1885.] Report on the Deposits of the Nile Delta. 221 



dry for study by reflected light; a second specimen from each was 

 mounted in Canada-balsam, so as to allow of the internal structure 

 and optical properties of the sand-grains being studied. 



The fine particles composing the several samples of mud were so 

 mounted as to be capable of examination by transmibted light, with 

 the highest powers of the microscope. 



The results obtained in the case of each sample were as follows : — 



I. Boring at Kasr-el-Nil, Cairo. 

 Sample 1. Depth, 6 ft. 



Loam of a dark reddish-brown colour. Contains 5* 77 per cent, 

 sand, 94*33 per cent. mud. 



Sand. — Dark coloured ; includes fragments of red brick, green glass, 

 straw, rootlets, and other vegetable matters. Rounded grains of 

 white quartz, evidently derived from granitic rocks, with a few of 

 jasper and rose-quartz ; angular or subangular grains of quartz, 

 hornblende, &c, with many of fine-grained, impure sandstone. 



Mud. — Much vegetable matter, with frustules of diatoms. Minute 

 chips and flakes of quartz and other minerals, with plates of biotite. 



Sample 2. Depth, 16 ft. 



Very sandy loam, of pale reddish-brown tint. Contains 86*27 per 

 cent, sand, and 13*73 per cent. mud. 



Sand, composed of about equal portions of well-rounded and angu- 

 lar or subangular grains. It is of a white or slightly yellowish tint. 

 The rounded grains consist of white (granitic) quartz, rose-quartz, 

 and red, brown, and black jasper ; with pebbles of slightly kaolinised 

 orthoclase felspar. The angular and subangular grains consist of 

 quartz, felspar, hornblende, sphene, and magnetite. 



Mud. — Appears to be largely made up of chips and flakes of the 

 above minerals with biotite. 



Sample 3. Depth, 17 ft. 6 in. 



Very sandy loam. Consists of 79*65 per cent, sand, 20*35 per cent, 

 mud. 



Sand. — Very similar to last sample, but the well-rounded grains 

 are fewer, and the angular and subangular ones more numerous. 

 The latter consist of quartz, orthoclase, plagioclase-felspar (rare), 

 hornblende, augite ; also black and brown jasper. 



Mud. — Similar to last sample. 



Sample 4 Depth, 38 ft. 6 in. 



Sandy loam. Consists of 65*05 per cent, sand, and 34*95 per cent, 

 mud. 



