Tub Composition and Use of Fertilizers. 317 



their real mannrial value as compared with the most available 

 forms common in the market. In the following tables the regular 

 schedule values have been used for these materials that are recog- 

 nized in the market and also for such materials as closely resemble 

 any of these. For most vegetable materials, the price of nitrogen 

 has been fixed at twelve cents a pound, that of phosporic acid and 

 potash at four cents a pound. These are probably fair values, 

 when we take the availability into consideration, and this should 

 be done in order not to overestimate the fertilizing value of many 

 materials. 



