(c) shall have a specific gravity of not less than 1.041 and not more than 1.065 (20°C/20°C); and

(d) shall contain, in 100 millilitres measured at a temperature of 20°C, not less than 0.24 gram and not more than 0.60 gram of ash of which not less than 50 per cent shall be potassium carbonate.