110 EXPERIMENT STATION. [Jan. 



all but one ease, and in this exception the commercial shortage 

 was less than 50 cents per ton. The average retail cash price 

 has been $42.58, and the calculated commercial valuation, 

 $43.83 per ton. The pound of actual potash as muriate has cost 

 on the average 4.13 cents. 



(3) Materials furnishing Phosphoric Acid. — Only two sam- 

 ples of dissolved bone black have been analyzed, one of which 

 showed a commercial shortage of over 50 cents per ton. 



Fourteen analyses of acid phosphate have been made, repre- 

 senting 25 samples. The average retail cash price has been 

 $15.35, and the average commercial valuation calculated from 

 the table of trade values has been $13.67 per ton. The pound 

 of available phosphoric acid from acid phosj^hate has cost 4.77 

 cents. 



Seventeen analyses of basic slag phosphate have been made, 

 representing 23 samples. Four analyses showed samples de- 

 ficient in available phosphoric acid. The average retail cash 

 price paid for basic slag was $15.19, and the average calculated 

 commercial valuation, $12.64 per ton. The pound of available 

 phosphoric acid from basic slag, as determined by the Wagner 

 method, has cost on the average 4.81 cents. Two brands showed 

 a commercial shortage of over 50 cents per ton. 



(/) Mixed Complete Fertilizers. 



The larger number of high-grade fertilizers that are being 

 sold from year to year in Massachusetts indicates that the aver- 

 age farmer realizes the importance of purchasing a high-grade 

 mixture. As has been pointed out in past years, there are many 

 advantages to be gained by choosing a formula from among the 

 high-grade goods. Summary tables have been prepared which 

 furnish valuable data bearing upon this point. 



(1) Grades of Fertilizer. — In separating the formulas into 

 different grades, those brands containing plant food having a 

 commercial value of $24 or over per ton have been classed as 

 high grade, those having a value between $18 and $24 per ton 

 medium grade, and those having a value of $18 or less per ton 

 low grade. 



