114 SCIENCE OF AGRICULTURE. 



Carbon is the combustible part of charcoal, enters 

 largely into mineral combinations, is a constituent 

 part of all vegetables; and the most rare and valua- 

 ble of all precious stones, the diamond, is pure 

 carbon. Oxygen combines with all metals, and 

 other inflammable or combustible substances, and 

 forms a great variety of bodies called oxyds, oxyd of 

 iron, oxyd of lead, &.c. 



The next ingredient or constituent of soils to be 

 considered, is the salts. Salts are formed by the 

 combination of acids with alkalies, earths, and 

 metallic oxyds. The salts most frequent in soils are 

 the salts of lime, and iron, sulphate of lime, (plaster 

 of paris) and phosphate of lime are found in all soils. 

 The importance of all these constituents of soils may 

 be inferred from the analysis of vegetables stated 

 above. 



The following table shews the quantity of earths 

 and metallic oxyds, in grains, (Troy weight) obtain- 

 ed by Schraider from thirty two ounces of the seeds 

 of the following kinds of corn: 



best suited to the production of each of these kinds 

 of grain. Here you see oats must take from the soil 

 more than double the quantity of lime drawn from it 

 by wheat. Of course it will be likely to be bene- 

 fitted by a larger application of lime as a manure. 

 But it should be known and remembered that every 

 species of plant is endowed by nature with powers 

 precisely adapted to its wants. If oats need more 

 lime than wheat, 'he roots of oats have greater 



' Probably pho-sphate of lime, and carbonate of lime. Otiier chemists have found 

 in the asiies ofoats, for instance, stalks and seed being burned together in 100 parts, 

 silica 55, phoephate of lime 15, carbonate 5, potash 20, some oxyd of iron, &c. 



