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Chemical colouring of aluminium
Surface Technology, 22 (1984) 15 - 20
15
CHEMICAL COLOURING OF ALUMINIUM S. JOHN, A. PERUMAL and B. A. SHENOI
Central Electrochemical Research Institute, Karaikudi 623006 (India) (Received August 15, 1983)
Summary In addition to anodizing, which is a very familiar process, there have been a number of conversion coatings available for aluminium over the years. In this paper a chemical colouring process is described wherein colours ranging from grey to black, yellow and brown are produced. An alkaline ammoniacal solution containing triethanolamine and metallic carbonates is used at temperatures of 80 - 90 °C.
1. Introduction Of the four well-known non-ferrous metals, namely aluminium, copper, lead and zinc, aluminium is the most important and widely used, even though it is the last of the four to enter into the service of man. Because of its high strength-to-weight ratio, good corrosion resistance, better formability and its good architectural characteristics, it has found innumerable uses in electrical applications, transportation, housing, packaging and canning, and engineering industries. Aluminium has a naturally bright and attractive surface appearance. For a great m a n y applications it is entirely suitable w i t h o u t the necessity for further finishing. However, many procedures and methods have been developed to satisfy our varied requirements. It is possible to alter the reflectivity, appearance and colour of bare aluminium by means of a variety of chemical and electrochemical methods. Although aluminium can be anodized and dyed almost any conceivable colour or tint through proper application of the appropriate organic dye after anodizing [1 - 3 ] , in the last few decades significant progress has been made in the single-step colouring of aiuminium by chemical treatment methods [4, 5]. In this paper the development of a simple chemical colouring solution to produce different shades for decorative applications is reported. Chemical conversion coatings based on oxides, chromates or phosphates on aluminium are well known and mainly serve as a base for paints, lacquers and enamels [6 - 11]. Some of the well-known processes such as the modified Baur-Vogel process produce iridescent shades which can be coloured with organic dyes, while the chromating process gives a yellow colour and the 0376-4583/84/$3.00
© Elsevier Sequoia/Printed in The Netherlands
16 c h r o m a t e - p h o s p h a t e coating gives a green colour. Black coatings may be obtained on aluminium by dipping it in a h ot solution containing molybdates or a n t i m o n y chloride [12]. A n o t h e r solution contains permanganate [1] and a further solution utilizes a nickel salt containing potassium thiocyanate [13]. The range of colours pr oduc e d is limited and is usually iridescent (with the exception of the c h r o m a t e - p h o s p h a t e coating); this makes the coatings suitable for i ndoor decorative applications. In this study, sparingly soluble metallic carbonates in an ammoniacal solution containing triethanolamine were utilized to pr oduce different colours. The solubilities o f the metallic carbonates used in the study are given in Table 1. TABLE 1 Solubility of metallic carbonates at 20 °C [ 14 ]
Carbonate
Solubility (g (100 g H20 ) l)
FeCO3 NiCO3 MnCO3 CuCO3 ZnCO3 PbCO3
0.072 0.090 0.040 0.030 0.070 0.014
2. Experimental details 2S aluminium alloy panels of size 75 mm × 50 mm were degreased with trichloroethylene, etched in 45 g NaOH 1-1, rinsed, cleaned in 15 vol.% nitric acid and finally rinsed. The panels were immersed in a chemical colouring solution containing the following: (NH4)2CO3, 20 g l - l ; metallic carbonate MCO a (M - Zn, Pb, Cu, Mn, Ni, Fe), 0.2 g 1-1 ; triethanolamine, 2 - 5 ml 1- l . L a b o r a t o r y grade reagents were used. The pH was adjusted electrometrically using a m m o n i u m h y d r o x i d e or acetic acid. The metallic carbonates were added after a slurry had been made. Deionized water was used for all the studies and the t e m p e r a t u r e was maintained by using a constant-temperature water bath. After the panels had been coloured, t h e y were rinsed and dried, and the colour was evaluated visually.
