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THE JOURNAL,OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
ture of tin plate, i t could be replaced by hydrogenated cottonseed oil with no loss in operating efficiency. With the industry adjusted t o the use of palm oil, the higher cost of hardened oils probably balances t h e advantage t o be obtained by their use, leaving little if any margin t o pay for the privilege of using the hardened oils. Heating experiments indicate t h a t a hydrogenated fish oil might be obtained which would be satisfactory for use in tin pots, though hardened t o a less degree than is necessary for the best results with cottonseed oil. LEAD COATED IRON’, By Charles Baskerville COLLEGE OF THE CITYO F NEWY O R K , NEW YORK,N. Y.
Protective coatings for the prolongatio‘n of t h e life of iron and steel fall i n t o three general classes, well described in a report from the Bureau of Standards (1919)as follows: I-Metallic coatings. a-Coatings in which the iron to be protected is itself converted a t the surface into some less corrodible compound. 3-Organic coatings (varnishes, paints, enamels, etc.). The present paper has t o do with the first of t h e three classes and is especially concerned with the use of lead and lead-antimony alloy as protective agents. If the iron be completely covered by another metal its life depends upon the ability of the covering metal t o withstand the corrosive action of air and water t o which i t may be exposed. This is materially affected by the presence of various chemical fumes and gases such as sulfur dioxide, nitrogen oxides, chlorine, sulfuric acid, alkali-mists, etc. Mechanical strains, vibrations and the rough handling which usually obtains during packing, transportation, installation, etc., may bring about ruptures and scaling in the protective coating and thus expose t h e iron or steel which may have been originally perfectly covered. The best manufacturing practice seeks a perfect coating initially but experience has shown the necessity for subsequent precautions because, where two metals, which always have a potential difference, are in juxtaposition in the presence of electrolytic water (acidulated, alkaline, or saline) electrolysis sets up with corrosion of one of them. If the iron be the electropositive member of the couple, it corrodes-the corrosion being activated by the presence of the other metal. Aluminum and zinc are electropositive t o iron, and therefore are theoretically the best practical metallic protective coatings for iron, where t h e coating is broken, as they bear the burden of corrosion. Zinc forms several alloys with iron which are also electropositive t o iron in a lesser degree. Tin, lead, copper, antimony and most of their alloys are electronegative, and hence facilitate the corrosion of the iron if i t is incompletely covered or exposed b y abrasion or other rough treatment. Practice has shown the importance of painting sheet tin and galvanized iron t o fill in the broken coating. 1 Presented at the 57th Meeting of the American Chemical Society, Buffalo, N. Y., April 1 1 to 13, 1919. 8 Most of the experimental work described was done by M i . V. A. Belcher.
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Since lead is the cheapest of all the metals used for coating iron, and in addition gives the covered metal certain other desirable qualities, a commercial method of application has long been sought. It is hardly justifiable t o incorporate here a bibliography on t h e subject. The most successful of the numerous efforts in this direction is the well-known terne plate, an alloy of about 75 per cent lead and 2 5 per cent tin, but this involves the use of costly tin. Lead has been successfully sprayed on iron by a n atomizer (Schoop process) and the process is well suited for certain detailed protective work, but i t is far too expensive in expert labor and time for tonnage production. Modern interest in electronic conceptions and in the difference in properties of metallic allotropes caused us t o investigate the processes covered b y United States patents granted t o Goodson,l which, briefly, consisted in subjecting a column of molten lead of small cross section in motion t o the influence of an alternating current of low voltage and high current density for several hours, i t being asserted t h a t the lead thus became “activated,” the molecular distribution effecting such change in physical condition t h a t i t would attach itself so firmly t o iron t h a t when the lead solidified it would not shrink away from the iron and leave exposed surfaces. Evidence of the production of a n iron-lead alloy binder did not appear. The conditions detailed in the patents were carried out most conscientiously, with such additional advice and assistance as the inventor was able t o give. It is hardly necessary t o describe the apparatus used. Some promising results were obtained, but on checking up with metal not treated electrically the results were virtually duplicated. Since i t seemed t h a t t h e problem of successfully and economically coating iron and steel with lead was not unsolvable, investigations were prosecuted along other lines and resulted in the production of products satisfactory for some purposes. I n working out a process for using lead and leadantimony alloys as a protective coating on sheet iron and steel, the fundamental problem was t o find a binder which would tie iron and lead firmly together. After much experimentation a preliminary coating of antimony proved t o serve the purpose. Melted lead shrinks materially when i t solidifies. Antimony tends t o overcome this shrinkage, as is well known from the conduct and composition of type metal. Moreover, the alloy formed is harder than lead. With a preliminary coating of antimony followed by dipping in lead, the latter acquires an increasing percentage of antimony. This fact, together with the other observations, caused us t o use a lead-antimony dip (eutectic of 1 2 . 5 per cent antimony) in the production of “protected iron” on a technical scale. Bending, twisting and hammering tests proved t h a t the iron foundation would break before the coating. Photomicrographs clearly disclosed the antimony binder. About 800 shingles, 9 X 16 in., of mild steel, of 24 1 U, S.Patents 789,690; 789,215; 900,846; 900,847; 978,448; 1,061,066; other applications pending.
