500 [Assembly 



I know that it would, general!}' speaking, be easy to bring up the 

 condition of land, if we could afford to raise crops for any other 

 purpose than to live on ; and I believe that this may be effected, 

 and yet enough produce may be sold off to make it worth our 

 young men's while to be farmers. 



Leaving the water and carbonic acid that are essential to the 

 existence of plants, we come to ammonia and salts, tliat exist only 

 in certain plants, and these in certain portions of their tissues. 

 These last substances vary in amount in different species, and 

 may vary in amount in different individual plants of the same 

 variety. Wheat growing on unmanured ground, contained for 

 for every (36 of starch, 9^ of gluten, while that growing on ground 

 manured with blood and urine, contained to every 45 parts of 

 starch, 35 parts of gluten. The mineral constituents of plants, 

 though they do not vary to so great ah extent, are still far from 

 fixed in their nature, and we have very good reason to believe, 

 that some of them in certain cases, take the place of others — that 

 potash sometimes does duty in place of lime or soda. The doc- 

 trine that plants are definite chemical compounds, constructed on 

 their mineral bases, cannot be for a moment maintained, and we 

 are not authorised, as yet, to draw any conclusions as to the neces- 

 sity of such inorganic ingredients from any premises other than 

 the most extended observations. 



III. Ammonia. — This is another gas somewhat similar to car- 

 bonic acid, and like it, soluble in water ; but unlike it, alkaline 

 in its properties. The solution of the one, as it exists in the soil, 

 is neutralized by that of the other forming a solution of the car- 

 bonate of ammonia. As we have seen that carbon can only enter 

 into the circulation of plants in the form of c.^irbonic acid, so 

 nitrogen only enters into their juices when in combination with 

 hydrogen, forming this gas ; and all the nitrogenized products of 

 vegetation, are indebted to the ammonia in the soil for their origin. 

 Again, as we have seen that carbonic acid exists originally in a 

 certain fixed condition in limestone and chalk, so ammonia to a 

 certain extent, exists in the natural deposits of sal ammonia and 

 sulphate of ammonia in volcanic regions. And further, as we 

 have seen that the only available resource of agriculturists for 



