1024 



New Forms of Potash Manure. [march, 



is valuable for a fodder plant, being eaten readily by cows 

 and sheep. It is said to be very valuable for cows giving 

 milk. It is a plant of first value in bringing these sands into 

 productive fields." The Michigan Bulletin quotes several 

 Belgian and other writers, who speak in high terms of the 

 value of spurrey. 



It is now generally known that in ordinary farm practice 

 crops have to be supplied with manures of one form or other 



containing the three materials referred to 



New Forms of • u .. 



* , , ,, commercially as nitrogen or ammonia, 



Potash Manure. , J ° - t 



phosphate, and potash, and that if a 



crop is starved as regards one of these, poor results will 

 be obtained, no matter how much of the other two 

 ingredients may be present and available. It is also 

 a matter of common knowledge that there are several 

 different sources of nitrogen and phosphate, and that 

 we may regard the supplies as inexhaustible, but that in 

 the case of potash the only sources of any consequence used 

 at present are the deposits occurring at Stassfurt, in Germany. 



At the same time, potash is a very common and widely 

 distributed substance, and it has been estimated that it makes 

 up about 2*8 per cent, of the earth's crust. The whole of 

 this can be traced back to the original rocks — granite and 

 others of similar composition — and to the more recently 

 formed rocks of volcanic origin. The most important com- 

 ponents of all these are various felspars, a family of minerals 

 many of which contain potash" in considerable quantities. 

 Thus orthoclase, with its sub-variety sanidine, is a double 

 silicate of potash and alumina, and contains when pure 

 16*89 P er cent, of potash. Many other felspars and allied 

 minerals consist of silicate of potash in association with 

 alumina, soda, and lime. 



Usually these potash-containing minerals are mixed with 

 such large amounts of quartz, &c, that the amount of potash 

 in the rock is only about 3 per cent., but in various parts of 

 the world there are enormous deposits of rocks and minerals 

 containing higher proportions. For instance, in several of 

 the States of America, notably Maine, Connecticut, Pennsyl- 

 vania, New York, and Maryland, in many parts of Norway, 