Feb., 1920
T H E J O U R N A L OF I N D U S T R I A L A N D E N G I N E E R I N G C H E M I S T R Y
and 2 8 gauge, were made. Some of these sheets were subjected t o aerated distilled water tests after having been pickled in sulfuric acid ( 6 : I ) , washed with water, thoroughly blackened by an antimony chloride solution, again washed in water, and while still wet dipped through zinc chloride flux into molten lead-antimony ( I 2 per cent), then into molten lead and finally quenched in oil. One series gave no iron rust indications during eleven days. I n another series, aerated t a p water tests brought out a few pinholes during the same period, but on t h e whole the condition of the samples was good. Allegheny iron, 26 gauge, showed some pinholes in both distilled and t a p water aerated during 5 days. Rust usually showed first wherever there were sharp angles. I n preliminary experiments many pinhole detection tests were made by the gelatinferricyanide method. Two exposure tests of these shingles were made by the Research Laboratory of the National Lead Company, in Brooklyn, and are being continued. One test was with the coated shingles, packed and shipped in t h e same way as tin plate is, from the Maurer, N. J., plant of the United Lead Company. The other test was made with a smaller lot prepared a t the same time, but painted on both sides. After an exposure t o the weather for over three years, with all the varying conditions of temperature, rain, and snow of t h a t period, both tests show IOO per cent efficiency, according t o the reports from the dkector, Mr. G. W. Thompson. Another test was made by Mr. V. A. Belcher, on a roof in Michigan. After a considerable time the shingles were reported t o be still in good condition. A test roof adjacent t o a chamber sulfuric acid plant at Maurer, N. J., did not give satisfactory results. These shingles are not t o be recommended, therefore, for use under the last-mentioned conditions, where considerable quantities of nitrogen oxides or sulfur dioxide may be in the air. The weight of t h e protective coating was determined by cutting from shingles, test pieces presenting approximately 3 sq. in. of covered surface. After accurate measurement each piece was weighed. The metal was stripped with acid, washed, dried and again weighed. Iron, which had gone into solution by stripping, was separated and weighed as Fe&. The total iron thus determined, subtracted from the original weight of a piece, gave the amount of protective coating for the surface exposed. The average coating was 3 1 9 . 2 mg. per sq. in., or approximately 92 g. of coating per shingle. This was subsequently checked by weighing ten shingles before and after pickling, and before and after coating. The average proved t o be 92 g. for 28 gauge and 9 3 . 5 g. for 24 gauge shingles, t h a t is t o say, 4 6 t o 4 7 g. (about 1 . 5 oz.) per sq. f t . Galvanized iron wire cloth was stripped with caustic soda. The wire was 23 gauge Trenton or 2 2 gauge B and S and corresponded t o 4 mesh cloth. The amount of zinc per sq. in. averaged 4 3 8 mg. (63 g. or about 2 oz. zinc per sq. f t . ) . The nodules of zinc where the wires crossed varied in size. With wire gauze, 2 0 gauge Trenton or 19 B and S, 4 mesh, 1 2 . 5 per cent
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lead-antimony alloy gave 2 1 2 mg. coating per sq. in. ( 3 0 g. or about I oz. per sq. f t . ) . When first dipped in 1 2 . 5 per cent lead-antimony and afterwards in lead, the coating proved t o be 2 7 0 mp. per sq. in. Cheap chicken wire and other netting may easily be coated with lead-antimony. Several hundred feet of iron wire were coated, using an improvised outfit for moving the wire through t h e process. Smoothly drawn annealed wire took a good coating. Barbed wire was not successfully coated, for the points and sharp edges of the barbs were not covered, and quickly showed rust in the corrosion tests. Extensive experiments were made in an ePort t o produce a satisfactory exterior coating on iron pipe t o be used for petroleum pipe lines. Three-foot lengths of 8-in. pipe, some pieces being thl;eaded a t both ends, couplings for the same, and smaller pieces of 2-in. and 3-in. pipe, were used. All were obtained from the Pittsburgh plant of t h e American Tube Company. Suitable pickling vats, washers, antimonizers, and lead baths were devised, and a special mechanism designed and installed for dipping the pipe while in motion, the revolutions being controlled a t will. Pipes were coated with lead and lead-antimony ( I 2 . 