The free acid turns blue litmus to a claret colour.
The solution reddens litmus and is an astringent.
It is a dark brown powder, which reddens litmus.
Tungstic acid, H 2 W0 4, is obtained as H 2 W0 4 H 2 0 by precipitating a tungstate with cold acid; this substance has a bitter taste and its aqueous solution reddens litmus.
To emphasize the " think small first " message, a small business litmus test was introduced last year.
