Two kinds of liquid or thin pulp called Orchil or Archil are met with: one termed blue orchil, the other red orchil. They are prepared as follows: blue orchil is procured by steeping the lichens before mentioned (see pp. 70 and 71) in an ammoniacal liquor in a covered wooden vessel. Red orchil is made with the same liquor in common earthen jars placed in a room heated by steam, and called a stove. In one manufactory which I inspected, the ammoniacal liquor was prepared by distillation from a mixture of lime, impure muriate or sulphate of ammonia obtained from gas-works, and water; but some makers still employ stale urine and lime. Both kinds of Orchil sold in the shops are liquids of a deep reddish purple colour and an ammoniacal smell. Red and blue orchils differ merely in the degree of their red tint.
According to Dr. Kane, Orchil consists of orcein, erythroleic acid, and azoerythrine. To these must be added ammonia.
Orchil is employed merely as a colouring agent. It is used for dyeing, colouring, and staining. It is sometimes used as a test for acids.