268 FIRESIDE SCIENCE. 



that it cannot exist without them. The mineral 

 portion of plants is small indeed, compared with 

 the nitrogenized and carbonaceous parts, and this 

 paucity of the mineral substances was undoubtedly 

 the reason why the early experimenters were led 

 into error. 



At present, we are acquainted with sixty-five 

 elements or primary bodies, of which all things 

 animate and inanimate are made. Twenty-two of 

 these have been found in plants, and therefore are 

 to be regarded as food material. Let us for a 

 moment consider the strange metals and other sub- 

 stances which plants absorb into their structures. 

 Among the metals we find iron, potassium, calcium, 

 sodium, magnesium, manganese, copper, caesium, 

 rubidium, and zinc. It has been stated that arsenic 

 has been found in plants, but this is doubtful. The 

 non-metals are iodine, bromine, fluorine, chlorine, 

 phosphorus, silicon, carbon, hydrogen, * nitrogen, 

 oxygen, and sulphur. Nothing can appear more 

 singular than the fact that the refractory metal, 

 iron, can find its way into the stalks and leaves of 

 plants, or that the rarer metals should be hunted 

 out of the soil by them, and appropriated as food. 

 Some varieties of plants have peculiar appetites, 

 and require most extraordinary elements in order 

 to thrive. Tobacco is one of these, and the ash 

 which clings to the end of the smoker's cigar con 



