Note (return) — Replies.
Reading edition
"Shake these well together, allow them to macerate twelve hours, and filter through paper. Before adding the nitric acid, test the liquid with a piece of blue litmus paper; if it remain blue after being immersed one minute, add one drop of dilute nitric acid[3], and test again for a minute; and so on, until a claret red is indicated on the paper. It is necessary to test the bath in a similar manner, frequently adding half a drop to a drop of dilute acid when required. This precaution will prevent the fogging due to alkalinity of the bath, so formidable an obstacle to young hands."