This section is from the "Henley's Twentieth Century Formulas Recipes Processes" encyclopedia, by Norman W. Henley and others.
The combined toning and fixing bath consists essentially of five parts— (1) water, the solvent; (2) a soluble salt of gold, such as gold chloride; (3) the fixing agent, sodium thiosulphate; (4) a compound which will readily combine with "nascent" sulphur—i. e., sulphur as it is liberated—this is usually a soluble lead salt, such as the acetate or nitrate, and (5) an auxiliary, such as a sulphocyanide.
The simplest bath was recommended by Dr. John Nicol, and is as follows: Sodium thiosulphate. 3 ounces
Distilled water....... 16 ounces
When dissolved, add
Gold chloride. ... 4 grains Distilled water ... 4 fluidrachms A bath which contains lead is due to Dr. Vogel, whose name alone is sufficient to warrant confidence in the formula: Sodium thiosulphate 7 ounces Ammonium sulphocyanide......... 1 ounce
Lead acetate ......67 grains
Alum............. 1 ounce
Gold chloride......12 grains
Distilled water.....35 fluidounces
A bath which contains no lead is one which has produced excellent results and is due to the experimental research of Dr. Liesegang. It is as follows: Ammonium sulphocyanide. ... 1/4 ounce Sodium chloride.. 1 ounce
Alum........... 1/2 ounce
Sodium thiosulphate......... 4 ounces
Distilled water. .. 24 fluidounces
Allow this solution to stand for 24 hours, during which time the precipitated sulphur sinks to the bottom of the vessel; decant or filter, and add
Gold chloride. ... 8 grains Distilled water. .. 1 fluidounce It is curious that, with the two baths last described, the addition to them of some old, exhausted solution makes them work all the better.