1846.] Alluvial i^oil of the Mle. 145 



a little mica, and a few fragments of tubes, such as are seen trav- 

 ersing the older portions of the soil already examined. This 

 composition indicates that this specimen has resulted from the 

 decomposition of primitive rocks, and that their debris has been 

 mixed with some portion of the anterior deposits along the river 

 banks. 



Analysis. 



1. Dried 100 grains and found the loss, 3.7 grains. 



2. Transferred the same to a well closed platinum crucible, and 

 ignited; which caused an additional loss of 3.57 per cent. The 

 powder having now a dull reddish gray color, was again heated, 

 and with access of air, stirring occasionally with a platinum 

 spatula, to facilitate the complete combustion of organic matter. 



By this treatment the additional loss was .13 grain, showing 

 the organic matter in the soil to be 3.70 per cent. To ascertain 

 what part of the matter was soluble, a secoml portion of 100 

 grains was placed in a green glass matrass and boiled for an hour, 

 with three ounces of a saturated solution of caibonate of ammo- 

 nia; the clear liquid was decanted, and a second portion of the 

 carbonate added, boiling as before, and in the same way a third 

 portion was subsequently added. The solution being acidulated 

 with acetic acid, acetate of lead was applied, producing when 

 dried, 4.7 grains of crenate of lead, equivalent to 2.28 grains of 

 crenic acid, and showing the insoluble organic matter to be 1.42 

 grains. 



3. Placed the reddened powder of the first ICO grains in a mat- 

 rass, and poured over it an ounce of pure water and half an ounce 

 of pure chlorhydric acid; boiled half an hour, decanted the clear 

 liquid, put in another ounce of water and half ounce of acid, 

 boiled for the same length of time, decanted once more and re- 

 peated the operation — then filtered, washed carefully, ignited and 

 weighed the residue, found it 70.2 grains, showing that 22.4 

 grains of matter have been dissolved by the acid. 



4. The solution in chlorhydric acid, reduced to a convenient 

 bulk, was boiled with a little nitric acid, to peroxidize the iron, 

 by which it was changed from greenish yellow to a fine deep red 

 color, and while still hot, precipitated with pure ammonia, boiled 

 to condense the precipitate, filtered, washed for more than 24 

 hours, and until all alkaline reaction ceased. 



5. The precipitate was boiled in a strong solution of caustic 

 potash, until the clear liquid yielded with chlorhydric acid the 

 usual indications of a sufficient excess of alkali. 



6. The remaining precipitate of oxide of iron was filtered and 

 washed for 12 hours, with hot water, separated, dried, and ignited 

 sufficiently long to reduce the whole to the state of peroxide, 

 which then weisfhed 9.18 sfrains. 



