MINERALS UNESSENTIAL OR INJURIOUS TO SOILS. 79 



rather common in the northeastern portion of the arid region 

 of the United States. Whether on the soil surface or in the 

 crevices of rocks, its needle-shaped, feathery crystals greatly 

 resemble those of Glauber's salt, but are readily distinguished 

 by the more intensely bitter taste. Epsom salt is frequently 

 the last remnant of sea-salts left in the soil after reclamation. 

 Though probably somewhat more injurious to plant growth 

 than Glauber's salt, the mineral Kieserite, one of the Stassfurt 

 salts and consisting essentially of Epsom salt, is sometimes 

 used as an application to calcareous lands instead of gypsum, 

 and with good results. Yet gypsum is usually the safer, and 

 equally effective. 



Borax (bi-borate of soda) occurs much more rarely than 

 the salts just described; most frequently in certain portions of 

 California, forming part of the "' alkali " in the soil. It is 

 injurious to plant growth, but is as readily dealt with as is the 

 carbonate of soda, by dressings of gypsum, whereby inert 

 borate of lime is produced. 



It is hardly necessary to say that saline waters containing 

 any of the above salts in notable amounts must be used for 

 irrigation very cautiously. The measures to be observed in this 

 respect will be discussed later. 



