454 ANNUAL REPORT OF THE Off. Doc. 



bone. All fertilizers in whose name the word ^'bone'' appears, were 

 therefore examined by miscroscopic and chemical methods to deter- 

 mine, 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 manufacturers and which should be 

 equally understood by tJie consumer, that it is, in certain case.-, prac- 

 tically impossible to determine the source of the phosphoric acid by 

 an examination of tJie finished fertilizer. The microscope shows 

 clearly the structure of raw bone, but does not make it possible to 

 discriminate between thoroughly acidulated bone and acidulated rock. 

 The ration of nitrogen to phosphoric acid in a raw bone — and only 

 sucli bone as has not been deprived of any considerable proportion of 

 its nitrogenous material by some manufacturing process can properly 

 be called ''pure animal bone" — is about 1 : 8, in cases w^here the ration 

 of phos]ilioric acid to nitrogen exceeds 8, it is clear that part, at least, 

 of the phosphoric acid has been supi)lied by something else than pure 

 animal bone; but, inasmuch as nitrogen may have been introduced in 

 some material otlier than bone and no longer detectible by the micro- 

 scope, the presence of nitrogen and phosphoric acid in the proportions 

 corresponding to those of bone is not proof positive that they have 

 been supplied by bone. Finally, the differences in the iron and silica 

 content of bone and rock respectively, afford means of distinction 

 useful in some cases; the usefulness of this distinction is limited, 

 however, by the facts that kitchen bone frequently contains earthy 

 impurities rich in iron and silica, and that earthy fillers can legally be 

 used in fertilizers and are in fact considerably used therein both as 

 "make-weights" and as "conditioners," or materials introduced to im- 

 prove the drilling qualities of the goods. The fact that the phosphoric 

 acid in bone and rock are identical in character is probably so well 

 known as to require no detailed consideration in this connection. 



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 guaran- 

 ties 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 tlie Secretary of Agriculture, in such connection 

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

 fortunate practice has grown among manufacturers of so word- 

 ing 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 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 considered to be the amount guar- 

 anteed. For compactness and because no essentially important fact 

 is suppressed thereby, the guaranties for soluble and reverted phos- 

 phoric acid have not been given separately, but are combined into a 

 single guaranty for available phosphoric acid; in cases where the 

 maker's guaranty does not specifically mention available T-tbr»<5'->horic 

 acid, the sum of the lowest figures given by him for soluble and re- 

 verted phosphoric acid is used. The law of 1897 allowed the maker 

 to express his guaranty for nitrogen either in terms of that element 



