34 



noted that the experiment has been in progress but one year and that 

 conditions for a maximum crop were poor, due to an exceedingly dry 

 summer, — hence positive deductions cannot be drawn. It seems safe 

 to state, however, that farmers are in no way warranted in purchas- 

 ing this class of material as a source of plant food. 

 The experiment will be continued another year. 



LIME COMPOUNDS. 



Samples of various lime compounds have been analyzed and are 

 listed in the tables as Agricultural Lime, Ground Limestone, Marl, 

 Lime Ashes and Gypsum. Among the brands of so-called agricul- 

 tural lime will be found the more active forms, such as ground 

 burned lime, containing a considerable proportion of caustic lime as 

 well as varying amounts of hydrated lime and carboaate of lime; 

 slaked or hydrated lime which has received just enough water to 

 cause it to crumble to a powder; air slaked and refuse lime, which 

 represents residues from the kilns used in burning the high grade 

 building limes. The ground limestone contains all of its lime in the 

 form of carbonate and is simply pulverized limestone. The marl 

 has the same chemical composition as the limestone; that is, the lime 

 is all present as carbonate. The material, however, has an amor- 

 phous instead of a crystalline form. Lime ashes are a refuse product 

 from the lime kilns. They are apt to vary considerably in composi- 

 tion, depending upon the length of time that they have been exposed 

 to the weather and upon the nature of the fuel used in the burning 

 process. When wood is used the ashes will contain an appreciable 

 amount of potash and a little phosphoric acid. Gypsum, or land 

 plaster, contains nearly all of its lime in form of sulfate. This prod- 

 uct does not have a sweetening effect upon the soils and should not 

 be bought for this purpose. It does have a beneficial effect upon 

 some soils, and by a chemical interchange of acids and bases, will 

 liberate insoluble plant food. 



The lime samples analyzed are as follows: 



Agricultural Limes, 21 analyses, representing 19 brands. 



Ground Limestones, 5 " "4 



Marls, 2 " "2 " 



Lime Ashes, 7 " "7 



Gypsum, 5 " "3 



On pages 93 and 95 will be found the results of analysis of the 

 various lime products, that is, the actual determinations. Reading 

 across on the opposite page will be found the probable combinations 

 of the ingredients as calculated from the analytical data. 



