. Journal of applied microscopy and laboratory methods. icro-chemical detectionof aluminum : I. Cesium Ammonium Fluoride. III. Primary Potassium Sulphate. IV. Staining Aluminum Hydroxide with Dyes. /. Cesium Sulphate added to solutions containing Aluminum SuIpJiate leads tothe formation of Cesium Almn. Al2(S04)3 + CS2SO4 = [AL^CSOJ;, . Cs.^S04 • 24H,0]. Method.—To a drop of the solution to be tested, add a drop of ammoniumhydroxide. Draw off or filter off the supernatant solution. Wash the precipitateonce with water. Then add a single drop of water and a trace of dilute sul-phuric
. Journal of applied microscopy and laboratory methods. icro-chemical detectionof aluminum : I. Cesium Ammonium Fluoride. III. Primary Potassium Sulphate. IV. Staining Aluminum Hydroxide with Dyes. /. Cesium Sulphate added to solutions containing Aluminum SuIpJiate leads tothe formation of Cesium Almn. Al2(S04)3 + CS2SO4 = [AL^CSOJ;, . Cs.^S04 • 24H,0]. Method.—To a drop of the solution to be tested, add a drop of ammoniumhydroxide. Draw off or filter off the supernatant solution. Wash the precipitateonce with water. Then add a single drop of water and a trace of dilute sul-phuric acid, only just enough to dissolve the aluminum hydroxide. Warmgently; cool, and to the drop add a fragment of the reagent. After a fewseconds, beautiful large crystals of cesium alum separate (Fig. To). The crystalsare regular octahedra, and the usual combinations of octahedron and cube, etc. Remarks.—Cesium chloride can be employed as reagent, providing that thesolution to be tested contains a little free sulphuric acid. The chloride is, how-. and Laboratory Methods. 15:>1 ever, not as satisfactory as the sulphate, particularlyin the hands of beginners, for cesium chloride crystal-lizes in the isometric system, thus sometimes leadingto confusion. Cesium sulphate, on the contrary,crystallizes in the orthorhombic system. An examina-tion of a preparation with the latter salt, betweencrossed nicols, will therefore permit of an easy differ-entiation between crystals of cesium sulphate andthose of cesium alum. Cesium sulphate is not found in the list of reagentsheretofore given. It is made from the chloride asfollows: Place a drop of sulphuric acid at the cornerof a slide or on platinum foil. Add a small crystal of cesium chloride, andevaporate to dryness. If no fumes of sulphur trioxide escape, add another dropof acid and heat again. It is evident that by this method of treatment, in themajority of cases, it is primary cesium sulphate that is formed, and not thenormal su
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