We will now observe and note the different action on these pieces of
cotton--(i.) of a Turmeric bath, (ii.) a Magenta bath, and (iii.) a
madder or Alizarin bath. The Turmeric dyes the cotton a fast yellow, the
Magenta only stains the cotton crimson, and on washing with water alone,
almost every trace of colour is removed again; the madder, however,
stains the cotton with no presentable shade of colour at all, produces a
brownish-yellow stain, removed at once by a wash in water. But let us
take the printed piece of cotton and dye that in the Alizarin bath, and
then we shall discover the conditions for producing colours with such a
dyestuff as madder or Alizarin. Different coloured stripes are
produced, and the colours are conditioned by the kind of metallic salts
used. Evidently the way in which, the turmeric dyes the cotton is
different from that in which the madder dyes it. The first is a yellow
dyestuff, but it would be hard to assign any one shade or tint to
Alizarin as a dyestuff. In fact Alizarin (the principle of madder) is of
itself not a dye, but it forms with each of several metals a differently
coloured compound; and thus the metallic salt in the fabric is actually
converted into a coloured compound, and the fabric is dyed or printed.
Pages:
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139