Xu. G. DUi'Aii'iWlENT OF AGl'.lCULTUKE. 919 



I'liosplioiic acid — total, that iioiiioii t^olnble iu water, aud, of liie 

 tusidue, tliat portion uot soluble iu warm amiiiouium citrate solution 

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

 the fertilizer), which is assumed to have little immediate food 

 valuo. B\ dillerence, it is easv 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 callc^d the "avail- 

 able" phosphoric acid. (:>) Totash 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, (o) Chloriu; 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 

 L.32G parts of potash to form the pure muriate; knowing the chloriu, 

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

 fn 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 liner 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 tiled 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 manufacturers of so 

 wording the guaranty that it seems to declare the presence in the 

 goods of an amount of valuable constituent ranging 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 guar- 

 anty 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 considered to be the amount 

 guaranteed. For compactness and because no essentially important 

 fact is suppressed thereby, the guaranties for soluble and reverted 



