has not been determined. To me it is not unthinkable that it may be made up of electrons in some state of motion or configuration which renders the resultant effect of the bunch as if they were charged positively. As an illustration of what I mean, take two negative charges or bunches of electrons and they repel each other. Take two parallel wires with the current in the same direction and they attract each other. Stationary charges repel and moving charges attract each other. Why can not the nucleus be made up of electrons the configuration and the state of which causes them to act as if they were positively charged?

I have thus in a more or less vague way attempted to explain some of the leading phenomena known about the atom. The Mayer figures are a great help in forming a concrete idea of the structure of an atom. To those interested in atomic structure the time used in setting up and in study of the Mayer experiment and the extension which I have proposed will be time well spent. It is a visible illustration of what may take place in an atom. Whether this model based upon Rutherford's atom will explain all other physical and chemical facts can be determined only by the results to be obtained in the future.

COAL TAR DYES.

BY HERMAN WRIGHT.

Within the last forty years modern chemistry has furnished the dyer with many beautiful colors prepared from material extracted from the refuse tar produced by the distillation of bituminous coal in the manufacture of illuminating gas. These colors are generally produced in aqueous solution and precipitated therefrom in a powdered or crystalline state by the addition of sodium chloride, common salt. When filtered out, washed and dried, they are ready for market. The coal tar colors are usually soluble in water. They possess a natural affinity for animal fibres, and the shades produced upon silk and wool are particularly brilliant. The coal tar dyes, however, are not classified according to their tinctorial power or the shades which they produce.

HISTORY.

Down to the middle of the nineteenth century, natural dyestuffs alone, with but few exceptions, were at the command of the dyer. But as early as the year 1834 the German chemist

Range noticed that one of the products obtained by distilling coal tar, namely, aniline, gave a bright blue coloration under the influence of bleaching powder. No useful coloring matter, however, was obtained from this product, and it was reserved for the English chemist, Sir W. H. Perkins, to prepare the first aniline dye, namely, the purple coloring matter, mauve, in 1856. The discovery of other brilliant aniline dyestuffs followed in rapid succession, and the dyer was, in the course of a few years, furnished with magenta, aniline blue, Hoffman's violet, iodine green, Bismarck brown, aniline black, etc. Investigation has shown that the products of distillation of coal tar are very numerous, and some of them are found to be specially suitable for the preparation of coloring matter. Such, for example, are benzine, napthaline, and anthracene, from each of which distinct series of coloring matters are derived. In 1869 the German chemists, Goaebe and Libermann, succeeded in preparing alizarin, the coloring matter of the madder root, from the coal tar product anthracene, a discovery which is the greatest of all in historical interest since it is the first instance of the artificial production of a vegetable dyestuff. Another notable discovery is that of artificial indigo by Baeger in 1878. Since 1856, indeed, an ever increasing number of chemists has been busily engaged in pursuing scientific investigation with the view of preparing new coloring matters of coal tar products, and of these, a few typical colors with the dates of their discovery may be mentioned: Cachon de Laval (1873); Eosin (1874); Alizarin Blue (1877); Xylidine Scarlet (1878); Biebrich Scarlet (1879); Congo Red (1884); Premuline Red (1887); Rhodamine (1887); Paranitraniline Red (1889); Alizarin Bordeaux (1890); Alizarin Green (1895). At the present time it may truly be said that the dyer is furnished with quite an embarrassing number of coal tar dyestuffs which are capable of producing every variety of color, possessing the most diverse properties. Many of the colors are fugitive but a considerable number are permanent and withstand various influences, so that the general result for some years has been the gradual displacement of the older natural dyestuffs by the newer coal tar colors.

As most of you know, the supply of dyestuffs has for the most part come from Germany for the last forty years. All users of dyestuffs know this and they also know that there have been various attempts made in this country to produce the coal tar dyes. At this time there is invested in the coal tar products

industry in Germany something like $400,000,000, probably more, employing some 50,000 people. Some of the factories pay dividends of 25 to 30 per cent after charging off a third of their profits to sinking funds for the erection of new plants and for other such purposes. This latter has been done for so long a period that most of the present property and plants do not appear on the books at all as assets, but have been built from the surplus profits. This is perhaps one reason why Germany has been so successful in the manufacture of dyestuffs. She has invested enormous sums of money, and as a result she manufactures these dyes on so large a scale that she can sell them at a very low price. Another reason for Germany's monopoly of the color-chemistry industry is the fact that there is a unity and solidarity of the various firms engaged in this industry, so that when one is menaced by any foreign competitor, they all act in unison. In America the field has been entered by many separated interests imperfectly acquainted with the complexity of the color problem, and a higher degree of unity is necessary in order to avoid overlapping and duplication of effort. Again, a reason why the United States has not been able to manufacture dyes is because Germans have discovered these dyes and have patented their manufacturing process, both in their own country and in the United States. The patents, however, are just now beginning to expire and the preeminence of German manufactured dyestuffs will soon be at an end.

