In 1913 the late Mr. J. J. Beringer suggested that it would be of interest to determine the solubility of crushed felspar (a) in distilled water free of carbon dioxide, and (b) in distilled water saturated with carbon dioxide. For this purpose crushed felspar (orthoclase) was covered with water in a silica basin (i) in a desiccator containing potassium hydroxide solution, and (ii) in a desiccator connected with a carbondioxide Kipp's apparatus. These were allowed to stand for a fortnight and the alkalinity of the water Was then determined by N/100 hydrochloric acid. This experiment was continued until the end of July, 1914. A definite solubility was determined in each case and the solubility in the carbon dioxide water was only slightly more than in the water free from carbon dioxide. Unfortunately Mr. Beringer died early in 1915, and the records of his experiment could not be found.