Mance: Quarry Industry of Southern Indiana 123 



were of value to the lands and were concerned in their increased 

 productivity is shown b}^ the fact that the limed fields are stil! 

 distinguishable by their greater productivity. 



Following a rather extended use of lime and calcium-bearing 

 compounds on the soil, there was a long period during which the 

 use of lime fell into disrepute. The cause of this disfavor was the 

 fact that the use of quicklime had become more general than the 

 use of chalk or limestone and the further fact that this dressing 

 had been used in too large quantities. In fact, we are only now 

 coming back to the use of this helpful form of soil dressing. Some 

 works on agriculture written as late as the early 'eighties are 

 inclined to treat the use of lime on the land as an unnecessary 

 waste of time and money. This attitude resulted from the fact 

 that the chemical action connected with the transfer of nitrogen 

 from the atmosphere to the soil was not thoroly understood. 

 F. H. Storer, professor of chemistry in Harvard University, in 

 his book on Agriculture, published in the late 'eighties, said 

 (Vol. II, p. 139) : 'Tn some parts of the world landlords have 

 often absolutely forbidden their tenants by contract from using 

 lime." Professor Hopkins (op. cit., p. 162) quotes the old German 

 proverb: ''Lime makes the fathers rich but the sons poor." 



Probably no scientific investigation ever did more to show 

 the value of lime on land than that which resulted in the discovery 

 of the bacteria that have the power of changing the nitrogen of 

 the air to nitrates, or, as the process is commonly spoken of, the 

 fixation of nitrogen. 



The average composition of the air by volume is usually given 

 as follows: 



Oxygen .20.61 



Nitrogen 77 . 94 



Carbon dioxide 05 



Aqueous vapor and other gases 40 



Plants need all of these constituents for their proper growth 

 and development. But one of the strange phenomena of nature 

 i^ the fact that while plants can appropriate the oxygen and carbon 

 dioxide directly from the air, the nitrogen is not directly available, 

 altho it constitutes over three-fourths of the entire atmosphere. 

 It has long been known that in some peculiar way the nitrogen of 

 the air was on some kinds of soils and with some crops finally 

 transformed to an available form, but the process of transforma- 

 tion was a mystery. Science has now demonstrated that certain 



