PliOCEEDIN^GS OF THE FaEMEES'^ ClUB. 475 



this correct? "What is tlie chemical difference, or is tliere any, 

 between water-shiked lime and air-slaked ? When stumps, roots, 

 leaves, &c., are burned, will the aslies from them be as rich in fertiliz- 

 ing qualities as if they w'ere allowed to gradually decay ? And will 

 not the ashes of burned weeds make as good a manure as the remains 

 of the same when they decompose ? What is the cheapest and best 

 remedy to pnrify cistern water, and keept it from stagnating or smell- 

 ing in -warm weather ? Tliis is important to many. I have seen 

 permanganese of potash recommended, in the proportion of one ounce 

 to fifty gallons of water. But as it sells here for two dollars per 

 pound, it is too dear for the purpose. In an agricultural paper I saw 

 alum recommended, but would not tliat be unhealthy ? Would 

 chloride of lime answer ? Please reply to the above in detail, as they 

 are of universal interest. 



Prof. Jas. A. Whitney. — ^When stone or caustic lime is treated with 

 water, a definite portion of lime unites chemically with a definite por- 

 tion of Avater, and forms hydrate of lime. When stone lime is 

 exposed simply to the atmosphere, it absorbs both water and carbonic 

 acid, which converts it into a mixture of hydrate Avith the carbonate 

 of lime, the latter being of a very different nature from the former, 

 wliich accounts for its inferior value for wdiitewashing purposes. 

 Stumps, roots and weeds had better be burned and the ashes used for 

 fertilizers, but leaves are such excellent materials for a compost heap 

 that they ought never to be used for any other purpose. It is impos- 

 sible to say whether the ashes from a given quantity of vegetable 

 matter would yield as much available manure to a soil as the same 

 material more finely divided by the process of decay. In practice 

 the results would vary much with the character of tlie soil. In a soil 

 deficient in humus, the rotting vegetable substance Avould assist the 

 retention of ammonia and do good. On ground of a diftereut kind, 

 a reclaimed bog, for example, it would only tend to make a soil, 

 already too loose, still more so, and would do harm. The only trust- 

 worthy method of purifying cistern water is by filtering it through 

 some substance like cliarcoal. The use of permanganate of potassa is 

 highly recommended, but it is probably too costly for the correspond- 

 ent, although an inferior quality sells for much less than two dollars 

 a pound in New York city. Alum will do little or no good; it will 

 spoil the water for all domestic uses. Chloride of lime Avould not 

 answer to put in the cistern, but it might be spread upon the ground 

 around it, to destroy the odor from the stagnant water. 



