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 (P0.22 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 P10 to P12. Potash is valued at about P0.26 per kilo and that removed with a crop of 75 tons would cost about P25. 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 contained 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 depends 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 carbonic, nitric, and organic acids. These have the power to act upon the mineral constituents and thus liberate other plant-food elements. The filter-press mud can very well be mixed with the bagasse ashes, and scattered about the cane rows as an almost complete fertilizer for sugar cane, the only element lacking being nitrogen, which was lost in the burning of the bagasse.