each of the manures supply to a crop, and also the amount to the 

 after crops. These show that 100 Ibs. of phosphoric acid in super- 

 phosphate has the same effect as 200 Ibs. of phosphoric acid in 

 basic slag, but the after effects are better from the basic slag. Of 

 100 parts of phosphoric acid there was removed by the first year's 

 crop : 



Superphosphate ... ... 63 parts. 



Peruvian guano ... ... 22 parts. 



Hone meal ... ... ... 7 parts. 



Coprolites ... ... ... 6 parts. 



Basic slag, Xo. i, finest ... 39 parts. 



Basic slag, No. 2, fine ... ... 43 parts. 



Basic slag, Xo. 3, coarse ... 15 parts. 



XX'agner then gives the amounts out of 100 parts of phosphoric 

 acid left by the first year's crop and that was removed by the three 

 succeeding crops. I have calculated these figures out to parts, or 

 percentages of the original 100 parts tisrd, which shows the after 

 effects more clearly. 



Calculated to percentage of 

 original 100 parts. 



Superphosphate ... 30 part ii'io per cent. 



Peruvian guano ... 9 parts 7-02 



Bone meal ... ... 13 parts 12*09 ,, 



Coprolites 6 parts 5*64 ,, 



Basic slag, No. i, finest ... 14 parts 8^54 ,, 



Basic slag, Xo. 2, fine ... 29 parts J 6'53 



Basic slag, X"o. 3, coarse... 24 parts 20-40 ,, 



XYagner found that 36 per cent, of slag was soluble in carbonic 

 acid water, while only 8 per cent, of nvneral phosphate was soluble. 

 The amounts found to be soluble in citrate of ammonia were slag 

 74 per cent., mineral phosphates 4 per cent. To have any effect 

 the slag must be in a fine powder. If used alone, it should be 

 applied four or five weeks earlier than superphosphates. The 

 following analyses of basic slags are : i, by Munro and Wrightson ; 

 2, by A. H. Griffiths: 



Xo. I. No. 2. 



Lime 41-54 43 '4 



Magnesia ... 6*13 6'2O 



Ferrous oxide ... i4'66 ir64 



Ferric ... 8-64 5-92 



Alumina ... 2'6o 172 



Phosphoric acid ... 1 4'3 2 iS'ii 



Sulphuric acid ... '31 '41 



Sulphur ... -23 -30 



Yanadium ... '29 '24 



Silica ... 7-40 6*90 



Manganous oxide 3-81 3-51 



09-93 99'99 



