A Dictionary of Chemical Terms (Paperback)

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. 1920 Excerpt: ...A family of elements including fluorine, chlorine, bromine, and iodine. Halogen Esters. The alkylogens or alkyl haloids. Halogenides. 1. Halides. 2. Halogen substitution products of organic compounds. Halogenous. (Haloid.) Pertaining to or containing a halogen. Halohydrines. The primary haloid esters of the glycols, e.g. glycol chlorhydrine, CH, Cl.CH, OH. Haloid. Halogenous (q.v.). Haptophore. Molecules and groups which combine the toxophores (of bacterial toxins) with similar groups in the tissue cells of the affected organism. Hard Water. A condition of water due to the presence of calcium salts with usual accompaniment of magnesium salts, termed hardness. If the compounds present are carbonates held in solution by carbon dioxide the water may be freed from hardness by boiling which drives off the carbon dioxide and precipitates the carbonates. Such water is termed "temporary hard water" and the condition is known as temporary hardness. When calcium sulphate and other soluble salts of calcium and magnesium are present boiling will not "soften" the water and it is referred to as "permanent hard water" the condition being called permanent hardness. Alkaline carbonates, zeolite, etc., are used to "soften" permanent hard water. Generally a sample of water possesses both kinds of hardness. Hardness. See hard water. Hardness, Degree of. An index of the amount of alkaline earth metal, calculated as calcium carbonate, present in a sample of water. Clark's scale used a degree based on one grain of calcium carbonate per imperial gallon. The French scale used a degree corresponding to one part of the same in 100,000 of water. The German degree corresponded to one part of calcium oxide per 100,000 of water. These scales have bee...