The Neglect of ChemUtry hy Practical Farmers. 437 



lime, as thereby the excess of humic-acid, that is always present 

 in such soils and is so hurtful to vegetation, is neutralised and 

 rendered inert, in the form of an insoluble salt. 



Soluble Salts. — The reader will notice that, in the heading of 

 the soluble salts, rain-water is mentioned, and not simply water. 



Bain-icater. — My reason for so doing, although it has never 

 been adopted by agricultural chemists, has been, that the farmer, 

 in his farming operations, has only to deal with this kind of 

 water, with regard to his manures, 6cc. ; and, from the fact of its 

 always containing some carbonic-acid dissolved in it, its solvent 

 powers are far greater than those of pure waters — so much so, that 

 it has been proved that scarcely any rock can withstand its influ- 

 ence, when continued through successive ages. 



I have not, however, noticed this latter power in arranging the 

 degrees of solubility of the different salts, but have only included 

 those which are so readily soluble as to be available for the 

 farmer's present use. 



Abundantly J Sparingly, Sf^c. — I have divided them into the 

 ' abundantly ' and ' sparingly ' soluble salts. 



The first is supposed to include the sulphates, phosphates, 

 and carbonates of the alkalies ; the chlorides, sulphate of magnesia, 

 and sulphate of iron, and phosphoric acid in the state of a super- 

 salt. The sparingly soluble include silica, sulphate of lime, 

 carbonate of lime, and carbonate of magnesia. Phosphate of lime 

 is very sparingly soluble in rain-water, but I have not considered 

 it sufficiently so to be classed with them. The carbonates are 

 totally insoluble in pure water, but are readily soluble when com- 

 bined with an extra dose of carbonic-acid ; and therefore the 

 degree of solubility they possess in rain-water depends upon the 

 amount of carbonic-acid that it may hold in solution. 



It must be remembered, that the analysts against whose names 

 these quantities appear, have not themselves stated the amount of 

 the soluble salts, and I have been guided solely by the names 

 of the salts, as given in their analyses, and therefore they may not 

 be always practically correct. 



It is certainly greatly to be desired that chemists should give 

 more attention to this hitherto neglected part of their investigation, 

 as, from a\Y that we know at present (though the present researches 

 of Professor Way on the absorbent powers of soils with regard to 

 manures, may throw some light on this obscure subject), it appears 

 that the soluble salts alone are in a fit state to be assimilated by 

 plants. 



Form 4. — There is a slight variation in the title of the fourth 

 part of the table on ' Liquid jNIanures.' Instead of giving the 



