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The Barnet Book of Photography A Collection of Practical Articles

As ammonium sulphocyanide is somewhat deliquescent


_Toning_

is usually our next operation, and for this purpose we have a variety of toning baths recommended by different workers. The sulphocyanide and gold is perhaps the chief favourite.

1. Ammonium sulphocyanide 10 to 15 grains. Gold chloride 1 grain. Water 8 to 10 ounces.

The proper way to mix this bath is to add the gold to the solution of sulphocyanide a little at a time. The following method will be found convenient. As ammonium sulphocyanide is somewhat deliquescent, it is convenient to keep it in solution. Therefore, one ounce of the salt dissolved in twenty ounces of (distilled or filtered rain) water gives us roughly a strength of twenty-two grains per ounce. Dissolve the contents of a fifteen-grain chloride of gold in fifteen drams of distilled water. To mix a bath, take of the sulphocyanide solution half-an ounce; to this add eight ounces of water. Now take one dram of the gold solution and dilute with one ounce of water. Then add this dilute gold solution a _little_ at a time to the eight ounces of sulphocyanide solution, and stir well with a glass rod. It will be noticed that as the gold solution drops into the sulphocyanide solution an orange-red precipitate is formed, which is redissolved on stirring. Hence the gold must be added to the sulphocyanide, and not _vice versa_.

2. Another favourite bath is as follows:--

style="text-align: justify;"> Ammonium sulphocyanide 22 grains. Soda sulphite 2 " Gold chloride 2 " Water 20 to 25 ounces.

Instead of weighing out two grains of sulphite it is more convenient to weigh twenty grains and dissolve in two-and-a-half ounces of water--_i.e._, at the rate of one grain per dram of solution. Thus, to mix this bath, take an ounce of the above-mentioned sulphocyanide solution dilute with twenty ounces water. To this add two drams (1/4 oz.) of the sulphite solution. Then take two drams of the gold chloride solution and dilute with an ounce of water, and add slowly with stirring as before.

3. Another favourite bath is:--

Sodium chloride (table salt) 60 grains. Ammonium sulphocyanide 15 " Gold chloride 2 " Water 10 to 12 ounces.

Some of the adherents of this bath recommend that the prints be only washed in running water for a few minutes and then put into the toning bath. Others advise the prints to be immersed in the toning bath without any previous washing--_i.e._, straight from the printing frame.

4. Here, again, is another bath which usually yields excellent results:--

Soda phosphate 5 grains. Sodium chloride (table salt) 20 " Gold chloride 1 grain. Water 10 ounces.

5. Other workers omit the sodium chloride and increase the phosphate and get good tones.

Soda phosphate 20 grains. Gold chloride 1 grain. Water 10 ounces.

6. Others, again, combine the phosphate and sulphocyanide baths thus:--

Sodium phosphate 10 grains. Ammonium sulphocyanide 15 " Gold 1 " Water 10 ounces.

The various toning baths mentioned above have one drawback common to them all in varying degrees--_viz._, that when once mixed and used they do not keep in good working order longer than a few hours.


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