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He succeeded in obtaining very small crystals, or diamonds, but the cost of production made his method impracticable from a commercial standpoint." "Ah! I see." "In 1872 a chemist named Rose converted graphite into diamonds by a similar process, but with the same result." "The cost of production being too great?" observed Nick. "Precisely." "Do you think that difficulty has now been overcome?"
POSITIVE Iron Silver Zinc Nickel Gold Cadmium Bismuth Platinum Tin Antimony Graphite Lead Copper NEGATIVE There being no chemical union between the hydrogen and copper in the zinc and copper couple, that gas accumulates on the surface of the copper plate, or is liberated in bubbles. Now, hydrogen is positive compared with copper, hence they tend to oppose each other in the combination.
There we find it in the fact that carbon occurs both in the form of the diamond, the hardest of all mineral substances, and also in the form of the softest, graphite. Here also, in the diamond's brilliant transparency, and in the dense blackness of graphite, carbon reveals its twofold relation to light.
How this great Eastern backbone of the continent was produced, what sort of animals lived while these rocks were being formed, or whether this preceded entirely the existence of life upon the earth, no man to-day may surely say. In the oldest of the rocks there are beds of graphite, from which lead pencils are made.
The best graphite in the world comes from Ceylon and Mexico. When graphite was first used for pencils, it was cut into slabs and these slabs into small strips. The broken and powdered graphite was not used until it was discovered that it could be mixed with clay and so made into sticks.
Rick studied the wall, and directly in front of the projector lens he found another of the same arrangements, but with a difference. This one was modern, and it had been painted to prevent rusting. There were traces of graphite or graphite grease where the pins went through the iron supports.
So he set his inventions to the task of evolving a blackmailing snare which might be set and sprung, and afterwards dismantled and hidden away without the intervention of the female knave of the species in any of its stages. Trust him smooth as lubricating oil, a veritable human graphite to turn the trick. He turned it. The upshot was a lovely thing, almost foolproof and practically cop-proof.
Stirring with a brush expedites the contact, and a decomposition takes place; the acid leaves the copper and forms with the iron sulphate a solution which floats off, while the copper is freed and deposited in a pure metallic form upon the graphite. The black surface takes on a muddy tinge with marvelous rapidity.
Many improvements in detail have been added since, in the processes as well as the appliances. Robert Murray introduced graphite as a coating for the form moulds. He first communicated his discovery to the Royal Institution of London, and afterward received a silver medal from the Society of Arts.
Some of the more important consumers of the electric power, named in the order of consumption, are for the manufacture of the following products: calcium carbide, aluminium, caustic soda and bleaching salt, carborundum, and graphite.