Napier, James, 1810-1884, Fesquet, A. A · Philadelphia : H. Carey Baird · leaf 132
The alkalime- ter is filled with the test acid, which is gently poured into this solution, stirring, as each drop is added, until a piece of blue litmus-paper, which may be kept in contact with the liquor, is turned red. The number of graduations taken to effect this indicates the percentage of… … until a neutral sulphate is produced,
Dyes and dyeing · Coal-tar colors
Internet Archive · Getty Research Institute · Public domain (published before 1931). Free to use for anything.