910 ANNUAL REPORT OF THE Off. Doc. 



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

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

 conditions under which (he fertilizer was kept in the warehouse. {2j 

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

 residue, that portion not soluble in warm ammonium 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 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 ac- 

 counts for all present, without distinguishing between the quantities 

 present in the several forms of ammonium salts, nitrates or organic 

 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 as- 

 sumption that the chlorin present, unless in excess, has been intro- 

 duced in the form of muriate of potash; but doubtless there are occa- 

 sional exceptions to this rule. One part of chlorin combines with 

 1.326 parts of potash to form the pure muriate; knowing the chlorin, 

 it is, therefore, easy to compute the potash equivalent thereto. (7) 

 In the case of ground bone, the state of sub-division 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 manufac- 

 turer in the office of the Secretary of Agriculture, in such connection 

 with the analytical results that ,the two may be compared. An un- 

 fortunate practice has grown up among manufacturers of so wording 

 the guaranty that it seems to declare the presence in the goods of an 

 amount of a valuable constituent ranging from a certain minimum to 

 a much higher maximum; thus, "Potash, 2 to 4 per cent." is a guar- 

 anty not infrequently given. In reality, the sole guaranty is for 2 

 per cent. The guaranteed amounts given for each brand in the fol- 

 lowing tables, are copied from the guaranties filed by the maker of 

 the goods with the Secretary of Agriculture, the lowest figure given 



