond holding the acetyl group. Once the dislodging has occurred, the acetyl group will be esterified, the chances of the necessary collision being very high, for there are initially,June, 1947) TRAN S-E STERI FICATION 241 with 0.1 N solution, about twenty hydrochloric acid molecules to-every acetyl.Also the freed amino group will be much more likely to attach a hydrochloric acid molecule than a free acetyl group. With the large excess of hydrochloric acid molecules, the collision rate will depend on the concentration of acetyl compound only; hence the first-order reaction, characterised by an exponential curve. An interesting case is that of 2 : 1 : 1 : 4 : 3-toluene-az~-diacetylaminotoluene- N : N N This compound behaves as would a mixture of an O-acetyl compound yielding 100 per cent. of the theoretical amount of acetyl in two hours, and an N-acetyl compound yielding 58 per cent. in one hour. A mixture of this kind would give 79 per cent. of the total acetyl in one hour, 96 per cent. in three hours, and 99.8 per cent. in six hours, figures which agree with the curve obtained. It would be expected that one group would be released, or expelled, at the same rate, approximately, as an O-acetyl group, and that the remaining group would be more strongly held. The derived figure of 58 per cent. per hour for the mono-acetyl derivative is similar to that for acetanilide, faster than that for acetyl-phenetidine (40.5 per cent.) and slower than that for diacetyl-9-phenylenediamine (70.6 per cent.). Every trans-esterification of an N-acetyl compound so far investigated has followed a fixed unalterable rate with remarkable accuracy, so much so that any variation from the theoretical curve showed an error in the technique, and thus helped in the improvement of design and method. SUMMARY- Determination of acetyl groups led to the investigation of the rate of trans-esterification of acetyl compounds to ethyl acetate, with hydrochloric acid as catalyst, and to the design of an apparatus which improved the accuracy of the method. All trans-esterifications followed exponential curves, the shape of the curve depending on the molecular structure of the acetyl compound. The time required to reach sufficiently quantitative yields was arrived at graphically. O-acetyl compounds yielded 100 per cent. after two hours. N-acetyl compounds gave rates depending on the substitution of the N hydrogen atom, on the substituent groups in other parts of the molecule and on the concentration of hydrochloric acid. My thanks are due to Mr. I. J. Fine for the glass-blowing construction, to Mr. T. Tusting Cocking for his advice and encouragement in the experiments described and to the Directors of The British Drug Houses, Ltd., for their permission to publish the results. REFERENCES 1. 2. 3. Matchett and Levine, I n d . Eng. Chem., Anal. Ed., 1941, 2, 98. Fenske, Tongberg and Quiggle, Ibid., 1934, 26, 1169. Still, J. E., Chem. and I n d . , 1946, 17, 130. GRAHAM STREET, CITY ROAD THE BRITISH DRUG HOUSES LIMITED LONDON, N.l Mwch, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200235

