T e c h n i c a1 C h e m i s t r y. Clarification of Turbid River Water. By LUEGER (BingZ. polyt. J., 254, 233--242).-The author discusses in detail the purification of water by filtration through sand. He states that the 1)rohlem to be solved requires the settlement of the following questions :--(1) Is the existing sand adapted for the clarification of turbid water? (2) At what pressure (head of water) is the complete clarification effected ? and (3) What is the magnitude of the total

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... surface for a certain quantity of wat8er t o be filtered ? An important element in the success of the filtration of water through sand is the uniformity in the size of the grain of the sand. Sand differing in its degree of fineness admits of the filling up of the l~ollow spaces between the coarser grains by the finer particles, so that eventually the filtering surface is rendered impermeable by water. Recovery of Hydrochloric Acid as a Bye-product in the Ammonia-soda Process. By L. MOND (Dingl. polyt. J., 254, 220). -The liquors resulting from the separation of the bicarbonate are heated in a distillation apparatas t o remove all volatile salts of ammonia. lnstead of treating the fixed salts of ammonia with lime,