3. Results and discussion
3.1. Influence o f metallic carbonates Preliminary experiments with various concentrations of (NH4)2CO 3 showed that a c o n c e n t r a t i o n of 20 g 1-1 is essential for the form at i on of good uniform coloured coatings. Higher concentrations (greater than 35 g l -l ) lead to a dull finish and the coating is m u d d y and streaky, whereas
17 l o w e r c o n c e n t r a t i o n s (less t h a n 10 g 1-1) lead t o i n t e r f e r e n c e colours. T r i e t h a n o l a m i n e (2 - 5 ml 1- l ) was also f o u n d t o be essential f o r t h e f o r m a t i o n o f u n i f o r m c o l o u r e d coatings. T h e c a r b o n a t e s o f zinc, lead, c o p p e r , iron, m a n g a n e s e and nickel were u s e d in c o n c e n t r a t i o n s o f 0.1 - 1.0 g 1-1 a n d t h e c o l o u r o b t a i n e d a f t e r imm e r s i o n f o r 10 m i n at 90 °C is s h o w n in T a b l e 2. Yellow, golden yellow, grey and b r o w n c o l o u r s were o b t a i n e d . When m i x t u r e s o f c a r b o n a t e s were i n c o r p o r a t e d in t h e s o l u t i o n , d e e p shades such as b l a c k were p r o d u c e d . T a b l e 3 s h o w s t h e c o l o u r o b t a i n e d with m i x e d salts. T h e c o l o u r o f the film can b e a t t r i b u t e d t o t h e p r e s e n c e o f insoluble c o m p o u n d s o f m e t a l and a l u m i n i u m f o r m e d as a result o f r e a c t i o n with the solution. TABLE 2 Colour produced with different metallic carbonates
Carbonate
Colour
ZnCO3 PbCO3 CuCO3 MnCO3 NiCO3 FeCO3
Brownish yellow Medium yellow Yellowish grey Dark yellow Golden yellow Brownish grey
TABLE 3 Colour produced with combinations of metallic carbonates
Carbonate combination
Colour
CuCO3 + NiCO3 FeCO3 + CuCO3 ZnCO3 + CuCO3
Black Brownish black Greenish yellow
3.2. Influence o f immersion time T h e i m m e r s i o n t i m e has a great i n f l u e n c e o n t h e c o l o u r d e v e l o p e d . Within 5 m i n t h e c o a t i n g s s t a r t t o f o r m and are usually light in s h a d e c o m pared with the darker colours obtained by prolonging the t r e a t m e n t time. T a b l e 4 s h o w s t h e c o l o u r o b t a i n e d f o r various i m m e r s i o n t i m e s f o r a solut i o n c o n t a i n i n g 20 g o f (NH4)2CO3 1-1, 2 - 5 m l o f t r i e t h a n o l a m i n e p e r litre a n d 0.2 g o f NiCO3 1-1 at 85 °C. A p r o l o n g e d t r e a t m e n t impairs the q u a l i t y o f t h e coating. 3.3. Influence o f pH A m m o n i a o r acetic acid was u s e d t o adjust t h e p H . S t r o n g alkalis m u s t n e v e r be u s e d as t h e y dissolve a l u m i n i u m as well as t h e coating. T h e p H was varied b e t w e e n 6 a n d 11. H i g h e r p H values ( p H > 10) lead t o a dull
18 TABLE 4 Influence of immersion time on the colour obtained using 0.2 g NiCO31-1
Immersion time (min)
Colour
3 5 10 15 20 45
Interference colours Light yellow Golden yellow Dark golden yellow Dark yellow Dark yellow (matt finish)
streaky finish, whereas low pH values (pH < 7) lead to interference colours. Hence pH 8 - 10 is f o u n d to be the optimum. Because of evaporation losses at the operating te m per a t ur e (above 80 °C) a continuous addition o f ammonia is required to maintain the pH.
3.4. Influence o f temperature The colouring t e m p e r a t u r e was varied f rom 70 °C t o the boiling poi nt o f the solution. An increase in the solution t em perat ure accelerates bot h the rate o f f o r m a t i o n of the film and the rate of attack on the metal surface. This can result in a change in the colour of the coating. The t e m p e r a t u r e o f the solution should be maintained between 80 and 90 °C to ensure consistent results. A lower t e m p e r a t u r e of the bath (less than 70 °C) leads to interference colours.
3.5. Influence o f solution agitation Agitation o f the colouring solution accelerates the reaction and provides a mo r e uniform film formation. Uniform coatings were p r o d u c e d in this s tu d y with air agitation, whereas a non-agitated solution gave a streaky finish.
