(A) = Milligrams of copper.
(B) = Milligrams of maltose.
(A) (B) (A) (B) (A) (B) (A) (B)
30 25.3 35 29.6 40 33.9 45 38.3
31 26.1 36 30.5 41 34.8 46 39.1
32 27.0 37 31.3 42 35.7 47 40.0
33 27.9 38 32.2 43 36.5 48 40.9
34 28.7 39 33.1 44 37.4 49 41.8
(A) (B) (A) (B) (A) (B) (A) (B)
50 42.6 94 81.2 138 120.6 182 160.1
51 43.5 95 82.1 139 121.5 183 160.9
52 44.4 96 83.0 140 122.4 184 161.8
53 45.2 97 83.9 141 123.3 185 162.7
54 46.1 98 84.8 142 124.2 186 163.6
55 47.0 99 85.7 143 125.1 187 164.5
56 47.8 100 86.6 144 126.0 188 165.4
57 48.7 101 87.5 145 126.9 189 166.3
58 49.6 102 88.4 146 127.8 190 167.2
59 50.4 103 89.2 147 128.7 191 168.1
60 51.3 104 90.1 148 129.6 192 169.0
61 52.2 105 91.0 149 130.5 193 169.8
62 53.1 106 91.9 150 131.4 194 170.7
63 53.9 107 92.8 151 132.3 195 171.6
64 54.8 108 93.7 152 133.2 196 172.5
65 55.7 109 94.6 153 134.1 197 173.4
66 56.6 110 95.5 154 135.0 198 174.3
67 57.4 111 96.4 155 135.9 199 175.2
68 58.3 112 97.3 156 136.8 200 176.1
69 59.2 113 98.1 157 137.7 201 177.0
70 60.1 114 99.0 158 138.6 202 177.9
71 61.0 115 99.9 159 139.5 203 178.7
72 61.8 116 100.8 160 140.4 204 179.6
73 62.7 117 101.7 161 141.3 205 180.5
74 63.6 118 102.6 162 142.2 206 181.4
75 64.5 119 103.5 163 143.1 207 182.3
76 65.4 120 104.4 164 144.0 208 183.2
77 66.2 121 105.3 165 144.9 209 184.1
78 67.1 122 106.2 166 145.8 210 185.0
79 68.0 123 107.1 167 146.7 211 185.9
80 68.9 124 108.0 168 147.6 212 186.8
81 69.7 125 108.9 169 148.5 213 187.7
82 70.6 126 109.8 170 149.4 214 188.6
83 71.5 127 110.7 171 150.3 215 189.5
84 72.4 128 111.6 172 151.2 216 190.4
85 73.2 129 112.5 173 152.0 217 191.2
86 74.1 130 113.4 174 152.9 218 192.1
87 75.0 131 114.3 175 153.8 219 193.0
88 75.9 132 115.2 176 154.7 220 193.9
89 76.8 133 116.1 177 155.6 221 194.8
90 77.7 134 117.0 178 156.5 222 195.7
91 78.6 135 117.9 179 157.4 223 196.6
92 79.5 136 118.8 180 158.3 224 197.5
93 80.3 137 119.7 181 159.2 225 198.4
(A) (B) (A) (B) (A) (B) (A) (B)
226 199.3 245 216.3 264 233.4 283 250.4
227 200.2 246 217.2 265 234.3 284 251.3
228 201.1 247 218.1 266 235.2 285 252.2
229 202.0 248 219.0 267 236.1 286 253.1
230 202.9 249 219.9 268 237.0 287 254.0
231 203.8 250 220.8 269 237.9 288 254.9
232 204.7 251 221.7 270 238.8 289 255.8
233 205.6 252 222.6 271 239.7 290 256.6
234 206.5 253 223.5 272 240.6 291 257.5
235 207.4 254 224.4 273 241.5 292 258.4
236 208.3 255 225.3 274 242.4 293 259.3
237 209.1 256 226.2 275 243.3 294 260.2
238 210.0 257 227.1 276 244.2 295 261.1
239 210.9 258 228.0 277 245.1 296 262.0
240 211.8 259 228.9 278 246.0 297 262.8
241 212.7 260 229.8 279 246.9 298 263.7
242 213.6 261 230.7 280 247.8 299 264.6
243 214.5 262 231.6 281 248.7 300 265.5
244 215.4 263 232.5 282 249.6
=145. Preparation of Levulose.=—It is not often that levulose, unmixed
with other reducing sugars, is brought to the attention of the analyst.
It probably does not exist in the unmixed state in any agricultural
product. The easiest method of preparing it is by the hydrolysis of
inulin. A nearly pure levulose has also lately been placed on the
market under the name of diabetin. It is prepared from invert sugar.
Inulin is prepared from dahlia bulbs by boiling the pulp with water
and a trace of calcium carbonate. The extract is concentrated to
a sirup and subjected to a freezing temperature to promote the
crystallization of the inulin. The separated product is subjected to
the above operations several times until it is pure and colorless. It
is then washed with alcohol and ether and is reduced to a fine powder.
Before the repeated treatment with water it is advisable to clarify
the solution with lead subacetate. The lead is afterwards removed by
hydrogen sulfid and the resultant acetic acid neutralized with calcium
carbonate.
By the action of hot dilute acids inulin is rapidly converted into
levulose.
Levulose may also be prepared from invert sugar, but in this case it
is difficult to free it from traces of dextrose. The most successful
method consists in forming a lime compound with the invert sugar and
separating the lime levulosate and dextrosate by their difference
in solubility. The levulose salt is much less soluble than the
corresponding compound of dextrose. In the manufacture of levulose
from beet molasses, the latter is dissolved in six times its weight of
water and inverted with a quantity of hydrochloric acid, proportioned
to the quantity of ash present in the sample. After inversion the
mixture is cooled to zero and the levulose precipitated by adding
fine-ground lime. The dextrose and coloring matters in these conditions
are not thrown down. The precipitated lime levulosate is separated by
filtration and washed with ice-cold water. The lime salt is afterwards
beaten to a cream with water and decomposed by carbon dioxid. The
levulose, after filtration, is concentrated to the crystallizing
point.[110]
=146. Estimation of Levulose.=—Levulose, when free of any admixture
with other reducing sugars, may be determined by the copper method
with the use of the subjoined table, prepared by Lehmann.[111] The
copper solution is the same as that used for invert sugar, _viz._,
69.278 grams of pure copper sulfate in one liter. The alkali solution
is prepared by dissolving 346 grams of rochelle salt and 250 grams of
sodium hydroxid in water and completing the volume to one liter.
_Manipulation._—Twenty-five cubic centimeters of each solution
are mixed with fifty of water and boiled. To the boiling mixture
twenty-five cubic centimeters of the levulose solution are added, which
must not contain more than one per cent of the sugar. The boiling is
then continued for fifteen minutes, and the cuprous oxid collected,
washed and reduced to the metallic state in the usual way. The quantity
of levulose is then determined by inspection from the table given
below. Other methods of determining levulose in mixtures will be given
further on.