1678 INDUSTRIES DEPENDING ON PLANT PRODUCTS 



The absorbing power of the sugar increases with the temperature and 

 strength of the acid, especially when brought near to the point of caramel- 

 Hng, and when this takes place it is the fructose which first decomposes. 



As the proportion of sulphur dioxide which combines with invert su- 

 gar varies ver\- much, the amounts of sulphur dioxide were compared 

 w^hich are absorbed b}* a natural must and by an artificial must obtained 

 by the action of yeast on saccharose. Both musts contained 175 gms. per 

 htre of sugar. The results are given in Table II. 



Table II. — Combination of sulphurous acid with grape must 

 and with sumr solution. 



Grape must '•' Sugar solution 



Amount 



of Amount of sulphur . Amount of sulphur 

 sulphur dioxide dioxide combined Ratio i dioxide combined Ratio 



'^ jj J of combined of com Dined 



per litre After After After , V' ^°}?^ -^ After After After . <,„,„^?,^°j^,;j„ 



^ . 1. o I. . sulphur dioxide , , c , snlphur dioxide 



I hours 24 hours 48 hours; ^ i hours 24 hours 48 hours ^ 



mgms. mgm.s. I mgrns. . mgms. { per cent mgms. : mgms. i mgms. 



100 80 90 95 95 38 i 45 ^ 50 



200 150 165 170 85 75 93 95 



per cent 



50 



47-5 



46.6 



300 195 235 242 80 90 140 140 



I 



400 212 285 295 73.7 I 108 175 178 i 44.5 



500 230 335 350 70 48 205 205 40.1 



750 270 340 450 60 40 250 285 38 



1 000 320 560 570 57 80 270 340 34 



2 000 350 840 940 47 60 360 550 27.5 



It has also been demonstrated that the organic substances which are 

 with the sugar in the cell juices can combine with the sulphur dioxide. To 

 prove this, there was added to one part of a solution of sugar inverted by 

 invertase from yeast, the residue obtained by evaporating nearly to dry- 

 ness an infusion of yeast corresponding in volume to about four times the 

 sugar solution. In this way the non-sugary elements were considerably 

 increased. To both these solutions, one with and one without the non- 

 sugary- yeast residue, and both containing 200 gms. of invert sugar per litre, 

 were added 400 mgms. of sulphur dioxide The same quantity of sulphur 

 dioxide was added to some yeast juice made in the warmth and to some made 

 in the cold. After 48 hours the sulphur dioxide had combined in the 

 following proportions. 



Residue per litre 

 Sulphur dioxide after evaporation 

 combined per litre to dryaess 



Solution enriched with non-sxigary substances 



Solution of invert sugar 



Yea'st juice made iu the warmth 



Yeast juice made in the eold 



