Dec, 1845.] 323 



hydrate of ammonia, and obtained calcined precipitate from the .3 grain of 

 oxide of manganese. 



11. A third portion of 100 grains of the soil, treated for carbonic add with all 

 the precautions of boiling the liquid, and alternately cooling off ten times, until 

 the pure baryta showed no more carbonic acid, and the successive weighings 

 gave identical results, the quantity of that ingredient was found to be only 

 1-4 grains. Hence the soil is composed of 



Moisture, .... 3.70 per ct. 



Carbonic acid, - 1-40 



Organic matter, ... 3.70 viz: 



Insoluble silicates, - - - 70.20 



Oxide of iron, . . - 8.76 



Alumina, ... - 6-55 



Lime, .... 3.80 



Oxide of manganese, • - - .30 



Magnesia, - - - - 1.89 



Phosphate of lime, - - - .15 



Soluble 2.28 

 Insoluble 1.42 



100.45 



The excess is here attributable in part to the peroxidation of the iron, which 

 in the soil is partly in the state of magnetic oxide, and in part to the pre- 

 sumed slight amount of potash still adhering to the oxide and alumina. 



Sand taken from the thermal spring at Okme, on the Southern frontier of the 

 Province of Butir-el-Hagar, on the Western bank of the Nile — where the 

 temperature of the water is 131° Fah. 



This sand obviously contains the debris of granitic rocks. Particles of 

 quartz and mica are very abundant, and the magnet takes up a notable portion 

 of magnetic oxide of iron. Particles of highly ferruginous clay ars inter- 

 spersed among it, resembling crumbs of bog iron ore, and leading to the 

 supposition that the heat of the spring is occasioned by the decomposition 

 of pyritius rocks, whose insoluble debris it brings in minute portions to 

 the surface. The gauze sieve already mentioned retains 25 per cent, of this 

 sand, including nearly all the particles of ferruginous clay. The portion 

 which passes the seive, resembles, in almost every particular, the sandy por- 

 tion washed out of the newly deposited soil, except of course the different 

 degree of its fineness. Both have particles of red and wmite quartz, both 

 show magnetic oxide of iron, the sand of the spring in the greater abundance. 

 It is remarked that the particles of this oxide in the portion of sand which 

 passes the sieve, is far greater than in that which remains upon it, which we 

 might anticipate, on the supposition that the sand is brought up by the spring. 

 The greater specific gravity of the particles of oxide than that of the quartz, 

 would allow larger masses of the latter than of the former to be thrown up 

 by a current of given velocity. 



