1674 Kepoet of Farmers' Institutes 



The slaking of lime with water is accompanied by the evolution 

 of considerable heat. Therefore, the dust which arises from 

 burned lime when it is handled, coming in contact with perspiring 

 men and animals, causes discomfort and sometimes quite serious 

 burning. Hjdrated lime is less caustic than burned lime and 

 therefore less disagreeable to handle. 



Burned lime and slaked lime, by the absorption of carbon dioxide 

 from the air and soil, eventually form cr.rbonate of lime, the same 

 compound from which they were made by the burning process. 

 The beneficial effects of lime on soil are thus due in the main to 

 carbonate of lime, regardless of the form in which the lime was 

 applied to the land. The application to the soil of fresh burned 

 lime, after slaking has taken place, has an advantage, perhaps, in 

 that intimate contact between the lime and soil is obtained because 

 of the fineness of the lime material secured by the slaking process. 



Air-slaked lime is formed by exposing burned lime or slaked 

 lime to the air, and is a mixture of hydrate and carbonate of lime, 

 the proportion of the two depending upon the time the lime has 

 been exposed, and upon the surrounding conditions. Burned lime 

 exposed to the air first absorbs water and then carl)on dioxide. If 

 the process is carried to the finish the result will 1)e calcium car- 

 bonate or air-slaked lime, in a finelv divided condition. 



On the market one frequently finds for sale so-called " agricul- 

 tural lime." This term is indefinite, since various products are 

 sold under this title — sometimes a mixture of carbonate 

 and hydrate; then again, refuse lime, or incompletely burned 

 limestone, unfit for masonry purposes, ground and mixed with lime 

 which has partially slaked. The only guarantee of the value of 

 this material is au analysis showing its actual lime content. 



]\rany by-product limes are of value for agricultural purposes. 

 They generally consist of a mixture of hydrate and carbonate of 

 lime or else are largely carbonate. All such materials are valuable 

 just in proportion to the amount of lime they carry. Among such 

 are waste lime from the manufacture of soda ash, carbonate of lime 

 from soap factories, lime from acetylene generators, waste lime 

 from sugar beet factories and tanneries and lime from gas purifiers. 

 Waste-gas limes should be used only after exposure to the weather 

 for a considerable time. 