3.6. Influence o f surface preparation The appearance o f the coating p r o d u c e d depends greatly on the initial surface co n d itio n of the metal being treated. The coloured film accurately reproduces the surface c ondi t i on of the base metal. Thus brilliant and attractive shades are p r o d u c e d on polished aluminium (chemically polished or electropolished), whereas etched and m a t t finishes produce dull shades.
3.7. Influence o f top coat The coloured coatings are very thin ( of the order of 1 - 4 tzm) and have less abrasion resistance than anodic coatings. T hey should n o t be used w i t h ou t an overcoating of transparent lacquer when resistance to wear and abrasion is required. The coating possesses satisfactory protective properties when it is used in c om bi nat i on with a top lacquer coating.
19 3.8. I n f l u e n c e o f a l u m i n i u m alloy
T h e c o l o u r is a f f e c t e d b y t h e p r e s e n c e o f alloying e l e m e n t s in the aluminium. G o o d colours are p r o d u c e d o n a l u m i n i u m alloys which do n o t c o n t a i n h e a v y metals and silicon. On c o m m e r c i a l l y p u r e a l u m i n i u m and 2S alloy t h e c o l o u r is u n i f o r m and attractive. 3.9. E c o n o m y
In c o m p a r i s o n with anodic films, c h e m i c a l l y c o l o u r e d coatings have advantages o f e c o n o m y , speed o f f o r m a t i o n and relative simplicity o f equipm e n t r e q u i r e d f o r t h e i r p r o d u c t i o n . T h e y are very suitable for p r o d u c i n g cheap i m i t a t i o n items such as bangles, earrings, bracelets, chains and buckles. When small parts are t o be c o l o u r e d b y this t e c h n i q u e , t h e y are k e p t in a plating barrel which is r o t a t e d gently as in plating.
4. C o n c l u s i o n A l u m i n i u m can be c h e m i c a l l y c o l o u r e d t o various shades o f yellow, b r o w n , grey and black using an alkaline a m m o n i a c a l s o l u t i o n c o n t a i n i n g metallic c a r b o n a t e s and t r i e t h a n o l a m i n e . T h e o p t i m u m c o n d i t i o n s are as follows: (NH4)2CO3, 20 g 1-1; metallic c a r b o n a t e , 0.2 g l - l ; t r i e t h a n o l a m i n e , 2 - 5 ml l -~ ; p H 8 - 10; t e m p e r a t u r e , 80 - 90 °C; i m m e r s i o n time, 5 - 20 min.
Acknowledgment T h e a u t h o r s ' t h a n k s are due t o Dr. K. S. Rajagopalan, Central Electroc h e m i c a l Research Institute, Karaikudi, for his kind permission t o publish this paper.
References 1 S. Wernick and R. Pinner, The Surface Treatment and Finishing of Aluminium and Its Alloys, Vol. I, Draper, Teddington, Middx., 1972. 2 W. Lewis, The Practical Anodising of Aluminium, McDonald and Evans, London, 1960. 3 A. W. Brace, The Technology of Anodising of Aluminium, Draper, Teddington, Middx., 1968. 4 G. H. Kissin, The Finishing of Aluminium, Reinhold, London, 1963. 5 T. Biestak and J. Weber, Electrolytic and Chemical Conversion Coatings, Warzawa Publications, Warsaw, 1980. 6 R. M. Burns and W. W. Bradley, Protective Coatings for Metals, Reinhold, London, 3rd edn., 1967. 7 S. Spring and K. Woods, Met. Finish., 79 (6) (1981) 49. 8 L. F. Spencer, Met. Finish., 58 (1) (1960) 58. 9 D. B. Freeman and A. M. Triggle, Trans. Inst. Met. Finish., 37 (1960) 56. 10 W. E. Pocock, Met. Finish., 52 (1.2) (1954) 48.
20 11 H. Silman, G. Isserlis and A. F. Averill, Protective and Decorative Coatings for Metals, Finishing Publications, Teddington, Middx., 1978. 12 Br. Patent 1,156,356-7, 1967. 13 N. V. Shanmugam, K. N. Srinivasan, S. John, M. Selvam and B. A. Shenoi, Proc. Natl. Solar Energy Cony., Allied Publishers, New Delhi, 1982, p. 7.021. 14 N. A. Lange and G. M. Forker, Handbook o f Chemistry, McGraw-Hill, New York, 1967.
