588 Transactions of the American Institute. 



But, as above shown, the five bushels or four hundred weight 

 of gypsum could fix only ninety pounds of ammonia, containing 

 seventy-four pounds of nitrogen, leaving, therefore, eighteen pounds, 

 or one-ffth of the whole to be derived from some other source. 



Now, this result supposes that none of the gypsum or sulphate 

 of ammonia was carried away by the rains, but that the whole 

 remained in the soil, and produced its greatest possible efiect on the 

 clover, and all in one season. But the eflfect of the gypsum does 

 not disappear with the crop to which it is actually applied. Its 

 beneficial action is extended to the succeeding crop of wheat, and 

 on grass lauds the amelioration is visible for a succession of years. 

 If, then, the increased produce of a single year may contain more 

 nitrogen than the gypsum can be supposed to yield, this substance 

 must exercise some other influence over vegetation than is involved 

 in its supposed action on the indefinite quantity of ammonia in the 

 atmosphere. 



Again, Mr. Barnard, of Little Bordeau, Hants, applied two and 

 a half hundred weight per acre on two-year old sainfond, on a 

 clayey soil. The increased produce of the first cutting was a ton 

 per acre; and of the second, in October, fully a ton — the undressed 

 part yielding scarcely any hay at all, while the dressed part 

 yielded one and a quarter tons. The second year no gypsum was 

 applied, and the difierence is said to be at least as great. 



Supposing the increased produce in all to have been four tons 

 of hay, and the nitrogen it contained to have been only one per 

 cent, the four tons (8,960 pounds) would contain about ninety 

 pounds of nitrogen. But two and a half hundred weight would 

 fix only forty-six pounds of nitrogen in the form of ammonia; and, 

 therefore, supposing it to have produced its maximum efiect, there 

 retnain fortyfour pounds, or nearly one-half of tJie whole unac- 

 counted for by the theory. 



A discussion followed the reading of Dr. Parmelee's paper, in 

 which several gentlemen advocated the views of Liebig, Johnson 

 and others as to the action of gypsum as a fertilizer; after which 

 the Association adjourned. 



