the ounce, of pure permanganate of potash and one gramme of chem- 2 Oo ically pure carbonate of soda are dissolved in half a liter of 12 grains. These proportions appeared to be the best, but CARBURETED HYDROGEN GAS. there was always a variation in the working of this com- water, yielding a… … frame, and expose to sunlight from fifteen to twenty minutes with. It is probably only the first and last of these tests that. fora thin negative. By opening one half the frame and greatly, and since the . discovery of the petroleum wells in will be found practical in photographic operations; they…
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