5 per cent). Corrosive experiments (aerated water tests, air exposure, burying in moist soil, etc.) showed a fairly good product, but not of sufficiently good grade t o warrant production. The irregular surface of t h e pipe produced in milling interfered with perfect pickling and the subsequent necessary rough handling with pipe wrenches, eta., abraded the softer metal, thus exposing the iron. At the request of the War Department, attempts were made t o apply the process t o produce a coating within shell t o hold certain poison gases. Owing t o the very irregular milled surface of the interior a perfect coating was not obtained. The unusual recent interest in “passive” iron raised the question whether iron rendered passive might take a better coating of lead-antimony alloy. Two general methods of making iron “passive” were used; namely, treatment with aqueous solution of oxidizing agents (permanganates and dichromates) and with acid solutions. The final conclusion was t h a t “passivity” did not improve the product. A process was worked out for forming a bin’der on cast iron upon which pure lead could subsequently be cast and molded, especially for filter presses and filter frames. This involved the removal of silica (sand adhering from the mold), which prevented a uniform deposit of antimony and lead. The coating is successfully accomplished by introducing an extra step of pickling in hydrofluoric acid prior t o treatment with the antimony salt solution. The coating thus produced is not sufficiently heavy and uniform t o admit of practical use, but forms an excellent binder for casting thereon lead or lead alloy of any desired thickness.’ 1 The process covering the treatment to secure the satisfactory binder is covered in application for U. S. Patent 847,323.
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T H E J O U R N A L OF I N D U S T R I A L A N D ENGINEERING C H E M I S T R Y
Sheet iron may be pressed into a variety of shapes without lubricants. If, however, the metal is subsequently t o be plated (nickel, copper, etc.), the shaped articles (caps for automobile hubs, etc.) require pickling. Iron in sheets lends itself t o pickling much more readily t h a n when already shaped and formed. Moreover, in pressing, the scale is often forced into the metal, making pickling an even more difficult and expensive process. Lead is soft and, even though the deposit be not devoid of pinholes, serves as a lubric a n t in pressing. Processes have been worked out in this laboratory for plating lead-coated iron with copper or nickel or both. SUGAR SIRUP FROM HOME-GROWN SUGAR BEETS 1 By John M. Ort and James R. Withrow LABORATORY OF INDUSTRIAL CHEMISTRY, OHIO STATEUNIVERSITY, cOLUiWBUS, OHIO
Sirup can be made from home-grown sugar beets for both culinary and table purposes. When made by published methods, this sirup is not always completely palatable and free from beet flavor. Experimental modifications of published processes gave a product leaving much t o be desired, though i t possessed no more objectionable flavor t h a n the average sorghum sirup. The complete elimination of green portions greatly advanced the production of a highly satisfactory sirup flavor. Interest in the subject among farmers is no new thing. Sugar beets are easily grown and a small plot would furnish the average rural household with ample Beet sugar making would probably be a universal farm industry in many parts of the country if there were any simple way of consistently eliminating objectionable beet flavor from the sirup, The beets contain from 1 2 t o 2 0 per cent sucrose, as high as 28 per cent having been observed. The yield of beet sugar per acre varies much, but averages from 0.8 t o 1 . 8 tons, while sugar cane is stated t o yield 4 t o 5 tons per acre. DELETERIOUS
SUGAR
BEET
FLAVORING
CON-
STITUENTS
I n the manufacture of sugar from beet juice most of the salts and deleterious material are left behind in the residual sirup or molasses, which is salable only as a cattle food or fertilizer. The removal of the impurities of beet sirup has been the subject of experiment ever since beet sugar manufacture began. To obtain good sugar a complicated treatment of liming, carbonation, etc., must be followed and considerable sugar is left in the molasses. The sugars are believed t o be held back b y the albumins, alkalies, soluble nonprotein nitrogenous matters, potash, and other salts. These probably form a large portion of the undesirable flavoring material, and it is the opinion of beet sugar men generally t h a t the sirup itself cannot be made suitable for human food. The Szcgar Beet, October 1906,p. 124, states: “The simple concentration of beet juice would yield a sirup of very objecI Presented before the Division of Industrial and Engineering Chemistry at the 57th Meeting of the American Chemical Society, Buffalo, N. Y . , April 7 to 1 1 , 1919.
