>"K Division of Agricultural Sciences UNIVERSITY OF CALIFORNIA The Lacquer Cement Method of Making Soil Monoliths Lloyd N. Brown CALIFORNIA AGRICULTURAL EXPERIMENT STATION . ' , S . ,•':■ . ' Soil monoliths set up in a display rack in a county of- fice of the Agricultural Ex- tension Service. The Author: Lloyd N. Brown is Extension Soils Specialist, Emeritus, Agricultural Extension Service, Berkeley. >< Equipment and Materials Needed: 4 / Making the Contents Monolith: 8 / Displaying the Monolith: 23 / Re- view of Literature on Soil Sampling: 24 / Litera- ture Cited: 26, JULY, 1963 In order that information in our publications may be more intelligible, it is sometimes neces- sary to use trade names of products and equipment rather than complicated descriptive or chemical identifications. In so doing, it is unavoidable in some cases that similar products which are on the market under other trade names may not be cited. No endorsement of named products is intended nor is criticism implied of similar products which are not mentioned. Lloyd N. Brown The Lacquer Cement Method of Making Soil Monoliths • Over 800 soil monoliths have been made by the lacquer cement method described in this bulletin. (The method is also known as the cellulose acetate method.) Making soil monoliths is an involved technical process. Four prime requisites are: technical knowledge, ingenuity, physical dexterity, and patience. • This method can be used on dry or nearly dry soils — not on wet soils. When the lacquer cement method is used, the soil in the finished monolith retains its dry color. These monoliths are very effective in classroom and Extension teaching, since it can be shown that the soil is made up of distinct horizons or layers, rather than being just an accumulation of dirt. • Displays of soil monoliths made by the method described here have been set up in over two-thirds of the county Extension offices, in the Divisions of Soils and Plant Nutrition on the Berkeley, Davis, and Riverside campuses, and in the Division of Irrigation and Soils on the Los Angeles campus. • Products used by the author were Lacquer Cement 3919 and Nitrate Dope and Lacquer Thinner 8518 (called "thinner"), which are produced by the Fuller Paint Company. The same or equivalent materials are made by other paint companies. The precise formulas are a trade secret. 1 Submitted for publication October 1, 1962. Spray gun connected to tire and ready for use. Note fittings at lower left which connect tire pump hose with spray gun hose. Equipment and Materials Needed Spray gun * ^ n making soil monoliths by the lacquer cement method, the spray gun is the most important piece of equipment. The type of gun used is known as the "nonbleeder" type, or "blowby type, syphon-feed, external mix." In this type of gun the spray material (explained in the next section) is held in a metal jar. The spray is syphoned or pulled up by the air which blows through the spray gun. As they leave the nozzle, the spray material and air are mixed. This type of spray gun requires that the air in the metal jar be at the same pressure as the outside air. To ac- complish this, a small hole has been bored through the fitting between the metal jar top and the gun barrel. It is important to see that this hole does not become clogged. If the spray gun is not functioning correctly, a stoppage in this small hole is very likely the trouble. End of tire pump hose shown at left, and end of spray gun hose at right. The fittings connect the two hoses. Hoses can be taken to a hardware store, where fittings necessary to make the connection can be purchased. Fittings may not necessarily be the same as shown here. Air to operate the spray gun is obtained from an extra automobile tire. The air in such a tire should be sufficient for about two soil monoliths. The spray gun operates best at between 15 and 50 pounds of air pressure. Higher pres- sures may blow away the soil instead of coating it, espe- cially if the soil is coarse textured. A 15-foot length of hose can be used to connect the spray gun to the extra tire or air supply. This is a complicated procedure. For normal painting use, there is a fitting on the end of the hose opposite the spray gun which connects to the air tank or compressor. For monolith use, two extra items should be purchased from an auto supply house and a hardware store: 1) a tire pump hose and 2) enough fittings so that one end will screw into the fitting on the spray gun hose and the other end will accommodate