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Updated: June 11, 2025
Colourless glass was not esteemed by the Egyptians as it is by ourselves; whether opaque or transparent, they preferred it coloured. The dyes were obtained by mixing metallic oxides with the ordinary ingredients; that is to say, copper and cobalt for the blues, copperas for the greens, manganese for the violets and browns, iron for the yellows, and lead or tin for the whites.
The various elements of the gneiss, with the exception of the quartz, are all softened; and new combinations of the acid with lime, iron, and manganese are continually in progress. The power of subterranean gases is well illustrated by the stufas of St.
Now it has been observed, that if this decomposition of the peroxide of hydrogen takes place in contact with some metallic oxides, as those of silver, and the peroxides of lead and manganese, it superinduces a corresponding chemical action upon those substances; they also give forth the whole or a portion of their oxygen, and are reduced to the metal or to the protoxide; although they do not undergo this change spontaneously, and there is no chemical affinity at work to make them do so.
Thus there is a strong resemblance between platinum and iridium; bromine and iodine; iron, manganese, and magnesium; cobalt and nickel; phosphorus and arsenic; but this resemblance consists mainly in their forming isomorphous compounds in which these elements exist in the same relative proportion.
Koenig, "alike resemble meteoric stones; in both rocks, those of the Orinoco and of Africa, the black crust is composed, according to the analysis of Mr. Children, of the oxide of iron and manganese."
The percentage of carbon also suffers diminution by oxidation, which latter process is impeded by presence of manganese, a fact of some importance in melting of cast iron in the cupola furnace.
This as an accelerating agent is by many considered superior to the other Bromide combinations. It can be readily prepared by passing a current of chlorine through a vessel containing bromine. A mixture of two parts muriatic acid and one of black oxide of manganese, should be put into a flask having a bent tube to conduct the chlorine vapor into the bromine in another vessel.
Red chalk was not the only substance employed. At Chatelperron, were picked up fragments of manganese; at Cueva de Rocca, near Valentia, pieces of cinnabar; in the Placard Cave, bits of black lead; and in the different stations in the Pyrenees, especially in that of Aurensan, ochre has been found which was doubtless used for the same purpose.
The most common alloys with aluminum are zinc, copper, and manganese, but in such small quantities that they do not change its appearance. With so many good qualities and so few bad ones, it is small wonder that aluminum is employed for more purposes than can be counted. A very few years ago it was only an interesting curiosity, but now it is one of the hardest-worked metals.
Experiments already made so that aluminum, silicon, boron, manganese, magnesium, sodium and potassium can be reduced from their oxides with ease. In fact, there is no oxide that can withstand temperatures attainable in this electrical furnace. Charcoal is changed to graphite. Does this indicate fusion or solution of carbon?
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