15
CHEMICAL COLOURING OF ALUMINIUM S. JOHN, A. PERUMAL and B. A. SHENOI
Central Electrochemical Research Institute, Karaikudi 623006 (India) (Received August 15, 1983)
Summary In addition to anodizing, which is a very familiar process, there have been a number of conversion coatings available for aluminium over the years. In this paper a chemical colouring process is described wherein colours ranging from grey to black, yellow and brown are produced. An alkaline ammoniacal solution containing triethanolamine and metallic carbonates is used at temperatures of 80 - 90 °C.
1. Introduction Of the four well-known non-ferrous metals, namely aluminium, copper, lead and zinc, aluminium is the most important and widely used, even though it is the last of the four to enter into the service of man. Because of its high strength-to-weight ratio, good corrosion resistance, better formability and its good architectural characteristics, it has found innumerable uses in electrical applications, transportation, housing, packaging and canning, and engineering industries. Aluminium has a naturally bright and attractive surface appearance. For a great m a n y applications it is entirely suitable w i t h o u t the necessity for further finishing. However, many procedures and methods have been developed to satisfy our varied requirements. It is possible to alter the reflectivity, appearance and colour of bare aluminium by means of a variety of chemical and electrochemical methods. Although aluminium can be anodized and dyed almost any conceivable colour or tint through proper application of the appropriate organic dye after anodizing [1 - 3 ] , in the last few decades significant progress has been made in the single-step colouring of aiuminium by chemical treatment methods [4, 5]. In this paper the development of a simple chemical colouring solution to produce different shades for decorative applications is reported. Chemical conversion coatings based on oxides, chromates or phosphates on aluminium are well known and mainly serve as a base for paints, lacquers and enamels [6 - 11]. Some of the well-known processes such as the modified Baur-Vogel process produce iridescent shades which can be coloured with organic dyes, while the chromating process gives a yellow colour and the 0376-4583/84/$3.00
© Elsevier Sequoia/Printed in The Netherlands
16 c h r o m a t e - p h o s p h a t e coating gives a green colour. Black coatings may be obtained on aluminium by dipping it in a h ot solution containing molybdates or a n t i m o n y chloride [12]. A n o t h e r solution contains permanganate [1] and a further solution utilizes a nickel salt containing potassium thiocyanate [13]. The range of colours pr oduc e d is limited and is usually iridescent (with the exception of the c h r o m a t e - p h o s p h a t e coating); this makes the coatings suitable for i ndoor decorative applications. In this study, sparingly soluble metallic carbonates in an ammoniacal solution containing triethanolamine were utilized to pr oduce different colours. The solubilities o f the metallic carbonates used in the study are given in Table 1. TABLE 1 Solubility of metallic carbonates at 20 °C [ 14 ]
Carbonate
Solubility (g (100 g H20 ) l)
FeCO3 NiCO3 MnCO3 CuCO3 ZnCO3 PbCO3
0.072 0.090 0.040 0.030 0.070 0.014
2. Experimental details 2S aluminium alloy panels of size 75 mm × 50 mm were degreased with trichloroethylene, etched in 45 g NaOH 1-1, rinsed, cleaned in 15 vol.% nitric acid and finally rinsed. The panels were immersed in a chemical colouring solution containing the following: (NH4)2CO3, 20 g l - l ; metallic carbonate MCO a (M - Zn, Pb, Cu, Mn, Ni, Fe), 0.2 g 1-1 ; triethanolamine, 2 - 5 ml 1- l . L a b o r a t o r y grade reagents were used. The pH was adjusted electrometrically using a m m o n i u m h y d r o x i d e or acetic acid. The metallic carbonates were added after a slurry had been made. Deionized water was used for all the studies and the t e m p e r a t u r e was maintained by using a constant-temperature water bath. After the panels had been coloured, t h e y were rinsed and dried, and the colour was evaluated visually.
