No. 6. DEPARTMENT OF AGRICULTURE. 515 



act. (5) Chlorin — this determination is made to afford a basis for 

 estimating tlie proportion of the potasli that is present as chlorid 

 or muriate, the cheaper source. The computation is made on the 

 assumption that the chlorin present, unless in excess, has been in- 

 troduced in the form of muriate of potash; but doubtless there are 

 occasional 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 dei)eud very largely on the fineness of its particles, the finer 

 being much more quickly useful to the plant. 



The legislation of 1909 lias made needful some additional tests. 

 Section 4, of the Act of May 1, 1909, prohibits the sale of "pulver- 

 ized leather, hair, ground hoof, horns, or wool waste, raw, steamed, 

 roasted, or in any form, as a fertilizer, or as an ingredient of a fer- 

 tilizer or manure, without an explicit statement of the fact." All 

 nitrogenous fertilizers have, therefore, been submitted to a careful 

 microscopic examination, at the time of preparing the sample for 

 analysis, to detect the presence of the tissues characteristic of the 

 several materials above named. 



The act of April 23, 1909, makes it unlawful to use the word "bone" 

 in connection with, or as part of the name of any fertilizer, or any 

 brand of the same, unless the phosphoric acid contained in such fer- 

 tilizer 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 determine, 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 w^hich should be equally understood by 

 the consumre, that it is, in certain cases, practically 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 ratio of nitro- 

 gen to phosphoric acid in a raw bone — and only such bone as has not 

 been deprived of any considerable proportion of its nitrogenous ma- 

 terial by some manufacturing process can properly be called "pure 

 animal bone" — is about 1 :8, in cases where the ratio of phosphoric 

 acid to nitrogen exceeds 8, it is clear that part, at least, of the phos- 

 phoric 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 detectable by the microscope, 

 the presence of nitrogen and phosphoric acid in the proportions cor- 

 responding to those of bone is not proof positive that they have been 

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

 tent 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 improve 



