BY-PRODUCTS OF SUGAR MANUFACTURE. 31 



USE OF ASHES. 



The ash of sugar cane constitutes the mineral matter that 

 has been taken out of the soil. This usually runs about 0.48 

 per cent of the total weight, according to Payson's classical 

 analyses. Chemically this contains the following: silica, iron, 

 aluminum, lime, magnesia, potash, sodium, phosphorus, sulphur, 

 chlorine, oxygen, water, etc. Of these various elements, the 

 phosphorus and potash are the most valuable to the planter. 

 Lime is also useful for many soils in correcting the acidity, and 

 occasionally in supplying that element, when it happens to be 

 lacking in a particular soil. 



The cost of different fertilizers is governed by the percentage 

 of these plant-food elements contained. Phosphoric acid is 

 worth $0.05 per pound (1*0.22 per kilo) in crude fertilizers. 

 At this rate the value of this element recovered from a crop 

 of 75 tons of cane per hectare would be from 1*10 to 1*12. 



Potash is valued at about 1*0.26 per kilo and that removed 

 with a crop of 75 tons would cost about 1*25. The lime contained 

 is a cheaper element but will not act as a detriment on any 

 soil, while on many it will be found very helpful. 



In spite of the great deficiency in these elements in the cane 

 lands here, and the high cost of commercial fertilizers, this 

 waste material is not only neglected at the majority of the 

 factories but is actually thrown away, yet the same elements 

 that command a high price in commercial fertilizers are con- 

 tained in these ashes. 



FILTER-PRESS REFUSE. 



In the defecation of cane juice, certain chemicals are often 

 used to precipitate the impurities, which are removed from the 

 subsiders after the clear juice has been drawn off, and sent 

 to the filter presses, where it is filtered through heavy cloths. 

 This material contains coarse particles of bagasse together with 

 other impurities including the lime and phosphoric acid which 

 were used in this* work. The composition of the material de- 

 pends upon the original composition of the juice and the amount 

 of the different chemicals that has been used in the clarification. 

 In any event, it makes a most valuable fertilizer because of 

 the organic matter, nitrogenous bodies, phosphoric acid, and lime 

 that it contains. This organic material is an ideal substance 

 to be applied to the worn-out cane lands (which consist almost 

 entirely of mineral substances) since it induces bacterial action, 

 and during its decomposition certain acids are freed, such as 