3. Results and discussion
3.1. Influence o f metallic carbonates Preliminary experiments with various concentrations of (NH4)2CO 3 showed that a c o n c e n t r a t i o n of 20 g 1-1 is essential for the form at i on of good uniform coloured coatings. Higher concentrations (greater than 35 g l -l ) lead to a dull finish and the coating is m u d d y and streaky, whereas
17 l o w e r c o n c e n t r a t i o n s (less t h a n 10 g 1-1) lead t o i n t e r f e r e n c e colours. T r i e t h a n o l a m i n e (2 - 5 ml 1- l ) was also f o u n d t o be essential f o r t h e f o r m a t i o n o f u n i f o r m c o l o u r e d coatings. T h e c a r b o n a t e s o f zinc, lead, c o p p e r , iron, m a n g a n e s e and nickel were u s e d in c o n c e n t r a t i o n s o f 0.1 - 1.0 g 1-1 a n d t h e c o l o u r o b t a i n e d a f t e r imm e r s i o n f o r 10 m i n at 90 °C is s h o w n in T a b l e 2. Yellow, golden yellow, grey and b r o w n c o l o u r s were o b t a i n e d . When m i x t u r e s o f c a r b o n a t e s were i n c o r p o r a t e d in t h e s o l u t i o n , d e e p shades such as b l a c k were p r o d u c e d . T a b l e 3 s h o w s t h e c o l o u r o b t a i n e d with m i x e d salts. T h e c o l o u r o f the film can b e a t t r i b u t e d t o t h e p r e s e n c e o f insoluble c o m p o u n d s o f m e t a l and a l u m i n i u m f o r m e d as a result o f r e a c t i o n with the solution. TABLE 2 Colour produced with different metallic carbonates
Carbonate
Colour
ZnCO3 PbCO3 CuCO3 MnCO3 NiCO3 FeCO3
Brownish yellow Medium yellow Yellowish grey Dark yellow Golden yellow Brownish grey
TABLE 3 Colour produced with combinations of metallic carbonates
Carbonate combination
Colour
CuCO3 + NiCO3 FeCO3 + CuCO3 ZnCO3 + CuCO3
Black Brownish black Greenish yellow
3.2. Influence o f immersion time T h e i m m e r s i o n t i m e has a great i n f l u e n c e o n t h e c o l o u r d e v e l o p e d . Within 5 m i n t h e c o a t i n g s s t a r t t o f o r m and are usually light in s h a d e c o m pared with the darker colours obtained by prolonging the t r e a t m e n t time. T a b l e 4 s h o w s t h e c o l o u r o b t a i n e d f o r various i m m e r s i o n t i m e s f o r a solut i o n c o n t a i n i n g 20 g o f (NH4)2CO3 1-1, 2 - 5 m l o f t r i e t h a n o l a m i n e p e r litre a n d 0.2 g o f NiCO3 1-1 at 85 °C. A p r o l o n g e d t r e a t m e n t impairs the q u a l i t y o f t h e coating. 3.3. Influence o f pH A m m o n i a o r acetic acid was u s e d t o adjust t h e p H . S t r o n g alkalis m u s t n e v e r be u s e d as t h e y dissolve a l u m i n i u m as well as t h e coating. T h e p H was varied b e t w e e n 6 a n d 11. H i g h e r p H values ( p H > 10) lead t o a dull
18 TABLE 4 Influence of immersion time on the colour obtained using 0.2 g NiCO31-1
Immersion time (min)
Colour
3 5 10 15 20 45
Interference colours Light yellow Golden yellow Dark golden yellow Dark yellow Dark yellow (matt finish)
streaky finish, whereas low pH values (pH < 7) lead to interference colours. Hence pH 8 - 10 is f o u n d to be the optimum. Because of evaporation losses at the operating te m per a t ur e (above 80 °C) a continuous addition o f ammonia is required to maintain the pH.
3.4. Influence o f temperature The colouring t e m p e r a t u r e was varied f rom 70 °C t o the boiling poi nt o f the solution. An increase in the solution t em perat ure accelerates bot h the rate o f f o r m a t i o n of the film and the rate of attack on the metal surface. This can result in a change in the colour of the coating. The t e m p e r a t u r e o f the solution should be maintained between 80 and 90 °C to ensure consistent results. A lower t e m p e r a t u r e of the bath (less than 70 °C) leads to interference colours.
3.5. Influence o f solution agitation Agitation o f the colouring solution accelerates the reaction and provides a mo r e uniform film formation. Uniform coatings were p r o d u c e d in this s tu d y with air agitation, whereas a non-agitated solution gave a streaky finish.
