Of late years the quality of these dyestuffs has greatly improved, and the best of them, like those mentioned below, when carefully dyed on cotton, are fast, if not very fast to light, although for washing the very best can hardly be classed even as fairly fast, without after-treatment. _List of Selected Dyestuffs._— Badische— Oxamine Fast Red, F Cotton, Yellow, G I Stilbene Yellow, G K Oxamine Blue, B Cotton Black, E, extra Cassella— Diamine Fast Red, F Diamine Fast Yellow, G G Diamine Fast Blue, F F G Diamine Fast Black, F Elberfeld— Benzo Fast Red, 8 B L Benzo Fast Yellow, 4 B Brilliant Fast Black, 4 B Pluto Black, F, extra Kalle— Naphthamine Fast Red, H Naphthamine Fast Yellow, 2 G L Naphthamine Fast Blue, 4 B L Naphthamine Fast Violet, R L Naphthamine Direct Black Metz— Dianil Fast Scarlet, 4 B S Dianil Orange, G Dianil Yellow, O O Dianil Fast Blue, 3 B Dianil Fast Black, conc. As above mentioned, even the very best dyes belonging to this class of Salt colors, give on cotton and linen results only “fairly fast” to washing. As the modern laundress is not averse to using stronger agents than good laundry soap in her washtub, and not infrequently indulges in considerable amounts of washing soda (sodium carbonate) and even of bleaching powder, to clean quickly a dirty piece of goods, dyes that are “fairly fast” according to the regular standard, will, in practice, need some care spent on them if they are to hold their color for long periods. Against light the best ones are almost as fast as any dyes known, but none of them are a match for the Sulphur colors, or especially the Vat colors, when exposed to severe washing. _After-treatment._—The professional dyer, who is occasionally called upon to produce fast colors with these dyes, and even with the inferior members of this class, has found various methods of after-treatment, by which the colors are rendered more permanent. A favorite process, where the dyer is enough of a chemist to carry it out, consists of making an entirely new dyestuff in the fibre, generally of an entirely different shade, and with much greater power of resistance to washing and to light, by treating the dyed goods first with a mixture of sodium nitrite and of sulphuric acid, and, after this, passing them through a solution of some organic chemical such as carbolic acid, alpha- or beta-naphthol, or others known as developers. This process, known as “diazotizing and developing,” is considerably used in the trade, especially for various shades of black, but is too complicated and delicate for craftsmen in general.