nh sub 2 sub 2 cs 0 0067m orzan s 12 0 g l______________________________________ this product showed a superior stability to deterioration in comparison to the same product in the absence of added nh 2 2 cs while i do not wish to be bound by theory it is believed that the addition of thiourea results in adsorption onto the colloid and provides protection against further deterioration homologs of thiourea were also used e g nh 2 2 co and nh 2 2 cse however their effectiveness was not as good as the thiourea it is further realized that it is the thio group str1 that provides the present effect and thus substituting other thio containing compounds falls within the spirit of this invention r 1 and r 2 may be various groups from alkyl amines aromatics hydrogen halogen and mixtures thereof a colloidal composition comprising the reaction product resulting from the admixture of the following reactants was prepared nucleation took place above room temperature final ph was about 12 the resulting colloidal composition showed a greater visual stability in comparison to the same without the added antimony hence antimony in combination with the copper primary metal is a useful combination a colloidal composition similar to above was prepared except that lead was used instead of the antimony trichloride specifically the lead was pb from fluoroborate solution at.