Oct., 1 9 1 8 ~
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
795
goods are dyed with mineral or pigment colors to produce the khaki brown. This color is obtained with a mixture of chrome and iron salts by simple precipitation of the oxides in the fiber. Sometimes manganese salts are also used, but a t the present time these are scarce and of high cost. In respect to tonnage of cotton dyed, this mineral khaki brown forms a very important item, as the cloth dyed in this way is mostly heavy canvas for tent material, wagon covers, tarpaulins, etc. In the selection of dyestuffs for cotton from the dyestuff manufacturer’s point of view, the first consideration is the quantity of the dye consumed by the trade. If this is only small and represents but an insignificant turnover during the year, it does not appeal to the business sense as an attractive proposition. Before the war the various German dyestuff houses had on the market quite a large number of direct cotton colors-one would believe almost too many for profitable production. Many of these varied very little in shade and properties, and the consumption of many was relatively small. It is hardly to be presumed that our American manufacturers are going to bring out all these various brands of dyestuffs. The most sensible procedure would be to fix on those which offered the most advantages with respect to quality of color and fastness, and if there are several very near duplicates of one another, select for manufacture the one most economical to produce. We must also bear in mind that many of the direct cotton colors have a serious lack of fastness to washing, and while they are extremely simple and easy to apply and give good clear colors in combination, yet fastness to washing is being more and more required for colored cotton goods, and dyes which do not possess this fastness will have a very limited use. It is believed that in the dyeing of cotton the sulfur dyes will have a greater development in this country than they ever had before. It is true they are somewhat limited in range of shades, but blacks, blues, browns, yellows, green, and orange are within the list. They also have the limitation that they are rather dull in tone. But their good fastness t o washing is greatly in their favor; also their fastness to acids allow of their use in cross-dye work which much extends their field of application. A large number of useful shades can be obtained by combinations of the sulfur dyes, although the want of a satisfactory red and green dye in this class seriously limits the possibilities for the production of,fancy shades,
NATURAL DYESTUFFS-AN IMPORTANT FACTOR IN THE DYESTUFF SITUATION By EDWARD S. CHAPIN Consulting Chemist, Boston, Massachusetts
