If a solution of yellow prussiate of potash be used in place of the pyro solution, a blue print is obtained.
Sulphite of soda, citric acid and sulphurous acid are used to keep the pyro from oxidizing.
After ascertaining the normal amount of pyro necessary to develop plates of a certain make, if it is desired to increase intensity add more pyro, if your plate is developing too intense or hard add more of the alkali.
Some plates require double the quantity of pyro that others do to produce the same quality of negative.
For development, ferrous oxalate or alkaline pyro are equally useful, and either may be employed, as suits the fancy or convenience of the operator.
The above is one of the best forms of ammonia pyro developer; it gives negatives of very fine quality.
The alkaline pyro developer is now in general use among professional photographers in this country, and there remains no doubt that it is the best developing agent for dry plates that has yet been brought into use.
Make a saturated solution of yellow prussiate of potassium and dilute with an equal bulk of water; add 2 drops of ammonia and 2 grains of dry pyro to each ounce used.
No more of the dilutepyro solution should be made up than is likely to be used during the same day, but it will keep well enough for a day or two.
Now to the diluted pyro solution add about a quarter or one-third of the ammonia and bromide solution, pour this mixture on the plate and observe what happens.
Provided that all the required detail is visible, small quantities of pyro solution may be added in order to gain opacity more quickly.
For this purpose pyro will be found to be the most suitable developer, in that it permits of a large amount of control.
The pyro stain can be more or less completely removed by immersing the plate for some time, with repeated rocking, in the alum solution given above, 1 drachm of sulphuric acid being added to every 10 ounces.
If it seems that the over-exposure has been considerable, a further quantity of pyro solution (10 to 20 minims per oz.
Not that the pyro developer is unsuitable, for if sufficient sulphite is used, and the quantity of pyro kept down, negatives of very beautiful quality for enlarging purposes may be produced.
A uniform stain, of a yellowish or brown colour, is produced when the pyro developer contains too small a proportion of sulphite or is allowed to act for a very long time.
Pyro will be found the most suitable developer, but it should contain a full proportion of sulphite, and not be too strong.
Fog should be avoided, as also should the yellow stain produced by pyro when improperly used.
For each ounce of developer take 20 minims of pyro solution and make up to the required bulk with water.
For use mix equal parts of dilutepyro solution and soda solution and pour over the plate.
The following is an ammonia-pyro developer, with which the writer usually works.
But I, apart from all, Hold this my creed alone: Ill deeds along bring forth offspring of ill Like to their parent stock.
Needless to say the translation--Dean Plumptre's in the main-- fails to bring out the force of the original.
In my opinion, pyro stands at the head of all developers of dry plates, and I am much mistaken if Merck's pyro, when known, does not lead all brands of pyro.
I have tested Merck's pyro carefully in comparison with the other pyros at present on the market, and I find that it is superior to any and all of them.
I shall, in future, certainly use no other pyro but Merck's.
Authorities place the solubility of pyro as one part in two of water.
I have been using Merck's pyroin my studio, and am very well pleased with it.
Merck's pyro has undergone a severe test in my hands.
The detail in light and shade is perfect, producing printing qualities unsurpassed by any pyro we have ever used.
I have tried Merck's pyro and must certainly say it is the best I ever used.
Lately I called attention to the metabisulphite of potassium as an addition to the pyro solution for development, and can give now some of my experiences with this salt.
A new addition to the pyro developer, with formulæ and results.
The cost price is about the same as that of the ordinary pyro developer.
The solution kept very well for four weeks in half-filled bottles, and showed a better preservation than the usual solution of pyro and sulphite of soda.
I commence development with a minimum ofpyro and work tentatively.
If the image does not gain sufficient density add more pyro and bromide, but unless very fully exposed it is difficult to avoid too much density, especially if white flowers are being photographed.
Prepare a saturated solution in water of the crystals of thiosinamine, and add from two to eight minims of it to an ordinary pyro or eikonogen developer.
Place an unexposed dry-plate in a normal pyro developer, and on it lay the copper coin.
The oxides of alkaline metals or their alkaline salts are not the only accelerators susceptible of being used in pyro development.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "pyro" in a variety of sentences. We hope that you will now be able to make sentences using this word.