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years.The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion.The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on.Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp.15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction June, 1947) TRAN S-E STERI FICATION 241 The Determination of Micro-Quantities of some Derivatives of Phenarsazine BY H. BARNES THE usual method for the determination of derivatives of phenarsazine involves wet oxidation of the compound followed by determination of the contained arsenic (Sartoris). When only small quantities of the arsenical are available either the Gutzeit method or the determination of the arsenic (after reduction and volatilisation as trichloride or as arsine) by the ammonium molybdate reagent, could no doubt be used.Delgal has described a colour reaction of phen- arsazine chloride; a yellow colour is obtained when aqueous solutions of this substance, in concentrations of 8 mg. or more per litre, are treated with a reagent consisting of silver nitrate in glacial acetic acid. This paper describes a simple, sensitive, although not specific method for determining some phenarsazine derivatives. Up to the present it has been principally used with pure[Vol. 72 solutions of the arsenicals in organic solvents (see, however, p. 243), but it has proved of con- siderable value in toxicity work. It depends upon the action of concentrated nitric acid on the arsenical and the subsequent addition of sodium hydroxide, whereupon an intensely red coloured solution is obtained.The nitro derivatives of 10-chloro-5 : 10-dihydrophenarsazine and the corresponding phenarsazinic acids yield red salts with sodium hydroxide when the nitro groups are in the 2 and 8 positions (Gibson and JohnsonJ2 Raiziss and Gavron,6 Wieland and Rheinheimer8). Further, Schmidt’ has shown that hot nitric acid oxidises and nitrates 10 :lO’-oxy-5:10- dihydrophenarsazine. It is suggested, therefore, that under the conditions used in the method given below, both oxidation and nitration take place with the production of the 2:8-dinitro derivative of the phenarsazinic acid, which on addition of sodium hydroxide yields the in- tensely red coloured quinonoid aci-salt . 242 BARNES: THE DETERMINATION OF MICRO-QUANTITIES OF SOME METHOD Reagents- Nitric acid (A.R.), concentrated.Aqueous acetone, 50 per cent. v/v solution. Sodium hydroxide, (A.R.), 10 per cent. aqueous solution. Sodium potassium tartrate (A.R.), 10 per cent. aqueous solution. Procedwe- Transfer the test solution to an evaporating dish and remove the solvent on a hot water bath. Add 2 ml. of nitric acid and evaporate just to dryness on a vigorously boiling water- bath-. After cooling, dissolve the residue in 10 ml. of aqueous acetone with the aid of a rubber- tipped glass rod and add 1 ml. of the tartrate solution. Add 0.4 ml. of sodium hydroxide solution with stirring. A red colour is produced on the addition of the alkali. Transfer the solution to the absorptiometer cell and measure the transmittance. Calibration curves may be obtained by the use of benzene solutions of phenarsazine derivatives.A blank should be run on the reagents and solvents used. Measzcrement of transmittance- For the determination of transmittances the Spekker photo-electric absorptiometer has been employed throughout, with a 1-cm. cell and green filters (Ilford 604). The instrument is set at 0.400 against distilled water. It has been the practice first to set the instrument and take a reading of the unknown; the instrument is then reset and, with the shutter closed, the drum is moved into the previous position of balance. The unknown is then placed in position and the final adjustment made rapidly. DISCUSSION The method has been applied to phenarsazine chloride (5-chloro-6 :lo-dihydrophen- arsazine) , phenarsazine oxide (10 :lO‘-oxy-5 : 10-dihydrophenarsazine) and 5-ethyl-5 :10- dihydrophenarsazine. Preliminary tests have indicated that the method could be applied to other derivatives of phenarsazine and to compounds with a similar structure.2. The maximum absorption is obtained with use of green filters (Ilford 604). With a l-cm. cell the calibration curves are linear over the range 5 to 25%. for all the above substances. 3. The limit of the method as given is of the order of 2 pg. of arsenical. It should be possible to determine smaller quantities by reducing the volume of the final solution, but this would necessitate the use of a smaller cell than the standard 1 cm. Spekker cell (approxi- mate volume 10 ml.) and slight changes in the technique may then be found necessary. 4. The spread of the calibration curve indicates that differences of 1 pg.correspond approximately to a drum difference reading of 0.010 (Le., one drum division). 5. The tartrate solution prevents the precipitation, when the solution is made alkaline, of any small quantities of impurities carried over from the reagents. 6. Care should be taken to bring all the material into solution when the aqueous acetone and the alkali are added; the upper portions of the dish should be carefully rubbed down since the substances show a tendency to “creep.” 