MODIFICATIONS OF MILK-SUGAR. 



11 



in contact with, milk-sugar, or by boiling, a saturated solution 

 containing 21 '64 per cent, can be obtained. Tte author is unable 

 to confirm the figure for the freshly prepared solution. 



The density of well formed crystals is r545 at tI-- , bad 



lo-o 



crystals — i.e., those which are strained, have, however, a lower 



density. 



The hydratc'd ".-modification is practical!}- insoluble in alcohol, 

 ether (in ether saturated with water it dissolves to the extent 

 of 0'00075 gramme per 100 c.c), chloroform, benzene, and other 

 organic solvents. It is slightly, but distinctly, soluble in amy! 

 alcohol on boiling, but is probably dehydrated. 



It is unaffected by heating to 100° C, but the water of hydra- 

 tion is given off at 130° C. ; at 170' a chanf;e takes place with 

 formation of lacto-caramel, and it melts at 2 13 '5 C. 



When dissolved in water the specific rotatory power remains 

 constant for a short period, 3 minutes at 20" C., 6 minutes at 

 15° C, and 15 minutes at 10° C. ; the rotation then gradually 

 falls. 



The following series of obseivations (Tabli- I.) will show the 

 nature of the change in rotation : — 



TABLE I. — C'hanck of Eotation of «-iliLK-Si(:.\K i.\ 



SoU'TlOX. 



Time T. 



I 



ObSClTOll KiitutiuM, U.. CillillliltL'il Rntati'iii 



I 



:RX 



12 



12'4<V 

 12-23' 

 11-91° 

 U-5V 

 11-ir 

 10-72' 

 8-03" 

 7-9."i' 



4- 08 

 - 0-112 

 ^ 012 



o-oi 



The solution used was examined in a 198"4 mm. tube using 

 the sodium light ; two determinations gave 7 '090 and 7 072 per 

 cent, of anhydrous milk-sugar, and, as the solution had a density 

 of r0265 at 17' (the temperature of observation), it contained 

 7 "651 grammes of hydrated milk-sugar per 100 c.c. 



