LIMK AS A MANURE. 219 



whole, hcinij the cause of tlio absorptive property, was inconsis- 

 tent Willi all the asccrtaint-d laws of chemical coniliination." 



After a series of experiments, Prof. Way came to tlic couclusioa 

 that there is iu clays a peculiar class of double silicates to which 

 the absorptive properties of soil are due. lie found that the double 

 silicate of alumini and lime, or soda, whether found naturally in 

 soils or produced artiticially, would be decomposed when a salt of 

 ammonia, or poUish, etc., was mixed with it, the ammonia, or pot- 

 ash, taking the place of the lime or soda. 



Prof. Way's discovery, then, is not that soils have " absorptive 

 properties" — that has been Ion? known — but that they absorb am- 

 monia, potash, phosphoric acid, etc., by virtue of the double sili- 

 cate of alumina and soda, or lime, etc., which they contain. 



Soils are also found to have the power (»f absorbing ammonia, 

 or rather carbonate of ammonia, from the air. 



" It has long been known," says Prof. Way, " that soils acquire 

 fertility by exposure to the influence of the atmosphere — hence one 

 of the uses of fallows. * * I find that clay is so greedy of ammonia, 

 that if air, charged with carbonate of ammonia, so as to be highly 

 pungent, is passed through a tube filled with small fragments of 

 dry clay, every pi rt.'cle of (h? g is is arrested." 



This power of the soil to absorb ammonia, is also due to the 

 double silicates. But there is this remarkable difference, that while 

 either the lime, soda, or potas'.i silicate is capable of removing the 

 ammonia from solut'on, the lime silicate alone has the power of ab- 

 sorbing it from the air. 



This is an important fact. Lime may act beneficially on many 

 or most soils by converting the soda silicate into a lime silicate, or, 

 in other words, converting a salt that will not absorb carbonate of 

 ammonia from the air, into a salt that has this important property. 



There is no manure that has been so extensively used, and with 

 such general success as lime, and yet, " who among us," remarks 

 Prof. Way, " can say that he perfectly understands the mode in 

 which lime acts ? " We are told that lime sweetens the soil, by neu- 

 tralizing any acid character that it may possess ; that it assists tJ3 

 decomposition of inert organic matters, and t'lerefore increases the 

 supply of vegetable food to plants : that it decomposes the remains 

 of ancient rocks containing potash, soda, magnesia, etc., occurring 

 in most soils, and that at the same time it liberates silica from these 

 rocks; and lastly, that lime is one of the substances found uni- 

 formly ana in considerable quantity in the ashes of plants, that 

 therefore its application may be beneficial simply as furnishing a 

 material indispensable to the substance of a plant. 