1.June, 19471 DERIVATIVES OF PHENARSAZINE 243 The transmittances should be determined within a short time; the red colour fades, particularly if the solution is left in the evaporating dish. In a covered cell no significant change takes place within 10 minutes.7. 8. Table I gives a series of results obtained by the method. Phenarsazine chloride , Present 3.4 5-0 4.4 6-2 11-8 12.2 12-8 14.0 14.8 15.0 15.2 15.2 15.2 25.0 28.0 Founi 4.0 5.8 4.0 5.4 11.4 12-2 13.4 13.6 14.8 14.8 15.0 15.4 15.2 24.0 27.6 TABLE I AMOUNTS IN MICROGRAMS 5-Ethyl derivative 7 Present 16.4 25.2 29.6 25.6 20.0 13.2 10.4 - - v Found 17.2 25.6 30.4 25.6 19.0 12-0 10.6 - - Phenarsazine oxide > A +resent 16.8 15.6 20-0 23.2 26.4 17-6 28-4 15-6 - - Found 16-8 16.2 19.4 22.6 25.2 16.8 27.2 15.0 - - THE DETERMINATION OF PHENARSAZINE CHLORIDE IN AQUEOUS SOLUTION Derivatives of phenarsazine have been used in experimental anti-fouling compositions3 and assessments of raft exposures have indicated their effectiveness. In recent work on the bebaviour of anti-fouling compositions containing cuprous oxide as the poisonous pigment , a so-called leaching technique has been developed (Harris: Ketchum et &a4).Painted panels (3” x 1” microscope slides, 12.9 sq.cm. painted area) are exposed in the sea and at regular intervals the rate of loss of cuprous oxide (leaching rate) is measured by a standardised laboratory method. These tests of leaching rate have proved to be of great value in inter- preting the behaviour of anti-fouling compositions and the technique has been adapted to investigate the rate of release of phenarsazine derivatives from compositions containing them, with or without cuprous oxide. In a four-hours leaching test, using 60 ml. of sea water, a “normal” composition will lose up to 30 pg. of arsenical.A relatively simple method was required, so that large numbers of test panels could be examined, and an application of the method outlined above appeared possible. Preliminary investigations indicated that under the prescribed conditions, in a slightly alkaline medium, hydrolysis of small amounts of phenarsazine chloride was virtually complete and the following method has been used for sea water solutions of this substance; in view of the rather specialised application only a brief description is given. The method must be regarded as of a preliminary nature, since the work has been interrupted before a more complete investigation was possible.* The sea water extract from the leaching test (60 ml.) is transferred to a 250 ml.separating funnel and shaken for three minutes with an equal volume of chlorofom; after the two layers have separated the chloroform layer is run off into a small distilling flask and the major portion of the solvent removed on the water bath. The remaining solution (about 3 ml.) is transferred to an evaporating dish, the flask is rinsed twice with small amounts of chloroform and the washings are added to the bulk. The solvent is then completely removed on a hot water bath and the residue treated exactly as in the direct procedure already described. (Under certain circumstances it may be necessary to centrifuge the solution after development of the red colour). A calibration curve is constructed using sea water solutions of phen- arsazine chloride which have been standing for some hours.In order to obtain satisfactory results it is essential to adhere to standardised conditions. Blanks are run on extracts from panels painted with a composition in which the arsenical is replaced by an inert pigment. * A progressive hydrolysis on shaking a benzene solution of phenarsazinechloride with alkaline solutions has been demonstrated by analysis of the benzene layer after varying periods. This hydrolysis is suppressed on replacing the slightly alkaline medium by concentrated hydrochloric acid. Preliminary work indicates that as with must substituted derivatives of arsenic trichloride, phenarsazine chloride is comparatively readily hydrolysed-the hydrolysis being difficult to detect or determine owing to the extreme insolubility of the product in water.244 BACHARACH: THE SEPARATION OF CRYSTALS AND “ GUMS” ON The distribution of the hydrolysis product is in favour of the water and this, together with the more involved procedure, renders the results less accurate than those of the direct method. Nevertheless, several hundred determinations by the method have indicated that it is capable of yielding useful information on the behaviour of phenarsazine chloride in anti- fouling paints. The author is indebted to the Marine Corrosion Sub-committee of the Iron and Steel Institute for permission to publish this work and to Professor J. E. Harris for his interest in it. REFERENCES [Vol. 72 1. 2. 3. 4. 5. 6. 7, 8. Delga, J., J . Pharm. et Chem., 1940, 132, 73. Gibson, C. S., and Johnson, J. D. A., J . Chem. SOC., 1929, 1229. Harris, J. E., Paper No. 20, Journal of the Iron and Steel Institute, 1946. Ketchum, B. H., Ferry, J. A., Redfield, A. C., and Bums, A. E., Ind. Eng. Chem., 1945,37, 456. Raiziss, G. W., and.Gavron, J. L., “Organic Arsenical Compounds,” New York, 1923. Sartori, M., “The War Gases,” London, 1940. Schmidt, J., J . Amer. Chem. SOC., 1921, 43, 2453. Wieland, H., and Rheinheimer, W,, Annalcn, 1921, 423, 1. THE MARINE STATION February, 1947 MILLPORT, SCOTLAND

