16 CHLORINE AND THE CHLORIDES. 



presence of nitrogen, a substance essential to the composition of the nutritive elements, as 

 albumen and fibrin. It is not the ammonia in its entire constitution which enters the 

 tissues of plants, and exists in them as such : it is necessary that it should undergo decom- 

 position, and part with its nitrogen, to combine with other elements for the purpose of 

 forming the tissues. One of the salts of ammonia exists ready formed in the cererls, viz. 

 phosphate of ammonia and magnesia. The bran is richer in this salt than the flour ; and 

 it is staled by chemists, that when horses have been fed upon bran for a considerable time, 

 balls of phosphate of ammonia and magnesia form and accumulate in the large intestines. 

 This circumstance, however, I believe is a rare occurrence. 



Ammonia exists in the soil either as a carbonate or sulphate, according to circumstances : 

 it exists also in a free state. Clay and oxide of iron both attract this substance strongly- : 

 they serve therefore to fix it, and prevent its speedy evaporation. 



Ammonia exists also in llie atmosphere, and is brought down in rain water and snow, 

 from which it may be obtained by evaporation. This fact probably explains the adage, 

 that "Spring snows are the poor man's manure." 



An important means of fixmg ammonia is furnished by the use of plaster or gypsum. 

 Privies and stables are in a measure freed of ammoniacal odor by sprinkling plaster upon 

 the floor, or about the place : this plaster becomes then doi:bly valuable as a manure. 

 The ammonia decomposes the gypsum, by coTibining with its sulphuric acid. The farmer 

 will always find it for his interest to employ plaster abundantly abonl his premises, or in 

 all places where decompositions are going on. 



CHLORINE. 



Chlorine is united to sodium or sodium and water, or potassium, when it exists in or- 

 ganized bodies. It is one of the elements of common salt. It combines with many other 

 bodies, as potash, lime, magnesia, ammonia, iron, etc. 



Common salt has often been extolled as a manure or fertilizer : its eflfects, however, are 

 not uniform, and hence conflicting opinions exist as to its true value in agriculture. It has 

 also been highly spoken of as a remedy for worms and insects, but here opinions do not 

 agree. It is probably more important to animals than vegetables. Chlorine is not abun- 

 dant in grains and seeds : it is more so in the stalks, leaves, etc. Clover contains more 

 than wheat. It is not improbable that much chlorine is lost in the process of burning. 

 We know that salt volatilizes by heat, or is carried off in the vapor of boiling water ; hence, 

 in this combination, it is undoubtedly lost in part. 



Chlorine exists in the soil in combination with sodium. In the vicinity of the sea, its 

 presence is readily accounted for by the spray and vapor carried inland by winds, which, 

 when very strong, have been known to carry a quantity suflicient to impart a saline taste 

 to leaves, grass, etc. to the distance of many miles. So it may be transported in a state of 

 more minute division from sea to sea, though it is only over or near the ocean that the 

 aunosphere is sufficiently charged to denote its presence by nitrate of silver. 



