Abstract: This invention relates to a level which detects a level line or horizontal surface. The mixed liquid, composed of a main agent, 2,2-dichloro-1,1,1-trifluoroethane and an additive agent, comprising one or more of a soluble agent selected from the group of methyl alcohol, ethyl alcohol, acetone, hexane, heptane, isoamyl alcohol, allyl chloride, isopropyl chloride, propyl chloride, diethyl ether, dipropyl ether, pentane, methyl hexane and silicon oil, is contained and sealed, having a ratio of about 60:40 to about 70:30 between the main agent and the additive agent, with the dyestuff in a transparent heat-resistant tube.