3.6. Influence o f surface preparation The appearance o f the coating p r o d u c e d depends greatly on the initial surface co n d itio n of the metal being treated. The coloured film accurately reproduces the surface c ondi t i on of the base metal. Thus brilliant and attractive shades are p r o d u c e d on polished aluminium (chemically polished or electropolished), whereas etched and m a t t finishes produce dull shades.
3.7. Influence o f top coat The coloured coatings are very thin ( of the order of 1 - 4 tzm) and have less abrasion resistance than anodic coatings. T hey should n o t be used w i t h ou t an overcoating of transparent lacquer when resistance to wear and abrasion is required. The coating possesses satisfactory protective properties when it is used in c om bi nat i on with a top lacquer coating.
19 3.8. I n f l u e n c e o f a l u m i n i u m alloy
T h e c o l o u r is a f f e c t e d b y t h e p r e s e n c e o f alloying e l e m e n t s in the aluminium. G o o d colours are p r o d u c e d o n a l u m i n i u m alloys which do n o t c o n t a i n h e a v y metals and silicon. On c o m m e r c i a l l y p u r e a l u m i n i u m and 2S alloy t h e c o l o u r is u n i f o r m and attractive. 3.9. E c o n o m y
In c o m p a r i s o n with anodic films, c h e m i c a l l y c o l o u r e d coatings have advantages o f e c o n o m y , speed o f f o r m a t i o n and relative simplicity o f equipm e n t r e q u i r e d f o r t h e i r p r o d u c t i o n . T h e y are very suitable for p r o d u c i n g cheap i m i t a t i o n items such as bangles, earrings, bracelets, chains and buckles. When small parts are t o be c o l o u r e d b y this t e c h n i q u e , t h e y are k e p t in a plating barrel which is r o t a t e d gently as in plating.
4. C o n c l u s i o n A l u m i n i u m can be c h e m i c a l l y c o l o u r e d t o various shades o f yellow, b r o w n , grey and black using an alkaline a m m o n i a c a l s o l u t i o n c o n t a i n i n g metallic c a r b o n a t e s and t r i e t h a n o l a m i n e . T h e o p t i m u m c o n d i t i o n s are as follows: (NH4)2CO3, 20 g 1-1; metallic c a r b o n a t e , 0.2 g l - l ; t r i e t h a n o l a m i n e , 2 - 5 ml l -~ ; p H 8 - 10; t e m p e r a t u r e , 80 - 90 °C; i m m e r s i o n time, 5 - 20 min.
Acknowledgment T h e a u t h o r s ' t h a n k s are due t o Dr. K. S. Rajagopalan, Central Electroc h e m i c a l Research Institute, Karaikudi, for his kind permission t o publish this paper.
References 1 S. Wernick and R. Pinner, The Surface Treatment and Finishing of Aluminium and Its Alloys, Vol. I, Draper, Teddington, Middx., 1972. 2 W. Lewis, The Practical Anodising of Aluminium, McDonald and Evans, London, 1960. 3 A. W. Brace, The Technology of Anodising of Aluminium, Draper, Teddington, Middx., 1968. 4 G. H. Kissin, The Finishing of Aluminium, Reinhold, London, 1963. 5 T. Biestak and J. Weber, Electrolytic and Chemical Conversion Coatings, Warzawa Publications, Warsaw, 1980. 6 R. M. Burns and W. W. Bradley, Protective Coatings for Metals, Reinhold, London, 3rd edn., 1967. 7 S. Spring and K. Woods, Met. Finish., 79 (6) (1981) 49. 8 L. F. Spencer, Met. Finish., 58 (1) (1960) 58. 9 D. B. Freeman and A. M. Triggle, Trans. Inst. Met. Finish., 37 (1960) 56. 10 W. E. Pocock, Met. Finish., 52 (1.2) (1954) 48.
20 11 H. Silman, G. Isserlis and A. F. Averill, Protective and Decorative Coatings for Metals, Finishing Publications, Teddington, Middx., 1978. 12 Br. Patent 1,156,356-7, 1967. 13 N. V. Shanmugam, K. N. Srinivasan, S. John, M. Selvam and B. A. Shenoi, Proc. Natl. Solar Energy Cony., Allied Publishers, New Delhi, 1982, p. 7.021. 14 N. A. Lange and G. M. Forker, Handbook o f Chemistry, McGraw-Hill, New York, 1967.