250 FERTILIZERS. 



mals : the vegetable performs all the strong work for animals ; they take matter in its rudest 

 form — in its strongest combinations, and break the links that hold the elements together ; and 

 yet how feeble are actions of vegetables, compared to those of animals ; how feeble is their 

 circulation, compared with that of vertebrated animals. Indeed the higher the animal rises in 

 the scale of organization, the more feeble it is in effecting changes upon matter. The lower 

 races may succeed in digesting inorganic matter, in some of its forms, but vegetables feed en- 

 tirely upon inorganic matter. Vegetables, then, stand between animals and dead matter, and 

 reconcile, as it were, the dead to the higher forms of life, which, were it not for this interme- 

 diate agency, life, with all its powers and attributes, would vanish before the inertr.ef^s of matter, 

 without a struggle. Is the energy of the vegetable unlike, in kind, to that of the animal ? It 

 is safer to say that it is of the same kind. The animal life is made weak ; animal life is put 

 to a better use than concocting the earths — inducing the elementary changes in inorganic matter. 

 Related as the races are to time, and to purposes, the functions would be too much interrupted 

 to be thus employed : hence they are constituted so as to take up and use what the vegetable 

 has formed ; these arc scarcely changed. The albumen, casein, legumin, etc., which has been 

 made by vegetables, is taken by the animal, much as it is ; it nourishes him by slight modifi- 

 cation, and out of the blood, with its corpuscules and plastic powers, forms organs to support 

 movement, and more than all, a throne, upon which reason may sit and guide the active and 

 intelligent agent. 



2. Magnesia and its Salts. 



Carbonate of .Magnesia. This substance is well known as a mild anti-acid and aperient 

 medicine ; it exists in many combinations in the rocks and minerals. It is associated with ser- 

 pentine, and is combined in certain limestones, called Dolomites. By itself it is never em- 

 ployed as a fertilizer. It is only sparingly soluble in water ; and we do not know that, as a 

 carbonate, it is taken into the tissues of plants. It is true, however, that some of the most 

 fertile soils are derived from the dolomites, a mixture or combination of carbonate of lime 

 and carbonate of magnesia. It might, from this fact, be inferred, that those magnesian lime- 

 stones, when burnt, would form an excellent fertilizer. Experience, however, proves that 

 magnesia, when caustic by burning, is injurious, though no more so than lime, except that it re- 

 tains causticity longer ; does not readily reabsorb carbonic acid. When, however, the magnesia 

 forms only a small proportion of a limestone, as in the hydraulic limestones, its action is not 

 injurious, inasmuch as the quantity is too inconsiderable to affect vegetation chemically, or the 

 soil mechanically, by forming an indurated mortar or cement. 



Sulphate of J\Iag7iesia. This salt, which is known in commerce imder the name of Epsom 

 Salts, is a soluble, disagreeable substance. It is a marine salt, and is obtained from sea-water. 

 It remains in a dissolved state after the muriate of soda (common salt) is crystallized out. The 

 water in which it is contained is called bittern. It may also be obtained from the magnesian 

 limestones, by employing sulphuric acid. Sulphate of magnesia may be classed among the 

 fertilizers : it increases the amount of many crops. .Thus upon a meadow, bearing grass, fifty- 



