Alum, ammonium potash

The word alum is derived from the Latin alumen, which was appHed to several astringent substances, most of which contained aluminum sulfate (20). Unfortunately, the term alum is now used for several different materials. Papermakers alum or simply alum refers to commercial aluminum sulfate. Common alum or ordinary alum usually refers to potash alum which can be written in the form K SO Al2(SO 24H20, or it can refer to ammonium alum, ammonium aluminum sulfate. The term is also appHed to a whole series of crystallised double sulfates [M(l)M (lII)(SO 2 12H20] having the same crystal stmcture as the common alums, in which sodium and other univalent metals may replace the potassium or ammonium, and other metals may replace the alurninum. Even the sulfate radical may be replaced, by selenate, for example. Some examples of alums are cesium alum [7784-17-OJ,... 

Although the latter had previously overlooked the new earth because of its similarity to alumina, he found in 1798 that the hydroxide that precipitates when caustic potash is added to an acid solution of the beryl does not dissolve in an excess of the alkali. It also differs from alumina in other respects, for it forms no alum, it dissolves in ammonium carbonate, and its salts have a sweet taste. Vauquelin s paper read before the French Academy on le 26 pluviose an VI of the Revolutionary Calendar, or the fifteenth of February, 1798 (6, 23), proved that, except for a little chromium in the emerald, the two gems have the same composition and that they contain a new earth, a sample of which he presented to the Academy. At the suggestion of the editors of the Annales de Chimie et de Physique, he called the new earth glucina, meaning sweet. The specimen of beryl that Vauquelin analyzed was presented to him by... 

About 2 gm. benzyl iodide are weighed into a flask and then 50 ml. 20% alcoholic potash solution are added and the mixture refluxed for about an hour. At the completion of the saponification the contents of the flask are allowed to cool and then transferred to a 500-ml. flask and made up to volume with water. 100 ml. of the resulting solution are placed in a distillation flask and distilled in steam after adding 10 gm. ferric ammonium alum and acidifying with sulphuric acid. By this treatment, the ferric salt is converted to the ferrous condition, liberating iodine which is distilled over into 5% potassium iodide solution. At the end of the distillation, the free iodine in the potassium iodide solution is titrated with a decinormal solution of sodium thiosulphate. From this, the amount of iodine and so the quantity of benzyl iodide in the sample may be calculated. 

Ammonium carbonate Ammonium chloride Ammonium sulfate Barium carbonate Barium chloride Barium hydrate Barium sulfate Borax Boric acid Calcium carbide Calcium hypochlorite Chrome alum Copper sulfate Carbon dioxide Carbon disulfide Carbon tetrachloride Caustic potash Caustic soda Chlorine Ferrous sulfate... 

Alumen (j5r.)-AJ.XSO,) (NHJ,SO, -t- 24 Aq 74 + 432—is the compound now usually met with as ofum, both in thia country and in England, ft differs from potash alum in being more soluble in H,0 between 20°-30° (68°-30 F.), and less soluble at other temperatures and in the action of heat upon it At 92° (197°.6 F.) it fuses m its Aq at 205° (401° F.) it loses its ammonium sulphate, leaving a white, hygroscopic substauce, very slowly and incompletely soluble in H,0. More strongly heated, it leaves alumina... 

The octahedral, cubic crystals are violet to black in colour, and appear ruby-red in thin layers and J. H. Kastle found that the intensity of the colour is very much reduced at liquid air temp. F. Klocke, C. F. Rammelsberg, C. von Hauer, and J. W. Retgers showed that the crystals are isomorphous with other alums, for they show similar corrosion figures. E. Dittler obtained overgrowth with potassium aluminium sulphate. T. V. Barker found a close connection between parallel overgrowths in chrome-alum, potash-alum, and ammonia-alum and the mol. vols which are respectively 542-2, 541-6, and 552-2. C. von Hauer found that with the introduction of a crystal of iron-alum in a sat. soln. of chrome-alum nearly all the latter separates out while L. de Boisbaudran found that a sat. soln. of basic ammonium aluminium alum does not affect the octahedral faces of the... 

In the industrial world, alum usually refers to simple aluminum sulfate terms such as potash (potassium) alum and ammonium alum designate the double salts. 

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