72 REPORT OF THE COMMISSIONEPv OF AGRICULTURE. 



to the trade. This suliiliate of ammonium varies in color from pure 

 •white to nearly black, according- to the quantity of tarry impurities pres- 

 ent. It has no odor when pure, and only a slight tarry odor when quite 

 imx>ure. A pure sample yields upon analysis 25.75 per cent, of ammonia 

 gas (NH3) ; commercial samples are valuable just in j^roportion to the 

 amount of ammonia they yield upon analysis. 



The following analysis rej^resents the composition of a very good com 

 mercial sami)le: 



Analysis of commercial ammonium sulphate. 



Moisture, loss at 110° C 23 



Iron oxido (FeO) 23 



Volatile tarry substances, by difference 1. 17 



Ammonia (NH3) 25. 6f) 



Sulphuric acid (SO3) GO. 64 



Oxygen, corresiionding with ammonia 12. 07 



100. 00 



These constituents were combined as follows : 



Moisture 23 



Volatile tarry substances 1. 17 



Iron sulphate (FeSO^, with trace Fej(S04)3) 49 



Ammonium sulphate ((NH<)2S04) 98.11 



100. 00 



Probably there is no better way of applying ammonia to the soil than 

 in the form of ammonium sulphate. 



Nitrogen may also be furnished to crops as — 



h. Potential ammonia. 



By the term "potential ammonia" we understand that the substance 

 spoken of contains a certain quantity of nitrogen, which, under favorable 

 conditions, may have a food value equivalent to a certain amount of 

 ammonia. The substances which contain nitrogen that may furnish this 

 potential ammonia are various both in chemical composition and physi- 

 cal form. Some of the x)rincipal kinds wiU be enumerated. 



1. — Bxcrements. 



Ordinary ham-yard manure., if properly housed and applied, is one of 

 the most valuable of fertilizers. It is very complex in its chemical com- 

 position, but contains a very considerable amount of nitrogen in such a 

 form as to readily furnish nitrogen to the growing plant. The urine of 

 animals is also rich in valuable nitrogenous matters, and when properly 

 applied will well repay the cost for storage and handling. Besides these 

 common forms there are a number of localities in our Southern States 

 where Mt excrements are found, usually in caves. These excrements are 

 very rich in potential ammonia, and have proven very valuable fertilizers. 

 In the annual report of this department for 187G, pp. 49 to 52, ynW be 

 found several analyses of bat guano. A sample this year received from 

 M. W. Townsend, Austm, Tex., contained the following A'aluable con- 

 stituents : Total nitrogen, 11.088 per cent., equivalent to 13.4C4per cent, 

 potential ammonia ; Potassium oxide (K2O), .91 per cent. ; and Insoluble 

 Phosphoric acid (P2O5), 6.18 per cent. 



Guano is another excrementitious substance which has been abundantly 

 used and with excellent results. It is rich in nitrogen in a readily avail- 

 able form. It should only be bought upon analysis of some reliable 

 chemist, as many inferior imitations are sold by unprincipled parties. 



