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The addition of bromides is superfluous, sometimes injurious. Bromides in quantities, as added to ammoniacal pyro, would reduce the sensitiveness to 1/10 or 1/20; will even retard the developing power almost entirely. Must a restrainer be resorted to, 1 to 3 min. of a 1:10 solution of potassium bromide is quite sufficient. By Professor REDWOOD.
After the second washing, wash the prints over with a strong solution of pyrogallic acid, when the print will develop black, and the ground, if the washings were sufficient, will remain white. A final washing completes the process. If a solution of yellow prussiate of potash be used in place of the pyro solution, a blue print is obtained.
The canary medium is inserted between the two sheets of glass 7¼ by 4½, the two glasses are then fastened on to the tin with gummed paper, a few holes are bored in the back for air, a funnel let in, and the thing is complete. The formula for development is as follows: Mix 30 drops pyro with from 30 to 60 drops bromide, then add 2 drachms ammonia solution and 2 drachms of water.
Within a short period sulphurous acid has become an important element in the preparation of an excellent pyro developer for gelatine plates; and as it is more or less unstable in its keeping qualities, some easy method of preparing a small quantity which shall have a uniform strength is desirable.
We now take the plate-holder in our dark room and prepare our developer. There are a great many developers on the market and we can scarcely make a mistake with any of them. Probably the best of all is "pyro," but the fact that it stains the fingers is a serious objection to it for amateur use, and almost any other developer, such as metol, eikonogen or hydroquinon will be better.
The operator, after having been dabbling for some time in hypo, or pyro, or silver solution, gives his hands a wipe on the focusing cloth, and straightway sets about making an enlargement, ending up by blessing the manufacturer who sent him paper full of black stains and smears.
They had never entertained any doubt that Arthur Pym, Dirk Peters, and Allen had perished, and this was only too true in Allen’s case. How, indeed, could they ever have imagined that Pyro and the half-breed had got hold of a boat and made their escape from Tsalal Island?
And I confess Pyro. I have taken much pleasure to see the Colours run along from the parts of the Steel contiguous to the flame, to the end of the Instrument, and succeed one another so fast, that if a man be not vigilant, to thrust the Steel into the tallow at the very nick of time, at which it has attain'd its due Colour, he shall miss of giving his tool the right temper.
And you may easily satisfie your self Pyro: of the differing hardness and toughness, which is ascribed to Steel temper'd at different Colours, if you break but some slender wires of Steel so temper'd, and observe how they differ in brittleness, and if with a file you also make tryal of their various degrees of hardness.
But it so happens that I owe a great deal of gratitude to this particular Friend. It was he who, at a time when I was so afflicted with rheumatism that I could scarcely leap five feet into the air without pain, said to me one day quite casually: "Have you ever tried pyro for your rheumatism?" One month later I could leap ten feet in the air had I been able to without the slightest malaise.
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