No. 10. 



Report of the Committee on Agriculture. 



307 



affinity for water, and when combining ra^ 

 pidly therewith, a considerable desfree of 

 heat is developed, as may be observed when 

 it is slackiniT. The heat is often sufficient 

 to ignite wood and otiier combustibles. The 

 compound of lime and water, constitutes 

 what is called hydrate of lime, or water 

 slacked lime ; its constitution is 



Lime, 

 Water, 



7fi parts. 

 24 •' 



100 



This hydrate is sparingly soluble in water, 

 and more so in cold than in warm water. 

 About 700 grains of pure water, free from 

 carbonic acid, will dissolve 1 grain of lime. 



Carbonate of lime, (common limestone,) 

 consists of 



Lime, 

 Carbonic acid, 



56 parts. 

 44 " 



It constitutes the great mass of the lime- 

 stone and chalk which form so large a por- 

 tion of the crust of the eartli. It is the 

 principal constituent of shells, and forms the 

 calcareous matter of marls. 



Carbonate of lime is nearly if not quite 

 insoluble in pure water, but is readily dissolv- 

 ed in water containing carbonic acid, and as 

 rain and snow water always contain carbonic 

 acid, lime upon or near the surface of the 

 earth is unceasingly being dissolved and di- 

 minished in quantity — an exceedingly inte- 

 resting fact in an agricultural point of view. 



Lime in combination with phosphoric acid 

 is called phosphate of lime, and sometimes 

 "bone earth." It constitutes, with a smaller 

 proportiqo of carbonate of lime, nearly all 

 the earthy matter of bones. It also exists 

 in small proportion in shells. 



It is insoluble in pure water, but the 

 presence of acids (even the weakest of all, 

 carbonic acid,) renders it soluble. Phospho- 

 ric acid and lime tmite in several propor- 

 tions, but the combination that most concerns 

 us, is that which forms part of bones and 

 shells, which is 



Phosphoric acid, 

 Lime, 



52 parts. 



48 " 



100 



Sulphate of lime, is well known imder 

 the names of gypsum or plaister of paris, 

 and when pure consists of 



Sulphuric acid. 



Lime, 



Water, 



46 parts. 

 33 " 

 21 " 



Having thus briefly glanced at some of the 

 properties and combinations of lime, we 

 proceed to treat of lime as a manure, &c. 



Of Lime as a manure or as a constituent 

 of plants. 



The elementary constituents of all plants, 

 for the most part consist of carbon, hydrogen, 

 oxygen and nitrogen. The first three exist 

 in the largest proportion, and form the great 

 bulk of the plant, the last is equally neces- 

 sary, and with tlie rest, form the albumen, 

 gluten and other nitrogenous compounds 

 which principally abound in the seeds and 

 juices of plants. The air of our atmosphere 

 always contains water, carbonic acid and 

 ammonia, which furnish to plants the above 

 named elements, nearly equal perhnps to 

 their wants, after the first stages of their 

 growth. In former days these were believed 

 to be all that were essential to vegetation, 

 but modern science has demonstrated that 

 certain mineral substances, which the re- 

 sults of combustion proved always to exist 

 in plants, were quite as essential to their 

 growth. 



We might illustrate this position by the 

 investigation of animal and vegetable physi- 

 ology, but we must avoid digressing more than 

 is absolutely necessary to the proper under- 

 standing of the subject under consideration, 

 and be content with the remark, that nature 

 has decreed that plants shall receive certain 

 matters, in a great part from the atmosphere, 

 and those we call their organic part — but 

 their mineral constituents mitst come from 

 the soil. The most important of these min- 

 eral substances are potash, soda, lime, silica, 

 magnesia, iron, manganese, phosphorus, sul- 

 phur, chlorine and iodine. There are others 

 found in smaller proportion in plants, but 

 most of these are perhaps non-essentials. 



The mineral matters constitute, generally, 

 from one to two per cent, of the living plant, 

 and are what we call ashes, when the com- 

 bustible parts have been burned away. Their 

 state of combination is varied by every dif- 

 ferent plant. 



The phosphorus is, perhaps, always united 

 to oxygen, forming phosphoric acid, which 

 in plants usually exists in combination with 

 lime or magnesia, or with both, as in the 

 grain of wheat, and in many other seeds. 

 The sulphur, in most instances, exists as 

 sulphuric acid, which is generally united 

 with lime in plants, but often is cornbined 

 with pota.-h, soda, &c. ; the chlorine is a 

 combination with tlie potash, or forms with 

 the soda the well known common salt. Iod- 

 ine only exists in plants growing in or near 

 the salt waters. Besides these mineral 

 acids, various other acids, the products of 

 vegetable organism, form in plants, com- 

 pounds with the above named alkalies, earths 

 and metalic oxides. 



