Ansco Color Negative, type 843
1952 – 1956
Subtractive 3 color: Chromogenic monopack, daylight, 16 ASA
(Ansco Division of General Aniline and Film Corporation)
Original Technical Papers and Primary Sources
Duerr, Herman H. (1952): The Ansco Color Negative-Positive Process. In: Journal of the Society of Motion Picture Engineers, 58,6, pp. 465-479.
Ray, Reid H. (1952): Use of Ansco Color Film in Commercial Production. In: Journal of the Society of Motion Picture and Television Engineers, 59,11, pp. 406–409.
“The Ansco Color Negative-Positive Process
By Herman H. Duerr
The basic principles of the Ansco Color Negative-Positive Process are outlined. The paper deals with the essential characteristics of the color film materials used for the process and outlines the printing and processing steps required. Methods used to comply with the requirements of the motion picture industry in regard to color dupes for optical effects, protection masters, color negative master dupes, and color release printing are described. Requirements of sound and procedures to produce silver sound tracks are discussed.
In 1945,1 the Ansco Color Process for professional motion pictures was proposed. This process was based on the principle of reversible development of monopack materials. Several motion pictures have been produced using this process. It was realized, however, that a color process using the negative-positive approach would be preferable for a number of reasons. In the first place, such a process would follow more closely the long established black-and-white practices of the motion picture industry. More important, however, a color film process using the negative-positive cycle is superior due to the higher speed attainable and the considerably greater latitude in exposure, processing and printing.
The Color Negative-Positive process, however, presented many problems, particularly in regard to methods of providing dupes for optical effects, protection masters and other essential requirements for the production of feature motion pictures. These problems have now been satisfactorily solved and the Ansco Color Negative-Positive process will now replace the older process using film types 735 and 732, requiring reversible development.
The Ansco Color Negative-Positive Process, like the earlier reversal process, is a subtractive color process, using the principle of color-forming development.
There are three different 35mm color film materials involved in the process:
Color Negative Film Type 843,
Color Dupe Negative Film Type 846, and
Color Positive Release Printing Film Type 848.
In addition to these color film materials, a panchromatic fine grain dupe film, such as the Eastman Panchromatic Separation Film, Type 5216, can be used for making separations.
The three multilayer color film types used in the negative-positive cycle are similar in structure, although quite different in other characteristics.
Figure 1 shows the layer arrangement typical for the three color film types used in the process. The conventional layer arrangement, with a red-sensitive bottom layer, a green-sensitive middle layer and a blue-sensitive top layer, is being used. This figure illustrates the Color Negative Film Type 843 before processing.
As has been described before,2 the three colors, cyan, magenta and yellow, in the Ansco Color Process are formed in their respective layers during one color developing step. It is one of the important characteristics of the Ansco Color Process that the nondiffusing, colorless color couplers are dissolved and uniformly distributed in the gelatin of the photographic emulsion layers and completely surround the individual light-sensitive silver halide grains. After exposure and during the color development, the developing agent becomes partially oxidized by reducing exposed silver halide grains to metallic silver. The partially oxidized developing agent reacts with the color couplers to form dye deposits. The oxidized color developing agent is soluble and can move freely in the layer. In order to produce a dye image in closest proximity with the originally exposed grain, it is, therefore, important that the color coupler surround the silver halide grain so that the coupling reaction can take place truly in situ with the silver halide grain. This characteristic of the Ansco Color Process is important and is responsible for the good image sharpness and definition.
A schematic illustration of the mechanism of dye image formation taking place in closest proximity to the exposed silver halide grains is shown in Fig. 2. The Ansco color couplers are immobilized in the emulsion layers by means of the specific chemical configuration of the color coupler molecules. To provide the characteristics of complete solubility and at the same time immobility and nondiffusing properties, the molecular structure has been arranged in such a way that a fatty acid molecule of large molecular size, through a short linkage, is chemically combined with the dye coupler molecule.3 The fatty acid molecule acts somewhat like an anchor, preventing the diffusion of the dye coupler and of the formed dye image within the layer, as well as from one layer to another.
A typical cyan color former of this configuration, with substitution referred to as “fat-tail,” is:
Ansco Color Negative Film, Type 843
Camera Requirements: The Ansco Color Negative Film, Type 843, can be exposed in conventional motion picture cameras as they are used for black-and-white photography. The only additional requirement is that, for maximum image definition, the lenses used should have good color correction.
