I freely admit, with no reservations, that Ceil Adams is the world’s smartest human being. However, Cecil is human, and (dare I say?) fallable. To wit: He did the wrong experiment.
From Cecil’s lab notebook:
“Then I carefully measured a whole passel of water into the Straight Dope tea kettle and boiled it for about five minutes. This was so I could compare the freezing rate of boiled H20 with that of regular hot
water from the tap. (Somehow I had the idea that water that had been boiled would freeze faster.)…Finally I put equal quantities of each type into trays in the freezer, checked the temp (125 degrees Fahrenheit all around), and sat back to wait…”
So Cecil has taken “hot water from the tap” and boiled water and made ice cubes. But we know that water will “outgass” at temps well below 100 C (see my previous post). Boiling is not necessary, just a short time in the family water heater.
"I subsequently did the same with two trays of cold water, which had been chilled down to a starting temperature of 38 degrees.
The results? The cold water froze about 10 or 15 minutes faster than the hot water, and there was no detectable difference
between the boiled water and the other kind."
Unfortunately, “the other kind” may refer to unboiled hot tap water, or cold tap water. In any case, unless the Straight Dope Water Analysis Facility has some expensive lab equipment (which Mrs. Adams would surely not allow in the kitchen), anyone would have a hard time detecting the difference I am discussing, i.e., the presence (or absence) of air molecules in solution.
Since I have already destroyed any chance of grace in the eyes of Our Cecil, I shall now describe the experiment he should have performed:
- boil some cold tap water in the Straight Dope tea kettle
- float the teapot in cold tap water until the temperature of the boiled water is equal to freshly tapped cold water. Don’t contaminate the boiled sample with cold tap water, and don’t agitate the teapot or you will dissolve air molecules in the boiled water.
- place equal volumes of cold tap water and carefully decanted boiled water into the Straight Dope Cryo Chamber. Grab some Cherry Garcia while the door is open.
- open chamber and observe samples periodically until discovery that (with initial temps, volumes, and environmental temps being equal to ensure that the cooling rates are the same), the outgassed water forms ice crystals first. Since the temps of the samples were the same since step (2), the outgassed water freezes at a slightly higher temp, and may be said to have frozen “first”
As a last and probably vain attempt to redeem myself as a devoted minion wannabe, Cecil gets the last word:
"Another old wives’ tale thus emphatically bites the dust. Science marches on.