DR. Xiril'»Ls' AlM>itKS<. 11 



fc'rtiliziu!>; substance having a eoainici-eial value. Very strenuous 

 attempts have been made to intlueo farmers !u purehaj^e grounil clam 

 anil oy.'iter shells, the venders alleging that they were C([ual to ground 

 bones in fertilizing nature. Clam shells are composed of carbonate of 

 lime, while bones are made up of the phosphate of lime, (^uite a differ- 

 ent sub.stanee chemically and agriculturally con.sidered. The shells are 

 (-•omposcd of carbonic acid and lime, the bones, of phosphoric acid and 

 lime, the former acid having no money value. Recently, the rock 

 substance known as dolomite, a double carbonate of lime and magnesia, 

 has been placed on the market and highly recommended as a fertilizer. 

 This powder is of but little service to plants, as it holds no elements 

 of food which are not supplied gratuitously by air and earth, in moai 

 localities, and it has the disadvantage of being quite insoluble. This 

 rock [towder, and other calcic carbonates, should not be confounded 

 with sulphate of lime which is plaster or gypsum. In this substance, 

 sulphuric acid or oil of vitriol is in combination witli the lime, in place 

 of carbonic acid, and a very different chemical and fertilizing agent is 

 supplied It has high value as an application to some fields, although 

 we cannot define positively its method of action. The experiments 

 which I have made with plaster go to prove its good effects are due 

 rather to the acid than the lime It has the power of fixing the ammo- 

 nia of the atmosphere and forming sulphate of ammonia which is a 

 salt of much value. In applying gypsum to our soil, we must remem- 

 ber that but a small quantity can be made available in a season, as it 

 requires nearly five hundred pounds of water to bring one pound of it 

 into .solution. Half a ton is sufficient dressing for an acre of ground. 

 The element hydrogen is freely supplied to plants by dew, mist and 

 rain, and therefore is costless to the husbandman. It is only through 

 water that hydrogen can bo presented to the plants, but this is by no 

 means its only inqjortant office. It enters the plant as water and it is 

 through its agency that all the various forms of food are rendered 

 assimilable. It is the liquid medium which holds all the inorganic 

 substances and forms the aqueous current which unceasingly flows 

 through the little cells of plants. They are ab.sorbed and appropria- 

 ted as food. 



Enormous (|uantities of water annually descend upon the land, 

 although we think we have good reason to conqViain of the supply fur- 

 nished during the past two years. If the rain fall be but^ twenty 

 inches per annum, it corresponds to something like two thousand and 

 twenty tons of water falling upon each acre every year. Much of this 

 is carried off by evaporation or through, drainage, still a large propor- 

 tion is retained by growing plants, or pa.sses through them, aiding their 

 mo.st iuqjortant functions. It can be shown that a gallon of water 

 passes through a single plant of wheat in a season, and the a{|ueous 

 exhalations from tlio ];roaddisk of a common sunflower each day amounts 

 to six 01 eight c»unces. 



The wonderful substance (formerly so rare and co.stly), phosphorus, 

 is .so e.s.sential an ingredient in the; food of plants, that not one of any 

 kind can flourish wiriiout it. This hiirhlv combustible body, so oflfon- 



