VALUATION OF MANURES. 37I 



three or more elements, for which no sure foundation is possessed, hccomes 

 absolutely necessary. 



In want of certain principles for guidance, I have sought to gain assistance 

 by proposing the question : How could the ingredients of the manure whose 

 value is to be determined, have been procured most cheaply in another way ? 

 Hence I have looked around for such materials as are met with in abundant 

 quantities upon the earth, and by means of which one or another of the ma- 

 nuring constituents could be furnished at the lowest possible cost. From the 

 market value of these materials, the price to be placed upon the individual 

 ingredients was then ascertained ; but this in many cases, must again be modi- 

 fied, for if it is taken as the groundwork for calculating the worth of those 

 manures that are actually met with in commerce and possess a fixed market 

 value, a disproportionate price, differing Avidely from the assumed commercial 

 value, is established. A perfect unison between the actual and theoretical 

 price cannot therefore be always obtained by this mode of computation ; never- 

 theless I maintain that the diiferences which will occur in calculations made 

 with care are of such a character, that the theoretical price, obtained by the 

 method of reckoning which I recommend, is entitled to be regarded as more 

 accurate than that actually exhibited in the present state of trade." 



Dr. Stockhardt then goes on to say : " It is impossible to specify 

 the reasons in detail which have induced me to increase the price 

 of one substance and to reduce that of others, because the entire 

 valuation depends in general more upon a reciprocal comparison, a 

 counterbalancing-, experimenting, and practical knowledge, than 

 upon fixed principles. If the prices specified are shown upon ex- 

 amination to be untenable, they must be altered. In any case they 

 cannot lay claim to permanent weight, inasmuch as they are sribject 

 to the same fluctuations as those of any other articles of trade." 



*Since Dr. Stockhardt, many eminent agricultural chemists, both 

 in Europe and America, have contributed efforts towards determin- 

 ing a schedule of prices for the ingredients which constitute 

 manures. Among these may be mentioned Prof. Anderson, chemist 

 to the Highland and Agricultural Society of Scotland, Professors 

 Way and Voelcker of the Royal Agricultural Society of England, 

 and Prof. S, W. Johnson of the Sheffield Scientific School at 

 New Haven. 



From the nature of the case it could hardly be expected that 

 different chemists would come to precisely the same conclusions, 

 but we find. so near substantial agreement as to give confidence of 

 near approximation to accuracy at the times they were made, or, at 

 least, from their point of observation,* But prices have changed, 



* It may be remarked here, that the values set by scientific men upon the several con- 

 stituents in a manufactured article have frequently fallen below a fair price by reason of 



