MAGNESIA COMPOUNDS. 115 



to it its bitter taste. It is met with in the ash of plants, and 

 also mixed with salt in the water of salt springs and in 

 rock salt. It therefore forms a constituent of the German 

 potash salts in which it exists in a considerable proportion ; 

 although it is not estimated at all in the market value of 

 these fertilizers. 



SULPHATE OF MAGNESIA, is the common Epsom salts. 

 It has been used as a substitute for gypsum in the same 

 manner, and for the same kinds of crops, but it is too costly 

 for this purpose. It has been considered as injurious to 

 crops by some farmers, and as it exists abundantly in al- 

 most all soils, and is an ingredient of widely distributed 

 rocks, but little interest is afforded by its consideration. 



CARBONATE OF MAGNESIA, is found abundantly in many 

 kinds of marble and other limestone as an impurity, and is 

 not considered of any value. 



PHOSPHATE OF MAGNESIA, exists in the blood and tis- 

 sue of all animals and in the ash of nearly all plants. It is 

 in this form that it chiefly enters into the substance of 

 plants ; but as it exists in the soil in sufficient quantities it 

 has never been brought to the notice of farmers as necessary 

 for the growth cf crops. No doubt there are conditions 

 under which the soil may be benefited by an application of 

 some form of magnesia, but this can easily be given indi- 

 rectly with the potash salts or with lime. It forms a con- 

 stituent of nearly all commercial fertilizers, in some com- 

 bination or other. 



PHOSPHORUS. This element does not exist in a free or 

 uncombined state in nature, this being impossible because 

 of its extreme inflammability. It is a soft, colorless, trans- 

 lucent, wax-like substance which takes fire on the slightest 

 friction and burns with much violence; emitting dense 

 white fumes of phosphoric acid. It is insoluble in water. 

 It was discovered by Brandt more than 200 years ago, and 

 because of its intensely inflammable character, was much 

 dreaded by the uninformed alchemists, who termed it "the Son 

 of Satan." It exists in vegetable and animal substance; 

 being a constituent of albumen and fibrin, and of the ner- 



