A large proportion of soap counteracts the effects of the salts, causing the dye-stuff to go on less quickly and tending to leave the silk lighter than the cotton, in some cases even almost white, a property which is valuable in many cases, especially as enabling the silk and cotton to be dyed in different colours to obtain shot effects. It is thus obvious that a general method applicable in all cases cannot be given; it will vary according to the effect desired, and partly also depend on the material to be dyed. The following particulars may serve as a guide for the first bath:-- For pale shades each 10 gallons dye-liquor should contain 3-1/4 to 6-1/2 oz. soap and 4 to 7 drs. soda or 3-1/4 to 6-1/2 oz. soap, 4 to 5-1/2 drs. soda and 3-1/4 to 6-1/2 oz. phosphate of soda. For medium and dark shades each 10 gallons dye-liquor may contain 3-1/4 to 6-1/2 oz. soap, 4 to 7 drs. soda, 3-1/4 to 6-1/2 oz. phosphate of soda and 6-1/2 to 13 oz. cryst. Glauber's salt. For two coloured effects or dyeings, in which the silk is intended to remain as pale as possible or even white, each 10 gallons dye-liquor may contain 4-3/4 to 8 oz. soap, 4 to 6 drs. soda, 3-1/4 to 8 oz. phosphate of soda and 4-3/4 to 9-1/2 oz. cryst. Glauber's salt. The temperature of the dye-baths is generally 175 deg. to 195 deg. F.; in practical dyeing it is usual to boil up the fully charged dye-bath, shut off the steam, enter the goods and dye for about three-quarters of an hour. For obtaining level dyeings in pale shades it is advisable not to enter the goods too hot, but to raise the temperature gradually. Raising the temperature, or dyeing for some time at the boil will deepen the shade of the cotton, but at the same time will have the same effect on the silk which may sometimes be an advantage when dyeing dark shades. As a complete exhaustion of the baths does not take place, especially when dyeing dark shades, it is advantageous, nay, even imperative, to preserve the baths for further use, they are then replenished with only about three-fourths of the quantities of dye-stuffs used for the first bath, of the soap only about one fourth, of Glauber's salt, soda and phosphate of soda only about one-fifth, of the first quantities are necessary. The first bath should be prepared with condensed water. If none is at hand ordinary water should be boiled up with soda and soap and the scum removed. Clear soap baths are absolutely necessary for the production of pure shades and clean pieces. After dyeing, the pieces must be very well rinsed, and the colour raised or brightened with 1 pint of acetic acid in 10 gallons of water. Many of the Diamine and Titan colours being very fast to acids, but few of them will be affected by this treatment. In the following tables are given those Diamine, etc., colours especially adapted for the dyeing of goods composed of silk and cotton, divided into three groups according to their relation to silk and cotton:--