Cool! Harry
On Fri, Jan 21, 2022 at 4:21 PM MSF <foster...@protonmail.com> wrote: > > How to make dry ice with a fire extinguisher: > > https://www.youtube.com/watch?v=tLNHDxd6nDc > > How to make dry ice with a paintball tank: > > https://www.youtube.com/watch?v=L7U2CbxfMMk > > ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐ > > On Friday, January 21st, 2022 at 8:08 PM, MSF <foster...@protonmail.com> > wrote: > > > 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 >
