Excerpt from Chemical Gazette, or Journal of Practical Chemistry, Vol. 5: In All Its Applications to Pharmacy, Arts and Manufactures; 1847 On the Precipitation and Separation of Alumina and Peroxide of Iron. By Dr. W. Knop. In the precipitation Of the peroxide of iron and alumina by am monia, and their subsequent separation by potash, it is a matter of common experience that these two oxides are extremely difficult to obtain perfectly free from one another. It was to be expected that a more perfect separation would be obtained if this mutual affinity were destroyed previously by combining one of the two substances with some other body. When the precipitate Of hydrated oxide of iron and alumina is boiled with potash with the addition of a suitable quantity of sulphuret of ammonium, until the liquid, which at first appears green, deposits, after being left quiet for a time, some black flakes, and appears yellowish, owing to the formation Of a slight ex cess of sulphuret Of potassium, and no longer passes green through the filter, which is very soon attained, the alumina, on subsequent precipitation, is Obtained on slow desiccation as a transparent mass, and on quick drying and calcining of such a pure white colour as to leave no doubt of its being extremely pure. If we add to this the observations recently published by Malaguti and Durocher*, with respect to the complete precipitation of alumina, which was found to be most perfect under all circumstances with sulphuret of ammo nium, it is evident that these two oxides should, when it is prae ticable, be directly precipitated with sulphuret of ammonium, the precipitate washed with water containing a little sulphuret of ammo nium, and the alumina extracted with potash to which a few drops of sulphuret of ammonium have been added, in order to obtain at once a perfect precipitation and separation of these two bodies. Journ. Fitr Praht. Chem, Oct. 9, 1846. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.