VERMONT AGRICULTURAL REPORT. 57 



2. Starch is the mother substance of the wood. If it forms slowly 

 the wood growth is inadequate. Starch occupies a very similar relation 

 to the sugar, pectin and pectose bodies of the fleshy portions of fruit. 



3. Several of the plant acids, like the malic of the apple, the citric 

 of the lemon, the tartaric of the grape and the like are in some measure 

 neutralized by the potash which is taken up by the plant, it forming the 

 most important base of the acid salts. 



LIME. 



Lime is a term somewhat loosely applied to several compounds con- 

 taining the metal calcium. Thus the common compound with oxygen 

 (quick lime), that with the elements of water (slaked lime), and that 

 with the elements of water and the carbonic acid of the air (air slaked 

 lime), are all spoken of as "lime." Strictly speaking, however, the term 

 is applicable to the oxide only, i. e. to the "quick lime." 



Lime is used in agriculture in its three more common natural forms 

 and in several artificial ones. The natural ones are: 



1. As carbonate in limestone, marble, chalk, some marls, oyster 

 shells, etc. (compounds with carbonic acid, the gas of the "soda water" 

 of the druggist, formed from carbon and oxygen). 



2. As sulphate in gypsum or land plaster (a compound with sul- 

 phuric acid and water). 



3. As phosphate in phosphate rocks of various kinds, bones, etc. (a 

 combination with phosphoric acid). 



The artificial forms of lime are: 



1. As oxide, in burned lime, quick lime. 



2. As hydrate, in water slaked lime (lime and water). 



3. As an impure hydrate mixed with carbonate, in air slaked lime 

 (lime slaked by the damp air and gaining both water and carbonic acid 

 therefrom). 



4. As an impure carbonate, in ashes of sundry sorts (combined with 

 the carbonic acid formed by the burning of woody matter). 



5. As phosphates carrying varying proportions of lime (formed by 

 the use of sulphuric acid in the manufacture of superphosphate or acid 

 phosphate from rock, bone blacks, etc.) 



Concerning the natural forms it may be said: 



1. Carbonate. Ground limestone or oyster shells are plentiful and 

 cheap. The lime they contain is not as available as is that in other 

 forms. 



2. Sulphate. Gypsum or land plaster is a well known and largely 

 used soil amendment, which deserves a still larger usage. It is mined 

 in Nova Scotia, Central New York and elsewhere, where it is ground to 

 a powder prior to use . 



3. Phosphate. While phosphate rock is mined and bones gathered 

 and ground mainly for the phosphoric acid they contain, their lime 

 content is a factor of some importance. 



