yERTILIZER CONTROL STATION. 267 



These values are applied to the valuation of superphosphates and 

 all mixed goods, as follows : 



It is assumed that the organic nitrogen of these goods has for its 

 -source such materials as dried blood, ground fish, or nitrogenous 

 substances of equally good quality, unless a special examination of 

 some particular brand shows that inferior material like leather has 

 ■been used. Organic nitrogen in mixed goods will therefore be valued 

 at seventeen and one-half cents per pound. 



The insoluble phosphoric acid of mixed fertilizers is considered 

 as coming entirely from bone, and not from South Carolina rock, 

 and is reckoned at three cents per pound. 



The potash is valued at the price of that ingredient in kainite and 

 ithe muriate, unless the chlorine present in the fertilizer is not sufficient 

 to combine with it, in which case the excess of potash is reckoned 

 as the sulphate. 



The valuation of a fertilizer is obtained bj^ multiplying the per- 

 centages of the several ingredients by twent}' (which gives the pounds 

 per ton), and these products by the prices per pound, and the sura 

 of the several final products is the market value of the fertilizing 

 ingredients in one ton. 



These estimated values should be studied in the light of the previous 

 explanations. It will probably rarel}' happen in this iState that a 

 •mixed fertilizer can be sold near the point of consumption as low as 

 the Station valuation, the excess of cost representing certain expenses 

 previously enumerated. The Station valuations give the consumer 

 a fair!}' accurate basis for estimating the relative cost of plant- 

 food in the various brands of fertilizers, and will help the farmer to 

 •determine whether he can in any way profitably change his methods 

 of buying fertilizing ingredients. A caution should be uttered, 

 however, against making too close an application of the Station 

 valuations, as a difference of a few cents, or even of a dollar, on a 

 ton between two brands may have no real significance, but may be 

 •due to unavoidable errors of sampling and analysis, that render it 

 impossible to determine to the utmost exactness the composition of 

 the entire bulk of material that is sold. 



The tables which immediately follow give on the left-hand pages 

 the history of the samples taken, and on the opposite right-hand 

 pages the results of the analyses. The selling prices given repre- 

 ■sent in most instances the rate at which single packages, and not ton 



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