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Hi. Am missing too many things with the growth of these crystals; can someone clarify details please ? As the molten bismuth is slowly cooling, do the crystals form embedded in the liquid, under the surface, as 'a diamond in a glass of water' ; Is that right ? Pouring out the molten metal leaves the solidified crystals in the pot, attached to portions of solidified metal ? How come the 'being poured out' molten metal does not leave particles and 'dew' attached to the crystals crevices ? They look soooo shiny and clean and smooth ! Do crystals grow only while submerged in their slightly hotter surrounding metal ? After the molten metal is drained, the crystals do not continue to grow, do they ? Does it make sense to say the longer the time waiting to pour out the molten metal, the larger the crystals would be ? But it is mandatory to drain before all becomes a solid piece, right ? ... Like 'the diamond being now captive in ice' If the melting pot had a cover, (with little air gap) there would be less/no formation of the grey layer on the surface because of less oxygen to produce it, is that right ? Is cooling preferred to start in the bottom of the core (if it was possible), and keep the pot walls hotter to achieve a better ideal draining? Edited: a nice site ----> http://www.amazingrust.com/Experiments/how_to/Bismuth_Crystals.html Thanks.

Hi all. Written English and chinese seem to me, a native spaniard; very memory intensive comparatively. In spanish, you do not have to memorize how to spell, words never heard before are easily written with no previous knowledge. A new written word can be pronounced properly with no previous knowledge. It is a fonetic language. You may not want to hear me to say the simple word 'focus' with my accent. That triggered this post. Well, ¿ would the forced memory exercising due to a language that is not fonetic play any role in better brain capabilities in lives of non fonetic speaking people ? Miguel

---> Wrong. heating elements in series do NOT increase voltage nor current. They increase resistance ---> That is what several cigarette lighters in series are: a higher resistance. a car battery would be if you want the heater on for many hours, possibly days. I like the chemical way from YT.

First time bee/wasp stings do make you feel much better the day after, but the next times you get stung the effect diminishes. I do not think it cures anything.

Hello. An automotive cigarette lighter heating element and a momentary pushbutton switch can serve well for your application. If drains the battery too fast, try a couple of them in series to get less temperature but more time. Or remove the heating wires and wrap them properly around the CO2 receiver.

Questions about these bismuth 'levitators'... Does the thickness or mass of the bismuth affects the amount of repulsion ? Can the same effect be achieved making the bismuth be the one floating above a magnet ?

...And I thought it was related to gyroscopic effect, as to keep the axis aligned:-(

Hi all ! and thanks for the replies to the related preamble post "Metal under the hot sun" found here: http://www.scienceforums.net/forum/showthread.php?t=35416 Let's imagine... Metal pipe(s), say 10cm ⌀, vertical, blackened, say 3metres long, vents at the bottom, exposed to sun heat. A nozzle misting seawater inside from their tops. Flow calibrated to always have a little brine draining at the bottom. A shaded wind cooled condenser at the top of the pipe(s) to collect evaporated water. There is room for some improvements as transferring the condensed water warmth to the incoming cool seawater with a exchanger, etc. but let's ignore those. There is a need to care for simplicity and cost. There is much more to ideas, there is calculations. Where do I start to speculate about productivity ? Miguel

If there is no heat capacity, no thermal conductivity, no mass and no density in the formula; I would say the plateau temperature reached calculates to the same figure no matter which material is under the sun. That does not make any sense to my ignorance. Where am I goofing? Does it mean wood and iron will have the same temperature but touching the wood will not burn because its amount of heat conducted to the skin due to poor conductivity will be dissipated sooner and not 'burn' ? [ The 1m^2 exposed surface is a good number for the analysis, all the different material plates under the same sun being that area, each being thicker or thinner to yield same mass, all painted same flat black and resting on the same insulation ] Miguel

Thanks. Let's see if I understood... Specific heat capacity (from Wikipedia) : Iron = 0.45 Aluminium = 0.897 Lead = 0.127 Copper = 0.385 This means that plates of the same dimension exposed to same sun, all kept say on top of a piece of insulator; the lead will increase its temperature the highest, and aluminium the least. and for thermal conductivity : Aluminium = 237 Lead = 35.3 Iron = 80 Copper = 401 Means that if all are at the same high temperature, touching copper will likely burn skin faster because transfers (conducts) its heat faster than lead. Is that right ?

