( 460 ) 



The intliieiico of the time of aotion at H0° is therefore practically 

 dependent on the amount of lime, and in the case of not too high 

 sugar concentrations a large excess, at this tenipei-atnre, will in the 

 long run lessen the "solubility". 



It appears to us that in the decomposing influence of a large 

 excess of lime must be sought the explanation of the fact well known 

 in sugar manufacture that in many cases a bad filtei-ing of the mix- 

 ture treated with carbon dioxide may be prevented by previously 

 adding more lime. It is generally held that the excess of lime renders 

 the filtered off mass more porous, but this mechanical explanation 

 seemed to us a little far-fetched. 



In our opinion, the cause will have to be looked for in the fact 

 that the large amount of lime has a decomposing action on small 

 quantities of eventually formed trisaccharate or on other gelatinous 

 compounds of lime, sugar and non-sugars present. 



Finallv, the following experiment may be connnunicated In order 

 to ascertain by the "residue method" whether in the ordinary tech- 

 nical manner of adding the lime, calcium saccharate is precipitated, 

 a 15 7 sugar solution was kept in a thermostat at 80^ in a vessel 

 in which a small sieve made of copper gauze was mechanically 

 moved up^vards and downwards On the sieve was placed 2V//„ (of 

 the liquid) of quick lime in the form of course lumps. After 20 

 minutes the lime was completely suspended (slaked). After allowing 

 the whole to settle, a little of the liquid was drawn off by means 

 of a pipette carrying a small cottonwool filter. The remaining liquid 

 was then decanted from the deposit. The ?ame exjieriment was 

 repeated with, finely divided (piick lime, which was placed care- 

 fully in small (piantities on the sieve. 



As will be seen in table 7 no trisaccharate had precipitated, so 

 that, in this way, it has been confirmed once more that in the 

 ordinary technical jirocess of adding lime no ti-i saccharate is preci- 

 fated at H0°. A fortiori this will also not be the case when milk 

 of lime is used. That this, however, applies only to high tempei-atures 

 and that one has to be careful at lower temperatures was shown when 

 the same experiments were carried out at 50° (with a 13 7^ sugar 

 solution). Even after subsiding for a long time, no clear filtrate could 

 be obtained eo that the CaO-content of the li(juids has been found 

 too hio-h, but this has little influence in the calculation of the 7o 

 of saccharate in the solid i)hases. The results (table 7) point to a 

 rather important saccharate precipitate. 



