1019 Uses of Albuminized Plates in Photography 1020 Photographic Engraving and Lithography 1021 Other Photographic Processes-Chrysotype 1022 Daguerreotype-Production of Images on Metallic Plates 1023 Prismatic Analysis of the Chemical Effects of Light 1024 Identity of Fluorescent and Chemical Rays 1025 Photographic Transparency of Various Media 1031 Aid derived from Isomorphism-Specific Heat, &c. 1032 Numerical Data upon which the Calculation of the Atomic 1033 Table of Atomic Weights . 1034 Numerical Relations of Atomic Weights. [N.B.-In the formulæ adopted in this volume the symbols for the new atomic weights are, in accordance with the present usual and convenient practice, indicated by barred letters, instead of by italics, as in the first volume. The conversion of any formula on the new notation into that in ordinary use is effected by doubling the numbers attached to the barred symbols. The result obtained will either be the ordinary formula, or its multiple by two. KHO, for instance=KHO,; and SnCl =z SnCl,.] UNIV. N PART II. INORGANIC CHEMISTRY. CHAPTER I. NOMENCLATURE-CLASSIFICATION OF THE ELEMENTS. (331) Principles of Chemical Nomenclature.-Before proceeding to a description of the chemical properties of the different elementary substances, and of the compounds which are the result of their union with each other, it will be needful to explain the principles upon which the nomenclature in use amongst chemists has been founded. The object of the inventors of this language was, not merely to give a distinguishing name to the substances spoken of, but also to convey a knowledge of their components, and even of the proportions in which those components occur. In the less complicated substances with which the chemist has to deal, this object is very completely attained. In those of a more complex nature, the employment of symbols (16) becomes necessary, in order to enable the composition of the body to be fully indicated; and the formula of a substance, especially if the substance be derived from the animal or the vegetable kingdom, becomes an indispensable supplement to its name. 1. Elements.—In the case of the elementary bodies, the common name of each is usually that by which it is distinguished in chemical language, if the substance-as is the case with many of the metals, such as lead, iron, copper, or zinc-be one which is familiarly known: if it be a body which the researches of the chemist have brought to light, the name is generally indicative of some marked peculiarity by which the element is characterized. Thus phosphorus (from pwc, popòc, light bearing) is so named because when exposed to the air it emits a feeble light which is visible in a darkened room; iodine derives its name from wông (violet), in reference to the violet colour of its vapour; hydrogen (producer of water, üdwp, yevváw) is so called from the circumstance that it is a necessary component of water; and so on. |