No. 7. DEPARTMENT OF AGRICULTURE. 687 



The determinations to which a complete fertilizer is subjected are 

 as follows: (1) Moisture, useful for the comparison of analyses, for 

 indication of dry condition and titness 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. 

 Ey difference, it is easy 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 quanti- 

 ties 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 

 chloride 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 1,326 parts of potash to form the pure muriate ; know- 

 ing the chlorin, it is, therefore, easy to compute the potash e(iuiva- 

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

 sion is determined by sifting through accurately made sieves; tlie 

 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 preceding paragraph sets forth the nature of the examinations 

 given 1o the several classes of fertilizers under the laws in force 

 prior to the present year. The legislation of 1909 has made needful, 

 however, some additional tests. Sec. 4, of the Act of May 1, 1909, pro- 

 hibits the sale of "pulverized leather, hair, ground hoofs, horns, or 

 wool waste, raw, steamed, roasted, or in any form, as a fertilizer, or 

 as an ingredient of a fertilizer or manure, without an explicit state- 

 ment of the facts." All nitrogenous fertilizers have, therefore, been 

 submitted to a careful microscopic examination, at the time of prepar- 

 ing the sample for analysis, to detect the presence of the tissues 

 characteristic of the several materials above named. The act of April 

 23, 1909, makes it unlawful to use the word "bone" in connection 

 with, or as part of the name of any fertilizer, or any brand of the 

 same, unless the phosphoric acid contained in such fertilizer shall 

 be the product of pure animal bone. All fertilizers in whose name 

 the word "bone" appears, were therefore examined by microscopic 

 and chemical methods to determine, so far as possible with present 

 knowledge, the nature of the ingredient or ingredients supplying the 

 phosphoric acid. It is a fact, however, well known to fertilizer man- 

 ufacturers and which should be equally understood by the con- 

 sumer, that it is, in certain cases, practically impossible to determine 

 the source of the phosphoric acid by an examination of the finished 



