Methods for the Examination of Milk; For Chemists, Physicians and Hygienists

Methods for the Examination of Milk; For Chemists, Physicians and Hygienists

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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1901 edition. Excerpt: ...with hot water and the hot supernatant liquid cautiously decanted, care being taken to retain the precipitate in the beaker. This precipitate is washed thoroughly with hot water by decantation. The soluble matter in the paper is completely removed by washing with water and finally the precipitate is transferred to the filter and again washed to remove the last traces of soluble copper. By careful manipulation the precipitated cuprous oxide in the majority of cases will be completely retained by the filter. If, however, any of the precipitate should run through it is best to begin the determination again. It is important in every case to remove all traces of the excess of Fehling's solution from the filter before transferring the precipitate. The washing of the cuprous oxide in the beaker should be continued until the washings show no alkaline reaction or give, when acidulated, no test for copper with potassium ferrocyanide. Soxhlet and Allihn suggest the use ola bulbed tube provided with an asbestos filter for carrying on these filtrations. The precipitate on the filter is dried at 100 degrees and ignited in a porcelain crucible previously dried and weighed. Continue the ignition until the filter is entirely incinerated. The flame is then removed and the copper oxide covered with a thick layer of powdered sulphur. The cover, provided with a gas inlet tube (Rose crucible), is then put on and hydrogen gas passed in until all of the air is displaced. Finally ignite for fifteen minutes in an atmosphere of hydrogen. By this means the copper oxide is converted into copper sulphide and is weighed as such. From this weight the known weight of filter ash is deducted and the percentage of lactose calculated from the accompanying table. Instead of...show more

Product details

  • Paperback | 26 pages
  • 189 x 246 x 1mm | 68g
  • Rarebooksclub.com
  • Miami Fl, United States
  • English
  • black & white illustrations
  • 1236678621
  • 9781236678621