The print is under-developed. This is known by the print being full of gradation and detail, but not sufficiently dense or black enough in the shadows. The addition of a little more ferrous sulphate solution and longer development is, of course, the remedy. In the case of a finished print intensification is the only remedy.
The print is over-developed. This is known by the print being too dark and heavy. The use of less iron or shortened duration of development, or, in the case of a finished print, reducing the same.
Faults dtie to the After-Operations of Clearing, Fixing,
Washing, etc. The print is yellow. This must not be confounded with the yellow deposit of ferrous oxalate, this yellowness being caused, first, by washing the print between development and clearing, or leaving it too long a time before immersing in the clearing bath ; second, insufficient acid, or too little clearing bath; third, in-sufficient washing between clearing and fixing ; fourth, insufficient washing after fixing, (i) The cause of this yellow stain is the action of the air upon the iron salt, or by the action of the alkaline and earthy salts in common water, when the print is washed between development and clearing. The sole action of the clearing solution is to eliminate the soluble iron salt, and prevent the precipitation of any insoluble iron compound. (2) Insufficient acid or insufficient use of the clearing-bath tends to exactly the same results as given under No. 1. (3) Insufficient washing between clearing and fixing produces not exactly the same kind of yellow stain. With the two former cases the stain is generally more or less defined, and tends to an orange hue, whilst the third fault in manipulation is generally characterised by a faint general yellow or lemon tint all over the print; and it arises, in this case, from the decomposition of the hypo by the acid of the clearing-bath, and consequent deposition of sulphur in the film and paper. (4) Insufficient elimination of hypo or imperfect fixation tends to subsequent yellowing of the paper consequent on the decomposition of the hyposulphites of silver. Using a fixing-bath too long or too weak also gives rise to the same result, or not allowing the prints to stay sufficiently long in the hypo will also cause the same effect. The prevention of these