The design principle of the lotion bottle is to use the contraction force of the spring to prevent air from entering the bottle, resulting in a vacuum state, and to use atmospheric pressure to push the piston at the bottom of the bottle forward. However, because the spring force and atmospheric pressure cannot give enough force, the piston cannot fit too tightly with the bottle wall, otherwise the piston will not be able to move forward due to excessive resistance; on the contrary, if the piston is to be moved forward easily and material leakage is likely to occur, Therefore, vacuum lotion bottles have very high requirements on the professionalism of manufacturers.
The modern thermos was invented in 1892 by the British physicist Sir James Dewar. At that time, he was conducting a research work to liquefy gas. To liquefy the gas at low temperature, first of all, the lotion bottle needs to be designed with a container that can isolate the gas from the outside temperature, so he asked the glass technician Berg to blow it for him. A double-layer glass container with two inner walls coated with mercury.
Then the air between the two layers is removed to form a vacuum. This kind of vacuum lotion bottle
is also called "Du bottle", which can keep the liquid in it at the same temperature for a certain period of time regardless of cooling or heating.
Since the thermos bottle is mainly used for hot water insulation in the family, it is also called a thermos bottle. The structure of the thermos is not complicated. In the middle is a double-layer glass bottle. The two layers of the lotion bottle are vacuumed and plated with silver or aluminum. The vacuum state can avoid heat convection.
The glass of the lotion bottle itself is a poor conductor of heat, and the silver-plated glass can reflect back the heat radiated from the inside of the container. Conversely, if cold liquid is stored in the bottle, the bottle can prevent the external heat from radiating into the bottle.