The cementation process (grouting) is applicable for both fissured rock and soft ground carrying much water, and has been used successfully in sinking a number of shafts, chiefly in Great Britain, Belgium and South Africa. Some of this work has been at depths of 1,200 to 1,600 ft. The process consists in injecting cement grout, under pressures of i,000 to 3,000 lb. per sq.in., through boreholes into the watery strata. The cement on setting consolidates the ground, which is then drilled and blasted with little trouble from water. Two methods are employed: (I) the boreholes are put down inside of the perimeter of the projected shaft ; the boreholes are outside of the perimeter, as for the freezing process. In the first method the ground is treated to a predetermined depth, the shaft being sunk and lined to that depth, after which another set of holes is drilled from the shaft bottom to a greater depth and the process repeated.
BIBLIOGRAPHY.-Sinking in Rock.-Peele's Min. Engrs.' Handbook, 2nd ed. (1927) sec. 7; Coll. Guardian, Feb. 12, 1926 and May 28, 1926 ; Trans. Instn. Min. & Met., vol. xv., P. 333 and vol. xxx., p. 243 ; Trans. Amer. Inst. Min. Engs., vol. xlvi., p. 151; North of England Inst. Min. & Mech. Engs. (1927) ; U.S. Bur. of Mines, Tech. Paper,
276; Coll. Eng'r, vol. iii. (Aug.-Nov., 1926) ; Coal Age, Sept. 13, 1923, p. 397 ; Eng. & Min. Jour., Mch. 26, 1921, p. 537, May 21, 1921, p. 862, Oct. 23, 1926, p. 657, Feb. 1o, 1923, p. 265; E. 0. F. Brown, Vertical Shaft Sinking (1927) ; South African Practice for Deep Shaft, Min. & Sci. Press, Apr. 26 and May 3, 1913. Kind-Chaudron Process: Proc. Instn. Civ. Engs., vol. lxxi., p. 178; North of England Inst. M. & M. Engs., vol. xx., p. 187 ; Rev. Univ. des Mines, Oct. 19o2. Sinking in Watery Strata.-J. Riemer, Shaft Sinking Under Difficult Conditions (transl. by Corning and Peele) ; Min. Engrs.' Hand book, 2nd ed., sec. 8 (1927) ; Bull. Soc. de find. Min. (1903) ; Trans. Amer. Inst. Min,. Engs., vol. xx., p. 188. Drop Shafts: Coll. Eng'r., Jan. 1915 ; Eng. & Min. Jour., Sept. 29, 1923, p. 535. Freezing Process: Coal Age, June 5, 1924, p. 831; Coll. Guardian, Sept. 28, 1917, Feb. 4, II and 18, 1927; Instn. Min. Engs., Jan. 1917. Cementation Process: Chem., Met. & Min. Soc. of So. Africa, vol. xviii., p. 256 and vol. xvix., p. 145; Instn. Min. Engs., 1925; Coll. Guardian, Mch.
2 and 9, 1917; Ann. des Mines, vol. xviii., p. 379. (R. PE.)