HIGHER GRADES MORE ECONOMICAL. 359 



alone is it considered unprofitable, and the chloride of potas- 

 sium considered the safer article. 



The chloride of potassium, on the other hand, has not 

 received such general commendation. Its use, as a fertilizer, 

 for potatoes and tobacco, has been decidedly discouraged ; 

 for it acts upon these crops more in the direction of quantity 

 than of quality. It is, however, highly recommended for 

 meadows, for pasture lands, and for all kinds of forage and 

 grain-crops, particularly when applied in connection with 

 phosphates. 



The relative agricultural value of both series of compounds, 

 chlorides and sulphates, is also frequently, in an unusual 

 degree, modified in consequence of the presence of larger or 

 smaller quantities of certain saline compounds, which are found 

 associated with them in the mines. Most prominent among 

 these are sodium chloride (common salt), magnesium chloride 

 and magnesium sulphate. The presence of magnesium chlo- 

 ride, beyond mere traces, is decidedly objectionable ; for its 

 action on plant-growth in general is known to be destruc- 

 tive ; it favors also the transformation of the lime into calcium 

 chloride, and thus assists in sending this valuable soil con- 

 stituent into the drainage waters. A large admixture of com- 

 mon salt — some of these fertilizers contain from 40 to 45 per 

 cent. — renders them unprofitable for the cultivation of some 

 of the most important industrial crops (for instance, tobacco). 



As the higher grades of the potash fertilizers are the 

 results of a careful process of manufacture, which aims at 

 the entire or partial exclusion of both common salt and mag- 

 nesium chloride, they are the preferable, because safer, 

 articles for us. Quite different are the opinions regarding 

 an admixture of magnesia sulphate, for its presence is known 

 to increase, in most instances, their agricultural value. 



Magnesia sulphate may act as a suitable absorber of 

 ammonia and of soluble phosphoric acid ; it will aid in a 

 rapid diffusion of the potash throughout the entire body of 

 the cultivated soil down to the lower strata, where the root- 

 crops and leguminous plants, as clover, etc., are mainly feed- 

 ing. Fertilizer No. VI., page 356, which contains from 52 

 to 56 per cent, of potassium sulphate, and from 30 to 38 per 

 cent, of magnesium sulphate, enjoys for this reason a superior 



