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of Sir H. Davy, the one on which all the praise or blame 

 has been bestowed for the success or failure of the red clover 

 crop. This eminent chemist found considerable quantities 

 of gypsum (a compound of sulphur) in the ashes of this 

 plant, and very justly concluded that it would be a valuable 

 compound to add to the soil producing it. At that time, 

 however, so little was known of the origin of the elementary 

 constituents of plants, that a creative power was usually 

 assigned to them, and the fact of their elements being derived 

 from the soil was not at all understood. So great, however, 

 became the rage for the use of gypsum, and valuable the 

 effects produced from it in some instances, that it was soon 

 lauded through the country as an universal specific. This, 

 however, like the lightning cultivation, was soon found to be 

 an illusion ; and it turned out that in some instances only it 

 was beneficial, while in others it failed. The true use of 

 gypsum is that of furnishing sulphur to plants, and in pre- 

 venting the ammonia, which is generated in the soil, or which 

 is brought down by the rains, again escaping into the air by 

 evaporation. If the soil contains a sufficient quantity of this 

 gypsum, both these will be accomplished without any further 

 addition, — it would of course be useless to add more. If, on 

 the contrary, there should be a deficiency, we should lose 

 considerable quantities of ammonia, a large quantity of which 

 the clover plant requires, and we should not supply it with a 

 necessary quantity of sulphur. In this case gypsum would 

 be of service, and, providing all the other elements were 

 duly supplied, might entirely prevent the failure of the crop. 

 It will be seen that one ton of clover contains 2 lbs. 5 oz. of 

 sulphur, which is contained in about 12 lbs. of gypsum; 

 2 tons, therefore, growing on an acre, would require only 

 24 lbs. of raw gypsum, a quantity which all ordinary soils 

 contain. It is true the soils subjected to analysis contain 

 unequal quantities of gypsum; the one where the clover plant 