ISSN:0003-2654    

DOI:10.1039/AN9477200241

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction 244 BACHARACH: THE SEPARATION OF CRYSTALS AND “ GUMS” ON [Vol.72 The Separation of Crystals and “Gums” on the Micro or Semimicro Scale BY A. L. BACHARACH (Communicated to the Annual General Meeting of the Microchemistry Group on January 31st, 1947) IT often happens during work on the isolation of individual compounds from complex materials of biological origin-and also, doubtless, during preparative and synthetic operations-that a rather intractable mixture is obtained, consisting of a relatively small quantity of obviously crystalline nature embedded in a more or less viscous fluid. Recrystallisation of such mixtures, with a view to isolating the crystalline constituent, is at best fraught with appre- ciable losses; at worst, it results in the whole of the mixture being taken up in the solvent and ultimate recovery, by evaporation, of the fluid material holding the crystals no longer in suspension but in solution.It is a common experience that such crystalline material is more soliihle in a solution of the accompanying “impurities” than in the solvent used; this accounts for the fact that purification by recrystallisation tends to become progressively easier as the fluid material is proportionately reduced. In this business it is the first step that counts (and may lose) most. For this first step there are also available chromatographic methods. Elegant and effective though these so often are, for a particular problem under consideration they involve a search for the right adsorbent and eluent, as well as several manipulative stages.What the chemist wants in the circumstances is a simple method that is so rapid as to reduce to a minimum waste of time in examining what may ultimately turn out to be crystalline material of no interest. (In work connected with the extraction of “active principles” from vegetable drugs-plants, leaves, roots-it is surprising how often the first crop of crystalline matter was found to be ammonium oxalate !) It therefore seems that a description might with advantage be given of a procedure first shown to me many years ago by the late Dr. Frank Tutin and now modified in two directions. On various occasions during the past twenty years the procedure has been described or demon- strated to colleagues working in the laboratory and the matter has generally been treated with indifference or scepticism, but recently Dr. C. H. Gray (private communication) has used the technique for recovering crystalline stercobilin hydrochloride from faeces. By this means he has on occasion been able to improve the yield of pure material by as much as 30 per cent. Although the mechanism of the procedure was never explained by Tutin-a man, in any event, not over-much given to theonsing-the experiments described below make it clear that it is merely an application of those phenomena of diffusion so brilliantly exploited by Conway for quantitative micro-analysis. In essence the device involves separating “gum” from crystals on porous plate, using a solvent and yet never wetting the mixture with the solvent.solvent. It will be found that after a comparatively short time, depending on the solvent chosen, the the relative amounts of gum and crystals and so on, solubility of the gum, the viscosity of the mixture, 4

