Haemoglobin and gold sol are examples of oppositely charged colloids. Haemoglobin is a protein that behaves as a positively charged sol in acidic conditions due to protonation of amino groups. Gold sol, prepared by reduction of gold chloride, adsorbs citrate or chloride ions and becomes negatively charged.

Thus, haemoglobin is a positively charged sol and gold sol is a negatively charged sol.

Final answer: positively and negatively charged sols, respectively