gen, phosphoric acid and potassium oxide, including the different 

 forms of each wherever different forms are recognized in the table), 

 in one hundred pounds of the fertilizer and multiplying each product 

 by twenty to change it to a ton basis. The sum of these values will 

 give the total approximate value of the fertilizer per ton at the prin- 

 cipal places of distribution. 



III. 

 DISCUSSION ON ASH ANALYSES OF PLANTS. 



It is well understood by chemists that our current modes of ash 

 analysis of plants possess quite frequently still some undesirable 

 features. A too low temperature with an insufficient amount of air 

 is apt to leave carbon behind, while, on the other hand, a too high 

 temperature in the presence of carbon is apt to cause a partial vola- 

 tilization of various mineral constituents ; these facts are too well 

 known to need any comment. The current publications of the aver- 

 age ash analyses of plants of former periods are known to suffer 

 more or less from these features. 



The question of an exact determination, qualitatively and quanti- 

 tatively, of the ash constituents of plants, forces itself, from day to 

 day, more and more upon the attention of agricultural chemists in 

 consequence of the inquiries into the physiological action of mineral 

 matter on plant growth. These circumstances require therefore 

 the application of methods for their determination which will admit 

 of no uncertainty, as it has become more and more apparent to 

 investigators that the increase or decrease of any one of the mineral 

 elements in plants often affects more or less the absolute and relative 

 amount of a variety of organic compounds found in plants. As the 

 amount of sugar, starch, protein substances, etc., in various plants 

 raised for industrial purposes, controls their market value, a reliable 

 system of special fertilization of plants, for special individual pur- 

 poses, can only be devised when the modes of analyses are, beyond 

 question, reliable. 



Contributions regarding more exact modes of analyses of plants 

 have deservedly received, of late, conspicuous attention by leading 

 investigators as Tollens, Wislicenus and others. 