ISSN:0003-2654    

DOI:10.1039/AN9477200244

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction 246 BOORMAN, DAUBNEY AND MARTIN : THE IDENTIFICATION OF [Vol.'is The Identification of Phenol from Synthetic and Natural Sources BY E. J. BOORMAN, C. G. DAUBNEY, AND A. E. MARTIN A NUMBER of specimens of phenol, derived from three sources, namely (1) alkali fusion of benzenesulphonic acid, (2) high temperature hydrolysis of chlorobenzene, and (3) fractionation of coal tar, have been examined in order to find whether these three types of phenol could be distinguished analytically with certainty, it being assumed that the material may be so dis- coloured as to prevent the use of the simple coloration test by passing of air. Each class of sample was always found to contain a small but identifiable quantity of characteristic impurity which was absent from samples of different origin.These impurities were, for class (l), o- and P-hydroxydiphenyls; for class (2), diphenyl ether; for class (3), naphthalene. . The 9-hydroxydiphenyl was usually isolated and identified by analysis (Found: C, 84.4; H, 5.7. Calc.: C, 84.7; H, 5-9 per cent.) and by the melting-point, 164" C., not depressed by admixture with an authentic specimen; but in general the identification was made by observing the infra-red spectrum of a solution of the residue i4 carbon tetra- chloride. 2.525 2.732 2.938 3.142 3.346 3.549 3751 3.951 WAVE LENGTH (p) Fig. 1. PROCEDURE (A)-Distil the sample at 1 to 1.5 mm. pressure (bath at 68" to 60" C.) until distillation ceases.Take up the residue from 1 kilo in ether, filter, evaporate and heat the residue at 100" C. in a current of air to remove traces of phenol. The yield of residue depends on the quality of the original phenol. Materials of class (1) yield from 0.3 g . to 10 g. of residue, consisting largely of o- and 9-hydroxydiphenyls in the ratio of approximately 4 to 10 parts of o- to 1 part of p-isomeride. Materials of class (2) or (3) leave not more than a trace of residue. Separate tests showed that added p-hydroxydiphenyl in amounts down to 0.02 per cent. can be recovered by this procedure. PROCEDURE (B)-Dissolve 500 g. of the sample in 800 ml. of sodium hydroxide solution (30 per cent. w/v) and distil in a current of steam until 200ml. have been collected.Add 80 ml. of the alkali to this, and repeat the steam distillation, collecting 100 ml. and allowing the condenser to become warm towards the end of the operation. Extract the final distillate with 20ml. of carbon tetrachloride and examine the infra-red spectrum of the solution. Materials of class (2) show the presence of a trace up to 13 mg. of diphenyl ether from 0.5 kilo of material. Experiments show that added o-hydroxydiphenyl does not appear inJune, 19473 PHENOL FROM SYNTHETIC AND NATURAL SOURCES 247 this distillate. Materials of class (3) yield from an identifiable trace to 10 mg. of impurity from 200 to 500 g. of sample and infra-red examination reveals the presence of naphthalene. INFRA-RED EXAMINATION-A grating spectrometer was used (compare Fox and Martin1), the solution, in an absorption cell 1 cm.or 5 cm. long, being compared with pure carbon tetrachloride in a second similar cell. For identification and estimation of the hydroxy- diphenyls the OH band at 2-77 p was used for the 9-isomeride, and for the o-isomeride a double band having the weaker limb at the same point. The C-H bands of phenol and 9-hydroxy- diphenyl at 3.283 p. and 3.295 p. respectively are distinguishable from each other and also from the related bands for m- and o-hydroxydiphenyls. Bands in the region of 3.3 to 3.6; p. are not useful, being obscured by absorption due to oily impurities. Fig. 1 shows a curve for the residue from a phenol of class (1) with the split-off band characteristic of o-hydroxydiphenyl (80 per cent. of ortho, 20 per cent. of para). Fig. 2 shows the diphenyl ether bands at 3.256, 3.288 and (weaker) 3-298 p. in residues from phenols of class (2). . .. WAVE LENGTH (r) Fig. 2. WAVE LENGTH (p) Fig. 3. Fig. 3 shows the-identification of naphthalene in residues from phenols of class (3) The authors are indebted to the Government Chemist for permission to publish this work. the main peaks being at 3.234, 3.259 and 3.276 p. REFERENCE 1. Fox, J. J., and Martin, A. E., Proc. Roy. SOC., 1937, A, 162, 419; 1938, -4, 167, 257. GOVERNMENT LABORATORY CLEMENT’S INN PASSAGE STRAND, LONDON, W.C.2 January, 1947

