58 CLASSIFICATION OF SOILS. 



Some definite rules of this kind might prove quite 

 useful to farmers in describing soils. 



Prof. Johnston has proposed the following : 



1. Pure clay, such as pipe clay or porcelain clay; from 



this no sand can be removed by washing. 



2. Strong clay, brick clay, contains from 5 to 20 per 



cent of siliceous sand. 



3. Clay loam has from 20 to 40 per cent of fine sand. 



4. A loam, has from 40 to 70 per cent of sand. 



5. A sandy loam, has from 70 to 90 per cent. 



6. A light sand has less than 10 per cent of clay. 



This classification may easily be made by means of 

 simple washing. The soil should first be dried, and 

 then after boiling in water should be thoroughly stirred 

 in some convenient vessel. The sand will settle first, 

 and when it is at the bottom, the liquid above, hold 

 ing the fine clay, etc. in suspension, may be poured 

 off; when this has been done a few times, nothing 

 will remain at the bottom of the vessel, beside nearly 

 pure sand; this may be dried and weighed, and the 

 quantity will indicate to which class of the above the 

 soil belongs. 



It is always possible to ascertain if there be much 

 lime in a soil, by adding a little muriatic acid, such 

 as may be obtained at any apothecaries. This acid, as 

 soon as it comes in contact with the lime, if there be any, 

 causes a brisk effervescence, owing to the bubblings up 

 and escape of carbonic acid gas, which is expelled 

 from its combination with lime by a stronger acid. It 

 is easy in this way to ascertain if any specimen of earth 

 is a marl or not. Such a simple test would often save 

 the farmer much trouble and expense, by preventing 

 him from applying useless material to his soil for the 

 purpose of fertilizing it. The distinctions between 

 light and heavy soils, so common among farmers, all 



