Scientific Papers of the Bureau of Standards, Volumen21U.S. Government Printing Office, 1927 |
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Términos y frases comunes
a-methyl acetate acetyl alcohol aldose amide amygdalin angle of contact aqua regia arabinose balancing condenser bromo-acetyl BUREAU OF STANDARDS calculated calibration cent Chem chim chloride chloro-acetyl chloroform circuit coefficients computed constant correction critical temperature curve density derivatives determined difference direction finder direction-finder coil eddy currents electromotive force equation expansion exposures Figure Fischer formula fractional distillation frequency fructose fused silica galactose gentiobiose glucose glucoside Hudson hydrogen hydroxide inductance iridium Jour lactone liquid maltose measurements meter method methyl molecular rotations mutarotation N₁ N₂ normal liter observed obtained octa-acetate panel paper penta-acetate phenylhydrazide phosphorus pentoxide phys plates platinum precipitate pressure r₂ rhodium rotatory powers samples shown sodium solution specific rotation spectral energy ẞ forms structure substance sugar group sugars sulphuric acid surface Table tion tube UNIV wave lengths wire zero
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Página 579 - Mag. vol. xxvii. p. 176, 1864), whose experiments led him to the conclusion that " other things being the same, the weight of a drop of liquid is proportional to the diameter of the tube in which it is formed.
Página 293 - Walden2 found the value 109°. Since the configuration of tartraminic acid may be regarded as consisting of half that of tartramide and half that of tartaric acid, the rotation of tartraminic acid may be expected to be the mean of +14 and +106.5 or +60°. In satisfactory agreement with this calculation Weerman* has found the value +64, and the last unit is uncertain because the actual reading that he observed was only about 4°. If Walden's value of 109 is used in the calculation the agreement is...
Página 241 - June 30, 1906, provided that analyses of foods and drugs shall be made in the Bureau of Chemistry of the United States Department of Agriculture...
Página 579 - When it comes to determining the lands and amounts of insurance to purchase the prospective insured encounters many difficulties, not the least of which is the fact that the insurance business is not organized to meet in full and in detail his particular needs.
Página 300 - ... cc. To this was added a solution of 93.5 g of pure potassium hydroxide in 250 cc of water. Air freed from carbon dioxide by passing over sodium hydroxide was then drawn through the mixture continuously for three days by the suction of a water pump. The diameter of the air inlet tube was 5 mm. The rate of flow was approximately 1.5 liters per minute. If the air is not admitted fast enough the solution will turn yellow, the color disappearing after several hours if the rate is increased. During...
Página 292 - R-CHOH.CONH.QHB, follow the same rule. It would be interesting to consider in a quantitative way the rotations of the amides that are mentioned in the table, but Weerman's actual readings are so small, in most cases less than two degrees, that the recorded specific rotations may be uncertain to the extent of several per cent. It seems possible, however, to draw at least one quantitative conclusion from them. By the same method of calculation that was used for the...
Página 301 - ... tube, hence [a]D=— 44.7°. Methyltetronic acid lactone that was obtained by Ruff and Kohn from the oxidation of methyltetrose with bromine melted at 121° and had a specific rotation of — 47.5°. The crystals of this lactone are easily soluble in cold absolute ether, contrary to the behavior of most lactones of the sugar group. Ruff and Kohn describe the crystals as rather difficultly soluble in benzene, ether or chloroform and very soluble in alcohol or ethyl acetate. We have verified these...
Página 281 - But it has been seen that if the ring forms on the /--carbon there are twenty-four agreements, no disagreements, and none in doubt. As the chances that an event which can happen in two equally probable ways will happen in exactly the same way twenty-four times out of twenty-four trials is only one in seventeen million, it seems certain that the lactonic ring in these monobasic sugar lactones. forms on the /--carbon atom.
Página 296 - It will be noticed that the numerical values decrease as the carbon atom is further removed from the amide end (the difference between the values for the y- and 0-atoms, both of which are very small, are probably near the limit of accuracy of the data). The alternation in the sign of the rotation of the successive carbon atoms is also noteworthy, suggesting the alternation in positive and negative affinity that is often ascribed to the carbons in a chain.
Página 263 - ... forms of the sugar. The nonreducing, nonmutarotating sugars (for example, sucrose, trehalose, raffinose) do not show this maximum rate of solution. By measuring the maximum rate of solution, or the initial and final solubilities, of many of the mutarotating sugars, it has been possible to obtain experimental evidence on the rotatory powers of those forms of these sugars which have as yet not been crystallized and measured directly. In the following table a summary is recorded of the specific...