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ious method of dry defecation proposed some years ago by W. D. Home. The ques- 

 tions of change in volume and precipitation of levulose, when the dry subacetate is used 

 in large amounts, as is always necessary with low-grade products, have given rise, 

 however, to some uncertainties, and the method has not met with universal approval. 

 To determine exactly the amount of error due to change in volume and precipitation 

 of levulose, mixtures of sucrose and invert sugar, with mineral and organic salts pre- 

 cipitable by lead, were prepared and the effects produced upon the polarization of 

 these solutions by different quantities of the dry acetate and dry subacetate of lead 

 noted. It was found that in quantities up to 0.5 gram but very little change could be 

 detected in the polarization of the original solution when either the dry acetate or 

 dry subacetate of lead was used. Using more than 0.5 gram of substance the dry 

 acetate invariably reduced the polarization owing to the increase in volume produced 

 by the dissolved salt; the effect of increased quantities of the dry subacetate, however, 

 was variable. Where but little invert sugar was present there was the same decrease 

 in polarization owing to increase in volume. Where considerable invert sugar was 

 present, however, this dilution error was counterbalanced, and often more than 

 counterbalanced, by the precipitation and lowering of the specific rotation of the 

 levulose and there was either no change in the reading of the original solution or an 

 increase. Used in very large excess beyond the precipitation of the levulose the dry 

 subacetate produced a continuous lowering of the polarization through dilution. 



The same facts were noted in connection with the polarization of commercial sugars, 

 as may be seen from the following polarizations made in New York by M. H. Wiley: 



Effect produced by different quantities of acetate and subacetate. 



The dry normal acetate by the addition of excess produced dilution in every instance 

 as is seen by the diminished polarization. This same dilution is noticed by the dry 

 subacetate, but to a much less extent on samples 1 and 3; on samples 2 and 4 doubling 

 the quantity of dry lead subacetate caused no change in the polarization through the 

 compensating effect of the levulose precipitation. It is needless to add that the 

 double quantity of lead used was beyond that necessary to secure clarification, so 

 that an idea may thus be formed of the probable errors due to excess. 



In some interesting clarification experiments by J. A. Hall in the New York Sugar 

 Trade Laboratory the effect of adding varying amounts of dry lead subacetate was 

 studied in another way. Starting with a minimum quantity of the salt, this amount 

 was increased and the effect upon the polarization and the amount of lead dissolved 

 in the clarified filtrate noted. By calculating the dissolved lead to the subacetate 

 it is possible to estimate the dilution, allowing 0.22 cc increase of volume to 1 gram of 

 subacetate as determined by Home. Only one experiment upon a No. 2 Philippine 

 mat sugar is cited: 