Film Characteristics: The layer arrangement of the Color Negative Film, Type 843, before processing has been shown in Fig. 1. The layers after processing are shown in Fig. 3.
More recently the Type 843 film has been supplied on gray base instead of on clear base with the soluble antihalo back layer, and results regarding halation in motion picture practice have been quite satisfactory. The gray base does not interfere with the subsequent printing operations and the absence of a soluble back layer on the negative film has certain advantages in processing.
Sensitometry: The sensitometric curves of the three emulsion layers of the Color Negative Film, Type 843, are illustrated in Fig. 4. When developed to the proper contrast for direct printing on Color Positive, Type 848, or for the preparation of black-and-white tricolor separations, the gamma values for the three layers, measured as integral densities on the Macbeth-Ansco Color Densitometer Model 12, should be approximately as follows:
Blue-sensitive layer (yellow) 1.25
Green-sensitive layer (magenta) 1.00
Red-sensitive layer (cyan) 1.00
Spectral Sensitivity: The spectral sensitivity of the color negative film is shown in Fig. 5. The sensitivity peaks are at 450, 555 and 655 mμ, respectively. The film is balanced for light of daylight quality. For interior illumination the overall color balance should be approximately 5400 K. While the overall color balance is not critical, it is important that the different light sources on a set be balanced to the same spectral quality. The use of ultraviolet filters, such as Ansco UV-16 or Wratten Filter No. 1, for outdoor exposures and indoor exposures with arc lights is recommended.
Absorption Characteristics: The dye images recorded in the color negative film are in colors complementary to the colors of the original. The absorption characteristics of the dyes in the color negative film are illustrated in Fig. 6. The absorption maxima are: yellow, 440 mμ, magenta, 540 mμ and Cyan, 675 mμ.
Sensitivity and Resolving Power: The color negative film has an exposure index of 16. The resolving power, as measured by the method proposed by Sayce,4 is 44–48 lines/mm.
Ansco Color Duplicating Negative Film, Type 846
Film Characteristics: The Color Dupe Negative Film is similar to the Color Negative Film Type 843 in layer arrangement and color absorption characteristics. However, the color sensitivity is different from that of Type 843, but it is similar to that of the Color Positive Film Type 848, as shown in Fig. 9. In order to produce dupe negatives with fine grain and good resolution, the emulsions used for this film type are much slower. The exposure index is approximately 0.6 to 1.0. This film type is also on gray base of the density of the Negative Type 843 so that it can be readily interspliced with it. The resolving power is approximately 66 lines/mm. The sensitometric characteristics of the color dupe negative film are shown in Fig. 7.
The color dupe negative film is used to make color negative dupes from tricolor separation positives made from the color negative originals. Optical effects, fades, lap dissolves and other special effects can be introduced via these color dupe negatives. The various methods which can be used to obtain a color positive release print will be described later, below.
Ansco Color Positive Release Printing Film, Type 848
Film Characteristics: In emulsion layer arrangement the color positive release printing film is similar to the color negative film shown in Fig. 1. The color positive film can be exposed either directly from color negative originals, from color negative dupes or from black-and-white tricolor separation negatives. The sensitometric curves of the individual layers of the color positive film, plotted as integral densities, are shown in Fig. 8. In Fig. 9 the spectral sensitivity of the color positive printing film is illustrated. Good separation of the spectral sensitivity ranges with a minimum of overlaps is desirable for good color reproduction in the printing film.
Dye Absorption: The absorption characteristics of the dyes produced in the color positive film are different from those in the color negative and dupe negative film. The absorption maxima are: 440 mμ for the yellow layer, 540 mμ for the magenta layer, and 660 mμ for the cyan layer.
Film Speed and Resolving Power: The sensitivity of the color positive film is similar to black-and-white positive, approximately exposure index 1.5. The resolving power is 64–66 lines/mm.
All three color film types used in the Ansco Color Negative-Positive Process are on low-shrink, safety base.
Color Processing Procedures and Solutions
The three color film types used in the process require very similar processing steps and processing solutions. Only the Color Negative Film, Type 843, requires a different color developing solution. The color dupe negative film and the color positive release printing film can be developed in the same solutions throughout. The color developing time of these two types is different, as shown in Table I.
