36 



11th. Why a rotation of manures, as it is called by 

 practical men, is necessary and where. 



12th. That the use of lime to a certain extent, and in 

 a prudent way, is necessary to the highest fertility. 



13th. That saline and nearly all other manures, do 

 more good upon light and open, than they do upon stiff 

 and close soils, and why. 



14th. How to economise the consumption of vegetable 

 food, and to adapt it to the purpose for which an animal 

 is fed. 



] 5th. How to prevent the disease called ^w^er^ and toes, 

 in turnips and other roots, and how to render mildew and 

 ague equally rare? 



To do these and many similar things economically, 

 skilfully, and with more or less success, are among the 

 practical ends to which chemical investigations have al- 

 ready led us. 



They also supply answers to many practical questions, 

 such as : — 



1st. Why cabbage crops so greatly exhaust the soil, and 

 how such exhaustion is to be repaired ? 



2nd. Why tares cut green exhaust the land, and give 

 inferior wheat ? 



3d. Why tares are seldom good after crops of clover ? 



4th. Why lime produces a more marked benefit on one 

 soil than it does upon another ? 



5th. Why one variety of lime is more useful generally, 

 or in particular districts on particular farms and fields, than 

 another ? 



Of special points and questions, I could enumerate 

 many more, in regard to which chemistry may be said to 

 have been, or to be capable of becoming, of obvious money 

 value to the fanner. Even to such of you, however, as 

 have not much attended to this subject, the above ex- 



