American Journal of Science - 1859 Author:Unknown Author Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: Art. III. -- Some Facts respecting the Nitrates; by John M. Ordway. While studying the nitrates of the sesquioxyds I found it advisable, for the sake of c... more »omparison, to examine the proto- nitrates also, with reference to some points not generally taken into account in enumerating the properties of these salts. And as the nitrate are among the most common and important salts, it may be worth the while to exhibit these gleanings in fields often gone over but not yet entirely cleared. There are few new facts to be brought forward, but the chief object of this paper is to show the fitness of certain means for the illustration of some general truths already well known. In most chemical text-books no good instances are given of the development of heat by mere solidification. It is indeed usually mentioned that water may be cooled many degrees below the freezing point and remain liquid, and that on congealing its temperature suddenly rises to 82 F. But the experiment is so troublesome to make, especially in the lecture room, that these truths commonly pass as matters of faith rather than of sight, and the important principles which they illustrate, often fail of being distinctly impressed on the mind of the student. Now many of the hydrated salts, and among them the nitrates, melt at points above the common temperature of the air, and are therefore well adapted for showing, at all seasons and with great ease and clearness, the inertia of bodies with regard to change of form and the liberation of sensible heat by crystallization. Nitrate of lime is preeminently suitable for the exhibition of these properties, since after having been fused and heated above 150 P., it may be cooled in a glass vessel as low as 60, and kept in the liquid state a long time, often for several days; but...« less