220 Analysis of Soils. [Oct., 



of their extent in referring to that time when large masses of 

 primitive rocks were removed from their original beds far into 

 the adjacent country. These blocks are called boulders, and we 

 find them scattered about districts of primary formations, in a kind 

 of zone or belt, diminishing in size as they are the farther re- 

 moved from the parent rock. We sometimes meet with these 

 boulders upon high ranges of country; some of them are of im- 

 mense magnitude, weighing by estimation a hundred tons or 

 more, and from fiity to a hundred miles from their starting place. 

 This will open to us a discussion of the theory of boulders, which 

 in connection with the drift formation, will be our subject for the 

 next number. 



ANALYSIS OF SOILS. 



BY CHARLES T. JACKSON. 



In order to ascertain the agricultural value of a soil, it becomes 

 necessary to examine its mechanical constitution and chemical 

 composition. We may notice the integrant minerals of which it 

 is composed while making the mechanical analysis, and thus in- 

 fer its geological origin, for the mineral ingredients of all soils 

 were once solid rocks, and the integrant minerals are rarely so 

 completely decomposed as to conceal their original nature. 



In a mechanical analysis, w^e sift the soil in sieves of different 

 degrees of fineness, using always the same sieves in comparative 

 examinations of soils. The coarsest sieve may have j\ inch 

 meshes, and should be made of copper wire. The 2d sieve should 

 have ^\' inch meshes, and may be made of copper gauze. Sift 

 the soil through the 1st sieve, and weigh the gravql and grass 

 roots left upon it. Then sift the soil through the 2d sieve, and 

 weigh the sand left on that. The soil which passes through the 

 2d sieve is fine loam, which may be sandy, clayey, or calcareous. 

 The fine loam may be mechanically divided still more by stirring 

 it up with water, and after allowing the coarse matter to subside? 



