Chapter 5

When we examine the Congo colors, amid a number of very fugitive colors, we find a few which are satisfactorily fast. Among the reds, for example, diamine fast red is quite remarkable for its fastness, both on wool and silk, and may certainly rank with alizarin; but on cotton, it is quite as fugitive as the rest. Of medium fastness on wool are brilliant Congo G and R, Congo G R; and on silk, diamine scarlet B, deltapurpurin 5 B, and brilliant Congo R.

Among the "Congo oranges and yellows," we find some of the fastest on cotton of this class of colors. Still they deserve only the rank of medium fastness. They are Mikado orange 4 R, R, G. Hessian yellow, curcumin S, chrysophenin. On wool, we have about half a dozen of medium fastness, viz., benzo-orange, Congo orange R, chrysophenin G, chrysamin R, brilliant yellow. On silk, however, we find in this group about a dozen of the fastest oranges and yellows with which we are acquainted for this fiber, viz., Congo orange R, chrysophenin G, diamine yellow N, brilliant yellow, curcumin W, benzo orange, Hessian yellow, chrysamin R and G, cresotin yellow R and G, cotton yellow G, and carbazol yellow.

Does it not appear somewhat remarkable that we should find among this generally fugitive group of coloring matters colors which are so eminently fast on silk, and which we entirely fail to meet with among those groups which usually furnish our fast colors, e.g., the alizarin group?

Passing on to the "Congo violets, blues, and purples," we find few colors worthy of particular notice for fastness. Diamine violet N appears, perhaps, of medium fastness on wool and silk, while sulphonazurin, benzo-black blue, and direct gray may claim the same distinction on silk.

In the small group of colors which are produced directly upon the fiber, none seems to call for special notice, except aniline black, which, notwithstanding its direct derivation from aniline, is probably the fastest color we have upon any fiber.

Now, in classifying the whole range of coal tar coloring matters into "mordant dyes" and "direct dyes," and the latter into acid, basic, Congo colors, etc., I have looked at them from the point of view of the dyer and arranged them according to color and mode of application. The chemist, however, classifies them quite differently, viz., according to their chemical constitution, i.e., the arrangement of the atoms of which they are composed, and thus we have nitro colors, phthaleins, azines, and so on.

In studying the action of light on the coal tar colors from this point of view, we find that whereas the members of some groups are for the most part fugitive, the members of other groups are nearly all fast, and it becomes at once apparent that the chemical constitution of a coloring matter exercises a profound influence upon its behavior toward light. Members of the rosaniline group are all similarly fugitive, while those of the alizarin group possess generally the quality of fastness. Particularly fugitive are the eosins, and yet some of these, by a slight modification of constitution, e.g., the introduction of an ethyl group, as in ethyl-eosin, are rendered distinctly faster.

In the azo group some colors are fugitive, others are moderately fast, and it is generally recognized that certain classes of the tetrazo compounds are distinctly faster than the ordinary diazo colors.

By a careful study of the influence of the atomic arrangement upon the stability of colors, information useful to the color manufacturer may possibly be gained, but at present my facts are not yet sufficiently tabulated to enable one to recognize any generally pervading law in this direction.

It is scarcely necessary to say that the fastness to light of a color is independent of its commercial value, this being mainly determined by the price of the raw material from which it is manufactured, the working expenses, and the profit desired by the manufacturer. Neither must we suppose that facility of application necessarily interferes with its fastness to light, for some of our fastest coal tar colors on wool, e.g., diamine fast red, tartrazin, etc., are applied in the simplest possible manner. On the other hand, the intensity or depth of a color has considerable influence on its fastness. Dark full shades invariably appear faster than pale ones produced from the same coloring matter, simply because of the larger body of pigment present. A pale shade of even a very fast color like indigo will fade with comparative rapidity. The fugitive character of many of the coal tar colors is, in my opinion, rendered more marked, because, owing to their intense coloring power, there is often such an infinitesimal amount of coloring matter on the dyed fiber. Hence it is that in the Gobelin tapestries pale shades on wool are frequently obtained by the use of more or less unchangeable metallic oxides and other mineral colors, to the exclusion of even fast vegetable dyes.

It is interesting to examine what is the action of light upon compound colors. Is a fugitive color rendered faster by being applied along with a fast color?

My own opinion, based upon general observation, is that it is not, and that when light acts upon a compound color the unstable color fades, while the stable color remains behind. A woaded color, for example, is only fast in respect of the vat indigo which it contains, and yet how frequent is the custom to unite with the indigo such dyes as barwood, orchil, and indigo-carmine, the fugitive character of which I have pointed out.

