400 
INDEX. 
Page 
Tanning principle, its application to tanning 81 
* quantity in different barks 83 
artificial 86 
Temperature of soils discussed 164 
Trees, habits of, discussed 236 
■ cause of their decay 226 
— — age of 229 
Urine, its use as a manure 265 
Vegetable matter, mode of ascertaining its quantity in soils 153 
its analysis 110 
decomposition of, described 246 
principles, their arrangement in plants 127 
life, phenomena of, discussed . 224 
Vegetables, their chemical composition _ 76 
• — improvement of, by cultivation 232 
renovation of the atmosphere 210 
the causes of their growth discussed 225 
Vegetation, influenced by gravitation 30 
. influence of light in 215 
progress of 202. 305 
— its effect on a soil * 322 
Veins or mines, their situations 180 
Water, absorption of, by soils 166 
its state in the atmosphere 189 
Wheat, transplantation of. 215 
- — crossing of. 233 
Wines, theory of their formation 121 
- — quantity of spirits they contain 124 
