Fertilizers 9 



phosphate, yet it has not increased as it otherwise would 

 have. In their natural state, bones yield phosphoric acid 

 to plants rather slowly ; but, being crushed and treated 

 with sulfuric acid, the phosphoric acid is made soluble and 

 so becomes available at once or in a short time. But 

 little bone, however, is now treated with acid, and " dis- 

 solved bone" has become a trade name for acid phosphate 

 made from rock. 



The packing-houses and slaughter-houses collect the 

 bones and harder part of refuse to grind up for fertilizer. 

 Blood and bone is a trade name given to refuse from 

 slaughtering establishments; its composition is rather in- 

 definite. The bones and refuse of fish in large fisheries, 

 also the carcasses of worthless fish, are used as a supply 

 of this important element of plant-food, as well as nitrogen, 

 under the name of " fish scrap." 



SOURCES OF POTASH 



In nature, soluble potash usually occurs as a chloride 

 (muriate), a sulfate, or a carbonate. It is also found as 

 an insoluble silicate in many rocks. It is very widely 

 distributed, occurring in all parts of the world, and is one 

 of the fertilizer ingredients that are left after plants are 

 burned ; in other words, it is one of the principal constitu- 

 ents of the ash of plants. Besides this general distribu- 

 tion, it also occurs in large bodies in a very few parts of 

 the earth. The largest and most important of these is 

 located in Stassfurt, Germany, where it is mined, much as 

 salt is in other parts of Europe. In this place it occurs 

 mainly as sulfate mixed with common salt and other sub- 



