chap, xxx.] THE SACCHARIMETER. 413 



DEXTRO-ROTATORY. 



Sucrose -f 73-84 



Glucose -f 56-00 



Lactose + 59 -30 



Galactose + 82-20 



Dextrine -j- 118-00 



Glycocholic acid + 29-00 



Cholic acid + 35.00 



Taurocholate of sodiurn (dissolved in alcohol) -j- 24-50 



L^EVO-ROTATORY. 



Levulose 106-00 



Albumen (egg, in watery solution) . . o5'50 



Albumen (serum) . . . . 56-00 



Gelatine - 130-00 



r ,, , . ( alkaline solution . . . - 213-50 



1 ( with great excess of alkali . - 552-00 



The measurements are all for rotatory power with 

 yellow light. 



Inosite (muscle sugar) is inactive, does not affect 

 polarised light. 



A six per cent, solution of quinine in alcohol gives 

 a rotation of 30 to the left. 



This rotatory action has been taken advantage of 

 to determine the strength of solutions of sugar, and 

 an instrument, the saccharimeter, has been constructed 

 for the purpose. 



The saccharimeter is shown in Fig. 185. It 

 consists of two Nicol's prisms a and b, between which 

 is placed a tube cc, filled with the sugar solution. 

 Suppose the tube to be removed, and the Nicols to 

 be crossed, the field will be dark. If the tube con- 

 taining the susrar solution be now inserted, the field 



o o j 



will be illuminated. If the Nicol's prism that acts 

 as analyser be now rotated, the field will be again 

 darkened, and the angle through which the prism 

 must be turned for this purpose gives the rotatory 

 power of the liquid. The rotation is effected by the 

 screw d, and its amount read oil on the scale e. 