the open end of the tire pump hose. Assemble these to make a connection between the air supply in the tire and the spray After the spraying is finished, clean the gun by releasing Spray material Brush and brush jar Boards Wire the trigger until the flow of spray material ceases and only air comes out of the nozzle. This is the only cleaning neces- sary at the time. Occasionally the nozzle assembly should be taken apart and cleaned thoroughly. If material has spilled on the gun or the nozzle has not been blown out after use, the material that collects around the nozzle can be cleaned off with a pocket knife. • The solution used as the spray is lacquer cement diluted with thinner until it will pass freely through the spray gun. To get the proper consistency for the spray, dilute the lac- quer cement from a newly opened can with about two parts of thinner. Spray material is usually not made this way, but this method gives a practical consistency. To prepare the spray material, clean out the empty lac- quer cement cans with thinner. Also use the contents of the paint brush jar (described below) when it becomes too thick for use. Thin these materials to the proper consistency and strain them through cheesecloth or similar material into the 1-quart jar. Replenish the material in the metal jar of the spray gun from the quart jar. The spray material should be as thick as possible and yet not so thick that it will not pass freely through the spray gun. Thin spray material not only wastes thinner but requires more air from the limited supply in the spare tire to form an adequate coating on the monolith. • The paint brush used to apply the lacquer cement is an oval sash brush, 1% x 1 inch. The brush must be pro- tected after use so that the lacquer cement does not harden on it. A half-pint jar about half full of thinner makes a good container. With use, the thinner will become pro- gressively thicker, both from evaporation and from the accumulation of dissolved lacquer cement. When the mix- ture becomes too thick, rinse it out with thinner to make spray material, and begin the process over again. • The boards used for the monoliths are 5 feet long, 6% inches wide, and made from %-inch Douglas fir plywood, A-D or shop grade. These grades have blemishes on one side. The most economical way to purchase boards is in mul- tiples of fourteen. A standard-sized sheet of plywood is 4 feet wide and 10 feet long. Have the sheet cut into two 5- foot lengths, then have each of these cut into seven boards, each approximately 6% inches wide. A lumber yard or cabinet shop can usually supply and cut the boards. • When a soil monolith has been taken from the bank, it is trimmed to show the various layers or horizons. As a re- sult, certain layers may be several inches thick on the Container for small tools, spray gun, brush, and spray material. board. These thick layers may fall away from the board unless they are wired to it. Use 16-gauge copper wire from which the copper-colored lacquer coat has been burned off with a blow torch. Wire treated this way is softer, and the color will blend into the soil shades. • A pH kit can be used to test the soil reaction, and 10% pH test hit hydrochloric acid can be used to detect the presence of free and 10%) carbonates. These two readings, among others, are neces- hydrochloric acid sary to determine the soil series. • The following tools are recommended for making mono- Tools liths: Soil auger Shovel Mattocks — large and small Crowbar Mason's 6-inch trowel Car ivith tailgate Butcher knife — 8-inch blade Boy Scout axe Screwdriver — 10 inch Crescent wrench — 10 inch Stillson wrench — 10 inch Claw hammer Pliers Wire cutter Tape measure — 6 foot Gasoline torch • A car with a tailgate is not absolutely necessary, but it ii practical because it furnishes a working area. Making the Monolith Optimal weather conditions Select the site • Ideal weather for making soil monoliths is warm, sunny, and windy. The bank to be sampled should be exposed to the sun on a warm, windy day, so that the lacquer cement will, dry rapidly on the soil. It is seldom that all the optimum weather conditions are found at one site. • The most likely place to find a typical soil series profile is in the central part of a large area mapped as that series. Small areas may not be too representative of the soil series. On the other hand, a satisfactory soil series profile might be found in an area that is too small to be shown on the soil map. A typical soil profile