_Leeds, January 29, 1872._
A CORRECTION.
_To the_ EDITORS.
GENTLEMEN,—In my communication to the Journal last week, at page 37,
under heading _Using the Substratum_, there is an omission which would
prevent the successful coating of the plates.
The strength of the albumen there given is that of the stock solution,
to use which _add two ounces of distilled water to every half-drachm
required_, half-a-drachm thus diluted being amply sufficient to coat
fifty plates.—I am, yours, &c.,