[SUPER- 12 b.]
1. Chem. A phosphate containing an excess of phosphoric acid; an acid phosphate.
1797. Pearson, in Phil. Trans., LXXXVIII. 17. It was … Scheele who discovered, that the urine of healthy persons contains superphosphate, or acidulous phosphate, of lime.
1811. A. T. Thomson, Lond. Disp. (1818), 479. By the strong acids it [phosphate of soda] is converted into superphosphate of soda.
1876. Harley, Royle’s Mat. Med. (ed. 6), 62. When the superphosphate is heated with charcoal, tribasic phosphate is re-formed, and phosphoric acid set free.
2. In full superphosphate of lime: an impure superphosphate of lime prepared by treating bones, coprolites, etc., with sulphuric acid, and used as a manure.
1843. W. Hay, in Farmer’s Mag., Jan., 42/2. By the action of sulphuric acid on bones a superphosphate of lime is produced.
1861. Times, 10 Oct., 10/1. Swedes, manured and sown with guano and superphosphate.
1868. Rep. U.S. Commissioner Agric. (1869), 221. A hundred and fifty to a hundred and seventy-five pounds of superphosphate [is] strewn in the furrows to be ridged over.
1879. Cassell’s Techn. Educ., II. 198/2. Mineral superphosphate is prepared by pouring sulphuric acid … on phosphorite or coprolites.
