204 ANNUAL OF SCIENTIFIC DISCOVERY. 



the clay contained in them. Filtration is only a method of exposing 

 the liquid in the most perfect form to the action of the clay, but it is 

 not necessary to the success of the process. In proof of which, Mr. 

 Way stirred up a quantity of soil with putrid human urine, the smell 

 of which was entirely destroyed by the admixture, and upon the sub- 

 sidence of the earth, the liquid was left clear and colorless. It appears, 

 therefore, that the clay of soils has the power of separating certain 

 animal and vegetable ingredients from solution ; but is this property 

 the only one exhibited ? Mr. Way had found that soils had the power 

 to separate also the alkalies, ammonia, potash, soda, magnesia, &c. 

 If a quantity of ammonia, highly pungent to the smell, is thrown upon 

 a filter of clay or soil, made permeable by sand, the water first coming 

 away is absolutely free from ammonia. Such is the case also with 

 the caustic or carbonated alkalies, potash, or soda. A power is here 

 found to reside in soils, by virtue of which not only is rain unable to 

 wash out of them those soluble ingredients forming a necessary con- 

 dition of vegetation, but even those compounds, when introduced arti- 

 ficially by manure, are laid hold of and fixed in the soil, to the absolute 

 preclusion of any loss either by rain or evaporation. 



Mr. Way has found that this property of clay applies not only to 

 the alkalies and their carbonates, but to all the salts of these bases, 

 with whatever acid they are combined. Here again is a beautiful 

 provision ; sulphate of ammonia, when filtered through a soil, leaves 

 its ammonia behind, but the sulphuric acid is found in the filtered 

 liquid ; not, however, in the free state, but combined with lime ; thus 

 sulphate of lime is produced, and brought away in the water. In the 

 same way muriate of ammonia leaves its ammonia with the soil, its 

 acid coming through in combination with lime, as muriate of that 

 base. The same is true of all the salts of the different alkalies, so far 

 as he has yet tried them. Thus lime in the economy of nature is des- 

 tined to one other great office besides those which have already been 

 found for it, it is the means by which the salts ministering to 

 vegetation become localized and distributed through the soil, and are 

 retained there until they are required for vegetation. Quicklime, when 

 dissolved in water, is removed by passing the water through clay or 

 through moist soils containing clay ; and carbonate of lime in solution 

 is so effectually removed, that hard water may be softened by the same 

 process. 



With regard to the extent to which these actions are capable of 

 being carried, it is not to be supposed that we could go on filtering 

 indefinitely with the separation of the salts contained in the liquid. 

 On the contrary, the limit is soon reached ; but although small in per- 

 centage quality, this power is, in reference to the bulk of the soil, 

 enormously great. Prof. Way has found that 1,000 grains of pure 

 clay will separate 2 grains of ammonia, and a cultivated clay soil, 

 for obvious reasons, nearly twice as much. Now an inch in depth 

 of soil over an acre of ground weighed about 100 tons, and would be 

 adequate to combine with and retain 2 tons of ammonia, a quantity 

 which would be furnished by about 12 tons of guano. Now, one six- 

 tieth of this power would suffice for the preservation of the ammonia 



