I dont get it. Whats a closed bottle of salt water got to do with the water in the pan? Are you saying put the closed bottle in the water they drink? Sorry, its not clear enough for me yet

Cold air draws heat from the fresh water which would normally allow it to solidify into ice, but since the salt water has a lower freezing point heat flows from it into the fresh water keeping it liquid.

Ok, so how many gallon jugs of high concentration salt water solution would I need to keep a 50 gallon water drum for cattle from freezing?, I have lost too many axe heads splitting ice!

Your explanation makes no sense. Whereas spreading salt on the road actually mixes the salt with the water and ice on the road, the only communication between the water in the saltwater bottle and the water outside it is conduction of heat through the plastic membrane separating the two, and that is strictly driven by actual temperature, not “thermal energy”. It doesn’t matter at all how much thermal energy is inside the bottle—you could imagine, for example, that you have a nuclear source at 2000K sealed in a capsule with a perfect insulator inside that bottle as well, but as long as the insulator is perfect, the surface temperature of the capsule is the same as the temperature of the surrounding saltwater, and it will do nothing to prevent any water, inside or out, from freezing. (Note that the capsule would quickly explode since its temperature would rapidly climb with no heat escaping.) IOW if the *surface temperature* of the bottle falls below 0°C, it does nothing to keep the external plain water from freezing. In fact, see below.

Cooling is a process of transferring heat from a substance at higher temperature to a substance at lower temperature. The transition from liquid water to ice in fact requires liberating a *lot* of heat—for plain water to go from 0.5°C liquid to -0.5°C ice, for example, liberates a *lot* more heat than going from 4°C liquid to 3°C liquid. (This is why HVAC cooling is measured in “tons”—a ton is the amount of cooling capacity required to freeze (or heating capacity to melt, as the process is conservative) one ton of water in a 24-hour period.)

What you are doing, by putting saltwater in the bottle, is moving the transition point for that liquid to a lower temperature. In this scenario, heat from the water is being transferred from the water in the bucket to the surrounding air (with a small amount also being radiated as infrared or escaping due to evaporation). The rate of heat liberation is determined by the air temperature, water temperature, convection, insulating factor of the material the bucket is made from, the surface area of the bucket and exposed water, and radiative heat sources (e.g. sunlight falling on the bucket). Making some portion of that water not freeze actually will accelerate the freezing of the rest, since that non-freezing water doesn’t need to lose as much heat in order to drop below the freezing point of the surrounding water. This is compounded by the fact that the specific heat of saltwater is lower than that of plain water, i.e. it takes less energy to heat a given mass of saltwater by 1° than it does to heat the same mass of plain water by 1°. That is, the temperature of the saltwater bottle will more readily drop below 0°C, both because of its lower specific heat and because it doesn’t need to undergo a phase transition, so displacing plain water that would not as easily do so simply means less heat needs to be liberated from the whole system to get it below 0°C.

If you want to do a *proper* experiment, you need two buckets of the same type starting at the same temperature, and two bottles also of the same type—one containing saltwater and one containing plain water—at the same temperature, stationed close to one another with no surrounding heat sources, and you need to measure when these two buckets respectively freeze. Just sticking a bottle into a bucket and subsequently observing that the bucket didn’t freeze establishes nothing about what the effect of the saltwater bottle was.

No electricity at my allotments!

Did you see she said she used 1/4c salt in the bottle?

Where we live, the water freezes quickly during the day. It’s not a matter of not giving them fresh water every day, but keeping the water from freezing during the day so they have access to water at all times.

You do realize IT SLOWS THE FREEZING my god how do you even have pets?

Please reread the post. It states that it slows it down and does not completely stop it. We do replace the water daily. Some days, however, we have to change it multiple times a day because of temps. This has given us less work, because the freezing has slowed down.