No. 6. DEPARTMENT OF AGRICULTURE. 525 



the differences in the iron and silica content of bone and rock re- 

 spectively, affords 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 tillers can legally be used in fertilizers and are 

 in fact quite often used therein both as "makeweights" and as 

 "conditioners", or materials introduced to improve the drilling qual- 

 ities 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 valuble ingredients present in any brand he may put 

 upon the market, chemical analysis is employed to verify the guar- 

 anties stamped upon the fertilizer sacks. It has, therefore, been 

 deemed desirable in this report to enter the guaranty filed by the 

 laanufacturer in the office of the Secretary of Agriculture, in such 

 connection with the analytical results that the two may be com- 

 pared. 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 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 

 guaranteed. For compactness and because no essentially important 

 fact is suppressed thereby, the guaranties for soluble and reverted 

 phosphoric 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 phos- 

 phoric acid, the sum of the lowest figures given by him for soluble 

 and reverted phosphoric acid is used. The law of 1879 allowed the 

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

 element or in terms of the ammonia equivalent thereto; since am- 

 monia is composed of three parts of hydrogen and 14 parts of ni- 

 trogen, it is a very simple matter to calculate the amount of one, 

 when the amount of the other is given; the amount of nitrogen mul- 

 tiplied by 1.214 will give the corresponding amount of ammonia, and 

 the amount of ammonia multiplied by 0.824 will give the correspond- 

 ing amount of nitrogen. In these tables, the expression is in terms of 

 nitrogen. The laws of 1901 and 1909 abolished the alternative and 

 required that the quantity shall be given in terms of nitrogen. 



Many manufacturers, after complying with the terms of the law, 

 insert additional items in their guaranties, often with the result of 



