Note 956 — I.—PHÆNOGAMOUS OR FLOWERING PLANTS. (continued 8)
Reading edition
Applied in the following manner:—Let bibulous paper be imbued with a fresh tincture of the wood or resin of guaiacum, and after drying, let it be moistened with a solution composed of one part of sulphate of copper in 2000 of water. Such paper moistened with water will assume an intense blue coloration in the presence of hydrocyanic acid.