540 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



sum or plaster) or a solution of lime in carbonated water, or 

 the sprinkling of these salts dry on the wet surface, where 

 they speedily dissolve, coagulates the clay as rennet curdles 

 the casein of milk i. <?., the lime-salts separate the clay atoms 

 from the water in which they were suspended, and shrinks 

 them together into distinct curd-like masses. Thus the clog- 

 ged pores between the sand-grains are opened and channels 

 formed which permit the clear water to run off." 



Reasons for Effects of Lime and Mineral Salts on Clay Soils. 



"The coagulation of clay by soluble saline matters assists 

 in explaining some facts long, if not widely, known in agri- 

 culture. It has been found in some regions of Germany that 

 the application of lime to clay lands is an effectual means of 

 loosening the texture of even the stiffest soils. It is doubt- 



CD 



less the bicarbonate of lime which acts in this case. The ef- 

 fect lasts for only a term of years, because the lime gradu- 

 ally dissolves away ; and as it disappears from the surface, 

 the clay recovers its original impervious quality. Mr. D. G. 

 Mitchell, of Edgewood, near New Haven, has found that a 

 soggy and nearly worthless hill-slope has become dry and 

 valuable for pasture, mainly as the result of an application 

 of lime. Mr. Lawes, the veteran English experimenter, in- 

 forms us that the continued use of nitrate of soda for many 

 years as a fertilizer on clay land has noticeably improved its 

 texture and relieved its heavy quality. The often-observed 

 good effects of spreading out stable-manure on the ground 

 during winter in improving the texture of the soil at time 

 of spring tillage may be due in part to the effect of the solu- 

 ble salts in coagulating the clay and preventing the clog- 

 ging and puddling of the soil." 



CHEMICAL PROPERTIES OF THE SOIL. SOIL-ABSORPTION. 



It should, perhaps, be said, by way of preface, that the ab- 

 sorptive power of the soil, and its ability to hold the valuable 

 ingredients of plant-food ammonia, potash, lime, phosphoric 

 acid, etc. and not suffer them to be leached away through 

 its lower layers into streams and lost, is one of the chief fac- 

 tors of its fertility. It is believed that the absorption of 

 bases is due mainly to zeolitic silicates, hydrous silicates of 



