You will need 2 large dyepots. Fill each dyepot with 4 litres of water. Add suffficient dye to each to make a fairly strong colour (enough to dye 1 lb of yarn). I used a CIBA acid dye, so I added vinegar to each dyepot to set the dyes.

Put the Magenta dyepot on the stove and heat until the dye solution is fairly hot. Add 1 dye skein and let it sit in the dye for about 20 minutes. Remove the dye skein, let it cool and rinse in cool water.

To create 40 different colours, the second dyepot solution is divided into 40 equal portions.
4 litres of water / 40 = .10 litres each
Using a measuring cup, measure out .10 litres of dye solution (Cyan)
Add .10 litres of Cyan to the Magenta dyepot and stir.

Put the 2nd dye skein into the Magenta dye mixture and let sit for about 20 minutes.
Remove the dye skein, let cool and rinse.

For the 3rd colour, measure another .10 litres of Cyan. Add this to the Magenta dyepot.
Put the 3rd dye skein into the Magenta dyepot. Let it sit for 20 minutes. Remove the dye skein, let cool and rinse.

Repeat this procedure until all 40 skeins have been dyed.

Put the Magenta dyepot on the stove and heat until the dye solution is fairly hot. Add 1 dye skein and let it sit in the dye for about 20 minutes. Remove the dye skein, let it cool and rinse in cool water.

To create 40 different colours, the second dyepot solution is divided into 40 equal portions.
4 litres of water / 40 = .10 litres each
Using a measuring cup, measure out .10 litres of dye solution (Cyan)
Add .10 litres of Cyan to the Magenta dyepot and stir.

Put the 2nd dye skein into the Magenta dye mixture and let sit for about 20 minutes.
Remove the dye skein, let cool and rinse.

For the 3rd colour, measure another .10 litres of Cyan. Add this to the Magenta dyepot.
Put the 3rd dye skein into the Magenta dyepot. Let it sit for 20 minutes. Remove the dye skein, let cool and rinse.

Repeat this procedure until all 40 skeins have been dyed.