downwards over the surface of the solution, and allowing it to remain for two or three seconds; the developed print should be passed at once into a bath of hydrochloric acid I oz., water 60 ozs., and allowed to remain for ten minutes ; it should be then passed into another bath for the same period, and lastly into a third; it can be then washed, dried, and mounted in the usual way. The developing solution may be used over and over again. For over-exposed prints solution at iooo F. can be used; for under-exposed over i8ooF. may be used with advantage.
Warm Tones with Platinum Prints. The Platinotype Com-pany issue a paper which gives a sepia tinge, which perhaps owes its colour to mercuric and cupric chlorides. The addition of a few drops of solution of these chlorides to the developer materially alters the colour of the image. Warmer tones may be obtained by the following process. The following solutions are required: -
Solution No. 1.
Oxalate of potash ... ... ... ... 463 grs.
Oxalic acid...... ......... 15 ..
Distilled water .:. ... ... ... 27 drms.
Dissolve and add
Solution No. 2 ... ... ... ... 3 drms.
Shake thoroughly, and leave; if crystals form they are of no consequence.
Solution No. 2. A.
Chloride of calcium, crystal ... ... 147 grs.
Distilled water ... ... ... ... 2 ozs.
Sulphate of copper, crystal ...... 249 grs..
Distilled water ... ... ...... 10 drms.
Dissolve. Mix A and B, filter, and label "Cupric Chloride Solu-tion, No. 2." Put solution No. 1 into an iron enamelled dish, and heat to 1800 F., then develop and treat the prints as usual.
The Cold Development Process. To sensitise the paper (pre-viously sized as already directed), dissolve 70 grains of chloro-platinite of potassium in 1 oz. of water, and immediately before use mix this with 1^ ozs. of ferric oxalate solution in which there