It seems as if you are going to do some serious experimenting, and would have to make that 5 hour trek more often than you would like. You could save yourself a lot of time and gasoline if you just made your own dry ice. It's pretty simple. You can buy the whole setup. It's basically a canvas bag connected to a CO2 cylinder. You can rent the gas cylinder from a welding supply house. Obviously, that's more expensive than buying some dry ice, but probably cheaper than making that trip frequently.
‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ On Friday, January 21st, 2022 at 6:15 PM, H LV <hveeder...@gmail.com> wrote: > Thanks. The same supplier also makes liquid nitrogen, although if I > > use liquid nitrogen then I would have to buy a special vessel. > > For a few years now I have been thinking about redoing a key > > experiment in the development of radiation theory and then following > > it up with an experimental modification which has never been tried > > according to my own historical research. The original experiment > > performed by Pictet in the 1790s involves placing a flask of > > ice/water/salt at the focus of one parabolic reflector and a > > thermometer at the focus of another parabolic reflector. The distance > > between the foci is several feet but the thermometer cools down > > significantly. Initially Pictet was surprised because he thought > > nothing would happen, but he later came to explain the effect in terms > > of what we now call radiative cooling whereby the parabolic reflector > > near the thermometer prevented the thermometer from being warmed by > > its surroundings causing it to lose heat to the ice. However, Count > > Rumford said it was cooled by the action of frigorific or cooling > > emanations from the ice being focused onto the thermometer. Pictet > > thought his explanation was closer to the truth but acknowledged that > > the experimental result could be explained equally well by either > > explanation. I want to redo the experiment but also perform a new > > experiment where the two parabolic reflectors are replaced with one > > elliptical reflector because it should produce a result which more > > clearly favors one explanation over the other. > > This is a diagram I made of the original experiment along with my > > proposed modification: > > https://drive.google.com/file/d/16HkSc_BvIvIWJCDwr_KwypW1fhuIUzCf/view?usp=sharing > > In this 1985 paper the authors describe Pictect's original experiment > > in more detail and the ideas that were in play at the time. They also > > describe their recreation of the experiment using liquid nitrogen, a > > brass ball and parabolic reflectors made of mylar and cardboard: > > http://webspace.pugetsound.edu/facultypages/jcevans/Pictet's experiment.pdf > > Harry > > On Thu, Jan 20, 2022 at 4:41 PM MSF foster...@protonmail.com wrote: > > > When transporting or storing dry ice, styrofoam is your friend. A Dewar > > flask would be preferable, but only thermos bottles are commonly available, > > and a lot of them are no longer Dewars. A styrofoam cooler would probably > > make your dry ice last the 2 1/2 hour trip as long as it's full. Large > > pieces are preferable just to reduce the total surface area. > > > > Since you would be traveling in a car, you would want to make sure of good > > ventilation to prevent carbon dioxide build up. > > > > Storing in a freezer could help, as long as the dry ice is inside a > > styrofoam container. The freezer, although far above the dry ice > > temperature would at least slow down the heat loss. > > > > Some of your fancier ice cream places are using liquid nitrogen to make > > instant ice cream, so if that would do the trick for your cooling purpose, > > there might be a supply nearer you. > > > > ‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > > > > On Thursday, January 20th, 2022 at 3:55 PM, H LV hveeder...@gmail.com wrote: > > > > > Does anyone here have experience transporting and storing dry ice? > > > > > > If you keep it stored in an ordinary freezer how long will ice cube > > > > > > sized pieces last? > > > > > > The closest supplier I can find is a 2.5 hour drive away. Will it even > > > > > > last 2.5 hours if stored in a cooler or thermos bottle? Would larger > > > > > > chunks be better? > > > > > > Thanks. > > > > > > Harry
