52 PHILIPPINE AGRICULTURAL REVIEW. 



be found on the market, under trade names, which have as their 

 base the above acid. "Clariphos" is one of these compounds, 

 which has found extensive use in many of the Louisiana sugar 

 factories. 



Another is known as "phospho-gelose," which is a combination 

 of dicalcium phosphate Ca 2 H,(P0 4 ) 2 and infusorial silica. It 

 is a patented preparation and is made by the absorption of phos- 

 phoric acid by a powdery compound known as "Kieselguhr." 

 After the absorption, the compound is heated to expel the water, 

 and then resaturated. This work is repeated several times until 

 the finished product, which is very hydroscopic, contains about 

 25 per cent of phosphoric acid. 



Kieselguhr. This is a fine light powder containing a high 

 percentage of silica. It is used purely for its mechanical effect 

 in forming particles upon which the impurities may collect, and 

 thus be more readily carried to the bottom. This material often 

 prolongs the workings of the filter presses by collecting the 

 gummy material, which would otherwise gather on the filter 

 cloths. Kieselguhr was used in the beet-sugar industry of 

 Europe many years ago, and is extensively used now for the 

 same purpose in the United States. 



Hydrosulphites. These are preparations of great bleaching 

 power, found on the market under various trade names. One 

 of these, widely used in the United States, in both the beet and 

 cane-sugar industries, is known as "Blankit." This is dehy- 

 drated sodium hydrosulphite with the chemical formula, Na,,S, 

 4 . It has a much greater bleaching and reducing action than 

 sulphurous acid, and oxydizes very readily in combination with 

 moisture, forming sulphate. On this account it is well to pur- 

 chase the reagent in small parcels for this climate, and to care- 

 fully guard the stored material from moisture. This substance, 

 which is a white powder, dissolves very easily in water, form- 

 ing an alkaline liquid, although this point is sometimes hard to 

 distinguish on account of hydrogen atoms liberated. 



There is a bleaching preparation made in France known as 

 "Redo," which is simply calcium hydrosulphite (CaS,O 4 ) . This is 

 used in the sugar industry to some extent, but it is claimed by 

 many that the results obtained are not as good as those obtained 

 from the sodium compound and that it deteriorates more easily. 



Hydrosulphites, unlike sulphurous acid, will bleach equally 

 as well in alkaline or neutral medium, as in an acid medium. 

 There is therefore less danger from loss of sugar by inversion 

 when they are used, while the permanency of their effect is 

 about the same. In any case where juices have been bleached 



