66 



NORTHEKN SUGAR INDUSTRY. 



acid gas I do uot claim iu this application, inasmuch as the same forms the subject 

 of a separate application filed herewith, to which reference is made for details of the 

 mechanism. 



I desire to call especial attention to the fact that the above-named substance, to 

 which I have given the name of " sulphureted cream of lime," is in fact not bisulphite 

 of lime, but is probably a combination of bisulphite, hyposulphite, and peutasulphite 

 of lime, or, in fact, all possible sulphites, inasmuch as it is made by the saturation of 

 cream of lime with sulphurous acid up to and beyond the satisfaction of all chemical 

 affinities. It must, when first made, and in best condition for use, show the yellow 

 color before mentioned, and give off" fumes of sulphurous acid gas. 



I am aware that bisulphite, of lime has been used for defecating sugar juice, and that 

 various processes of defecation are iu existence depending upon the use of that ma- 

 terial. I desire to disclaim any and all processes of sugar delecation w^liich depend 

 upon the addition of bisulphite of lime only to the liquor to be tested. 



I am also aware that there are known processes of sugar defecation involving the 

 use separately of quicklime and sulphurous acid in solution, these materials not being- 

 combined, but being successively added to the liquor. Such use or separate applica- 

 tion of sulphurous acid and quicklime form no part of my invention, and is hereby 

 disclaimed. 



To the cane juice collected in the tank I add buch a x^roportion of the sulphurous 

 acid and cream of lime, combii.ed as before stated, as will render the contents of the 

 tank slightly turbid. No definite proportion can be stated, nor is it necessary to do 

 so for practical purposes. The test of turbidity is sufficient, and itself determines 

 the amount of the mixture to be added. It is important to note, however, that the 

 condition of the juice hastens or delays the turbid appearance. Thus, if the juice is 

 normally neutral a very small proportion of the mixture will render it turbid. On 

 the other hand, if the juice is acid the turbid condition will be delayed iu some pro- 

 portion to the acidity. The effect of adding the mixture to the juice is to cause a pre- 

 cipitation of the coloring matters and other impurities, excepting the mucilage or 

 gum. This effect is btst produced when the mixture is used immediately after pro- 

 duction, as it should be. The mixture deteriorates if allowed to stand in air. If it is 

 necessary to keep the mixture for any length of time it should be hermetically sealed 

 up in air-tight vessels Avith a solution of sulphurous acid in water over the top of the 

 liquid, on which it will float. The precipitation takes place immediately, and the 

 juice may be at once pumped or otherwise removed from the tank to the defecators, 

 where it is heated and the scum is removed in the usual way. The principal defeca- 

 tion, of course, takes place iu the tank, as already described, and a still further defe- 

 cation occurs through the action of heat in the defecating vessels. From the defeca- 

 tors the juice goes to the evaporators, thence to the vacuuui pans, then to the coolers 

 or mixers, and finally to the centrifugal machine, the course of the juice after leaving 

 the defecators being the same as it ordinarily follow^s when known processes of defe- 

 cation are employed. In order to remove the sulphurous flavor of the sirup, which 

 comes from the centrifugal machine, I find it advantageous to collect said sirup in a 

 suitable tank provided with perforated steam pipes, through which live steam is in- 

 jected into the sirup. This injection of steam is continued until the sulphur taste is 

 no longer apparent. The sugar resulting from this process contains considerable of 

 the natural gum, and, although quite light in color, has a small grain, and is not easy 

 to purge in the centrifugal machine. It is, however, an excellent marketable prod- 

 uct, and gives a high polariscopic test. 



Returning, now, to the defecated juice in the tank, I find that a somewhat better 

 sugar may be produced by continuing the process in the following way: I prepare a 

 Aveak solution of sulphuric acid — preferably about one volume of acid to four vol- 

 umes of water. I do not limit myself to sulphuric acid, as I have found that other 

 acids, notably hydrochloric and acetic acids, when in a weak solution, will accom- 

 plish substantially the same result. It is desirable, however, that the strength of 