Having thus rapidly surveyed these numerous coal tar colors, both in their dyed and exposed conditions, I again ask why are they so generally regarded as altogether fugitive?

First, because we have, especially among these "direct dyes," a very large number which are undoubtedly very fugitive.

Moreover, all the earlier coal tar dyes--mauve, magenta, Nicholson blue, etc., belonged to a class which, even up to the present time, has only furnished us with fugitive colors. They were indeed prepared from aniline, and it appears to me that the defects of these early aniline colors, as well as their designation, have been handed down to their successors without due discrimination, so that in the popular mind the term "aniline color" has become, as a matter of habit, synonymous with "fugitive color." But science is progressive, fields of investigation other than aniline have been opened up, so that now, although a large number of fugitive dyes are still manufactured from coal tar, there are others, as we have seen, which are as fast and permanent as we have ever had from natural sources.

Finally, and perhaps this is the most important cause of all, many of the fugitive coal tar colors are gifted, I will not say with fatal beauty, but with a facility of application, and such comparative cheapness in consequence of their intense coloring power, that the dyer, tempted by competition, applies them not unfrequently to materials for which, because of their ultimate uses, they are altogether unsuited; and so it comes about that we find the most fugitive colors applied indiscriminately and without due discretion.

As we look upon these multitudinous colors, one other thought cannot fail to cross our minds. Is there not surely an overproduction of these fugitive coal tar colors? Is not the dyer bewildered with an _embarras de richesses_, so that he knows not where to choose?

There is indeed much truth in this. With rare skill and ingenuity an army of chemists is busy elaborating these wonderful dyes; but in such quick succession are they introduced into the dye house that the busy dyer has no time sufficiently to prove them, and it is not surprising therefore that he is liable to commit errors in their application.

But if there is an over-production of fugitive colors, there is also at work, as in the organic world around us, the counteracting influence of the law of the survival of the fittest. Sooner or later, the fugitive colors must give way to those which are more permanent, and already the number of coal tar colors which have been discarded, for one reason or another, is considerable.

Not unfrequently one is asked the question, Is there no method whereby these fugitive colors can be made fast? Knowing the efficacy of mordants with certain coloring matters, is there no mordant which we can generally apply with this desirable object in view? The discovery of such a universal mordant I believe to be somewhat chimerical, and yet, curiously enough, a number of experiments have been recorded in recent years, which almost seem to point in the direction of selecting for such a purpose ordinary sulphate of copper.

Some of these diagrams before you this evening show clearly the fastness to light generally of the lakes formed with copper mordant. This peculiarity of the copper compounds has not escaped the notice of other observers. Dr. Schunck, for example, during the progress of his research on chlorophyl, noticed the very permanent green dye which this otherwise fugitive coloring matter gives in combination with copper.

Then there is the assertion of practical dyers, that the use of copper sulphate in dyeing catechu brown on cotton assists materially in rendering this color fast to light.

The use of copper mordant with phenolic coloring matters is perfectly natural. Some time ago, however, it was successfully applied, for the purpose of rendering more permanent, to certain of the Congo colors on cotton, e.g., benzo-azurine, etc., in the application of which, metallic salts had not hitherto been deemed necessary.

Noelting and Herzberg have also observed that the fastness to light, even of basic colors, e.g., magenta, methyl violet, malachite green, etc., is increased by a subsequent treatment of the dyed fabric with copper sulphate solution, although in many cases the color is much soiled thereby.

Still more recently, A. Scheurer records that by impregnating or padding certain dyed fabrics with an ammoniacal solution of copper sulphate, the colors gain considerably in fastness to light. As the result of his experiments Scheurer concludes that this protective influence of copper on dyed colors is a general fact, apparently applicable to all colors; that it is not necessarily due to its action as a lake-forming substance, since intimate union between the coloring matter and the copper salt is not necessary. He seems rather inclined to ascribe its efficacy to the light being deprived of its active rays during its passage through the oxide of copper.

Knowing, however, the strong reducing action of light in many cases, and with the absence of positive knowledge concerning the cause of the fading of colors, it seems to me that the beneficial influence of the copper may just as probably be due to its well known oxidizing power, which counteracts the reducing action of the light.

It is interesting to note, in connection with Scheurer's view, that, many years ago, Gladstone and Wilson (1860) proposed to impregnate colored materials with some colorless fluorescent substance, e.g., sulphate of quinine, evidently with the idea of filtering off the active ultra-violet rays. How far some such method as this might prove successful I cannot say, but since we cannot keep our dyed textile materials in a vacuum, as Chevreul did, nor is it desirable to impregnate them with mastic varnish for the purpose of excluding air and moisture, as Mr. Laurie proposes, in order to preserve the colors of oil paintings, it is perhaps well to bear in mind the principle here alluded to as a possible solution of the difficulty.

