Note 9 — Chapter XVIII · SILICON AND THE OTHER ELEMENTS OF THE FOURTH GROUP
George Kamensky translation
The amount of heat developed by the solution of silicic acid, SiO2nH2O, in aqueous hydrofluoric acid, xHFnH2O, increases with the magnitude of x and normally equals x5,600 heat units, where x varies between 1 and 8. However, when x = 10 the maximum amount of heat is developed (= 49,500 units), and beyond that the amount decreases (Thomsen).