ISSN:0003-2654    

DOI:10.1039/AN9477200246

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction 248 GLYNK : REDUCTOMETRIC DETERMINATION OF THE SULPHOXIDE [Vol. 72 Reductometric Determination of the Sulphoxide and Amine Oxide Groups BY ERICA GLYNN (Read at the Meeting of the Society on February 5th, 1947) FROM the analytical point of view the presence of the sulphoxide or mine oxide groups has hitherto been determined indirectly from the figures for the ultimate analysis of the substance under investigation.A direct method is clearly desirable for the sake of accuracy and in order to distinguish, for example, a dioxide from the isomeric sulphide sulphone. The problem is similar to that of the nitro and azo groups, and similar methods should, therefore, be applicable. For these groups reduction with an excess of stannous chloridG or titanous chloride2 is commonly used and the excess titrated back with standard iodine or ferric alum. Stannous chloride and ferric alum have been adopted in the present work, for iodine is unsuitable in presence of organic sulphides.Choice of an indicator-The end-point in presence of thiocyanate was found not to be very sharp and an oxidation-reduction indicator was, therefore, adopted. The oxidation- reduction potential concerned lies between 0.55 and 0.22 volt.s Nile Blue, Lauth’s Violet and Brilliant Cresyl Blue were tried and rejected owing to the dependence of the colour on acid concentration. Potassium indigo tri~ulphonate~ was finally chosen (value of wo = 0*332), as the passage of the final blue to a deep blue with a reddish tinge, as seen in artificial light, was sharp and easily recognisable. (This characteristic reddish tinge is not observed in absence of artificial light. It is sufficient to place an electric lamp directly behind the flask during the ti tration.) METHOD REAGENTS-water and acid used for the preparation of all reagents should be boiled free from air and saturated with carbon dioxide.Standard iodine solution-Approximately 0.1 N , standardised against potassium iodate in the usual way. Standard stannous chZoride solzdion-Approximately 0.2 N . Dissolve 54 g. of stannous chloride in 150 ml. of concentrated hydrochloric acid and 1850 ml. of water. Preserve under carbon dioxide and syphon direct into the burette. Standardise by titration against iodine under carbon dioxide with starch as an indicator. Ferric alum solution-Approximately 0.1 N . Dissolve 100 g. of ferric ammonium alum in 400 ml. of 5 N sulphuric acid and 1600 ml. water. Filter after it has stood overnight and keep at least a week before use. Standardise this solution by adding an excess of stannous chloride and titrating with iodine.The oxygen equivalent of 1 ml. of 0.1 N ferric alum is 0.0008g. In titrating the stannous chloride with the ferric alum solution take 20 ml. of diluted hydrochloric acid (1 + l), with carbon dioxide bubbling, add 10 ml. of stannous chloride from the burette, 5 to 10 drops of 1 per cent. potassium indigo trisulphonate solution and 10 ml. of water and titrate in the cold with ferric alum solution, shaking thoroughly after each addition in the last 0.5 ml. and allowing 5 to 10 seconds for any change of colour, until one further drop causes no further deepening in the final reddish blue. The result agreed with the iodimetric titration within 0-1 per cent. In titrating a sulphoxide, introduce 20 ml.of an air-free solution in water or alcohol of the substance, containing approximately 0-5 g. of reducible oxygen per litre, into a 250-ml. conical flask on a hot plate, passing carbon dioxide throughout the operation, and add 10 ml. of stannous chloride from the burette. Now add 10 ml. of hot concentrated hydrochloric acid and boil gently for 45 minutes, adding a further 25 ml. of hot water and 5 ml. of concentrated acid after 15 minutes. Finally add 20 ml. of concentrated hydrochloric acid, 10 ml. of water and 5 to 10 drops of 1 per cent. potassium indigo trisulphonate solution and titrate as above with ferric alum. Carry out a blank titration with 20ml. of air-free water in place of the solution of the substance, heating as before. Correction of the blank titration-The blank titration is essential, as some oxidation of stannous chloride by atmospheric oxygen is inevitable.It is safe to assume that the reduction of the sulphoxide is largely completed in a very short time and the actual amount of stannous PROCEDURE-(^) (2)June, 19471 ASD AMINE OXIDE GROUPS 249 chloride subsequently liable to oxidation is the excess then left in solution. Using the simple blank estimation, the results were in fact found to be low (92 to 98 per cent. of the calculated figure). Ingold and Smith,5 in titrating the nitro group with titanous chloride, adopt the device of adding, in their blank experiment, only the amount of reducing solution found to be in excess. The method used here is to make a correction of the blank titration based on the same principle.It has the advantage that the blank determination need not then be repeated for each titration. If a constant volume, n ml., of stannous chloride solution is always used and titrations are in ml. of standard ferric alum solution, then if titration (cold) without substance is v,, and titration with heating for a definite period without substance is vA, whilst titration with heating for the same period with substance is v,, the apparent titre for the substance (blank uncor- rected) is 'IIh - v,. The true value should be the apparent titre (v, - v,) less the blank correction x (1 - fraction of stannous chloride used up in the reduction of the substance). That is to say, the true titre X is given by which gives As the total hot blank v, - v h approaches zero, so the true value of x approaches vb - v,- The application of this device is shown in Table I with dithian dioxide as the substance analysed .TABLE I 19.965 ML. OF A SOLUTION OF 2.6964 G. (0.01772 G.-MOL.) OF 1 IdrDITHIAN DIOXIDE IN 1 LITRE, TITRATED WITH 0.09977 N FERRIC ALUM v c ml. VA ml. X Peroxidic 0% v, ml. found ml. (calcd. 14.18) (calcd. 21.02) 26.76 25.21 11-30 14.21 21.06 25.76 24.33 10.92 14.20 21.04 25-76 24.33 11.01 14-10 20.9 1 26-76 24-33 10.87 14-25 21-13 21-32 19.63 6.53 14.21 2 1-06 Results with a number of sulphoxides or sulphones are shown in Table 11. TABLE I1 Substance Total 0% (Calcd.) a-Dithian dioxide . . .. .. . . 21-02 Dithian monoxide .. .. .. . . 11-74 Dithian trioxide .. .. .. . . 28-54 Dibenzyl sulphoxide .. .. .. . . 6-95 Dibenzyl sulphone . . .. .. . . 12-99 a-Phenylene-l : 3-dimethyl disulphoxide . . 15-82 a-2 : 5-Dimethyl-thiolbenzoic acid dioxide . . 25.98 Peroxidic oxygen 7 7 Found yo Calcd. % 21.04 21.02 11.77 11-74 9-41 9-6 1 6-87 6-95 0 0 16-82 16.82 12.95 12-99 Amine oxides-The determination was carried out as for sulphoxides. Amine oxides are often most conveniently isolated as picrates and for the analysis of these salts the picric acid must first be removed. To the solution of an amine oxide picrate in alcohol, add alcoholic potassium hydroxide, warm and allow to stand overnight. Filter into a 100-ml. flask, wash the precipitate with absolute alcohol, make up to 100 ml. with water and take aliquot portions for analysis. The results for two amine oxides are given below: Peroxidic oxygen Total oxygen t-*-, Substance Calcd. % Found % Calcd. % Dimethylaniline oxide picrate . . . . 34.9 4-37 4.28 Diphenylpiperazine a-dioxide octahydrate . . 38-7 7-76 7.73250 WYLIE : DETERMINATION OF SULPHATE IN SODIUM DICHROMATE [Vol. 72 SUMMARY A method is described for the determination of sulphoxide and amine oxide groups by quantitative reduction with excess of stannous chloride and back titration with ferric alum, using potassium indigo trisulphonate as an indicator. Results are given for some sulphoxides, sulphoxide sulphones, amine oxide and amine oxide picrate; the average error was less than 1 per cent. The author's thanks are due to Dr. G. M. Bennett for suggesting this investigation. REFERENCES 1. 2. 3. 4. 6. Limpricht, H., Ber., 1878, 11, 36; Hensen, J . Prakt. Chcm., 18,78, 193. Knecht, E., and Hibbert, E., Bev., 1907, 40, 3819. Kolthoff, I. M., "Die Massanalyse," 1927, 74. Sullivan, M. X., Cohen, B., and Clark, W. M., Pub. Health Reps., 1923, 38, 1689. Ingold, C. K., and Smith, M. S., J . Chem. SOC., 1938, 908. Compare Hinkel, L. E., Ayling, E. E., and Walters, T. M., J . Chem. SOC., 1939, 403. KING'S COLLEGE STRAND, W.C.2

