Solochrome Dark Blue Mixture

A mixture of 1 part of solochrome dark blue with 99 parts of freshly ignited anhydrous sodium sulfate.

Complies with the following test.

Sensitivity to calcium Dissolve 0.2 g in 5 mL of water. To 1 mL of the solution add 50 mL of water, 10 mL of 1m sodium hydroxide and 1 mL of a 1% w/v solution of magnesium sulfate; a blue colour is produced. Add 0.1 mL of a 0.15% w/v solution of calcium chloride; a violet colour is produced. Add 0.1 mL of 0.01m disodium edetate VS; a pure blue colour is produced.