FIRST CENTURY OF DAIRYING IN NEW SOUTH WALES. 



substances containing nitrogen putrify in contact with bases lime, 

 potash, &c. By the agency of the latter the nitrogen, instead of unit 

 ing with hydrogen, combines with oxygen ; and in this way nitric acid 

 salts nitrates are formed, from which plants have the power of ab- 

 stracting nitrogen. In this manner nitrate of lime is generated from 

 the mortar of the walls of stables, and the nitrogen of urine upon 

 rubbish heaps. We rind nitrogenv4-for the most part, indeed, in small 

 quantities in soils and in water, sometimes in the humus, at another 

 in the form of ammoniacal or nitric acid salts ; but these are invariably 

 derived from animal and vegetable substances which have putrefied or 

 decayed in the earth. The more, therefore, such decaying matter is in- 

 troduced into the ground, the richer will it become in nitrogen. Dew 

 and rain water always contain ammonia, because they bring down to 

 the earth the ammonia which has become volatile during the process 

 of putrefaction and decay. This is why rain is almost invariably more 

 beneficial to plant life than either spring or bore water, however free 

 it may be of objectionable constituents. 



"(d) The inorganic or mineral substances requisite to the growth 

 of plants are conveyed to them through the soil and the water. The 

 fundamental mass of our various soils consists of crumbled rocks, and 

 these for the most part, except perhaps inert, siliceous sand, or pure 

 bog earth, contain all the, mineral substances which plants require for 

 their support, although some of them in very inconsiderable quantity. 

 In the solid rock these are insoluble in water ; but Nature provides 

 for this, inasmuch as from year to year portion of its mass is loosened 

 and decomposed. Chemical forces, sustained by air and water, warmth 

 and cold, plants and animals, here effect at length the reduction of 

 solid rocks into pulverulent earth, and insoluble, into soluble salts, 

 available for plant food." 



How Nature proceeds in order to produce from three nutrients car- 

 bonic acid, water, and ammonia, with the aid of a few mineral sub- 

 stances, the innumerable proximate constituents of vegetables, is a 

 subject upon which we still know nothing or practically nothing. The 

 actual production of organic substances effected in these by the crea- 

 tive power inherent in living plants, we cannot imitate by art, although 

 we know with certainty that it uses chemical forces for the perform- 

 ance of its work. On the other hand, we can imitate several of those 

 transformations of one vegetable substance into another, such as the 

 conversion of starch into gum, of gum into sugar, &c. In this respect, 

 indeed, Art can accomplish more than Nature, .{or it can produce such 

 combinations as alcohol, ether, and a thousand other compounds. 



Nature provides, by means of rain and de\v. decay and putrefaction, 

 by physical, chemical, and volcanic forces, that the three universal 

 articles of food, water, carbonic acid, and ammonia, shall not be want- 

 ing to the plants upon our globe : and man and brute also, without 

 exactly intending it. contribute their share by the processes of respira- 

 tion and combustion. 



If we give abundant and invigorating food to an animal it becomes 

 vigorous and fat ; on scanty and slightly nutritive food it continues 

 poor and lean. Jt is precisely the 1 same with plants. If they find all 

 the .-ubstances which they require for their nourishment and full de- 

 velopment in abundant quantity and in suitable form in the soil and in 

 the air they will grow up more vigorously, and put forth more shoots, 

 leaves, tlnwers. am' fruits than when they meet with these >ui>stances, 

 or even only one of them, in insufficient quantity. P>y rich and 

 abundant food the farmer fattens hi> plants ; by rich and abundant 

 iood he al-o .fattens his cattle. The mily difference between the plants 

 and the animals is that the former lias but a small range to seek its 

 food, whereas the latte- ha- th- power of roaming over the greater 

 11 >f the paddock* where they are peniMtKd by their owners to 

 gra/e. 



308. 



