Minute Ingredients of Soil. 435 



Finding a difficulty in appreciating the relative qualities of the soils 

 analysed, I set my&elf to discover some easy method of reducing his 

 quantities into pounds weight per English acre, hoping it might be of 

 some practical utility, in forming an idea of what sort and quantity of 

 manure any given soil would require, 



I therefore took the specific gravity (from an old table I had at hand) 

 of various earths, rocks, and minerals, and arrived at the conclusion that 

 the surface of a statute acre, 1 foot in depth, may be fairly estimated on 

 an average to weigh 7,000,000 of lbs., or 3125 tons. This would give 

 5,000,000 lbs. as the weight of the surface of an acre 8^ inches deep 

 (or Sf in.), or 4,000,000 lbs. at a depth of nearly 7 inches (6f in.). I 

 give you the calculation at foot. 



The simplest way to look at Liebig's analysis of soils is to read the 

 figures as whole numbers, and consider them to represent so many lbs. 

 in every 100,000 lbs. weight of soil. Then if you multiply any of the 

 quantities by 40, it will give the lbs. weight of the ingredient throughout 

 an acre to the depth of 7 inches; if multiplied by 50, the weight 

 throughout an acre to the depth of 8J inches ; and if multiplied by 70, 

 the weight throughout an acre to the depth of 1 foot. 



I will give two examples from the second edition of Liebig's work : — 



Analysis of a fertile Soil, page 229, No. 27. ' 



Per 100 parts I'^r acre at 8^ 



(in decimals). "Z,"^'^ f P* ^ 



^ -^ throughout. 



Silica and very fine silicious sand . . . 79*174 3,958,700 



Alumina (p. 87) 3*016 150,800 



82-190 4,109,500 



Peroxide of iron (p. 87) 4*960 248,000 



Peroxide of manganese * 600 30,000 



Carbonate of lime (pp. 98, 99) . . . 2*171 108,550 



Carbonate of magnesia (p. 149) . . . 2*226 111,300 



Potash, in combination with silica (p. 143) . 0*025 1,250 



Soda, ditto (pp. 98, 99) 6*349 317,450 



Phosphoric acid (pp. 144 and 148) . . 0*534 26,700 



Sulphuric acid a trace 



Chlorine 0*005 250 



Humus soluble in alkalies 0*782 39,100 



Ditto with nitrogenous matter . . . . 0*158 7,900 



This may be read as either 100 parts, or] t/ah-aaa e aaa nr^A 



100,000 lbs . .jlOO^^'^O 5,000,000 



Analysis of a sterile Soil, page 211, No. 5. 



Silica with coarse silicious sand . . . 95 '843 4,792,150 



Alumina 0*600 30,000 



96*443 4,822,150 



