in the container 1 is low and the rest amount has become small it is notable that the float 15 catches not only the floating power produced by the liquid phase of the carbon dioxide in the container but also the floating power produced by the gaseous phase therein which is generated when the temperature is higher than the critical point of the carbon dioxide therefore it is possible to detect the accurate total rest amount in the container 1 at any desired time for example during the feeding at valve operation to close or open it and so on of course one of the detecting member 16 and the magnet 29 of the indicating member 9 may be substituted by magnetic materials such as iron steel and so on instead of magnet the articulating or flexible part 18 according to the invention may be modified variously as seen in fig8 to 17 for example a modified articulating or flexible part 18 shown in fig8 comprises a universal joint 42 with a cross member inserted on the way of the rod 13 another modified articulating or flexible part 18 shown in fig9 comprises a spring joint 43 disposed along the rod 12 another modified articulating or flexible part shown in fig1 comprises a double springs 52 and 53 both of which may contribute to suspend the float 15 as well as the spring 14 shown in fig1 and 2 further modified articulating or flexible part 18 as seen in fig1 comprises a spring 44 which is connecting upper and lower parts of the float 15 the float.