1 92 CHEMICAL FERTILIZERS 



If we take the simpler view of assuming the curve to be 

 almost a straight line, and adopt the formula V = a + bp, 

 a works out at 2 35. 4^. The error allowed for in the 

 case of basic slag is as much as 2 % in the analysis, 

 corresponding to 2s. 8d. The assumption that the price 

 fits a straight line only causes a maximum error of 

 is. gd. which is easily within the allowed limit. There is, 

 with basic slag, no justification in departing from the simpler 

 straight line, and the table might be made simpler without 

 error. 



It will be noted that in the case of basic slag, however 

 one may calculate the figures, the large zero price of over 

 2 per ton is allowed in contradistinction to sulphate 

 of ammonia, which seems to have been allowed only a minus 

 zero price. On consideration of the conditions under which 

 these articles are manufactured, it will be noted that there is 

 a striking difference between the position ot the two manu- 

 factures. The manufacturer of basic slag may dump all his 

 material in a heap, at a very small cost ; therefore, the whole 

 cost of breaking, grinding, sieving, bagging, etc., must be 

 paid by the farmer, who pays a high zero price. On the 

 other hand, the sulphate of ammonia manufacturer is not at 

 liberty to run his waste ammonia liquors into the nearest 

 stream ; it would cost him, in any case, something to dispose 

 of his ammonia liquors, even if there was absolutely no market 

 for it. There is, therefore, a reason why the zero price of 

 sulphate of ammonia should be lower than that of basic slag. 

 The values which have been officially placed upon the 

 handling of manures are given under the head of compound 

 fertilizers, and have been readjusted by Smetham where 

 cost of mixing, bagging, distributing and transfer is assigned 

 by him to be worth about 2 75. 6d. per ton. Assuming 

 that the cost of grinding the slag and the cost of mixing 

 compound manures is not likely to be very seriously dissimilar, 

 2 7$. 6d. is probably a fair estimate of the zero price, 

 which agrees very well with the figures deduced from the 

 curve. It makes little difference to the manufacturer whether 

 the slag is of high or low grade percentage of phosphate ; as 