may be found in a great number of places, but the most likely area is in a large body of the soil. Sites where profiles may be made with the least effort are on the banks of soil exposed along highways, gullies, streams, drainage ditches, and excavations for pipe lines, foundations, septic tanks, and trench silos, among other places. Sometimes additional bank must be exposed by digging. Occasionally it is necessary to dig a hole to expose a profile. Digging may be necessary in flat areas of recent soils where the work is not too difficult. Dig the hole about 3x4 feet and 4y 2 feet deep and so oriented that one of the 3-foot sides faces south. In this way, the sun will shine on the profile being taken. « A typical site for taking a monolith. The bank of the roadcut on the far side exposes a typical profile of the San Joaquin Soil Series. The immediate background shows a gently sloping to undulating topography, with hogwallow microrelief characteristic of this series. The light area in the bank about 30 inches below the surface indicates the hardpan layer. The San Joaquin Soil Series is a reddish-brown, friable, sandy loam, slightly acid or neutral, developed from granitic alluvium. It is found on old terraces located on the east margin of the San Joaquin and southern Sacramento valleys. • Smooth the bank into a plane about 8 inches wide and 4% feet long, with a slope of about 4 inches toward your feet. The slope will make it possible to drip or run the lacquer cement onto the bank, rather than painting it on. This will be explained in detail later. It is difficult to obtain a good surface in soil containing gravel or rocks. In this type of soil, it is usually necessary to prepare a bank 2 feet wide and then pick out the most desirable 8-inch strip in it for the monolith. If the soil has pronounced horizontal layers, the slope should be as steep as practical so that the distortions of the layers will be minimal in the finished monolith. Prepare the bank • Place a monolith board against the bank and, using a trowel or knife, mark the bank on both sides of the board. Then measure 48 inches down from the surface and make a horizontal line between the two vertical lines. This out- lines the area to be sprayed and painted. Outline the monolith area > Excavated area of bank shown in previous photo- graph. The bank has been smoothed into a plane which slopes about 4 inches toward the worker's feet. In this instance, duplicate monoliths were made. Not all monolith banks can be made as smooth as this one, particularly if the soil is gravelly or a dry blocky clay. In this case the moisture conditions were ideal for producing a smooth surface. Dry the bank • If the bank is not dry, the lacquer cement will turn white and will not adhere to the soil. To dry out wet soil, use a gasoline torch. If the bank is very wet, it may be wiser to let it dry for a day in order to save time with the gasoline torch. Drying with a gasoline torch may take as long as an hour. If roots protrude from the bank, burn them off so that the lacquer cement will make better contact with the soil. If the bank is dry but cold, warm it with the torch to speed up the drying of the lacquer cement. Blow off dust and loose soil with the spray gun • Before you spray the bank, blow off the dust and loose soil with the spray gun. Pull back the trigger just far enough so that air but not lacquer cement is pulled through the gun. When the loose material is blown off, the lacquer cement will make good contact with the soil. 10 Drying the bank with a gasoline torch. • Once the loose material is blown off, spray the thinned lacquer cement on the bank by pulling the trigger of the spray gun all the way back. This spray will form a film on the soil so that a coating of lacquer cement can later be dripped on without carrying off surface particles. On fine- textured massive soil, little or no spray is needed, but several applications may be necessary on sandy soil. On coarse sandy soil, apply the spray under an air pres- sure of 25 pounds or less. If the air pressure is too great, the soil material will be blown away. Although this soil texture is the most difficult to work with, once the tech- nique described here is mastered, the soil can be handled with relative ease. Do not use more than two-thirds of the contents of the metal jar or it may become difficult to suck the diluted lacquer cement up into the spray gun to make a spray. Spray the bank area outlined 11 Spraying the bank area out- lined. The