1846.] Alluvial Soil of the Mle. 141 



ALLUVIAL SOIL OF THE NILE. 



The following report of the examination and analyses of the 



alluvial soil of the Nile, from Korosco, in Nubia, was read before 



the Academy of Natural Sciences of Philadelphia, by Walter 



R. Johnson, and published in the proceedings of the Society: 



The specimens about to be described are the same which were 

 on the 21st of January last presented to the Academy, by Mr. 

 Gliddon, from Dr. Richard Lepsius of Berlin, then in Egypt, (see 

 proceedings of the Acad. vol. 2, p. 195,) and referred to the re- 

 porter for examination. 



No. I. — Earth of the Mile taken from the summit of hillocks at 

 thirty feet above the ■present level of the river about a mile above 

 Korosco. 



This earth is partly in powder and partly in lumps. In some 

 of the latter, distant traces of folia, or plies, marking an imper- 

 fect stratification, are to be seen. Along these seams fractures 

 often occur. Throughout the lumps are to be observed innumera- 

 ble cavities or spiracles of a tortuous form, giving the impression 

 of having been produced by some species of vermes, i'tlany of 

 these are lined, and some nearly filled up with carbonate of lime. 

 Tubes of the same material are found in a separate state, and 

 some plane surfaces are covered with it. The whole has a light, 

 spongy appearance, and the resemblance is strengthened by the 

 vermicular cavities, which remind one of the v;hite tubes often 

 found traversing masses of common sponge. Very fine micaceous 

 particles are distributed pretty copiously through the masses, dis- 

 tinctly perceptible to the eye, and clearly exhibiting their forms 

 under the lens. To the naked eye no ferruginous appearance is 

 discernible, but the microscope shows innumerable points of a deep 

 red color. The mud appears to have been deposited at successive, 

 but not very distant periods; while soft, to have been penetrated 

 by myriads of animalculse; then dried and baked into a solid 

 mass, imprisoning and destroying the animals, and forming a very 

 porous soil, which, on subsequent exposure to water, strono-ly im- 

 pregnated with lime, received so much of the latter as to fill up 

 many of the pores when the water came to be dried up. 



Analysis. 1. The existence of roots, stems, or of any other 

 fibrous matter was sought for in vain in this specimen, and the 

 magnet separates from it, only minute quantities of magnetic 

 oxide of iron. 



2. Fifty grains placed in a syphon-shaped drying tube in which 

 it was exposed to a heat of 212° for thirty minutes, and over 



