110 EXPERIMENT STATION. [Jan. 



all hut one case, and in this exception the commercial shortage 

 was less than 50 cents ])('r ton. The average retail cash price 

 has been $42.58, and the calcnlated commercial valuation, 

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

 on tlu! average 4.13 cents. 



(3) Materials furnisliing Phosplioric Acid. — Onlv two sam- 

 ples of dissolved bone black have been analyzed, on(> of which 

 showed a commercial shortage of over 50 cents per ton. 



Fourteen analyses of acid i)hosphatc have l)oen made, repre- 

 senting 25 samples. The average retail cash price has been 

 $15.35, and the average commercial valuation calculated from 

 the tal)le of trade values has been $13.G7 per ton. The pound 

 of available phosphoric acid from acid phosphate has cost 4.77 

 cents. 



Seventeen analyses of basic slag phosphate have been made, 

 representing 23 samples. Tour analyses showed samples de- 

 ficient in available phosphoric acid. The average retail cash 

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

 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 grnd(\ those having a value between $18 and $24 per ton 

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

 low irrade. 



