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remarkable increase in the quantity consumed in this country. This increase has been brought about by two outstanding developments in the application of these colors to textile fibers and fabrics-namely, (1) their application to silk, and ( 2 ) their application on piece goods by the “pad and jig” method. Both developments are of American origin. Today large quantities of silk and an enormous yardage of cotton piece goods are being dyed with these, the fastest of all dyes. In both cases the manufacturer has played a large part in the solution of the difficulties encountered by the textile people in these two modes of application. Especially is this true in the case of the application of these dyes by the “pad and jig” method, and the problem of producing these colors in a form whereby they could be successfully “padded” was one of the most difficult which the manufacturer was called upon to solve. It will therefore .be discussed briefly. These colors, being insoluble, are for the most part marketed in the paste form and it is in this form only that they can be applied to cotton by either the printing or the padding process. The presence of sand or grit in the paste is fatal to the cotton printer, for his copper printing rolls are easily scratched and each scratch means a corresponding impression in the fabric being printed. Likewise the presence of small particles of dry color, or in fact particles of color that are not of colloidal dimensions, is sufficient to render a paste useless for application by the padding process. Both d%culties have been overcome by the application of the principles of milling and of classification, so that today pastes are being produced in this country which are practically 100 per cent colloidal, which are sand-free, and which the printer and padder can use without fear of scratching his rolls or spotting his fabrics.
Vol. 18, No. 12
The American manufacturer has contributed in another direction to a solution of the difficulties which the textile people encounter in the application of these colors. It is a well-known fact that colors marketed in the paste form are not so easy to apply as are those which come in the powder form. Pastes dry out, they freeze, some settle out, and some ferment. As stated before, pastes are essential for the printing and padding of these colors. But for other methods of application, such as the dyeing of raw stock, powders are preferable to the pastes, provided the powders are available in a foqm whereby they are readily dispersible in water and easily vatted. Therefore, both American manufacturers have placed these colors on the market in the powder form, and it can be stated without fear of contradiction that American-made powders are superior in every respect to those made anywhere else in the world. ConcIusion
This is, very briefly, the story of the progress of the American vat color industry. There are many problems yet to be solved, many yields to be increased, many operating problems to be straightened out, many by-products to be utilized, and finally, as a result of the solution of these difficulties, many costs to be reduced. Furthermore, the American chemist will not be content to follow always in the footsteps of another, to duplicate and to improve upon that which has already been accomplished. He has already launched out into the realm of vat colors that are to be and has brought back into the realm of reality a number of .new vat colors, new, not in the sense of being simply homoIogs of heretofore known colors, but new in every sense of the word. He faces the future with confidence in his ability not only to imitate but also to create.
The Contribution of the Color Laboratory to Industry’ By H. T. Herrick COLORLABORATORY.BUREAUOF CHBHISTRY, WASHINGTON, D. C.
REVIOUS to the beginning of the World War two lines of work relating to dyes were being carried on by the Bureau of Chemistry of the Department of Agriculture. These lines included the work of the Contracts Laboratory on inks, pigments, and similar substances, and that on the certification of food colors. The outbreak of the war brought troubles and complications to all branches of chemical industry, but to none more than the manufacture of dyes. After a hard fight against adverse conditions, most of the dye firms that had made a start during the latter part of the nineteenth century had succumbed, and those which survived were engaged chiefly in the assembly of dyes from German intermediates, the supply of which promptly ceased, along with all dye importations, with the tightening of the British blockade of Germany. As the users of dyes began to feel the pinch, a great call for American-manufactured dyestuffs went up from every side, and the United States Government was importuned to do its share in the rush of dye investigation. Accordingly, Congress, on August 11, 1916, appropriated $50,000 “for investigation and experiment in the utilization for coloring purposes, of raw materials grown or produced in the United States.” As most of the chemists in the government service who
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1 Contribution No. 125 from the Color Laboratory, Bureau of Chemistry, Washington, D. C .
