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%20experiment.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 >
