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§ 33. Determination of the specific rotation of tartrate of ethyl and of its mix-
tures with alcohol, wood-spirit, and water
PAGE
77
81
§ 35.
Method of determining the specific rotation of active solids
83
§ 36.
§ 37. Details of determination by Tollens and Schmitz of true specific rotation
of cane-sugar
Details of the author's determination of the true specific rotation of
ordinary camphor
84'
§ 39.
§ 40.
Worthlessness of many existing statements of specific rotation values
Conditions necessary that specific rotation values may serve as character-
istic marks of substances
§ 41. Molecular rotation-two uses of the expression
93
V. PROCESS OF DETERMINING SPECIFIC
ROTATION.
§ 42. General statement of data necessary
A. Determination of the Angle of Rotation.
§ 43. Apparatus for the qualitative examination of rotatory power
§ 44.
Classification of instruments used for accurate determinations
§ 47. Mode of observation with white day or lamp-light
Description of lamp for sodium-flame. Mode of observation with homo-
geneous light..
99
102
§ 48. Larger form of instrument for taking observations at constant tem-
perature
(c.) HALF-SHADE INSTRUMENTS OF JELLETT, CORNU, AND LAURENT.
§ 58. Optical principle of Laurent's instrument
§ 59. Process of taking observations. Examples of actual observations
(d.) COMPARISON OF MITSCHERLICH'S, WILD'S, AND LAURENT'S INSTRUMENTS.
§ 60. Experiments to determine the degree of concordance among the results
obtained by different observers and with different instruments
(e.) DETERMINATION OF THE ANGLE OF ROTATION FOR DIFFERENT RAYS.
BROCH'S METHOD.
122
§ 63, V Lang's method by using artificial sources of light
124
125
B. Measurement of the Length of Tubes and their
Adjustment.
§ 64. Description of tubes, and mode of closing their ends
§ 65. Different water-bath arrangements for constant temperature
§ 66. Process of measuring tube-lengths
C. Estimation of percentage Composition of Solutions.
§ 67. Preparation of solutions by weighing the active and inactive constituents 133
§ 68. Alteration of percentage in filtration
§ 69. Reduction of weighings to weight in vacuo
134
135
§ 72. Preparation of solutions in graduated flasks
§ 73. Standardizing the flasks. Table of density of water from 0° to 50° Cent.
§ 74. Mohr's graduation
F. Influence of the several Observation-Errors on Specific
Rotation Values.
§ 75. Amounts of error from different sources, and their respective influence on
the result
144
145
148
149
VI. PRACTICAL APPLICATIONS OF ROTATORY
POWER.
A. Determination of Cane-sugar. Optical Saccharimetry.
§ 76. Principles on which the method is based
§ 81. Graduation of Ventzke's scale. Calculation of concentration, or of per
cent. composition of saccharine solutions
162
§ 83.
§ 84.
§ 82. Correction of saccharimeter readings for slight disproportionality between
rotation and concentration. Schmitz's table of corrections for each
degree on the scale..
Conversion of degrees (Ventzke) into degrees of angular measurement
Correction of errors due to imperfect construction. Scheibler's method
of double observation
163
..
§ 85. Influence of temperature on determinations by the saccharimeter.
Mategczek's table of corrections ..
Tables of correction for imperfect proportionality between deviation and
concentration, and for changes of temperature..
175
(c.) WILD'S POLARISCOPE WITH SACCHARIMETRIC SCALE.
§ 89. Table of correction for imperfect proportionality between rotation and
concentration
(d.) SACCHARIMETER WITH ANGULAR GRADUATION ON MITSCHERLICH'S, WILD'S,
OR LAURENT'S PRINCIPLE.
§ 90. Calculation of sugar percentage, assuming the specific rotation as
constant
§ 91. Schmitz's table for correction of error due to variability of specific
(e.) PREPARATION OF SOLUTIONS FOR THE SACCHARIMETER.
§ 92. Standardizing the 50 and 100 cubic centimetre flasks. Weighing the
sugar-samples
§ 93. Process of clearing solutions. Error due to presence of precipitates
formed
§ 94. Decoloration of solutions with animal charcoal.
(f.) DETERMINATION OF CANE-SUGAR IN PRESENCE OF OTHER ACTIVE SUBSTANCES.
§ 95. Removal of optically-active impurities
§ 96. Estimation of cane-sugar in presence of invert-sugar. Inversion method
of Clerget
B. Determination of Glucose.
187
§ 97. Calculation of the percentage of glucose in dilute solutions from the
angle of rotation
190
§ 98.
Table of corrected values for solutions of higher concentration
99. Use of saccharimeters with Ventzke's or Soleil's scale, or with special
§ 100. Determination of grape-sugar in diabetic urine
§ 101. Detection of potato-sugar in "chaptalized" wine
194
195
C. Determination of Milk-Sugar.
$ 102. Rotatory power of milk-sugar. Determination of its amount in milk
D. Determination of Cinchona Alkaloids.
$ 103.
§ 104.
Rotation constants of quinine, cinchonidine, quinidine (conchinine), and
cinchonine, and their salts, according to Hesse
Oudemans' investigations on the rotatory power of quinine, cinchoni-
dine, and quinidine, and their salts
198
203
§ 105. Determination of the purity of samples by means of their rotation-
angle..
205
§ 114.
Derivatives of the sugars (amyl-alcohol, valerianic acid, para-lactic acid) 226