Review of Essays on Calcareous Manures. 139 



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importance which they know to exist in them, hat which they were 

 willing to consider as merely adventitious. Thus the person who 



• reads a treatise on general chemistry, may rise from its perusal in the 

 belief that plants contain no other essential elements but carbon, hy- 

 drogen, and oxygen, with the occasional addition of nitrogen, while a 

 course of actual experiment could show earthy and saline substances 

 of large amount wholly neglected in the estimate. Phosphorus too, 

 which forms so large a portion of the mass of those animals whose 

 whole subsistence is derived from the vegetable kingdom, is never 

 named* among the elements of vegetables, yet it has on some occa- 



i sions been detected in them, and there can be no doubt that if it were 

 diligently sought it must be found in almost every case. When the 

 gigantic bones of the elephant are known to consist to so great an 

 extent of phosphate of lime, it would be vain to deny that the 

 phosphorus and calcium exist in some state or other in the herbage 

 he feeds upon, as well as the oxygen which forms the other ingredient 

 of the phosphate. So far in fact from those substances which are 

 neglected by chemists being unimportant in the constitution of plants, 

 they must modify the manner in which the other elements combine, 

 and although the vital action does in many cases compel them to 

 enter into combinations in direct opposition to the ordinary laws of 

 chemical affinity, w r e may in many instances safely attribute the 

 great difference which exists among compounds said to be of the 

 same elements, to the very matters that are usually rejected in the 

 examination. 



" It is said that putrescent manures serve for the nutriment of 

 plants. But the same might be also stated in relation to substances 

 which improve the soil, which furnish to it matters necessary to 

 render it fertile ; which impart to vegetables, the earth and saline 

 compounds which enter as essential elements into their composition, 

 texture, and their products. Such improving substances well de- 

 serve to be regarded as nutritive. " 



* Probably the author refers to the necessary elements of plants, among the ad- 

 ventitious bodies; we believe it is usual to name the bodies which he has designa- 

 ted, e. g.— from a work now lying before us, take the following passage — " Besides 

 the elements above named, that are essential lo organized bodies, (carbon, oxygen, 

 hydrogen, and nitrogen,) there are others, which are present in different cases, in 

 greater or less quantity : such are phosphorus, sulphur, chlorine, iodine, bromine, 

 potassium, sodium, calcium, silicium, magnesium, iron, manganase, &c. but gen- 

 erally they are in minute quantities," &c. Silliman's Chemistry, Vol. II. p. 391. 

 Within these remarks, both organic kingdoms are included. — Ed. 



