224 Analysis of Soils. [Oct., 



double filters. Per-oxide of iron and alumina are thus collected 

 on the filter, and if the soil contained oxide of manganese it will 

 also be thrown down with the per-oxide of iron. Phosphate of 

 alumina and phosphate of iron are thrown down also. Wash the 

 filter thoroughly wuth boiling hot distilled water, and when the 

 soluble matters are all washed out, (as may be known by collect- 

 ing a drop of the liquor from the funnel neck on a piece of plati- 

 num foil and evaporating it to dryness) dry the filters, separate 

 them, burn them separately, and w^eigh; the w^eight is that of 

 the per-oxide of iron and alumina. This may be set down for 

 the present, but this matter is to be farther analyzed, as will be 

 described presently. The alumina and per-oxide of iron might 

 have been separated while in their gelatinous state, by the action 

 of a boiling solution of pure potash, but we should have lost the 

 advantage of a check weight, which is gained by weighing them 

 as mixed. 



Having noted the weight of the alumina and per-oxide of iron 

 which we will call 5 grains, we have next to separate the lime 

 from the ammoniacal solution, filtered from the per-ox. iron &c. 

 For this purpose add a sufficiency of a solution of oxolate of am- 

 monia, to precipitate all the lime as an oxalate, which may be 

 known by observing when more of the oxalate of ammonia is 

 added, that no white precipitation is produced. When this is the 

 case, set the flask in a warm place, say in the drying closet or on 

 the furnace plate, and let the precipitate have time to form and 

 subside. This will generally take place in a single night. We 

 then filter on double equal filters, and wash and dry as in the pre- 

 ceding cases. Then burn the oxalate of lime at a dull cherry 

 red heat, and it is converted into carbonate of lime. If a higher 

 temperature is employed, part of the carbonic acid may have 

 been driven off, and if such is the case, it is necessary to add a 

 few drops of a solution of carbonate of ammonia to the burned 

 lime, and to heat it again to dull redness. The weight of car- 

 bonate of lime obtained is set down, and after we have determined 

 in what state it existed in the soil, we calculate those salts of 

 lime, and express the proportions as deduced from the carbonate 



