The last time I updated this blog, I wrote about wondering about insignificant things. One thing I could have included in the “wonder why” update is why does milk come in square containers and (most) other liquids and drinks come in round containers. I had actually wondered about this some time ago and did some extensive research to come up with some plausible explanations. The generally accepted answer to this puzzlement is that because milk must be refrigerated, rectangular containers occupy less shelf space and the shelf space is more valuable when the space has to be cooled.
I’m pretty sure that’s not the reason — it makes sense, but using that logic, soda (and beer, etc.) containers should be made square to conserve space. I think the real reason is just plain physics. Any liquid that requires pressure for storage uses round containers because they withstand pressure much better than square ones. If you stored coke in a square can, the pressure would push out the sides and it would become “rounded.” If you look at a soda can, you’ll see it’s not just a perfect cylinder with a flat top and bottom — obviously a lot of engineering went into designing these cans, and it’s all about pressure. For environmental (and probably economic) reasons, the cans have become thinner and thinner and yet they still maintain the pressure without rupturing or bulging. If the top and bottom of the cylinder were completely flat they would be prone to bulging. That’s why soda cans taper a bit at the top and why the bottoms are built bulging inward.
But back to milk…. when I was young, I remember that milk came in round, glass bottles. We got ours at the store, but when Claire was growing up in Cleveland, milk was delivered — in round glass bottles — to their door every day by the milkman. We all know that milk must be refrigerated to keep it from spoiling or “going bad.” Before refrigerators, (some) people had ice boxes — they were exactly what they sound like — kind of an insulated “box” where ice was put — in big chunks, usually 25 or 50 pound “chunks.” Of course the ice, even in an insulated box didn’t last very long and had to be replenished ever day or so. Anyhow, that’s where a lot of people kept their milk before refrigeration. The bad news is that milk didn’t last very long. The good news is that milk was often delivered in those glass bottles every day, so you always had fresh milk — you just had to drink it real fast.
The milk carton was patented in 1915. GE produced the first refrigerators along about 1910. So people could keep their milk longer, but they preferred to keep them in those glass bottles — most didn’t think much of those new fangled cardboard containers — that were square.
When I was in China in 1972, milk was packaged in plastic bags (paint was packaged that way too, but that’s another blog.) They were just flimsy plastic bags. You had to cut the corner of the bag off to get the milk out and there was no way to “close” or re-seal it. If you weren’t going to drink the whole bag of milk, it seemed like an inefficient way to keep it. You just had to carefully balance the bag in the refrigerator so it wouldn’t turn over.
I forget the point of this whole thing — I suppose it might be that things around us are designed to be exactly how they are — maybe we should pay more attention.
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Actually the milk bottles that were delivered to our house every other day were rectangles – there were six half-gallons in each crate.