446 ANNUAL REPORT OF THE Off. Doc. 



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 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 the consumer, that it is, in certain cases, prac- 

 tically impossible to determine the source of the phosphoric acid by 

 an examination of the 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 

 such 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 where the ration 

 of nitrogen to phospohric acid exceeds 8, it is clear that part, at least, 

 of the phosphoric acid has been supplied by something else than pure 

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

 some material other 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. Finallj^, the difference 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 filler can legally be 

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

 "making-weights" and as "conditioners," or materials introduced to 

 improve the drilling qualities of the goods. The fact that the phos- 

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

 well known as to require no detailed consideration in this connec- 

 tion. 



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 re]>ort 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 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 phosphoric 



