were 'petrified' snakes, and carved 'heads on them.
Posted on 03/01/2004 2:08:45 PM PST by vannrox
Here is an excerpt from a Google search pulled from NYT that deals with common de-icers available here on earth:
"Not all de-icers are created equal," said Edward Chouinard, president of Standard Tar Products, a company based in Milwaukee that makes Snomelt Instant Ice Melter. "But virtually all de-icers work on the same basic principle: They lower the freezing point of the water produced by the ice they melt."
Mr. Chouinard, whose company manufactures de-icing products used by homeowners, commercial property managers and state and local highway departments, explained that while plain water freezes at 32 degrees Fahrenheit, the freezing point of water containing a de-icing chemical is lower than that — sometimes much lower.
"The nice thing about Snomelt is that it's exothermic," Mr. Chouinard said. "That means that when you mix it with water, it creates heat."
Some de-icers — for example, sodium chloride, better known as halite or rock salt — are endothermic, meaning that they need to absorb heat from the atmosphere, sunlight or friction from tires to melt ice or snow. As a result, while rock salt is the least expensive de-icing agent available — selling for anywhere from $2.50 to $4 for a 50-pound bag — it is only effective at temperatures above 15 or 20 degrees Fahrenheit.
Products like Snomelt, on the other hand, which is 90 to 95 percent calcium chloride and sells for about $15 for a 50-pound bag, can melt ice or snow at temperatures as low as minus 59 degrees Fahrenheit, depending on the concentration of the chemical in the solution produced by the melting ice — a solution that de-icing experts call "brine."
In fact, it is the brine produced by a de-icing product — rather than the melting action of the product itself — that does the work the homeowner is hoping to avoid.
Rick May, marketing manager for Dow Chemical in Midland, Mich., said that most de-icing products work by penetrating the ice, dissolving into brine and then seeping into the pores of the concrete under the ice. Once there, the brine breaks the bond between the ice and the sidewalk, making it easier to remove the ice.
Mr. May added that while calcium chloride can indeed melt ice at minus 59 degrees Farenheit, that is the "laboratory limit" of the chemical's effectiveness. "In the real world, its practical effective temperature is more like minus 28 degrees Fahrenheit," he said, adding that the effective temperature of the chemical decreases because its concentration in the brine becomes lower as more and more ice melts.
When the rover makes a cup of tea from Martian water, I'll be a believer.
Alas, Spirit and Opportunity left the kettle behind...however, I shall be delighted to make you a cup of Lady Grey when we get there. :^)
A geologist here says they do not look like fossils. Scratch and Sniff are purely geology robots, unequipped to do organic testing. The ESA bot that crashed was equipped with some organic instruments. Sounds like later bots will have instruments more appropriate to analyze brine minerals.
Well I think they need at least one Paleontologist on the team. Squyres really comes across as an arrogant saganistic ass to me at least. I don't view him as an asset for NASA and he could have been more tactful with the one reporter who asked about the possible existence of surface water within the last couple of centuries. I find the non-mention of obvious biological indications disgusting. I also have no sympathy for Squyres should he bear later scorn and it would probably be better for me to reserve additional comments until a later date...
I can tell you this though, any bare foot ten year old who has ever picked up a gravel rock from a dirt road and seen the prehistoric indications of sea critters would look at these images returned by the rovers and say yea, those are fossils.
They'd better watch out. Next come the dart guns . . . then the thorazine shuffle with yer butt hanging out the back of a blue gown.
(That damn cat didn't need to take over the ping list AND throw in all that background context)
Well, I'd like to know how may of those "in-the-know" folks were skulking about with dour, unhappy faces after the "big" news release.
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