surface soil to a depth of about 24 inches is a sandy loam. Next is about a 6-inch layer of dense blocky clay, which rests abruptly on the hardpan. The surface soil should be sprayed heavily in order to obtain a firm surface to which the lacquer cement can be applied. The clay and hardpan need little spraying. The sprayed bank should be left to dry for about 5 minutes before starting the brush application of lac- quer cement. Successful operation of the spray gun is a skill learned only by experience. Instructions merely serve as a guide. Apply lacquer cement • Before applying the lacquer cement by brush, allow the sprayed material to become firm. Dip the oval sash brush into the lacquer cement and hold it above the top end of the monolith, letting the lacquer cement run off the brush and down onto the monolith. Do not let the brush touch the soil if it is sandy or granular, since this will break the sprayed-on film. If you should accidentally break the film, it will probably be necessary to clean off the balance of the sprayed layer and make a fresh start. As the lacquer cement is applied, it collects in streams and runs down the monolith. This streaming can be com- pensated for by adding material to the highest bare spots. If the soil at the lower part of the monolith is firm enough, paint the lacquer cement directly on this portion of the monolith. This will avoid waste, since it will prevent 12 Applying the lacquer ment with a brush. the lacquer from running off the lower end of the mono- lith. However, if there is some doubt about the firmness of the lower soil, simply drip the lacquer on as described above. When the monolith is coated with lacquer cement, allow it to dry until the cement is firm and tough but not until it gets hard and brittle. This may take about one hour under favorable conditions, while it may take as long as two hours or more under unfavorable conditions. As the lacquer cement dries it shrinks, and on sandy soils it will curl up and drop off if it is left to dry too long. With these soils, begin taking the monolith as soon as the edges start to curl. On massive soils, curling is not a problem. • The area outlined on a bank and treated with lacquer cement is the size of a board, 6% inches wide by 4 feet long. Using a board as a straightedge, take a knife and outline an area 5^2 inches wide, approximately in the Outline the monolith within the lacquered area 13 Outlining and excavating the monolith. The untrimmed mono- lith on the left is the width of the monolith board — 6% inches wide; the one on the right has been trimmed to a width of bVi inches. It is difficult to obtain sharp sides on the monolith by trimming to the edge of the painted area; therefore, the monolith is reduced in width. In this soil, the surface layer was loosened with a mason's trowel, the clay layer with a shovel, and the hardpan with a crowbar. ^a ^H I^J . *+Jt Excavate along the sides of the monolith middle of the 6% inch strip. This will be the width of the finished monolith. This method of trimming will give sharp, straight edges and improve the appearance of the monolith. • One purpose in making monoliths is to show the physical differences of the soil in the various horizons. A recent coarse-textured soil results in a thin monolith something like sandpaper. On the other hand, a claypan or hardpan soil monolith should show the claypan and hardpan. An upland soil with the parent rock less than 4 feet below the surface should show a piece of such rock. The thickness of the soil profile is usually limited to about 4 inches. If profiles are made thicker than this, they become difficult to handle and preserve. Excavate along the sides of the monolith to a depth that will show the profile characteristics when the monolith is broken away. For sandy soils, little or no excavation is needed. For clay, rocky or hardpan soils, the excavation 14 Placing a board against the loosened monolith. along the sides should be at least 4 inches deep. The idea is to get enough soil in the monolith so that it can be trimmed to the desired thickness, as explained later. • In sandy soils, insert a mason's trowel at intervals along the sides and under the monolith to pry it loose. Massive clay soils and rocky soils can be broken loose by jabbing and prying with a shovel. Hardpan and solid rock can be loosened with a crowbar by jabbing until the monolith cracks loose. Use the crowbar as a wedge, rather than trying to pry with it. Hold the crowbar at an angle