FERTILIZERS. 19 



parts pure potash. The cost of the potash in these combi- 

 nations varies somewhat from year to year, but, at their 

 lowest figure thus far, may be set down at seven cents per 

 pound for the potash in the combination of sulphate, and 

 three and three-quarters to four and one-half in muriate and 

 kainite. One reason why the sulphate bears a higher price 

 is, because it is sold as a purer article, costing more to pro- 

 duce, being especially freer from salt than either of the. 

 others. 



It has been found in reality, however, that much of 

 the so-called sulphate is really mostly muriate. Both the 

 muriate and kainite forms have salt in their composition, 

 which is considered injurious in its effect on some crops, 

 especially tobacco and potatoes ; affecting the quality of 

 the leaf in the former, and, by decreasing the proportion of 

 starch, tending to make potatoes watery. Because of the 

 heavy per cent of salt, I have found it dangerous to apply 

 kainite in the hill where -small seed, such as cabbage, are to 

 be planted : it is better to apply it around the plants just 

 before their second hoeing. There is also the objection to 

 kainite, that it sometimes comes not purified from the chlo- 

 ride of magnesia, which is considered by agricultural 

 chemists to be generally injurious to vegetation. Those 

 forms of the salt containing sulphate of magnesia help 

 diffuse the potash throughout the soil, carrying in down ; 

 and hence such potash compounds (muriate oftentimes, 

 and kainite generally) having it in their combinations are 

 especially recommended for use when growing deep-rooting 

 crops, such as clover, beets, etc. This combination has 

 also another valuable characteristic, its great power to 

 absorb or " fix " ammonia, and so preventing its escape, 

 being in this respect far superior to plaster. 



It also has a rare and remarkable power of gathering 

 nitrogen from the air. A chemist experimented on several 



