Laporte Industries Limited

Ian K Egerton

Andrew D Broome

A copper arsenate composition suitable for incorporation in a copper/chrome/arsenic wood preservative composition is made by reacting copper metal with a source of 5-valent arsenic such as arsenic acid under the oxidizing influence of hydrogen peroxide. The quantity of arsenic acid used may be made consistent with the arsenic to copper ratio required in the final wood preservative composition which may be made up by including a suitable source of chromium with the copper arsenate reaction product.

Wood preservative compositions and a process for their production

Wood preservative compositions containing as active ingredients compounds of copper, of chromium and of arsenic are produced by mixing copper arsenate and sodium dichromate in an aqueous medium into which is introduced strong acid, for example sulphuric acid, effective to achieve a soluble product. The acid addition is preferably effective to reduce the pH to below 0. The composition so produced is a homogeneous paste which may be dissolved in water to working concentration and used for the preservation of wood by impregnation techniques.

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Runcorn, United Kingdom

Ian K Egerton