Official Methods of Analysis, Part 2

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Page 245 - ... in a glass-stoppered flask. Add to this 5 cc of strong hydrochloric acid. Allow the solution of sodium thiosulphate to flow slowly into the flask until the yellow color of the liquid has almost disappeared. Add a few drops of the starch paste, and with constant shaking continue to add the sodium thiosulphate solution until the blue color just disappears.
Page 79 - Continue the titration cautiously until the color due to free iodin has entirely vanished. The blue color changes toward the end to a faint lilac. If at this point the thiosulphate be added drop by drop and a little time be allowed for complete reaction after each addition there is no difficulty in determining the end point within a single drop.
Page 1 - ... of water. Keep the mixture in a warm place for several days, or until a portion heated to 40" C. deposits no yellow precipitate of ammonium phosphomolybdate. Decant the solution from any sediment and preserve in glass-stoppered vessels.
Page 262 - ... hydrochloric acid, without previous washing or extraction, and the solution is made up to 250 cc before filtering and drawing off the aliquot. 9. Crude Fibre.
Page 234 - Shake the tubes well and allow to stand. In the presence of azo dye the test tube to which the acid has been added will show a pink to wine-red coloration, while the potash solution in the other tube will show no color. If...
Page 242 - When the temperature of the alcohol-water mixture rises to about 6 below the melting point, the disk of fat begins to shrivel, and gradually rolls up into an irregular mass. The thermometer is now lowered until the fat particle is even with the center of the bulb. The bulb of the thermometer should be small, so as to indicate only the temperature of the mixture near the fat.
Page 105 - Carbonize the mass at a low heat, dissolve the soluble salts with hot water, burn the residual mass as above, add the solution of soluble salts, and evaporate to dryness at 100 C., ignite gently, cool in a desiccator, and weigh.
Page 250 - To prevent bumping, pass a slow current of carbonic acid into the liquid through a finely drawn out tube reaching nearly to the bottom. Allow the mixture to separate into two layers, siphon off the water, and boil the oily layer with fresh water until it is no longer acid to litmus paper.
Page 174 - ... after each addition. Let stand until clear, then pour off through a filter, and wash the cylinder and filter with a mixture of...
Page 182 - as follows : Grind aldehyde ammonia in a mortar with ether and decant the ether. Repeat this operation several times, then dry the purified salt In a current of air and finally in a vacuum over sulphuric acid. Dissolve 1.386 grams of this purified...

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