DANIEL LEE'S ADDRESS. 387 



800 of the elements of water, and fifty of nitrogen, attended 

 by the extraction Irom the soil of about 150 pounds of incom- 

 bustible soluble salts. Whatever effect the sulphate of lime 

 may have on the growth of a ton of dry clover, the above is 

 not far from its composition. Clover is a plant that contains a 

 good deal of sulphur ; and salts having this mineral as one of 

 their constituents, are extremely liable to be dissolved out of 

 the surface soil by tillage and cropping. Thus, when sulphuric 

 acid combines with magnesia, it forms Epsom salts. With 

 soda, it forms glauber salts ; with alumina and potash, it forms 

 alum; with iron, copperas ; and with lime, gypsum. Except 

 the last, all these salts are well known for their ready solution 

 in water, and it is obvious that they do not, as a general thing, 

 abound in unmanured, cultivated lands. So long as the sul- 

 phuric acid lasts from its combination with iron, either as a 

 sulphurct or sulphate, or with alumina, (the basis of all clay) 

 liming will suffice to form gypsum in the soil ; but after the 

 sulphur is consumed, or nearly so, then gypsum, not lime, must 

 be added to the soil. Similar remarks will apply to the use of 

 bone dust, or burnt bones and lime. So long as phosphoric 

 acid exists in the surface of the earth in combination with 

 alumina and iron, the application of simple lime will suffice to 

 form bone earth ; but when this acid is measurably consumed, 

 then bone dust, guano, or phosphorus in some other manure, 

 must be applied to the impoverished land, to renovate it. 



So far as we can see and judge of her operations, all the things 

 that nature consumes in forming our several crops are equally 

 important and useful ; but they are not equally abundant. 

 Hence the necessity of knowing how cultivated plants grow ; 

 what atoms they imbibe to augment their weight, and from 

 what sources they are derived. Direct experiment has demon- 

 strated the fact that, in forming 100 pounds of corn, wheat or 

 potatoes, nature does not use an equal weight of the substance 

 of the soil in which the plants grow. The quantity of this 

 actually consumed, depends in a good degree on the solubility 

 of its mould, and incombustible salts. A poor soil that has 

 very little organic food in an available condition, with a lair 

 supply of the mineral elements of crops, will force them to 



