Naphtha, and the Coal Oil of our gas-works, are even more powerful solvents than the vegetal essential oils; but, on this account, and the bad scent of the latter, they are less eligible for the painters' use as vehicles: the rectified coal oil may however be deprived of its nauseous smell, by agitating it during several days with dilute sulphuric acid, and subsequently washing the oil with a little powder, or milk of lime.