672 ANNUAL, REPORT OF THE Off. Doc. 



lated rock phosphates, furnishing, phosphoric acid only; 21 ground 

 bones, furnishing phosphoric acid and nitrogen, and seven miscel- 

 laneous samples, which group includes substances not properly 

 classified under the foregoing heads. 



The determinations to which a complete fertilizer is subjected are 

 as follows: (1) Moisture, useful for the comparison of anah'ses, for 

 indication of dry condition and fitness for drilling, and also of the 

 conditions under which the fertilizer was kept in the warehouse. (2) 

 Phosphoric acid — total, that portion soluble in water, and of the 

 residue, that portion not soluble in warm ammonia citrate solution 

 (a solution supposed to represent the action of plant roots upon the 

 fertilizer), which is assumed to have little immediate food value. 

 By ditference, it is esay to compute the so-called ''reverted" acid, 

 which is the portion insoluble in water, but soluble in the citrate. 

 The sum of the soluble and reverted is commonly called the "avail- 

 able" phosphoric acid. (3) Potash soluble in water — most of that 

 present in green sand marl and crushed minerals, and even some of 

 that present in vegetable materials, such as cotton-seed meal, not 

 being included because insoluble in water even after long boiling. 

 (4) Nitrogen — This element is determined by a method which simply 

 accounts for all present, without distinguishing between the quan- 

 tities present in the several forms of ammonium salts, nitrates or or- 

 ganic matter. (5) — Chlorin — this determination is made to afford a 

 basis for estimating the proportion of the potash that is present as 

 chlorid or muriate, the cheaper source. The computation is made 

 on the assumption that the chlorin present, unless in excess, has 

 been introduced in the form of muriate of potash; but doubtless 

 there are occasional exceptions to this rule. One part of chlorin 

 combines with 1.32() parts of potash to form the pure muriate; know- 

 ing the chlorin, it is, therefore, easy to compute the potash equiva- 

 lent thereto. (7) In the case of ground bone, the state of sub-divi- 

 sion is determined by sifting through accurately made sieves; the 

 cost of preparation and especially the promptness of action of bone 

 in the soil depends very largely on the fineness of its particles the 

 finer being much more quickly useful to the plant. 



The law having required the manufacturer to guarantee the 

 amount of certain valuable ingredients present in any brand he 

 may put upon the market, chemical analysis is employed to verify 

 the guaranties stamped upon the fertilizer sacks. It has, therefore, 

 been deemed desirable in this report to enter the guaranty filed by 

 the manufacturer in the office of the Secretary of Agriculture, in 

 such connection with the analytical results that the two may be 

 compared. An unfortunate practice has grown up among manu- 

 facturers of so wording the guaranty that it seems to declare the 

 presence in the goods of an amount of a valuable constituent rang- 

 ing from a certain minimum to a much higher maximum; thus, 

 "Potash, 2 to 4 per cent." is a guaranty not infrequently given. In 

 reality, the sole guaranty is for 2 per cent. The guaranteed amounts 

 given for each brand in the following tables, are copied from the 

 guaranties filed by the maker of the goods with the Secretary of 

 Agriculture, the lowest figure given for any constituent being con- 

 sidered to be the amount guaranteed. For compactness and because 

 no essentially important fact is suppressed thereby, the guaranties 