For uniform processing of all types of color film materials good control of the processing solutions at all times is very important. Basic control procedures which apply also to the handling of color negative-positive have been described by Bates and Runyan,5 while analytical procedures to control and maintain solution strength and uniformity have been presented by Brunner, Means and Zappert.6 General information in regard to color sensitometry may be found in the report of the SMPTE Color Sensitometry Subcommittee.7
Methods of Release Printing From Ansco Color Negatives
Methods of release printing from Ansco color negatives for the printing of Ansco color negative originals from different methods and certain variations thereof can be used to produce color positive release prints. These methods are summarized in Fig. 10.
Not all of these methods are equal in regard to color quality and cost. A more detailed discussion of the advantages and disadvantages of each of these methods is, therefore, in order.
Method A. Printing From Original Color Negatives Interspliced With Opticals on Color Dupe Negatives
This method, shown schematically in Fig. 11, comes closest to present black-and-white practices, at least as far as domestic releases are concerned. The color negative originals, which may represent 60–75% of the total footage, are interspliced with optical effects such as fades, lap dissolves, etc., made on Color Dupe Negative Film Type 846 Tricolor separations on Fine Grain Duplicating Pan Film are made from the full-length negative. They are used as protection masters. The optical effects are produced from sections of these black-and-white separations by printing on Color Dupe Negative Film Type 846. Method A, which involves a minimum of color printing by the use of color negative originals except for opticals and effect shots, leads to the best color quality. This method would be first choice for domestic releases.
Method B. Printing From Full-Length Master Dupe Negatives
In Method B, as shown in Fig. 12, release printing is done from master color dupe negatives. This method is recommended where the original color negatives cannot be made available for release printing. This is frequently the case for foreign releases. Tricolor separations on panchromatic duplicating film are made from the cut negative. Master color dupe negatives on Type 846 are made from all scenes, including opticals and special effects. Scene-to-scene conformance can be attempted in making the separations, as well as in printing the master dupe negatives, so that only minor color balance and light corrections have to be made during the release printing steps. The black-and-white separations also serve as protection masters.
As in Method A, the release printing is done by contact printing. In both methods conventional equipment, such as a Model D or Model E Bell & Howell or similar printers, can be used.
The filters required to correct for the overall and scene-to-scene color balance variations in printing are determined by the use of a color scene tester similar to the one described by F. P. Herrnfeld.8
On the Model D printer provisions should be available for the insertion of color balance filters.8 Following a suggestion made by the Metro-Goldwyn-Mayer Laboratory, a special material for colored traveling mattes for the Model E Bell & Howell printer has been made available. Film base dyed uniformly to produce various color filter combinations, coated with positive fine-grain emulsion, is exposed and processed by the Laboratory to produce a “variable width” type light control strip in the center of the film, as shown in Fig. 13.
Appropriate lengths of different colored matte negatives, representing the various light and color balance changes are spliced together. This colored traveling matte automatically corrects for scene-to-scene variations in color balance and density and the full speed of the printer can be utilized.
In the preparation of master color dupe negatives on Type 846 film, the following sensitometric conditions are representative:
Sensitometric test strips exposed with a light source approximately 3200 K, using an intensity scale sensitometer and measured on a Macbeth-Ansco Model 12 Color Densitometer.
*Black-and-white separations exposed on an Eastman Type IIb Sensitometer and measured on Western Electric RA-1100B Densitometer.
The method described next requires optical printing and is shown schematically in Fig. 14.
Method C. Release Printing From Black-and-White Separation Negatives
In Method C three-color separation positives on fine-grain Pan Duplicating Film are made from the color negative originals. These positives are printed on the same fine-grain duplicating film, this time developed to a lower gamma negative. Optical effects can be introduced during this printing step. The black-and-white three-separation negatives, including the optical effects, are used for release printing on Ansco Color Positive Film Type 848, preferably using multihead printers with good registration.
Method C avoids one color printing step as compared with Method B, and if very carefully controlled allows somewhat higher color brilliance. However, due to the fact that optical printers have to be used, the release printing is considerably slower and the method requires great accuracy in sensitometric and registration control, and for that reason is not generally recommended. A fourth method not requiring tricolor separations should also be mentioned. Although the color degradation produced by this printing Method D is definitely noticeable, results have been better than expected. This method is briefly outlined in Fig. 15.
