Purchase of Fertilizers 165 



already stated, unless it is thoroughly understood, it is 

 likely to be misleading. 



What has been said of the different statements of guar- 

 antees of the raw materials, is also true in the case of the 

 mixed goods. In the first, the percentages of the elements 

 that are given represent the amounts when they exist 

 in combination with other elements: nitrogen, as am- 

 monia ; phosphoric acid, as bone phosphate ; and potash, 

 as sulfate. While in the other, the percentages given 

 indicate the content of the actual constituents; namely, 

 nitrogen, phosphoric acid and potash. 



The advantages and disadvantages of purchasing raw mate- 

 rials and mixed fertilizers. 



In the purchase of fertilizers, therefore, two methods 

 may be adopted : First, the buying of fertilizing materials, 

 as distinct from fertilizers, which furnish single constitu- 

 ents like the standard high-grade products, or which fur- 

 nish one or two of the constituents, like ground bone, tank- 

 age, fish and the miscellaneous products ; these are called 

 "incomplete," because they do not furnish all of the three 

 essential constituents. Second, the purchase of the mixed 

 manufactured brands, which contain all of the three essen- 

 tial constituents, nitrogen, phosphoric acid and potash, 

 which are prepared to meet the demands of different soils 

 and crops, and are called "complete," because containing 

 all of the essential manurial constituents, or those liable 

 to be lacking in any soil. The relative advantage of these 

 different methods of purchase depends, first, upon the cost 

 of the constituents, and second, upon the use that is to be 

 made of them. 



It may be urged that, on theoretical grounds, there 

 are no good reasons why nitrate of soda, sulfate of am- 