of about 30 degrees from a line per- pendicular to the monolith, and strike the bank gently along both sides of the monolith. Repeat, perhaps with a little more force, until the hardpan or rock breaks loose in one piece. Do not pry too hard with a crowbar until the monolith cracks loose or the hardpan or rock may break into several Pry the monolith loose from the bank 15 Pulling the monolith away from the bank. pieces. The monolith is then not only difficult to handle, but is not a natural monolith. Jabbing and prying loose is probably the most important step in getting a natural looking monolith. In soils made up of varying layers, different tools may be needed for jabbing and prying on each layer. Proceed deliberately and cautiously. When the monolith is being cracked loose from the bank, parts of it may be completely loosened and will tend to slump or fall away. To prevent this, support the soil with a board, as shown in the photograph on page 15. It may be necessary to hold the monolith board in place to prevent slumping. If the monolith contains roots of shrubs or trees, sever these after the monolith is loosened from the bank. Pull the monolith away from the bank 16 • Place a board against the loosened monolith. It will re- quire two persons to pull the monolith away from the bank. One person should kneel down and place one hand ^S*$ ^ ne monolith detached *^?i* * *Wf* from tne bank. a few inches above the bottom of the monolith, and the other hand about 18 inches above this and on the opposite side. The fingers should be inserted in the crack where the monolith has broken loose, and the thumbs should be on the outer side of the board. The second person should place one hand near the top of the monolith and the other hand about 18 inches below this. The hands of both men should alternate; that is, the right hands should both be in the lower positions and the left hands in the upper positions, or vice versa. By rotating the board and monolith slightly, first to one side then to the other, a crack is opened into which each man can in- sert his fingers. Both men should squeeze the monolith to the board at the same time, and pull back the board and soil until the monolith board rests on the shoulder of the kneeling person. This man can then stand up and carry the monolith on his shoulder over to the lowered tailgate of the car, where the final work on the monolith can be completed. 17 Trimming the monolith. Trim the * Remove the excess soil so that the various horizons and monolith tne so ^ structure are exposed. Also chip away tool marks. This should be done carefully so that the final sample looks natural. Outline the monolith on the board • Slide the top of the soil monolith down 12 inches from the top of the board and center it from both sides. Then cut off the lower end of the monolith about 1 inch shorter than the board. With this 1-inch allowance at the bottom, the finished monolith can be mounted in the slot on a display rack. When the monolith is positioned on the board, outline it lightly with pencil. Do not make the marks too heavy or they will show on the finished monolith. Transfer the monolith to a spare hoard 18 • Thin monoliths can be transferred quite easily to a spare board. Thick, heavy monoliths, however, must be trans- ferred from one board to another by two persons. Place a Positioning and outlining the monolith. The monolith is 12 inches down from the top, cen- tered from each side, and trimmed 1 inch shorter than the board at the bot- tom. spare board on the tailgate on the inner side of the mono- lith board. Both men can then pick up the monolith board — the left hand of one should be under one end of the board and the right hand of the other under the opposite end. The monolith board should be held about three quarters of the way over the spare board and tilted until the monolith starts to slide off and one edge of it rests on the spare board. The monolith board can then gently be pulled away, leaving the monolith resting on the spare board. Each man can use his free hand to guide and coax the monolith into its new position during the transfer. Wipe the dirt and dust off the monolith board, and paint a heavy coat of lacquer cement inside the pencil- marked area. (Note photographs on pages 20 and 21.) • Reverse the process outlined under "Transfer the mono- lith to a spare board." Hold the spare board slightly above the monolith board so that the lacquer cement will not be Transfer the monolith 19 Transferring the