riSPEKSION OF PHOSPHATE OF LIME IN SOIL. 139 



Accordingly, the second series of these numbers 

 expresses that if a certain quantity of ammonia in its 

 passage through the soil penetrates to a depth of 10 

 centimetres, the same quantity of potash will attain a 

 depth of 11 centimetres, and a like quantity of phosphate 

 of lime will reach 23*6 centimetres. 



In a soil like the Bogenhausen, which absorbs per 

 cubic decimetre 1098 milligrammes of dissolved phos- 

 phate of lime, let us suppose that granules of phosphate 

 of lime are dispersed, and that in one spot of the 

 ground one of these granules weighing 22 milligrammes 

 (J- of a grain) during the course of a certain time be- 

 comes soluble in carbonic acid water, and spreads in- 

 the surrounding soil ; first of all the earth immediately 

 around this granule will be saturated with phosphate 

 of lime, then as the carbonic acid remains in the water 

 and its solvent power continues, a fresh solution will 

 be formed, which will again offer phosphate of lime for 

 absorption to a wider extent of earth ; at length, when 

 the 22 milligrammes of phosphate of lime are thorough- 

 ly diffused in the surrounding earth, they will supply 

 20 cubic decimetres of earth with the maximum of this 

 nutritive substance in the form best suited for absorp- 

 tion. The rapidity with which the phosphate of lime 

 will dissolve and spread depends upon its extent of sur- 

 face ; accordingly, if we suppose the granule to be 

 converted into a fine powder, a solution will be formed 

 richer in phosphate of lime just in proportion to the 

 greater number of particles exposed within the same 

 time to the solvent action of the carbonic acid. There- 

 fore, assuming that in a certain state of greater division 

 twice or three times as much is dissolved in a given 



