Royal Blue.

Scientific American 43, 15.7.1848

This is a color which for beauty is unequalled. The true modus operandi is not known to many and in no published work can we find a proper description of the dyeing of it. It is but a few years since it was introduced into this country from England, and the receipts for dyeing it have been sold at from five to twenty five dollars. There are two ways of dyeing dark shades, first by bottoming, as it is technically termed, with logwood and then dyeing with the prussiate of potass, or first dyeing with the prussiate and then topping with the logwood. The latter mode is the best.

For a dark blue the goods do not require to be perfectly white, as the operation strips off old colors, while the blue is gradually becoming combined with the goods. To every pound of Circassian or merino goods, which must be perfectly washed and clean, two ounces of the prussiate of potass is put into the dye kettle along with two ounces of tartar, and nitric and sulphuric acid added until the liquor (after the tartar and prussiate is dissolved tastes like glauber salts. The goods are then entered, if in pieces they must be well salvaged or winched, and if yarn well turned, and the liquor in the dye kettle gradually brought up to the boiling point. The goods are then taken out and a little more sulphuric acid added. After the goods are boiled for twenty minutes or half an hour, a beautiful and rich sky blue will have been imparted to them. They are then taken out of the dye kettle, washed and hung up for a few moments to drip. Another dye kettlewith a small quantity of logwood liquor, (say a teacup full of strength No. 3 in the hydrometer, for every pound of goods,) should be now boiling, to which add a wine glass full of the muriate of tin, stir well and enter the goods. The kettle must tat kept boiling for halt an hour, when it will be found that a deep velvety richness will be imparted to the blue color, and by adding a greater quantity of logwood with a proportional quantity of spirits (muriate of tin) a deep violet color will be the result. If cochineal is used instead of logwood, a clear and beautiful crimson tinge is imparted to the goods. This color may almost be considered permanent—it at least occupies more than a middle place in the scale, between the fugitive and permanent. From its exceeding clear and rich appearance, this color on goods has received the name of royal blue. The stuffs that are employed to dye it are nearly colorless, but their combination forms a salt which is deposited or combined with the woolen goods by means of electricity elicited in the process, and enters minutely into all the fine pores of the goods, and the salt so formed reflects the prismatic blue color.—

Electricity is the prime agent of the dyer and calico printer. For nearly three thousand years the effects of mordaunts have been well known to produce various shades with a single drug. Madder with different mordaunts will produce a bright red, or a deep black—a lilac or a purple. But no theory explanative of these chemical manipulations, that we are aware of, has ever been set forth to reconcile the art of dyeing with the Newtonian theory, only so far as it relates to prismatic reflection—the decomposition and mingling of the different rays. " That colors produced on goods in the process of dyeing, is the result of electric action—a decomposition in the first place, and a deposition in the second—whereby certain salts are deposited on certain animal or vegetable substances to reflect certain prismatic shades," is a theory which we are not aware of ever having seen set forth in any treatise, either by Field, Crum ­or Thompson, the latter the best writer on the subject in this country, and the fame of Walter Crum as a chemist and dyer, is world wide. The royal blue is a color which at once establishes this theory—the process is like a deposition of metals in their cyanides by the galvanic battery. This theory is backed up by the whole process of steam colors in calico printing, and by Bain's electric telegraph. Electricity is always developed rapidly in steam and the dye kettle is the galvanic bat­tery of the dyer.

To those who have little interest in the abstruse part of this article, we would say that coarse goods dyed by the above receipt, may be made a very deep blue by the greater quantity of logwood used, and if the goods were first of all prepared with a small quantity of the sulphate of iron—so much the better.— The above receipt could not be purchased for less than fire dollars from any dyer, and any person may dye the color perfectly by follow­ing our description. As we have advanced a theory different from any that we have ever seen, and as we have much yet to say to ex­plain it fully and establish it, we shall do so in a separate article next week.

R. Bartholomew.