1905 G. S. Newth (ed. 11) 637 By the partial withdrawal of water from three molecules of silicic acid a number of hypothetical trisilicic acids may be derived... Felspar, or orthoclase, is a trisilicate, Al2K2(Si3O8)2.
1911 H. E. Roscoe & C. Schorlemmer (ed. 4) I. 920 Derivatives of trisilicic acid, H4Si3O8[3Si(OH)44H2O].