324 Kansas Academy of Science. 



cents. Many chemists believe that the second method, that 

 of designating the fertilizer by its food element or elements, is 

 to be preferred. The chemical analysis would then give the 

 weight of each chemical element in the fertilizer that will be of 

 use to plants. The current practice is illustrated in the fol- 

 lowing table given in a much-used book on agriculture. This 

 table gives the tons of "essential plant food" per acre-foot of 

 different types of soil : 



Table of "Essential Plant Foods." 



Sandy soil, Clay soil, Loess soil, Humus soil, 

 tons. tons. tons. tons. 



Potash (K2O) 2.42 6.38 8.70 6.39 



Lime (CaO) 1.70 12.34 116.40 37.86 



Magnesia (MgO) 96 9.12 73.84 8.68 



Phosphoric acid P2O5 1.74 2.82 4.00 1.50 



Sulphuric acid SO3 1.10 1.50 1.80 1.48 



This and other tables given by the author of this book are 

 of high value when translated into modern scientific language. 

 When so translated the tables will be true in fact and in 

 science ; now they are true in form to neither. Potash is caustic 

 potash, and no one who knows its qualities would think of using 

 it as a fertilizer, and still less would he class it as a plant food. 

 In the form of a salt, such as potassium carbonate, it is a 

 valuable accessory plant food. The same may be said of lime 

 and magnesia. Phosphoric acid is H:>P04, not P2O.-., and sul- 

 phuric acid is H2SO4, not SO3. Both of these are destructive to 

 plant tissue and are never used as fertilizers unless they are in 

 combination with some base forming a salt. Furthermore, 

 not any of the oxids listed in the above table is found as an in- 

 gredient of any soil, and therefore the table is false in fact as 

 well as in chemistry, and in plant economy except to one versed 

 in ancient science. It is true that, according to the modern 

 theory of solutions, mineral salts are believed to be dissociated 

 into cations and anions. Thus potassium sulphate is thought 

 to be dissociated in a water solution into the metal potassium 

 (cation) and the negative radical, sulphur tetroxid (anion). 

 But neither of these ions has the composition given in the above 

 table, and therefore the table is incorrect in all respects when 

 considered in the light of modern science. 



SUMMARY. 



Most of the general principles (major premises) of mathe- 

 matics and the physical sciences have been the property of the 



