Prussian blue is made by adding a solution of ferrocyanide of potassium (yellow prussiate) to a solution of ferric chloride, or by adding the former to a solution of ferrous sulphate (green viti-iol) and afterwards with nitric acid or other oxidising agent. The pivripitate is allowed to settle, washed several times with water by decantation, collected in filter bags, pressed, and slowly dried. Yermilionettes are made by mixing orange lead and barytes with water, then adding eosin and lead acetate until the colouring matter is entirely precipitated upon the barytes and orange lead. The pigment is finished as in the case of Prussian blue. '! In colours are made in large wooden vats; filter presses and drying stoves are required also.