Flask

The utility model provides a flask and belongs to the technical field of chemical experiment instruments. The problem that in the prior art, the nesting joint of an upper hemisphere bottle body and a lower hemisphere bottle body is abraded, and consequently air tightness becomes poor is solved. The flask comprises an upper half flask body and a lower half flask body which are detachably connected, a first flange is arranged at an opening of the upper half flask body, a second flange capable of being attached to the first flange is arranged at an opening of the lower half flask body, and a plurality of fastening devices used for fixedly connecting the first flange and the second flange are arranged between the first flange and the second flange. The fastening device comprises a buckle body and an adjusting bolt, one end of the buckle body abuts against the second flange, the other end of the buckle body penetrates through and is in threaded connection with the adjusting bolt, and the lower end of the adjusting