had had experience in color work were in the Bureau of Chemistry, the Color Laboratory, as it was called, was assigned to the Department of Agriculture, and work on the new project was started. A building was erected on the Arlington Farm, and plans were made for the laboratory investigation of colors and the substances entering into their composition, and also for the reproduction of laboratory processes on a technical scale. The building, 150 by 70 feet, contains six chemical and physical laboratories, besides offices and a library. All these rooms are on the second floor on one side of the building, with a fully equipped machine shop, storeroom, etc., beneath. Next to the machine shop and storeroom on the ground level is a technical floor, 150 by 40 feet, with a large assortment of chemical apparatus. There is also an auxiliary equipment in the way of a 10-ton crane, a &ton ice machine, and two 100-horsepower boilers. Power is likewise available in any voltage from 6600 volts down. There is a small MG set for producing direct current. Tools for all sorts of research, both in a laboratory and a technical way, are available. Because of the customary delay between making an appropriation and its expenditure, and also because of difficulties arising from war complications, the Color Laboratory personnel did not move to its new building until nearly four years after the first appropriation was made. I n the meantime much valuable work was accomplished under the di-
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INDUSTRIAL A N D ENGINEERING CHEMISTRY
rection of Dr. Gibbs, the first chemist in charge. After moving to Arlington, the work was continued under the supervision of Dr. Johns and Dr. Ambler, who obtained many *other important results. It was found that the wording of the original appropriation was much too confining for the work which was planned for the Color Laboratory. Accordingly, the 1921 appropriation was made to read as follows: “for investigation and experiment in the utilization, for coloring, medicinal and technical purposes, of raw materials grown or produced in the United &States.” Please note the broad language of this act. Accomplishments
The question of just what the Color Laboratory has accomplished has been asked many times. I n view of the fact that there have been one hundred and seventeen separate .contributions2 from this laboratory, only the high spots can be touched upon in a brief outline of its work. First of all, much work has been done on what may be termed “the tools of industry.” Prominent among these is a compilation of American dye patents, in abstract form, manuscript copies of which, for a number of years, were loaned by the Bureau of Chemistry to those interested in synthetic dyes. This was intended for publication, but funds were not available. It has now been brought up to date by the Bureau of the Census, and published upon a subscription basis by the Chemical Publishing Company. Other useful contributions under this head are methods of analysis of various organic compounds of interest to dye manufacturers, such as the naphthalenesulfonic acids, accurate determinations of the boiling points and vapor pressures of important intermediates, and work on the spectrophotometer as a means of identification of dyes. A second function of the laboratory has been to undertake the manufacture, from time to time, of various commercial products unobtainable in other ways. This has been done t o fill needs felt for these substances, when it was found that they were not being produced commercially, either through the inability of manufacturers to make then1 or because their production did not seem profitable. The outstanding .example of this work is the synthesis, in 1919 and 1920, of the photosensitizing dyes. Because of the great call for these colors, they were manufactured a t the Color Laboratory and furnished as needed. This work was discontinued, however, as soon as the dyes were made successfully elsewhere. Similarly, certain medicinal dyes for me in staining have been produced in the laboratory, and tested by co-operative arrangements. This is a service that the Color Laboratory will always be glad to render, provided the substances needed cannot be obtained from commercial sources. An important part of commercial research is the improvement of existing processes, with a view either to increasing 4 certain amount of this yields or to cutting down costs. . has been done on a laboratory scale a t the Color Laboratory. An example is the experimental work on the alkali fusion ,of resorcin and indigo. Up to the present time the most important phase of the work of the Color Laboratory has been the development of new and more efficient processes for the manufacture of important chemicals. The best known example of this type of work is, of course, the manufacture of phthalic anhydride from naphthalene by a catalytic oxidation. So much has been said about this process and so much is known about its importance to the dye industry that no more than a passing reference will be made to it here. Suffice it to say that
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A list of these papers is on file at the Color Laboratory, and copies may be obtained 011 application
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it stands as the leading contribution of the Color Laboratory to industry. Many chemical compounds, still listed as curiosities, would be of great value to the manufacturing world, if they could be profitably and cheaply produced. Research on such substances usually combines the discovery of a cheap and plentiful raw material with the development of a simple and economical method of using it. Furfural was a material that until very recently was known only as a product obtained by the distillation of pentoses and pentosans with hydrochloric acid. The Color Laboratory collaborated in working out a method by which it could be easily made from a number of agricultural wastes, and now it is a commercial product. Certain other compounds are now being studied, which it is hoped will be of great value in medical work, both as stains and for their therapeutic properties. Of a similar nature is the question of the utilization of byproducts in the production of useful substances. The Color Laboratory has produced colors from sulfite waste through p-cymene, has studied the possibility of lignin as a source of fine chemicals, and has recently produced alizarin from o-dichlorobenuene, a well-known industrial waste material. A statement of the accomplishments of the Color Laboratory would not be complete without some reference to the certification of food colors, which was started in 1907 and transferred to this Laboratory as a logical part of its work. Certification of food colors has grown to a point where 311,434 pounds of primary colors, 32,234 pounds of repacked straight dyes, and 301,040 pounds of mixtures were certified for use in foods during the year ending June 30, 1926, by more than forty manufacturers. Through the work of its chemists, the laboratory has endeavored to simplify and standardize the requirements for certified food colors and the methods of analysis. It stands ready a t all times to cooperate with dye manufacturers in anything which will promote the use of these colors by the public or make their production easier for the manufacturer. Future Policy
The Color Laboratory in the future will cooperate with industry and with the individual research worker in matters of procedure as well as in problems which come within the scope of its activities. For such cooperation, it is necessary that all the functions of the laboratory be fully understood and appreciated. It is not the function of the laboratory to compete in any sense with any branch of industry, nor is it its function to engage in work on any problem which may suitably be handled by commercial firms. Founded for “investigation and experiment in the utilization, for coloring, medicinal and technical purposes, of raw materials grown or produced in the United States,” it is not limited in its endeavors to the field of dyes. It may well be a link between agriculture and industry. For industry it may cut down waste and offer new raw materials. For agriculture it may find new outlets, not only for materials for which there is no real or appreciable demand, but also for those products of which the farmer now produces a surplus. At present the laboratory is studying the effects of the growth of various organisms on solutions of corn sugar, recently produced in a pure, cheap, and plentiful form. Results indicate that it may well be a source of valuable organic products. The Color Laboratory has a field that is all its own. Its work lies in handling those broad problems of research which may involve a number of industries, and are actually too large or too involved to be dealt with by any single concern. We solicit such problems from industry and in the prosecution of such research we ask its indulgence and assistance.
