{
  "url": "https://openlegislation.uk/eu-directive-1969-493/annex-II/division-1/division-1.3",
  "json_url": "https://openlegislation.uk/eu-directive-1969-493/annex-II/division-1/division-1.3.json",
  "legislation": "eudr/1969/493",
  "legislation_title": "Council Directive of 15 December 1969 on the approximation of the laws of the Member States relating to crystal glass (69/493/EEC)",
  "legislation_url": "https://openlegislation.uk/eu-directive-1969-493",
  "path": "annex/II/division/1/division/1.3",
  "kind": "division",
  "number": "1.3",
  "heading": "Determination of K2O",
  "text": "by precipitation and weighing of potassium tetraphenylborate.\nProcedure:\n2 grammes of glass are attacked, after crushing and sieving, by\n2 millilitres concentrated HNO3\n15 millilitres NClO4\n25 millilitres HF\nin a platinum dish on a water-bath then in a sand bath. After dense fumes of perchloric acid have been given off (continue until dry), dissolve with 20 millilitres of hot water and 2-3 millilitres concentrated HCl.\nTransfer to a 200 millilitres graduated flask and adjust to volume with distilled water.\nReagents: 6% solution of sodium tetraphenylborate: dissolve 1·5 grammes of the reagent in 250 millilitres distilled water. Remove the light cloudiness which remains by adding 1 gramme of hydrated aluminia. Shake for five minutes and filter, taking care to re-filter the first 20 millilitres obtained.\nWashing solution for the precipitate: prepare a little of the potassium salt by precipitation in a solution of about 0·1 grammes KCl to 50 millilitres N/10 HCl into which the solution of tetraphenylborate is poured while stirring, until precipitation ceases. Filter through a sinter. Wash with distilled water. Dry in a desiccator at room temperature. Then pour 20-30 milligrammes of that salt into 250 millilitres of distilled water. Stir from time to time. After thirty minutes, add 0·5-1 gramme of hydrated alumina. Stir for a few minutes. Filter.\nMethod of operation: Take an aliquot of the acid digest corresponding to about 10 milligrammes of K2O. Dilute to about 100 millilitres. Slowly add the reagent solution, about 10 millilitres per assumed 5 milligrammes of K2O, while gently stirring. Allow to stand for a maximum of fifteen minutes then filter through a tared sintered crucible of porosity 3 or 4. Wash with washing solution. Dry for thirty minutes at 120 °C. Conversion factor 0·13143 for K2O.",
  "extent": "E+W+S+N.I.",
  "status": null,
  "version": "current",
  "annotations": [
    {
      "type": "X",
      "label": "X1",
      "text": "Substituted by Council Directive No 69/493/EEC of 15 December 1969 on the approximation of the laws of the Member States relating to crystal glass (Official Journal of the European Communities, No L 326, p. 36),."
    }
  ],
  "outstanding_effects": [],
  "provenance": {
    "source": "legislation.gov.uk",
    "source_url": "https://www.legislation.gov.uk/eudr/1969/493/annex/II/division/1/division/1.3",
    "retrieved_at": "2026-11-01T15:23:53.885678+00:00"
  },
  "licence": "Open Government Licence v3.0",
  "licence_url": "https://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/",
  "attribution": "Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives."
}