A Manual Of Photography

SUMMARY OU THE OPERATIONS. 49 “ O-r the Fixed Impression.—The stains left by the washing Water must be removed with rouge and water slightly acidulated with nitric acid (at 36° Fahr, at this season [April P], and less in summer). Afterwards, the plate must be polished with oil and rouge, in order to remove all traces of the image. The operation is then continued just as I have described for the second preparation of the new plate, and beginning with the employment of alcohol. “On the Unfixed Impression (but whose sensible layer has been removed in the ordinary manner).—First, the plate must be rubbed with alcohol and rouge, in order to remove the traces of oil which serve for receiving the foregoing impression. We afterwards proceed as indicated above for the new plate, begin- ning with the employment of alcohol. “ The summary of the operations will include in the First Preparation—1. Corrosive sublimate, with tripoli first, and rouge afterwards, in order to polish the plate: 2. Cyanide of mercury, heated and dried with cotton and rouge : 3. Acidulated oil, with rouge for polishing the layer of mercury: 4. Gold and platinum, heated and dried witli cotton and rouge. “And in the Second Preparation—5. Acidulated oil, with rouge, for polishing the layer of gold and platinum: 6. Absolute alcohol, for removing, as much as possible, the oil and rouge: 7. Cyanide of mercury, employed cold, and rubbed only with cotton: 8. Oil rubbed very strongly, and equalised in the last place witli rouge sprinkled on it. “Then on the Fixed Proof we use—1. Nitric acid at 36° F. With rouge for removing the stains : 2. Oil with rouge for removing the traces of the image and for polishing. Continue then as above, setting out from No. 6, alcohol, &c. “And on the Unfixed Proof—Alcohol with rouge for removing the traces of oil, and continuing as above, beginning from No. 6, alcohol, Ac. ." On Iodising.—The colour of the impression depends on the tint given to the metallic iodide ; it may, therefore, be varied at will. However, I have found the violet rose colour most suitable. " For transmitting the iodine to the plate, the sheet of card- hoard may be replaced by an earthenware plate deprived of enamel. The iodine transmitted by tins means is not decom- P sed. It is useless, 1 may even say injurious, to heat the plate before exposing it to the vapour of iodine. “Wasinng witli Hyposulphite of Soda.—In order to remove tiie sensitive layer, the solution of hyposulphite of soda must not be too strong, because it destroys the sharpness of the impres- E