ISSN:0003-2654    

DOI:10.1039/AN9477200248

出版商:RSC    

年代:1947

数据来源: RSC

摘要:

426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents.It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate.There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE. By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international.The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr. Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively.Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies. Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited.The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time. The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation.Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice. Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction426 REVIEWS INKS : THEIR COMPOSITION AND MANUFACTURE.By C. AINSWORTH MITCHELL, D.Sc., F.I.C. Fourth Edition. Pp. xi + 408. London: Charles Grihn tt Co., Ltd. 1937. Price 12s. 6d. net. This, the fourth edition of the standard and, indeed, so far as the reviewer’s knowledge goes, the only text-book on the subject in the language, bridges L gap of 13 years. The author, pre-eminent in his particular sphere, needs little more introduction to the world of technical industry than he does in his official capicity to readers of THE ANALYST, while his reputation in forensic science in all that appertains to handwriting is international. The chemistry of ink, difficult as it is and at times not a little obscure, hcl- riot developed markedly in the interval since 1924; but what progress has been made is covered by Dr.Mitchell in this edition in a very thorough manner. He has found it necessary to enlarge his work to the extent of some 20 per cent. and, in addition, to rewrite a large portion. The arrangement of the book follows the lines of previous editions. After a comprehensive historical introduction, the work is divided into three sections dealing with writing inks, printing inks, and inks for miscellaneous purposes, respectively. Under Section 1 are considered the chemical nature and treatment of the various raw materials used for writing inks from lcmp black to galls, the composition of finished iron-gall, logwood, vanadium, aniline black, and coloured inks, as well as a comprehensive scheme €or the tech~ical examination of inks, handwriting specimens and the identification of forge:-ies.Section 2 deals with the manufacture and examination of printing inks. ,tnd Section 3 with the miscellaneous materials entering into the compositilxx of copying, marking, safety, sympathetic, typewriter inks and so on. Amongst new matter may be noted references to the use of lignone sulphni--,ites in connection with writing ink, a scheme for the identification of individual con- stituents in inks in the form of writing, and the application of filtered ultra-.& if )let light and of infra-red photography in the elucidation of those problems to which such methods are suited. The British Government Standard Specificatior:s for Writing Inks, revised in 1928, are included for the first time.The avaihble evidence upon the constitution of gallotannin is brought up to date and <tbly reviewed, and there is a Comprehensive list of British patents. It is as difficult to withhold admiration of the encyclopaedic scope cjf the matter and references in this book as it is of the erudition and industry displiiyed in its compilation. Practically nothing that comes to mind has escaped atterition, and it is with rather impish glee that the reviewer, after careful search, asserts that he finds no specific reference to the type of alkaline (ammoniacal) gallotannate- iron ink, said t o find favour in the United States, although the di-ammonium hydroxyferrigallate compound of Silbermann and Ozorovitz receives notice.Nor is there mention of that class of quick-drying writing fluids which depend for their efficiency upon partial destruction of the paper sizing by caustic alk 1.5 or sodium silicate. There is no evidence that lignone sulphonate inks have proved se-rious competitors to iron-gall writing inks (pp. 15 and 175). Apart from the unkttmwn quantity of permanence, the principal failing of this type lies in their liability to contain traces of free sulphurous acid to which suspicion attaches in connt-ction 250 WYLIE : DETERMINATION OF SULPHATE IN SODIUM DICHROMATE [Vol. 72 Determination of Sulphate in Sodium Dichromate BY A. W. WYLIE FOR the determination of sulphate in the presence of sexivalent chromium compounds, it is usually recommended that chromium be reduced to the tervalent state before precipitation of sulphate with barium chloride.Various combinations of acids and reducing agents have been proposed. Haring and Barrows1 used hydrochloric acid and ethyl alcohol. Willard and Schneidewind2 recommended hydrochloric acid and either ethyl or methyl alcohol, hydroxylamine hydrochloride or hydrogen peroxide. Acetic acid and formaldehyde were suggested by Nikitina and Babaeva3 and by Rabovskii and Raskatova.* Macchias advocated the use of acetic acid and hydroxylamine. The method proposed by Haring and Barrows for the determination of sulphate in chromic acid yields low results unless acetic acid is added before precipitation of barium sulphate. The addition of acetic acid was proposed by Willard and Schneidewind, after Weinlands had shown that acetic acid displaces non-precipitable sulphate groups from complex chromium ions and thus brings about almost complete precipitation of sulphate by barium chloride.Most subsequent experimenters have added acetic acid to the solution, whether hydrochloric acid was present or not. In the course of experiments to find whether small amounts of sulphate could be determined in sodium dichromate with the same accuracy as in chromic acid, it has been found (1) that the method of Willard and Schneidewind is equally applicable to sodium dichromate ; (2) that increasing proportions of hydrochloric acid increase the quantity of barium sulphate precipitated in the absence of acetic acid; (3) that sulphate may be satis- factorily determined in sodium dichromate without the addition of acetic acid provided 2.7 times the theoretical requirement of hydrochloric acid is used, and the solution is allowed to stand for 15 hours.It has also been found that the presence of large amounts of acetic acid in hydrochloric acid solutions of chromic chloride may cause high results, although it is more usual to obtain results which are slightly low. To determine approximately 1 per cent. (dry basis) of sodium sulphate in sodium di- chromate the procedure of Willard and Schneidewind for the determination of sulphate in chromic acid may be varied as follows: A 1 to 2 g. sample should be taken and the procedure described below followed; the volume of hydrochloric acid (sp.gr. 1.178) added should be 1.3 times the theoretical requirement and the volume of glacial acetic acid used should be equal to the volume of hydrochloric acid. The precipitation volume should be 500 ml. The time of standing should be 15 hours for the best results (error approx. -0.5 per cent.) although fairly satisfactory results may be obtained by doubling the volume of acetic acid and allowing the solution tocstand 1 hour (error approx. -1.5 per cent.). To determine sodium sulphate in sodium dichromate without the addition of acetic acid, a 1 to 2 g. sample should be used and 2.7 times the theoretical requirement of concentrated hydrochloric acid must be added. If the procedure is then carried out as before, the time of standing being 15 hours, the accuracy of the results is equal to that obtained in the presence of acetic acid.June, 19471 