monolith to a spare board. wiped off. During the transfer, do not be concerned about the exact positioning of the monolith. It can be slid into its exact position after the transfer. Thin monoliths or thin areas of monoliths may arch up from the monolith board. Hold these areas down with your hands until the lacquer cement dries enough to hold them down — perhaps 2 or 3 minutes. If any of the lacquer cement squeezes out from under the monolith, scrape it off before it dries. If this excess is not removed it will keep the varnish from penetrating the wood, leaving these areas a different color. Wire heavy monoliths to the board 20 • It may be necessary to wire heavy monoliths to the board to prevent the soil from breaking off. Wires can be seen on the Olcutt, Tierra, and Cowell monoliths in the photo- graph on page 2. Sixteen-gauge copper wire is suitable for this use. Be- fore using the wire, burn off the thin protective coating Painting the penciled area with a heavy coat of lac- quer cement. with a gasoline torch. This will remove the copper color, making the wire more nearly the color of the soil, and also anneal or soften the wire. Hardpan layers and bedrock can be wired on when the monolith is first made. Clay layers and fine-textured soils, if wet, must be left to dry until they are firm enough so that the wire will not cut into them. • In spite of all precautions, occasionally a monolith will break — usually in the transfer from the bank to the board. If this happens, transfer the sections to the board piece by piece. Then trim and outline the monolith as usual, and transfer the monolith piece by piece to the spare board and back to the lacquered board. If the joints show, pour on a little lacquer cement and cover the areas with suitable soil material. With a little patience, you can produce a monolith which cannot be distinguished from one which has not been broken. Broken soil monoliths 21 Transferring the monolith to the painted area. Apply soil to bare spots • When the soil monolith is glued to the board, there may be some spots which are bare — that is, there may be spots which have no soil on the lacquer-cement backing because the cement has bridged over low spots. These areas can be made to look natural by dripping on lacquer cement and then sprinkling on soil taken from the bank at the same level as the bare spot. With a little practice, these bare spots can be repaired so that they cannot be detected. Place the * A transporting rack, such as that shown on page 23, can monolith in the De ma de to hold the monoliths. With this piece of equip- transporting rack ment 5 monoliths can safely be transported from the field, and, later, they can be carried to and from meetings. 22 Loading the monolith into the transporting rack. Displaying the Monolith • The display rack shown on page 2 has been designed to hold six monoliths. Each monolith can be identified by a legend and a picture. The legend contains such informa- tion on soils as texture, use, native cover, drainage, relief, parent material, profile group, and rating. The accompany- ing picture usually shows the land use — such as crops, range, woodland, or forest. Dust which collects on the monolith should be blown off from time to time with compressed air because it distorts the original color. • When monoliths are moved often — such as back and forth to meetings — they progressively deteriorate. For this reason, most monoliths must be replaced from time to time. Deterioration of monoliths 23 Review of Literature on Soil Sampling • About 1870 two eminent scientists, V. V. Dokuchaev in Russia and Eugene V. Hilgard in the Lnited States, came to the conclusion that soil was not a geologic deposit, but rather a unique series of layers or horizons from the sur- face down to the geologic deposit (1) , (2) .* As the study of soils progressed, it became evident that some system of collecting soil samples for further study and display was needed. Over the last 70 years, many methods have been used. At the 1893 Columbian Exposition in Chicago, the Mary- land College had a collection of soils from that state dis- played in glass jars (3) . In 1899 Whitney reported an ac- cumulation "of 2,000 soil samples in two-quart preserve jars and the second 2,000 in pint preserve jars" (4). Hil- gard is mentioned as having contributed California soils to this collection. In 1904, Loughridge reported a method of taking sam- ples for display in which "each foot [was] taken separately, the whole to be shown in vertical columns of bottles" (5). The 1912 Report of the Department of Agriculture stated, * The numbers in parentheses refer to references in ''Literature Cited," page 26. 