Inhaltsangabe
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated.1870 Excerpt: ... METALS. Foe the purpose of analytical chemistry, the metals may be arranged in the following groups: I. Metals which are not precipitated by H2S either from an acid or ammoniacal solution (metallic sulphides soluble in water). (A). Metals whose carbonates are soluble in water (alkali-metals). (B). Metals whose carbonates are insoluble in water (metals of the alkaline earths). II. (C). Metals which are not precipitated by NH5S from acid solutions, but which are precipitated from solutions neutralized with NH50 (ammonic sulphide group). HI. Metals which are precipitated by H2S even from slightly acid solutions (hydrosulphuric acid group). (D). Metallic sulphides insoluble in NH5S. (E). Metallic sulphides soluble in NHsS. (A). ALKALI-METALS. 1. Potassium. K = 39.1. Is a silver-white, soft meta1, of.865 sp. gr., which melts at 62. It oxidizes in the air so rapidly that it must be kept under naphtha. Water is decomposed by potassium, even at ordinary temperatures, with evolution of H2 (formation of KH0). The potassium is thereby ignited, burning with a violet flame. Almost all potassium compounds are soluble in water. Solutions of potassium salts which are acidulated with HC1, and are not too dilute, will give precipitates with PtCLi, H2SiF6 and C4H606 (tartaric acid). Potassio-platinic chloride, K2PtC16, is a yellow crystalline salt, which is difficultly soluble in water, absolutely insoluble in ether-alcoho1, and breaks up at a red heat into chlorine, platinum and potassic chloride. Potassio-silicic fluoride, K2SiF6, is a gelatinous precipitate which becomes distinctly visible upon addition of alcohol. Hydro-potassic tartrate, KC4H506 (acid potassic tartrate), separates only from very concentrated solutions; rubbing the sides of the vessel hastens its formatio...
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