Publisher's Synopsis
This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1906 edition. Excerpt: ...of reducing gases, are absorbed readily by these clays, as by those discussed above, and a gray coloration appears such as we have observed in every instance when reducing gases are in action. The clay of Greppin, after being heated two hours in an atmosphere of illuminating gas and carbon bi-sulphide, emitted a strong odor of hydrogen sulphide, when breathed upon, had a dark ashy gray color and contained 2.77 per cent of sulphur. Yet this sulphur and the gray color also disappear entirely when the clay is heated a short time in the air, but the yellowish color characteristic of the action of the air upon these clays does not return; in place of it a red color appears, deepest at the surface, but extendfng through all the paste. This red color is deeper and has more of a violet-red tinge, the higher the temperature at which the action of the sulphuretted reducing gas took place. However this red color does not have the same intensity under all circumstances; it is deepest under the action of carbon bi-sulphide alone or oi carbon dioxide containing carbon bi-sulphide, less deep when carbon dioxide or hydrogen is present in the sulphuretted atmosphere and cannot be produced at all by a mixture of hydrogen and hydrogen sulphide. Even under the action of sulphuretted illuminating gas the red color could not always be produced artificially in the clay. From this it appears that the presence of large quantities of hydrogen or hydro-carbons retards or prevents altogether the appearance of this peculiar red color while the presence of much carbon dioxide together with the sulphur compound aids its appealance. This red color does not disappear when heated, even at a high temperature with admission of air, but if the color is not very deep, it does...
