112 BOARD OF AGRICULTURE. 



it is, moreover, a large ingredient of many limestone formations, 

 occupying extensive tracts in this and other countries. This 

 light metal, as you see, is capable of being made into wir6. 

 Now, it has a very curious property, which I shall try to show 

 you. [The professor here put the wire into the flame of a com- 

 mon lamp, and it burnt with great brilliancy.] You perceive 

 it burns with a very vivid combustion. The intense brilliancy 

 of the flame is due to the suspended particles of the volatilized 

 metal and its oxide produced by the combustion. This white 

 product which you see, is common calcined magnesia. The 

 process was simply this : the rusting, which is naturally very 

 slow, was here carried on with great rapidity, so as to combine 

 the oxygen in the atmosphere with this metal, and thus to 

 reproduce the magnesia from which the metal has been actually 

 manufactured. This, then, is another illustration of what we 

 have chemically in the soil. 



I have introduced these two experiments, perhaps a little out 

 of place, but they serve to show how impossible it is to investi- 

 gate one department of physical science, independently of the 

 rest — how entirely reciprocal and intermingled in their laws ase 

 all the provinces of nature and all the parts of each. Not a 

 star in the visible heavens but sends its light to every other 

 star, and is in return the recipient of radiance from all the 

 rest. 



In the. course of my various explorations of the geology of 

 portions of the United States, especially of the Middle and some 

 of the Southern States, I had particular occasion to observe the 

 relations of the soil to the subjacent rocks. I know that in 

 speaking to the farmers of this region of Massachusetts about 

 the relations of the soil in other parts of the country, they will 

 not consider that I am broaching a subject unfitting the occa- 

 sion, for we are students of the whole subject, in its largest 

 comprehensiveness and extent. 



Now, it will be observed at once that there is a character 

 which marks the surface material of the New England States, 

 and of the Northern and North-Western States generally, which 

 is quite peculiar to them as compared with the States lying 

 further to the south. It is this : that over a very large part of 

 this northern area, the soil is not at all determined by the subja- 

 cent rock, because the surface is covered up, sometimes to a 



