Background art A bottle cap is the thing to keep liquid in the bottle. An existing Bottle cap haven't had the function not to leak the carbonic acid gas in the bottle to keep the carbonated water fresh for a long time.

The bottle cap for carbonated water can keep the carbonic acid gas in the bottle for the longer time by the body of revolution than the existing bottle cap.

Brief description of the drawings Fig. 1 shows the cross-sectional figure of the present invention.

Fig. 2 shows the plane figure of the body of revolution.

Fig. 3 shows the side figure of the body of revolution.

* Description of the numbers in drawings 1. Bottle cap 2. Body of revolution 3. Convex surface 4. Axis of revolution 5. Bottleneck 6. Groove for revolution 7. Bottle

Disclosure of invention The present invention provides the utility to be able to keep carbonated water fresh for longer time than the existing bottle cap does.

To keep carbonated water fresh for a long time, the present invention has the body of revolution between the cap and bottleneck. The structures of this invention is explained in details as follows.

Figure 1. shows the cross-sectional figure of the present invention.

Figure 2. shows the plane figure of the body of revolution.

Figure 3. shows the side figure of the body of revolution.

In the figure 1. There are bottle cap (l) and bottleneck (5) and the body of revolution (2) to prevent from leaking carbonic acid gas out of the bottle.

In the figure 2. there are convex surface (3) to set the body of revolution (2) at level when the bottle is not leant. The bar level of the bottle result from the convex surface (3) that is heavier than the other part of the body of revolution (2). And the axis of revolution (4) that is fitted with the groove of the revolution (5).

The body of revolution (2) would revolve by the power of the water out of bottle (7) when the carbonated water is poured out and the body of revolution (2) would be at a level by the weight of the convex surface (3) when carbonated water does not poured out.

In the figure 3. there are convex surface (3) that is heavier than the other part of the body of revolution (2).

In the figure 4. the axis of revolution (4) is inserted in the groove of the revolution (5). The body of the revolution would be kept a bar level when the bottle is not inclined to pour carbonated water.