Method D. Release Printing From Color Dupe Negatives via Color Dupe Positives
In Method D color positive prints on Color Dupe Film Type 846 are made from the original color negatives using sharp cutting filters. The filters recommended are Ansco UV-16 for all printing steps in addition to the three-color separation filters:
Wratten Filter No. 70;
Wratten 16 plus Wratten 61; and
Wratten 23 plus Wratten 48A.
These filters are also recommended for making the three-color separations in Methods A, B and C.
The Color Dupe Film Type 846 is developed as a color positive. Optical effects can be introduced at this step or the next one, in which the color positive dupe is again printed on Color Dupe Stock 846 with the same sharp cutting filters. This time the 846 Film is developed as a low-contrast color negative. The contrast of this dupe negative should be kept as closely as possible to the same contrast as the original color negative. This second generation color dupe negative can be used for release printing on a conventional contact printer. The Method D does not provide for black-and-white protection masters. For this reason this method is not recommended for feature pictures. A description of this method has been included because there may be occasions where this procedure may offer certain advantages; also, the fact that color rendition is still quite acceptable is a good indication of the flexibility of the Ansco Color Negative-Positive Process.
Sound on Ansco Color Release Printing Film Type 848
The reproduction of sound from multilayer color films using developed dye images has for some time presented a problem, especially in connection with the red sensitive photocell, which is today the standard for 35mm motion picture projection.9 In order to obtain a track which is efficient in absorption in the infrared region of the 868-type phototube, a method to produce a combination silver-plus-dye track having response characteristics similar to the conventional black-and-white silver tracks has been worked out.
Sound Track Development
As shown in Table I, the Color Positive Release Printing Film Type 848, after color development, fixing, bleaching and washing, is surface-dried by effective air squeegeeing. At this stage the sound track area carries a sound image consisting of a dye image from the original color developing step plus a silver ferrocyanide image, produced in the silver bleaching step. Using an applicator wheel or a pen-type applicator, a high viscosity rapid developer solution is applied to the sound track area only. This developer reduces the silver ferrocyanide-plus-dye sound image to a metallic silver + dye image. For the selective treatment of the sound track area, the following steps are important.
1. Effective air squeegeeing to remove surface moisture. The air squeegee should be close to the applicator station to prevent diffusion of moisture to the surface of the emulsion before developer solution is applied in the form of a bead covering the sound area only.
2. Application of high viscosity sound track developer, treating time approximately 30 sec.
3. To accelerate the development of silver track, infrared heat lamps at this stage are advantageous.
Cross-modulation and listening tests have indicated that variable-area sound negatives used for printing Color Positive 848 should have about the same densities as used for printing on black-and-white positive fine-grain film. Densities between 2.40 and 2.70, as read on a Western Electric RA-1100 Densitometer, are satisfactory. Sound printing with filtered light to confine the sound image to the two top layers is preferable. The top layer alone may be used for variable-area tracks.
The variable-area silver-plus-dye track of the edge-treated color positive film shows very good cancellation, fully equal to black-and-white tracks. The contribution of, and the effect of the dye image underlying the silver track image is insignificant in terms of the 868-type phototube response. A yellowish stain in the track area reduces the volume only by about 2 db.
Experience with variable-density recording is still somewhat limited, although satisfactory recordings have been made. In order to produce satisfactory gradation and resolution characteristics, the sound track should be confined to the two top layers, with equal contributions by both layers.
The development work reported in this paper represents the combined efforts of many people of the Ansco Research and Development Dept., as well as the Ansco technical staff in Hollywood. The valuable assistance of the Metro-Goldwyn-Mayer Laboratory, in particular J. M. Nickolaus, J. Arnold and D. Shearer, in cooperating on the various phases of the process and in supplying sample negatives and dupes for this presentation, is gratefully acknowledged.
1 H. H. Duerr and H. C. Harsh, “Ansco Color for professional motion pictures,” Jour. SMPE, 46: 357–367, May 1946.
2 F. Wing, “Ansco Color Film,” Ansconian, 3–11, Sept.-Oct. 1943. J. L. Forrest, “Machine processing of 16mm Ansco Color Film,” Jour. SMPE, 45: 313–326, Nov. 1945.
