are formed on the walls of t h e storage vessels. It is necessary t o remove these deposits a t intervals of 2 t o 3 mo., as they contain an appreciable amount of ammonium salts. S U M M A R Y This permutit method of preparing ammonia-free water is applicable if distilled water is used. It has advantages over other methods of preparation in ease of operation and production of large quantities a t minimum expense. The disadvantages of the method are t h a t it gives a water of higher mineral

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... ent and does not remove nitrate, nitrite, or albuminoid nitrogen. Investigations made thus far would indicate t h a t the American permutit, except the prepared Folin permutit, will not quantitatively remove ammonia. German permutit has proved very satisfactory, and indications are t h a t the English permutit is equally efficient. There is a possibility t h a t Refinite and Boromite may possess similar properties.