Patent GB-443444-A (GB)
Title: Improvements in parasiticidal compositions
IPC: A01N59/20
Filed: 1934-09-06
Abstract: A lyophillic zinc silicate gel for use in parasiticidal compositions is precipitated by slowly mixing dilute alkali silicate and zinc salt, for example zinc sulphate solutions while agitating.  The precipitation is usually complete at a pH of about 6.8--7.5.  The ratio of alkali to silica in the silicate solution may be varied to control the character of the gel.  The precipitate is washed and may be dried and ground.  A copper zinc ammonium silicate is similarly made by adding sodium silicate (Na2O : SiO2 = 1 : 3.22) and ammonia solutions to a solution of zinc and copper sulphates.  Precipitation is usually complete at pH = 6.8--7.2.  Bordeaux mixtures which contain copper and calcium can be improved by incorporation of silicate.  A complex copper calcium silicate is preferably made by p precipitating calcium silicate and immediately adding a solution of a copper salt and agitating.  Zinc equivalent to 5--20 per cent of the copper may be incorporated.  Thus, lime and sodium silicate solution (Na2O : SiO2 = 1 : 3.86) are mixed and to the suspension of calcium silicate obtained are added solutions of copper and zinc sulphates with agitation.  The atomic ratio of Cu to Zn in the precipitate is approximately 5 to 1.ALSO:Parasiticidal compositions containing water-insoluble active ingredients which in water-soluble form are harmful to growing vegetation are stabilized against solution in acids generated by natural agencies by means of a water-insoluble compound of zinc or calcium with the ion of a very weak water-insoluble inorganic acid.  Such a compound is zinc or calcium silicate or aluminate. Active ingredients specified are materials containing copper, mercury, arsenic, lead or sulphur especially when used together with mineral oils.  In particular, copper ammonium silicate which is a known active ingredient can be precipitated together with zinc silicate.  A lyophillic zinc silicate gel can be precipitated by slowly mixing dilute alkali silicate and zinc salt, for example zinc sulphate solutions while agitating.  The precipitation is usually complete at a pH of about 6,8-7,5.  The ratio of alkali to silica in the silicate solution may be varied to control the character of the gel.  The precipitate is washed and may be dried and ground.  A copper zinc ammonium silicate is similarly made by adding sodium silicate (Na2O : SiO2=1 : 3,22) and ammonia solutions to a solution of zinc and copper sulphates.  Precipitation is usually complete at pH=6,8-7,2. Bordeaux mixtures which contain copper and calcium can be improved by incorporation of silicate.  A complex copper calcium silicate is preferably made by precipitating calcium silicate and immediately adding a solution of a copper salt and agitating. This can be further stabilized by incorporating zinc equivalent to 5-20 per cent of the copper.  Thus lime and sodium silicate solution (Na2 : SiO2=1 : 3.86) are mixed and to the suspension of calcium silicate obtained are added solutions of copper and zinc sulphates with agitation.  The atomic ratio of Cu to Zn in the precipitate is approximately 5 to 1.  The aluminate radical is substantially equivalent to silicate.