black paste was then set aside in the dye house where he was employed, 

 and after a while, thinking it was useless, the dyer threw the compound 

 out the window onto the snow. As the snow melted Mr. Seidelman 

 "saw . . . the beautiful blue veins of the dissolved indigo. He at once took 

 part of it in a tumbler of hot water, added some alum and dipped some 

 wool yarn into it; the result was a new color" (Haserick, 1869, p. 17). 

 Supposedly he later sold his secret in England for $6,000. 



Apparently this rather inferior dye was used by professional dyers on 

 coarse goods throughout the 19th century; with impro\'ed methods of 

 application, its use continued until the early 20th century. 



PRUSSIAN BLUE 



Also known as bleu de Prusse (Fr.); das Berlinerblau (Ger.) 



One of the earliest chemical dyes used in America, Prussian blue is 

 made by combining prussiate of potash with an iron salt in which the 

 prussiate acts as a dye and the iron salt as a mordant. They combine to 

 form a white solution that turns blue when oxidized. 



Its discovery is credited to a German chemist of the first decade of the 

 18th century, but its practical application was delayed for about a hundred 

 years until a method of fixing it on fabrics was developed. The first use 

 of Prussian blue in this country appears to have been in 1832, when F. 

 Tassard of Philadelphia dyed broadcloth "Lafayette" blue. Specimens of 

 this cloth, made in Dedham, Massachusetts, were exhibited at the Fair 

 in the American Institute in New York in 1833 (Bishop, 1866, vol. 2, 

 p. 372). 



Prussian blue-dyed cotton is extremely fast to light; however, the same 

 coloring agent darkens on wool and decomposes in boiling soap solutions. 

 In applying Prussian blue to silk, only the prussiate of potash needs to 

 be applied if the silk has been weighted previously with iron salts. Weight- 

 ing eliminates the need for an extra mordanting step, and thus simplifies 

 the dyeing procedure. 



Prussian blue was used until the early 20th century when improved 

 means of achieving the same color made it obsolete. 



Red Dyes 



* MADDER {Rubia tinclorum) 



Also known as common madder; garance (Fr.); der Krapp (Ger.) 



It is well known that Madder is so essential to dyers and callico-printers, that neither 

 business can be carried on without it. The consumption of it is so great in England, that, 

 upon a moderate computation, more than 180,000 sterling, is annually paid for what 

 is imported from Holland, exclusive of their supplies from other parts; and as in a little 

 time, manufacturers of these kinds, must of necessity, progress in America, the sooner 

 some attention is paid to this article, the better. 



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