We now take up that more important branch of the collodion process,
vis., that for negatives.
The formulæ and instructions already given for positives might
enable one to make a negative, but the negatives so made would bear
even a remoter relation to one made by the formula about to be given
than would a positive made according to these formulæ bear to a good
one made by the appropriate means. Important modifications are
necessary to reach the highest excellence in either process.