3 W. Schneider, A. Fröhlich and H. Schultze, “Die diffusionsfesten Farbbildner des Agfacolor Films,” Chemie, 57: 113–116 (DEZ.) 1944.
4 L. A. Sayce, Photographic Journal, 80: 454, 1940.
5 J. E. Bates and I. V. Runyan, “Processing control procedures for Ansco Color Film,” Jour. SMPE, 53: 3–24, July 1949.
6 A. H. Brunner, Jr., P. B. Means, Jr., and R. H. Zappert, “Analysis of developers and bleach for Ansco Color Film,” Jour. SMPE, 53: 25–35, July 1949.
7 A Report of the Color Sensitometry Subcommittee, “Principles of color sensitometry,” Jour. SMPTE, 54: 653–724, June 1950. (Reprinted as a booklet.)
8 F. P. Herrnfeld, “Printing equipment for Ansco Color Film,” Jour. SMPTE 54: 454–463, Apr. 1950.
9 R. Görisch and P. Görlich, “Reproduction of color film sound records,” Jour. SMPE, 43: 206–213, Sept. 1944. A. M. Glover and A. R. Moore, “Phototube for dye image sound track,” Jour. SMPE, 46: 379–386, May 1946. R. O. Drew and S. W. Johnson, “Preliminary sound recording tests with variable-area dye tracks,” Jour. SMPE, 46: 387–404, May 1946. A. B. Jennings, W. A. Stanton and J. P. Weiss, “Synthetic color-forming binders for photographic emulsions,” Jour. SMPTE, 55: 455–476, Nov. 1950. J. L. Forrest, “Metallic-salt track on Ansco 16mm Color Film,” Jour. SMPE, 53: 40–49, July 1949.
J. G. Frayne: Dr. Duerr mentioned a variable density track density of 0.85. This would be high for unmodulated density and would yield low level output. Do you propose using variable density tracks that are that dark?
H. H. Duerr: The density of 0.85 obtainable in the top layer alone referred to, is the maximum density. The unmodulated, unbiased operating density would, of course, be considerably lower and closely related to regular black-and-white practice. The best median density has to be established by further tests.
Dr. Frayne: Does this density figure 0.85, include the base?
Dr. Duerr: No. This is the maximum density obtainable in the top layer.
C. R. Daily: Do you intend to produce a tungsten-type film for use with a color temperature of approximately 3350 K?
Dr. Duerr: We are now producing only a film for daylight-type illumination, but expect to have a tungsten-type film available later on. Whether it will be balanced for 3350 K or a somewhat lower color temperature is not yet certain.
Frank E. Carlson: You referred to a color temperature of 5400 K for the negative film. Is the film balanced to the spectral emission of a black body radiator at that color temperature?
Dr. Duerr: Yes.
Richard H. Ranger: I have no question, but would like to compliment Dr. Duerr on his presentation, because the work shown here tonight represents great strides over the results demonstrated to a group of engineers in Wolfen shortly following the end of hostilities in Germany several years ago.
Presented on October 18, 1951, at the Society’s Convention at Hollywood, by Herman H. Duerr, Ansco Division of General Aniline & Film Corp., Binghamton, N.Y.”
(Duerr, Hermann H. (1952): The Ansco Color Negative-Positive Process. In: Journal of the Society of Motion Picture and Television Engineers, 58,6, pp. 465–479.)
“Use of Ansco Color Film in Commercial Production
By Reid H. Ray
The selection of a 35mm color film for the documentary or commercial motion picture producer is a problem of choosing an economical and, from a processing standpoint, a practical type of color film. Both color and black-and-white (35mm and/or 16mm) are sometimes required and a color film which adequately fills such requirements is described here.
Documentary and commercial motion picture producers frequently must supply to their sponsors 35mm and 16mm color prints, and for television either 35mm or 16mm black-and-white prints. A color film which might be used for multiple purposes would be an economical as well as a practical medium. Production time would be saved, as one crew, with a single camera setup, could produce a master 35mm color negative.
An acceptable 35mm negative-positive type of color film, which meets the requirements of such multiple duty, has been in use at our studio since April 1951. From the one original color negative, four types of release prints have been made (Fig. 1):
1. 35mm color prints,
2. 16mm color prints,
3. 35mm black-and-white prints, and
4. 16mm black-and-white prints.