The American people are just waking up to the fact that we are not doing for ourselves what we are able to do. It seems as though in the past there has been a tendency for the American people to let things of this nature be taken up and advanced by others. As long as the nations remained at peace with each other the United States succeeded in having their dyes produced in Germany without going to the trouble of manufacturing them themselves. Since the war, however, we have come to the realization that we must "help ourselves," as it were, and not depend upon other nations for the things which we can manufacture ourselves. One result of the war, according to an English authority, will be to put the United States on a footing of independence with regard to dye production, so that we will not only make all our own dyes, but export to foreign countries. The English writer in "Nature" (London, Dec. 16) warns his countrymen that when thus forced into new fields we may prove formidable competitors in the world's dye market. Before the war,

he tells his readers, American dye-factories employed not more than 400 workmen and produced annually 3,000 tons of dyes, prepared chiefly from intermediate coal tar products made in Germany. Since that time new plants have been built, and the output of American coal tar colors will soon be trebled, while the production of benzine and toluene has increased fivefold.

So you see according to this we have not been altogether idle and we can do a thing and do it well after it has started, but owing to the extreme manufacture of explosives it is difficult at present to secure large quantities of these hydrocarbons for color production. Nevertheless, twelve firms have embarked on the manufacture of aniline; the Edison Company is now turning out three tons of this intermediate product daily. A remarkable and novel development has arisen in this branch of color industry. The firms engaged in dyeing aniline black are setting up small aniline plants, costing $1,500 to $2,000 each, capable, under the supervision of one operator, of producing daily 100 pounds of aniline from benzine.

Now if these various firms owning the small plants, were to cooperate with each other and with any other companies which might develop later, the United States would be producing dyes on much the same principle as is Germany and, in time, on much the same scale. At present, however, the seven companies engaged on finished coal tar dyes are restricting drastically the number of colors produced and are concentrating on increased output. Although the existing equipment for natural dyes installed in six large American works has proved to be a national asset of great value, yet the total supply of dyes is still far short of customary requirements, and the American public is urged to meet the abnormal situation in a spirit of generous compromise. The existing shortage will soon disappear, inasmuch as the United States possesses all the enterprise, inventive talent, and technical ability requisite for the development of an American dye industry.

Perhaps some skeptical person will now come forward and inquire as to the use of these coal tar dyes. True, we dye clothes and most textile fabrics and we have come to regard dyestuffs and their colors as highly important factors in the production of fabrics, nevertheless, if we approach the subject from the utilitarian point of view, we find that dyestuffs do not add any real quality to the fabric; the color of the cloth may add much to its artistic appearance and give it beauty and charm that appeal to

our esthetic taste, but it cannot be said that color increases the durability, the strength, or the wearing qualities of the fabric. Outside of a certain influence upon heat and light rays, it is doubtful if color has any real influence upon the material value of the fabric. Our clothes would be of the same practical value to us if they were undyed as if they were dyed, they would wear just as well, in fact better, if they were never ornamented by the dyer's art.

dyestuffs to the textile infirst place to satisfy man's

Wherein, then, is the value of dustry. To answer this: in the natural love for ornamentation. Even the savage, wild as he is, decorates his scanty clothing with the varied, though limited, colors at his command. He is cultivating the love of beauty and any new color has a special attraction for him. It is this innate desire to decorate oneself and the things which one possesses and uses that has led to the widespread and almost universal application of dyestuffs in the manufacture of textile fabrics. In the second place, wholly aside from the artistic value is the desire to avoid, or rather to cover up, several undesirable features. When we wear our clothes for any length of time they become soiled. If the fabrics we use are white or undyed, their soiled condition is made apparent in a disagreeable manner. Consequently, we dye them in suitable colors, and though they still retain the same objectionable impurities, they are not so noticeable and we ignore them. Such of our clothing and other necessary articles, collars, undergarments, bed linen or table linen, towels, etc., as are left undyed are whitened thoroughly by bleaching, in order that when they become soiled they may present a disagreeable appearance and force us to take proper steps in cleansing them. Have you ever stopped to think why Italians prefer red bandana handkerchiefs, and why khaki colored shirts are so popular with camping parties? Think about it and you will find sufficient reason why dyes are important to the textile industry.

Now, why are coal tar dyes in more demand than the vegetable dyes which, it seems, are easier to produce? Or why have the synthetic dyes replaced the vegetable coloring matters? It is simply for the reason that the synthetic dyes could be produced cheaper and could be applied more simply and conveniently. Also, because more of the vegetable dyes were of an inferior quality as compared with the coal tar products. In the first place, the vegetable dyes were far from pure coloring matters. They consist principally of wood extracts and contained.