WYLIE DETERMINATION OF SULPHATE IN SODIUM DICHROMATE 251 EXPERIMENTAL AnalaR sodium sulphate and twice recrystallised sodium dichromate were used in all experiments.Solutions of these reagents were standardised, the former by determination of sulphate as barium sulphate and the latter by titration with ferrous ammonium sulphate, using barium diphenylamine sulphonate as indicator. Mixed aliquots of these solutions were acidified with hydrochloric acid (sp.gr. 1*178), or hydrochloric acid and glacial acetic acid, and 50 ml. of ethyl alcohol were added. If the weight of sodium dichromate exceeded 1 g., 70 ml. of alcohol was used. Chromium was completely reduced by heating this solution, of total volume 200 ml., for 30 minutes at 90" to 95" C.The solution was then diluted to 500 rnl., heated to 90" C . and treated with 20 ml. of 10 per cent. barium chloride solution added dropwise from a burette. During precipitation, and for periods of standing up to 4+ hours thereafter, the solutions were maintained at 90" C. ; for standing periods of 15 hours or more, the solutions were kept at 90" C. for 1 hour only and then cooled to room temperature. The precipitated sulphate was filtered on a No. 42 Whatman paper, thoroughly washed with hot water and ignited at 800°C. Blank tests showed no sulphate in any of the reagents employed. The ignited precipitates were white or only slightly discoloured when cold but usually showed a faint yellowish green colour when hot.Each determination was made in duplicate and the mean values are recorded in Tables I to 111. When the error in the mean weight of sodium sulphate found did not exceed f 5 per cent. the maximum variation of duplicates from their mean was f0-2 mg. and the average variation 0.08 mg. When the error in the mean weight of sodium sulphate exceeded f 5 per cent., agreement between duplicates was less satisfactory. An average value, however, is recorded for purposes of comparison. EFFECT OF HYDROCHLORIC AND ACETIC ACIDS ON THE PRECIPITATION OF BARIUM TABLE I In each experiment 5-00g. of Na2Cr20, and 0-0546g. of Na2S0, were present in a final volume of 500ml. Expt. acid* acid period found Error Error 1 12.5 10 15 0.054Q - 0.6 - 1.1 2 14.0 10 15 0.0540 - 0.6 - 1.1 3 15.0 10 15 0.0541 - 0.5 - 0.92 4 16.0 10 15 0.0544 - 0.2 - 0.37 5 16.0 10 2 0.05 17 - 2.9 - 5.3 6 13.0 25 15 0-0556 + 1-0 + 1-8 7 13.0 50 15 0-0553 + 0-7 + 1.3 8 13.0 75 15 0-0554 + 0.8 + 1.5 SULPHATE IN PRESENCE OF CHROMIUM SALTS Hydrochloric Acetic Standing Na,SO, ml.ml. hrs. g. mg. per cent. 9 12.5 nil 15 0.0247 - 29.9 - 54.8 10 25.0 nil 15 0.0510 - 3.6 - 6.6 11 35.0 nil 15 0.0540 - 0.6 - 1.1 * Volume of hydrochloric acid theoretically required to convert Na&r,O, to NaCl and CrCl,, 13.0 ml. Experiments 1 to 4, Table I, lend no support to the contention of Willard and Schneide- wind that decreasing concentrations of hydrochloric acid cause an increase in the quantity of barium sulphate precipitated from solutions of chromium salts in presence of hydrochloric and acetic acids, and suggest that the contrary may be true.Experiment 5 emphasises the necessity of allowing solutions of the concentration used to stand for longer than 2 hours. Experiments 6 to 8 show that high results may be obtained when larger amounts of acetic acid are added. Experiments 9 to 11 indicate that a fairly reliable result may be obtained in absence of acetic acid if the quantity of hydrochloric acid added is 2.7 times the theoretical requirement, excess hydrochloric acid up to this total producing a marked increase in the quantity of barium sulphate precipitated. This optimum quantity of hydrochloric acid may be compared with that recommended by Haring and Barrows for the determination of sulphate in chromic acid, v k , approximately 1.5 times the theoretical requirement.Experiments 1 and 3 (Table 11) reveal no increase in the quantity of barium sulphate precipitated in presence of acetic acid when the concentration of hydrochloric acid is lowered. The smaller concentration of chromium in solution appears to convert a positive error of the order of 1 to 2 per cent. which might have been expected when the volume of acetic acid is twice that of hydrochloric acid (Table I, Experiment 6) to a negative error of the same order (Table 11, Experiment 1). Experiments 5,7 and 9 confirm the results of Experiments 9 to 11,252 WYLIE : DETERMINATION OF SULPHATE IN SODIUM DICHROMATE [Vol. 72 Table I. It is also shown (Experiments 6 and 8) that prolonged standing greatly increases the quantity of barium sulphate precipitated in absence of acetic acid, particularly at lower TABLE I1 In each experiment 2.0g.of Na,Cr,O, and 0-0219g. of Na,SO, were present in a final volume of 500ml. Hydrochloric Acetic Standing N+SO, Expt. acid* acid period found Error Error ml. ml. hrs. g- mg- per cent. 1 5.2 10 15 0.0216 - 0.3 - 1.4 2 5.2 10 1 0.02 16 - 0.3 - 1.4 3 7.0 10 15 0.0218 -0.1 - 0.46 4 7.0 10 4.5 0.02 17 - 0-2 -0.91 5 7 - 15 0.0092 - 12.7 - 57.9 6 7 - 64 0.0198 -2-1 - 9.6 7 8 - 15 0.0152 - 7.7 - 35.2 8 8 - 40 0.02 12 - 0.7 - 3.2 9 14 - 15 0.02 17 - 0-2 - 0.9 10 14 - 2 0.0199 - 2-0 -9.1 * Theoretical requirement of hydrochloric acid 5.2 ml. concentrations of hydrochloirc acid. would be precipitated under these conditions if sufficient time were allowed.acetic acid the time factor is of less importance. It seems reasonable to assume that almost all sulphate In presence of TABLE I11 In each experiment 1=Og. of Na,Cr,O, and 0-0219g. of Na,SO, were present in a final volume of 5OOml. Expt . acid* acid period found Error Error Hydrochloric Acetic Standing Na$O, ml. ml. hrs. g- mg- per cent. 1 3 10 4.5 0-02 18 - 0.1 - 0.46 2 3 10 15 0.022 1 + 0-2 +0-91 3 7 10 4 0.02 17 - 0.2 -0.91 4 3 - 15 0-0103 - 11.6 - 53.0 5 5 15 0.0164 - 5.5 - 25.1 6 7 -- 15 0.02 18 -0.1 - 0.46 7 7 - 2 0.0192 - 2.7 - 12.3 - * Theoretical requirement of hydrochloric acid 2-6 ml. The results in Table I11 confirm previous findings. The high result in Experiment 2 is attributed to the relatively large volume of acetic acid present. No obvious explanation is apparent for the high results obtained in the presence of larger quantities of acetic acid but such results could be caused by occlusion of greater quantities of chromium or barium salts in the precipitates. The assistance of Miss J. Mather in carrying out the experimental work involved in this investigation is gratefully acknowledged. SUMMARY A method for the determination of small quantities of sodium sulphate (1 per cent.) in sodium dichromate is described. An amount of hydrochloric acid equal to 2.7 times the theoretical requirement is added and the dichromate reduced to a mixture of chromic chloride and sodium chloride by heating with excess of ethyl alcohol. Sodium sulphate in the re- sulting solution is then precipitated as barium sulphate and the solution allowed to stand for 15 hours before filtration. REFERENCES The results, on the average, are 1 per cent.10~. 1. 2. 3. 4. 5. 6. Haring, H. E., and Barrows, W. P., U.S. Bureau of Standards, Tech. Paper No. 346, 1937, 342. Willard, H. H., and Schneidewind, R., Trans. Amer. Electrochem. Soc., 1929. 56, 333. Nikitina, E. A., and Babaeva, A. V., Trans. Inst. Puvc Chem. Reags., Moscow, 1930, 10, 9; Chem. Rabovski, G. V., and Raskatova, G. V., Zavod. Lab., 1934,3, 592; Brit. Chem. Abst., A, 1934, 1189. Macchia, O., Idustria chimica, 1930, 5, 1346; Chem. Abst., 1931, 25. 1760. Weinland, R., quoted by Willard and Schneidewind, Reference 2. COUNCIL FOR SCIENTIFIC AND INDUSTRIAL RESEARCH Abst., 1931, 25, 3593. DIVISION OF INDUSTRIAL CHEMISTRY November, 1946 MELBOURNE, AUSTRALIA

ISSN:0003-2654    

DOI:10.1039/AN9477200250

出版商:RSC    

年代:1947

数据来源: RSC