The thermos is also called the thermos flask, when I was young, the thermos was only a glass liner, coated with a layer of silver, made into a double layer and vacuumed to keep warm, at that time there was no current thermos cup.
Especially when I was in middle school, I used it a lot, and on winter mornings, I took cold water and felt like I was going to freeze to death. At that time, the school was a residential school, and everyone in the dormitory had a hot water bottle, and every night after Xi went to line up to make boiling water, brought it back to the dormitory, scalded his feet at night, and used the rest to wash in the morning.
When living in school, most of them use a 5-pound hot water bottle, a bottle of boiling water, just enough, and a very small number of people use 8-pound hot water bottles, now I will tell you how to distinguish between a 5-pound and an 8-pound hot water bottle.
The 5-pound and 8-pound thermos are not the same size, one holds five pounds of water and the other holds eight pounds of water. 5 pounds of water 2268 kg 2268 liters, 8 pounds of water 36288 kg 36288 liters.
In appearance, the two pound thermos are about the same height, but the 8-pound one is significantly thicker than the 5-pound one, and the 8-pound one is larger than the 5-pound one on the mouth.
If there is only one hot water bottle, depending on the weight after filling it with water, it weighs about 7 pounds and weighs about 4 pounds and weighs 5 pounds.
For people who used to use hot water bottles a lot, it is easy to tell the difference.