# Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1996, Paragraph 7: PRECIPITATION OF THE CALCIUM OXALATE


Add approximately 100 ml of water. Bring to the boil, add 8 to 10 drops of indicator solution (4.8) and, slowly, 50 ml of the hot ammonium oxalate solution (4.4), stirring constantly. If a precipitate forms, dissolve by adding a few drops of hydrochloric acid (4.1). Neutralise very slowly with ammonia solution (4.3) while stirring continuously to a pH of 4.4 to 4.6 (change of indicator (4.8) from green to blue). Place the beaker in a boiling hot water bath (5.2) for approximately 30 minutes.
Remove the beaker from the bath, leave standing for an hour and filter through the crucible (5.1).

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/20./paragraph/7 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-20./paragraph-7
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.