I have dwelt rather long on this important question of the action of light on dyed colors, but I have done so because I thought it would most interest you. With the remaining portions of my subject I must be more brief.

(_To be continued._)

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To introduce free fat acids from an oil, it must be decomposed. This may be done by the use of lead oxide and water or by analogous processes. To clarify an oil, expose to the sun in leaden trays. Often washing with water will answer the purpose.

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COMPOSITION OF WHEAT GRAIN AND ITS PRODUCTS IN THE MILL.

Probably the most striking difference in the average mineral composition of the grain of wheat is the very much lower proportion of phosphoric acid, and of magnesia also, in the dry substance of the best matured grain; and it is now known that these characteristics point to a less proportion of bran to flour, or, in other words, of a greater accumulation of starch in the process of ripening, and consequently of a whiter and better quality of bakers' flour. The study of the chemical composition of wheat and its products in the mill, therefore, and of the amount of fertilizing matters (nitrogen, phosphoric acid and potash) removed from the soil by the crop, becomes of direct interest not only to the producer from whose soil these ingredients are removed, but to the consumer of the byproducts as well, who desires to know what proportion of these elements of fertility he is returning to his own soil in the different products he may use as animal food. It is desirable also to determine what is the average composition of wheats and the flour made from them, in order to see in what direction efforts should be turned, by the selection of seed wheats, to improve the present varieties for the production of the best quality of flour. This can only be done after we determine what variation there is for different years due to climatic influences and variations of soil, for it has been shown in our former papers that environment very largely influences the quality of wheat grain, and also of the flour. When these have been determined, than we may hope to be able to determine which factors under our control enter in to permanently improve the better flour-producing quality of wheats.

A mixture, in equal proportions, was made of Clawson, Mediterranean, and early amber wheats, and submitted to the mill, using the Hungarian roller process. From this mixture for each one bushel of the grain of 60 lb. weight was furnished the following proportion of products:

Lb. per Bushel. Per cent. Flour. 44 73.3 Middlings. 4 6.7 Shipstuff. 2 3.3 Bran. 10 16.7 -- ----- Total. 60 100.0

These data furnish us a means of estimating the amount of the different ingredients removed in the various products in one bushel of wheat with the foregoing component parts.

FLOUR.

The analysis of the flour shows us that the 44 lb. obtained from the one bushel of grain would contain the following ingredients:

Lb. per Bushel of Wheat. Water. 5.834 Ash. 0.167 Albuminoids. 4.620 Woody fiber. 0.532 Carbo-hydrates (starchy matters). 33.391 Fat. 0.453

WHEAT MIDDLINGS.

The middlings form the inner coating of the wheat grain, next the floury or starchy portion, and contain particles of the germ and a larger percentage of carbohydrates than either shipstuff or bran, and a less proportion of fiber, while the percentage of albuminoids usually stands between that of shipstuff and bran. The following data are obtained from the 4 lb. procured from a bushel of wheat:

Lb. per Bushel of Wheat. Water. 0.562 Ash. 0.138 Albuminoids. 0.657 Woody fiber. 0.142 Carbo-hydrates (starchy matters). 2.307 Fat. 0.193

SHIPSTUFF.

That part separated and known as shipstuff is a very thin layer next outside of the middlings, and contains the germ not found in the middlings or left as a part of the flour. The quantity produced, 2 lb. from a bushel of wheat, is very small and rarely kept separate from the bran. The following shows the analysis:

Lb. per Bushel of Wheat. Water. 0.282 Ash. 0.101 Albuminoids. 0.349 Woody fiber. 0.160 Carbo-hydrates (starchy matters). 1.088 Fat. 0.099

BRAN.

Bran, the outer coating of the wheat, contains twice or three times as much fiber as does either of the other products from wheat, and proportionately less of each of the other ingredients except ash, which is greater, perhaps partly due to foreign matter adhering to the kernel. The following analysis shows the amount of constituents removed by the bran (10 lb.) from one bushel of wheat:

Lb. per Bushel of Wheat. Water. 1.459 Ash. 0.506 Albuminoids. 1.416 Woody fiber. 1.000 Carbo-hydrates (starchy matters). 5.277 Ash. 0.342

From the foregoing milling products obtained from one bushel of wheat of 60 lb. in weight, the ash on analysis gave the following constituents, which shows the amount that was abstracted from the soil by its growth:

