95. Method Of Lindet.—Courtonne recommends the method of Lindet for securing the inversion instead of the method of Clerget.[58] Modified by Courtonne, the method is as follows:

Make two or three times the normal weight of sugar dissolved in water to a volume of 200 or 300 cubic centimeters, as the case may be. After thoroughly mixing proceed as follows:

First, to Obtain the Polarization Direct.—Place fifty or 100 cubic centimeters of the prepared solution in a flask marked at fifty and fifty-five or at 100 and 110 cubic centimeters, add a sufficient quantity of lead acetate to secure a complete clarification, make the volume to fifty-five or 110 cubic centimeters, shake thoroughly, filter, and polarize in a 220 millimeter tube.

Second, to Obtain the Rotation after Inversion.—Place twenty cubic centimeters of the original solution, in a flask marked at fifty cubic centimeters, containing five grams of powdered zinc. The flask should be placed in boiling water. Add, little by little so as to avoid a too rapid evolution of hydrogen, ten cubic centimeters of hydrochloric acid made of equal parts of the strongest acid and water. After the operation is terminated, cool to the temperature of the room, make the volume to fifty cubic centimeters, polarize, and determine the rotation. The volume occupied by the zinc which is not dissolved, will be about one-half cubic centimeter, hence the deviation should be multiplied by the factor 2.475 in order to get the true deviation which would have been produced by the pure liquor. We have then:

The amount of sucrose, therefore, would be calculated by the formula of Creydt,[59]

X = C - 0.493A ;
0.827

for raffinose the formula would be

Y = A - S ;
1.57

in which S is the deviation due to the sucrose present. The solutions inverted in the manner described are absolutely colorless. There is no need of employing bone-black to secure the saccharimetric reading nor does it present any uncertainty. It is thought by Courtonne that this method will soon take the place of the method of Clerget on account of the advantages above mentioned. The method will be somewhat improved by adopting the following suggestions: