hat the colouring principle of logwood forms a black
colour lake with iron and also one with chromium.

There are many ways of dyeing logwood blacks on cotton, whether that be
in form of hanks of yarns, warps or pieces. While these blacks may be,
and in the case of hanks are, dyed by what may be termed an intermittent
process, yet for warps and piece goods a continuous process is preferred
by dyers. Examples of both methods will be given. As in the dyeing of
Turkey reds it is probable that no two dyers of logwood blacks quite
agree in the details of their process, there may be variations in the
order of the various baths and in their relative strengths. Typical
methods will be noted here.

=Dyeing Logwood Black on Yarn in Hanks.=--Operation 1. Sumacing: Prepare
a bath with 10 lb. sumac extract in hot water. Work the yarn in this for
half an hour, then allow to steep for six hours or overnight, lift and
wring. The liquor which is left may be used again for another lot of
yarn by adding 5 lb. sumac extract for each successive lot of yarn. In
place of using sumac the cheaper myrabolam extract may be used.

Operation 2. Ironing or Saddening: Prepare a bath with 3-1/2 gallons
nitrate of iron, 80 deg. Tw. Work the yarn in this for fifteen minutes, then
wring out. The bath may be used again when 1 gallon of nitrate of iron
is added for each lot of yarn worked in it. In place of the nitrate of
iron, the pyrolignite of iron or iron liquor may be used.

Operation 3. Liming: Work for ten minutes in a weak bath of milk of
lime.

Operation 4. Dyeing: This is done in a bath made from 10 lb. logwood
extract and 1 lb. fustic extract. The yarn is entered into the cold or
tepid bath, the heat slowly raised to about 150 deg. F, then kept at this
heat until a good black is got, when the yarn is taken out, rinsed and
wrung. The addition of the fustic extract enables a much deeper and
jetter shade of black to be dyed.

Operation 5. Saddening: To obtain a fuller black the dyed cotton is sent
through a bath of 1-1/2 lb. of copperas, then washed well.

Operation 6. Soaping: Work for twenty minutes in a bath of 2 lb. soap at
140 deg. to 150 deg. F. Then wash well.

Much the same process may be followed for dyeing logwood black on warps
and piece goods, jiggers being used for each operation.

Another method is to first work the cotton in pyrolignite (iron liquor)
at 10 deg. Tw., until it is thoroughly impregnated, then to dry and hang in