24 "Several years ago the Bureau of Soils put together a set of soil samples. . . . Soils were distributed to the agricultural colleges for use in instruction" (6) . From 1897 to 1940, soil profiles were taken in wooden boxes about 4 feet long, 6 inches wide, and 4 inches deep. To make these profiles, a soil bank was exposed, a core of soil was prepared, the wooden box was fitted over the core, and the soil was broken off so as to fill the box. The earliest record found of making soil monoliths by this method is an excellent report by the Tennessee Agricultural Experiment Station published in 1897 (7). Many workers have since used this or very similar methods (8), (9), (10). The main objection to this method was that the units were bulky and heavy, and they deteriorated rapidly if they were moved about. In looking for a method to make less- bulky soil monoliths, several workers experimented with various types of adhesives to produce soil monoliths similar to those now obtained with lacquer cement (11), (12). (13, (14), (15). In the late 1930's, the lacquer cement method of making soil monoliths was developed independently by workers in different countries (16), (17), (18). This is the method described in detail in this bulletin. During the last twenty years the process of making soil monoliths has been refined, and several new methods have been developed for making soil displays for use in teaching, research and Extension (19). 25 Literature Cited (1) Baldwin, Mark, Charles E. Kellogg, and James Thorp 1938. Soil classification, p. 979-1,001. In U. S. Department of Agriculture yearbook of agricul- ture. 1,232 p. (2) Kellogg, Charles E. 1957. We seek, we learn, p. 1-11. In U. S. Department of Agriculture yearbook of agriculture. 784 p. (3) Columbian Exposition 1893. History of the world's Columbian exposition. Chicago. 4 v. (See especially Vol. 3, p. 52.) (4) Whitney, Milton 1899. Catalogue of the first four thousand samples in the soil collection of the Division of Soils. U. S. Dept. Agr. Div. Soils Bull. 16:1-145. (5) LOUGHRIDGE, R. H. 1904. Report of Division of Soils. Twenty-second report of the Agricultural Experiment Station of the University of California. Univ. California Agr. Expt. Sta. 228 p. (See especially p. 28-34.) (6) U. S. Department of Agriculture 1912. Educational sets of soil samples, p. 611. Annual reports of Department of Agriculture. U. S. Dept. Agr., Washington, D.C. (7) Vanderford, Charles F. 1897. The soils of Tennessee. Univ. Tennessee Agr. Expt. Sta. Bull. 10(3) : 1-139. (8) MlKLASZEWSKI, S. 1928. La prise des monoliths de sols. L'Exp. Agr. 3 :8-15. (9) Polynov, B. B., V. A. Blatz, and Z. J. Schokalsky 1929. Instructions for collecting soil monoliths and soil samples for laboratory investigation. Publication of Academy of Science of the USSR, Dokuchaier Institute of Soil Science. Leningrad. 18 p. (10) Spilsbury, R. H. 1940. A method of taking soil monoliths. Sci. Agr. 20(5) :297-300. (11) Bushnell, T. M. 1930. The Purdue technique for taking and mounting monolithic soil profile samples. Soil Sci. 29:395-397. (12) Prescott, J. A. 1930. A convenient method for the reproduction of soil profiles. Imp. Bur. Soil Sci. Tech. Commun. 7:8. (13) Morwick, F. F. 1932. Preservation of soil monoliths. Sci. Agr. 13(1) :l-6. (14) Harper, Horace J. 1932. A study of methods for the preparation of permanent soil profiles. Oklahoma Agr Expt Sta. Bull. 201. 15 p. (15) Lyford, W. H., Jr. 1939. Preservation of soil profiles by Voight's method. Soil Sci. Soc. Amer. 4:355-357. (16) Gracanin, M., and D. Janekovic 1940. The Zagreb film-lacquer method of taking pedagological soil profile samples. Soil Res. 7:22-32. (17) Storie, R. Earl 1941. Collection of soil monoliths by the cellulose-acetate method (used in California). Univ. California, Berkeley. Mimeo. 26 (18) Voight, Ehrhard 1936. Ein neues Verfahren zur Konservierung von Bodenprofilen. Ztschr. f. Planzenernahr., Dungung. u. Bodenk. 34:111. (19) Brown, Lloyd N., and R. Earl Storie 1957. How to collect and use soil monoliths in teaching, research, and Extension. Proceedings of the 9th Pacific Science Congress, Chulalongkorn University, Bangkok, Thailand, Nov. 18 to Dec. 9, 1957. (Multilithed copies available from Department of Soils and Plant Nutrition, Univ. of California, Berkeley.) 7im-7,'63 (1)7407) A.M.