_____________________________________________________ | CONSTITUENTS FROM ONE BUSHEL OF WHEAT. | _____________________________________________________| | | | | | |Nitrogen.|Phosphoric| Potash. | Lime. | | | Acid. | | | | | | | | +---------+----------+---------+---------+ | | | | | Flour. | 0.739 | 0.092 | 0.054 | 0.013 | Middlings. | 0.105 | 0.064 | 0.024 | 0.002 | Shipstuff. | 0.056 | 0.044 | 0.021 | 0.003 | Bran. | 0.228 | 0.251 | 0.083 | 0.012 | +---------+----------+---------+---------+ Totals. | 1.118 | 0.454 | 0.182 | 0.030 | ____________|_________|__________|_________|_________|

Or we may express the results in another form, the amount contained in one ton of straw, and the products of 30 bushels of wheat, which may be reckoned as an average crop, expressing the amounts in pounds as follows:

AMOUNTS OF SELECTED CONSTITUENTS IN THIRTY BUSHELS OF WHEAT AND ITS PROPORTION OF STRAW. _____________________________________________________ | | | | | |Nitrogen.|Phosphoric| Potash. | Lime. | | | Acid. | | | | | | | | +---------+----------+---------+---------+ | | | | | Straw. | 11.20 | 2.67 | 13.76 | 6.20 | Flour. | 22.17 | 2.76 | 1.62 | 0.39 | Middlings. | 3.15 | 2.01 | 0.72 | 0.06 | Shipstuff. | 1.68 | 1.32 | 0.63 | 0.09 | Bran. | 6.84 | 7.53 | 2.49 | 0.36 | +---------+----------+---------+---------+ Totals. | 45.04 | 16.29 | 19.22 | 7.10 | ____________|_________|__________|_________|_________|

From numerous investigations it has been found that in regard to the nitrogen and the ash constituents, there is striking evidence of the much greater influence of season than of manuring on the composition of a ripened wheat plant, and especially of its final product--the seed. Further, under equal circumstances the mineral composition of the wheat grain, excepting in cases of very abnormal exhaustion, is very little affected by different conditions as to manuring, provided only that the grain is well and normally ripened. Again, it is found that the composition may vary very greatly with variations of season, that is, with variations in the conditions of seed formation and maturation, upon which the organic composition of the grain depends. In other words, differences in the mineral composition of the ripened grain are associated with differences in its organic composition, and hence the great value of proper selection both for seed and for milling purposes.

AMERICAN WHEATS.

In a comprehensive treatise on the composition of American wheats, Mr. Clifford Richardson says we cannot attribute the poverty of American wheats in nitrogen as a whole to an enhanced starch formation, and for the following reasons: An enhanced formation of starch, there being no poverty of nitrogen in the soil, increases the weight of the grain and diminishes the relative percentage of nitrogen. Were this the cause of the relatively low percentage of nitrogen in the American wheats, the grain from the Eastern States, which are poorest in this respect, would be heavier than those from the middle West, which are richer in albuminoids; but this is not the case. Formation of starch is attributed by Messrs. Lawes & Gilbert to the higher ripening temperature in America, but Clifford Richardson has found that there is scarcely any difference in composition or weight between wheats from Canada and Alabama, and if anything those from Canada contain more starch than those from the South, and the spring wheat from Manitoba with its colder climate more than those from Dakota and Minnesota, with its milder temperature. In Oregon is found a striking example of the formation of starch and increase in the size of the grain, at the relative expense of the nitrogen, due to climate, but not to high ripening temperature. The average weight per hundred grains of wheat from this State has been found to be 5.044 grains, and the relative percentage of nitrogen 1.37, equivalent to 8.60 per cent. of albuminoids. These are the extremes for America, and are due, as has been said, to the enhanced formation of starch. This, however, is said to be not owing to high ripening temperature, because most of the specimens examined were grown west of the Cascade Range, which has an extremely moist climate and a summer heat not exceeding 82 deg. F. for any daily mean. The climate in another way, however, is, of course, the cause, by producing luxuriant growth, as illustrated by all the vegetation of the country. Numerous other analyses form illustrations of the important effect of surroundings and season upon the storing up of starch by the plant, and consequent relative changes in the composition of the grain.

As a whole, the poverty of American wheats in nitrogen, decreasing toward the less exhausted lands of the West, seems to be due more to influences of soil than of climate, while locally the influence of season is found to be greater than that of manure, confirming the conclusions of Messrs. Lawes & Gilbert. Also from the analyses of the ash of different parts of the grain, as from the analyses of roller milling products, we learn that a large percentage of ash constituents, other things being equal, is indicative of large proportion of bran, and consequently of a low percentage of flour.--_The Miller._

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PRECIOUS AND ORNAMENTAL STONES AND DIAMOND CUTTING.[1]

[Footnote 1: Abstract from Census Bulletin No. 49, April, 1891.]

By GEORGE FREDERICK KUNZ.