Does anyone know about rubber behavior ?

What material presents in greater magnitude the property of shrinkage when warm -say 25 Celsius and expand when cold -say 5 Celsius ?

Thanks. OK, it is truly hotter, got it. Yes, it has to be, feet at 37 Celsius get blisters on pavement, and fried blisters on a steel plate. That can reach a guessing 70 Celsius Now, the metal mass has nothing to do with the temperature after reaching plateau, right ? (am not saying amount of heat!) What material index, property, constant... tells which metal will be hotter under the same sun? Stainless steel, plain iron, aluminium, brass, lead... which will be at the higher temperature ? And if all of the above receive the same flat black coating of paint, would they all be at the same temperature or still differ ?

Sixty Celsius is about the maximum you can handle without burning your hands... That piece of metal left under the sun, or a car bumper, or the beach sand can burn your skin but the ambient temperature is only 30 Celsius. What is going on ? How does the metal gets way hotter ? It is not only the thermal conductivity from the material-to-skin; it is truly hotter. Or seems to be

There is no carburettor to modify in a diesel engine; and to my opinion the abbreviations are the degeneration of a language, and have no temperature. Sooo... it is not carbohydrates modernized... Miguel

Hi. What does "carb mods" means ?

What they dress is what works best for them, no doubt. If the body produces and regulates heat to 37 Celsius, it seems logic to think that only happens at ambient temperatures below 37; If the body is already 38 degrees, then the mechanism should stay idling. It seems logic too, that avoiding additional heat intake from above 37 ambient is desirable, but physiologically, their genes? simply make their bodies to waste less nutritional energy into making heat. Or something like that. Does the human body temperature regulation mechanism acts if ambient is above corporal 37? By sweating only ? By stopping the heat production ? If stopping the production of body heat saves energy from food intake, it could explain something about desert dwellers... and camels.

Yes, sunny in both cases. The hat use in the discussion link above is understood to provide shade, but wrapping the head in a black rag has to fry the brains. http://picasaweb.google.com/TusharPhotos/Ca_stanford/photo#5100235315459422610 Is it about insulating above 37 Celsius ambient to avoid the intake of more heat; is it about ventilating(evaporation) with minimal dressing under 37 Celsius ambient to release heat ? Something does not click... Is there some customary factor -not fashion- involved ? Central american natives wear nearly nothing on similar climate... Could it be that humidity plays a major role ? Miguel

As shown on the picture, it is a goofy audio analyzer that analyzes nothing as shows no vertical nor horizontal scales. It is supposed to tell the frequencies and the signal level on each, plus peaks reached.

Seen desert dwellers in Sahara heat to wear heavy clothing. Seen other tribes nearly naked because of hot climate. What is the rationale on each that makes the choice? How does each case work ?

The rate of beer consumption to balance the amount of exercise to keep the beer cold points the camper to better carry dry ice in a polyestirene insulator box, it will be lighter than carrying the human powered generating contraption plus the refrigerator. Many years ago I saw an invention of a chemical jacket for cans or jars that was activated by pulling a string or something, instantly cooling its core. The modern habit of 'wanting' a drink to be cold is a psychologic 'desire' that contributes little of nothing to body hydration compared to not cooled drinks. If you insist, can carry an absorption refrigerator and feed its heat with sun and lenses, -or fire-. A strong mule may barely be enough.

Hi. I use canned chemicals to 'freeze' electronics as one tool for troubleshooting; and would like to know if there is any canned product that works by heating instead of using a heat gun. Has to be electrically non-conductive, capable of reaching about 80 Celsius.

It is surprising, car makers have improved their radio suppliers specifications a great deal since the seventies; perhaps you drive in a difficult propagation zone. The antenna trimming on older car radios is for the AM band only. Modern ones are fitted with circuits of automatic gain, cheap but work. The FM band has no user adjustment and generic modern radios are built for cheap price rather than sensitivity and selectivity. Miguel

----Ovation ! ----

There is no such thing as healthy hair. Hair is dead, very dead, no matter what shampoo advertisers say. Pretty, shiny, smooth, whatever else yes, but healthy, nope.