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NO. 2
tionable flavor and odor. To overcome this difficulty numerous laboratory experiments have been made during t h e last 50 years. None of the processes proposed had t h e slightest practical value, for all the products obtained were absolutely worthless.” I n the same publication i t is stated t h a t Salisbury and Kramper suggested t h a t maple sirup be added t o give the desired flavor. C. 0. Townsend and H. C. Gore1 describe “ a simple process of making from sugar beets a palatable a n d nutritious table sirup with a pleasant flavor. A patent for the process was issued to the authors of this bulletin for the benefit of the public so t h a t any one is free t o use Tests by farmers as well as b y the Department have proved the process t o be practicable.” The authors give very complete directions in the Bulletin emphasizing especially the fallowing points: off the crowns of beets “at the point of I-Cutting the lowest leaf scar.” The reason assigned is “that the crown or upper part of the beet contains a large part of the salts taken from the soil in the process of growth. I t is desirable t o have the sirup as free as possible from these mineral salts which, if present in too large quantities, would render the sirup unpalatable.”3 2-Scrubbing free from dirt. 3-Skimming the boiling sirup. The authors state: “This operation removes the strong beet-like flavor and leaves a wholesome and palatable product.” 4-Slow boiling. 5-Avoid scorching. Although the method was simple, many reports of failure came ta Ohio farm journals. Improper topping of beets was supposed t o cause the difficulty. References t o the actual constituents causing taste and odor in the beet sirup are not plentiful. Classen4 states t h a t “the injurious nonsugars are defined as alkalies and soluble nonprotein nitrogenous matters.” Leach and Winton5 state t h a t “beet sugar molasses is unfit for food, due t o the presence of nitrogenous bodies which give i t a very unpleasant taste and smell.” Ware6 gives “albumin amides” as a n occurrence in the raw juice. Reference is also made t o the presence of “alkalies, ammonia, and organic bases.” Of the substances identified as constituents of sugar beets, the nitrogen derivatives are apparently not the cause of the undesirable flavor. Trimethylamine is sometimes suggested as the offensive constituent, but i t does not seem to exist in the sugar beet. The fact t h a t i t results as a destructive distillation product of the molasses does not prove t h a t other processes 1 “Sugar Beet Syrup,” U. S. Dept. of Agr., Farmers’ Bulletin 818 (1917), 2. 2 U. S. Patent 1,155,806 (Oct 5, 1915). 3 See also G . I ,. Spencer, Agricultural Yearbook, 1898, 313. 4 “Beet Sugar Manufacture,” Trans., Hall & Rolfe, 2nd Ed., p. 81, John Wiley & Sons, Inc., N. Y.,1910. 5 “Food Inspection and Analysis,” 3rd Ed., p. 570, John Wiley & Sons, Inc., N. Y. 1st Ed , 1 (1905), 136, e “Beet Sugar Manufacturing and Refining,” 346, J. Wiley & Sons, Inc , N Y .
