EXPERIMENTS WITH SALTS OF AMifOXIA. 301 



1858, on the part of the General Committee of tlie Agvi- 

 cultiu-al Society of Bavtuia, a series of comparative expe- 

 riments in the district of Bogenhausen, as to the opera- 

 tion of guano, and various salts of ammonia containing 

 an equal amount of nitrogen, the results of which are 

 decisive. 



The experiments were conducted upon a field (a loam) 

 which had gone through the usual rotation, and which, 

 with ordinary farm-yard manure, had borne rye and then 

 oats twice successively. Of eighteen plots in this field, 

 each 1914 square feet in area, four were manured with 

 salts of ammonia, and one with guano, one plot remained 

 unmanured. 



As a starting pohit for estimating tlie quantity of 

 manure to be employed, it Avas assumed that 400 lbs. 

 of guano per acre Enghsh (=493 lbs. avoir.) correspond 

 to the full measure of farm-yard manure usually 

 apphed. According to this proportion, 20 lbs. ( == 

 24f lbs. avoir.) of guano were reckoned for the area in 

 question. 



The samples of good Peruvian guano selected were 

 previously analysed, and in 100 parts a quantity of 

 nitrogen was found corresponding to 15-39 of ammonia. 

 As a general rule, only one-half of the nitrogen in guano 

 is present as ammonia ; the other half appears as uric 

 acid, guanine, &c., of the operation of which upon the 

 growth of plants little or nothing, as we have before 

 observed, is known. But it was assumed that the nitrogen 

 in these other substances was just as operative as that in 

 the ammonia, and the quantum of the various salts of 

 ammonia (which Avere likewise analysed previously to 

 ascertain exactly their amount of ammonia) was reckoned 

 in accordance with this assumption. Accordingly, for the 

 above 20 lbs. of guano, 1719 grammes ( = 3-75 lbs.) of 