The material used is “Ansco 35mm Color Camera Film, Type 843, Daylight Balance.” This film supersedes Ansco Type 735, a reversible color material which was discussed by the author in a previous paper published in the Journal.1 The characteristics of this color negative have been described in the Journal.2 This paper will describe the use of this color film in the commercial field. (A demonstration reel was shown at the conclusion of the paper.)
The speed of Type 843 Ansco Color Negative is rated at ASA 10 and an ultraviolet 16 filter is recommended for both interior and exterior photography. Arc illumination is used for interiors with Y-1 correction filters on high-intensity arcs. Both incident and reflected light readings are taken in various locations on the set to check evenness of illumination. To achieve a warmer tone in a background, 5-kw or 2-kw solar spots may be added to supplement the key- and backlighting from arcs.
For exterior photography with this type of color film, as in all color work, bright, clear sunlight is a prime requisite, and generally the rule of “the sun behind the camera” holds. However, very pleasing and excellent results have been achieved with sidelighting. Close-ups of characters completely backlighted by the sun, and frontlighted by booster lights or aluminum-foil reflectors show good latitude in the flesh tones.
Makeup used for interior photography for men is Max Factor No. 27 Pancake sparingly applied. For women, ordinary street makeup is recommended.
The exposed negative material which our studio produces is sent to the Houston Color Film Laboratories for developing and printing. A brief summary of these processes are3:
The negative material is developed in a color developer containing a non-toxic color developing agent called S-5. The negative is developed approximately 10 min, based on a gamma of 0.85 for the cyan layer of the monopack film. The film is then short-stopped, hardened, washed, bleached, washed, hypoed, washed and dried.
A scene test for prints from Ansco 843 Negative is similar to a cinex, the main difference being that each frame on the strip is made from a different filter balance, but each frame receives the same printing light intensity. This necessitates three tests being made on each scene, generally three printer points apart, in order to give a density range. The scene tests are developed in a positive developer similar to the negative developer, except that it does not have an accellerator in the solution.
The negative is timed from the scene tests. Separate filters are made up for scene-to-scene color correction and a modified Bell & Howell printer with an automatic filter changer handles the filter combinations (Fig. 3). This filter change is made in conjunction with the notch used for the printer light changes.
The positive stock used is Ansco Type 848 and is developed to a gamma of 2.30 on the red record, being the cyan layer.
The sound is printed from a black-and-white negative track. In order to obtain normal transmission through the optical system, since the positive stock is a monopack film, it is necessary to redevelop the track area with an application of a viscous solution containing a high-energy developer. With the track area so treated there is no difference in sound level between this type of color print and a normal black-and-white print.
When 16mm color prints are required they are made from a 35mm “soft” color print by optical reduction to a 16mm color duplicating stock. The sound is optically reduced from a 35mm re-recorded direct positive track.
A satisfactory 35mm black-and-white negative can be produced by using the original color negative to print a fine-grain master print on Eastman 5365 stock and by developing this to a gamma of 1.2. From this, a duplicate negative is made on Eastman 5203 or similar duplicating negative material. This duplicate negative is developed to a gamma of 0.66.
The commercial producer works without benefit of large budgets and he must turn out color motion pictures under conditions not always conducive to extensive production conveniences. The producer who wishes to operate with a minimum crew and regular black-and-white camera equipment, may use a multipurpose color film described in this paper to good advantage.
(The demonstration reel consisted of: first, a 35mm color print, followed by portions of the same footage in 35mm black-and-white print from the dupe negative.)
1 Reid H. Ray, “Use of 35mm Ansco Color Film for 16mm color release prints,” Jour. SMPE, 53: 143–148, Aug. 1949.
2 Herman H. Duerr, “The Ansco Color Negative-Positive Process for motion pictures,” Jour. SMPTE, 58: 465–479, June 1952.
3 Data furnished in 1951 by Robert F. Burns, Laboratory Manager, The Houston Color Film Laboratories, Inc, Burbank, Calif.
Presented on October 18, 1951, at the Society’s Convention at Hollywood, Calif., by Reid H. Ray, Reid H. Ray Film Industries, Inc., 2269 Ford Parkway, St. Paul 1, Minn.”
(Ray, Reid H. (1952): Use of Ansco Color Film in Commercial Production. In: Journal of the Society of Motion Picture and Television Engineers, 59,11, pp. 406–409.)