Any ice experts out there?!

You'll have to think about weight and density as well. Usually, ice is less dense than water, so it floats.

MarkEsq said:

The coffin melts overnight and in the morning a tramp fishes a wallet out of the lake

Click to expand...

You'll also need to figure out why and how the waterlogged wallet would float.

Sorry, but if I were reading your story, I think I'd have a hard time believing that a person would think a floating chunk of ice was a diamond..particularly if his hand touched it, and it felt, well, ICY....

MarkEsq said:

Here's one for the scientists:

I am writing a mystery in which the murder victim is encased in an ice coffin and dumped in a lake. Here's what I would like to have happen, but I need to know whether it is feasible:

The coffin melts overnight and in the morning a tramp fishes a wallet out of the lake and his hand bumps against a fist-sized lump of the ice. He takes it out, thinking it's a diamond, and the story goes on from there.

The novel is set in Texas and it can be any time of year.

Thermodynamics anyone? How long does an ice coffin take to melt down to one lump, and what time of year would it need to be?

Click to expand...

Rather odd that someone would dispose of a body and forget to remove the wallet. Rather odd to dispose of a body in a floating lump of ice. And rather odd that the wallet should free itself so quickly. It’s odd that it should float to shore, when it’s one of the few things that would sink. It’s odd that this tramp can distinguish a wallet in the water and yet not distinguish a floating lump of ice from an unbelievably large diamond, which does not float. If your story starts this way, with all these odd things, you’re going to lose your readers immediately.

MarkEsq said:

Thanks for the feedback everyone, and I see why you think it might not work. Let me address these points and see if I can change your minds.
First, the murderer is an ice sculptor - he bops the victim on the head and dumps him into an ice coffin. He has conceived this idea as a clever way to transport the body to the lake (an obvious dumping ground) while ensuring there is no forensic evidence whatsoever in his van.
He does frisk the victim for id but doesn't find the wallet because it is a boating/waterproof one that hangs around the neck. He just doesn't think to look there, which I think is understandable. So, when the ice melts, the body is supposed to sink, which it does. The wallet, though, gets loose and drifts to the shore along with the last remnant of the ice coffin.
These are found by poor old Harvey, the homeless fellow who is a little delusional and an easy target for the police. He doesn't know what the wallet is until he fishes it out of the water, at which point his hand bumps the ice which he also retrieves.
Is that better?!

Click to expand...

Better, if somewhat bizarre! Still, to freeze a person in a block of ice, you have to submerge him in water, in which case the wallet should float, because it is (mysteriously) a floating wallet. So it should float to the surface when he submerges the body to freeze it. What the hell, what's this?

Okay, looking back, I see that you say ice coffin, as though ice sculptors make ice coffins every day. So, let's say he makes it special for his victim. And maybe he wraps the guy with chain. Then how does he ever get this ice coffin with a body wrapped in chain to the lake? It's bloody heavy as hell! (Or course, he may have a hoist in his van for moving around heavy sculpture.) Anyway, he gets it out there and pushes it out into the lake. Maybe he gets on it and paddles out, then swims back. He watches it with trepidation as it slowly melts, then sinks below the surface. He leaves, pleased that his complicated plan has worked. It would have been simpler to wrap him in plastic, maybe, but he wasn't thinking too clearly. Spending too much time in the freezer, probably.

Anyway, all the ice melts, the wallet comes off and halfwit Harvey finds it.

Fine.

But I’m not buying that he thinks the ice is a diamond. Nope, don’t buy it.

Maybe the victim (not Captain America, by any chance?) bleeds, and the ice is discolored. So Harvey finds pink ice. Now that's something to mention. Pink ice in a Texas lake. You don't find that every day!

Ice Harvesting

Hey there- I just happen to live near a lake and mansion of a very prominent ice harvester. Well- he's long dead- but that's the history of the area- Bear Creek Village, PA. If you call the Luzerne County Historical Society and ask for Jesse he can help hook you up with someone who may know about ice. Hope that helps. They are on Franklin Street in Wilkes-Barre, PA.

MarkEsq said:

He has conceived this idea as a clever way to transport the body to the lake (an obvious dumping ground) while ensuring there is no forensic evidence whatsoever in his van.

Click to expand...

He'd have to have some way of making sure the ice didn't scratch up his van. That's going to be hard to do if he has to get the ice-coffin-and-body-plus-weight-to-make-it-sink out of the van himself.

He does frisk the victim for id but doesn't find the wallet because it is a boating/waterproof one that hangs around the neck. (snippage) The wallet, though, gets loose and drifts to the shore along with the last remnant of the ice coffin.

Click to expand...

I'm just not buying that a wallet made specifically not to get lost in water just somehow comes loose from a corpse. And why would the victim be wearing such a wallet? And wouldn't the murderer think it's kind of odd for someone to be out with no ID, and keep looking?

He doesn't know what the wallet is until he fishes it out of the water, at which point his hand bumps the ice which he also retrieves.

Click to expand...

Is there some reason this homeless man (even delusional) wouldn't recognize ice, and keep thinking it's a diamond despite the fact it's 1) cold, and 2) floating, which are not characteristic of diamonds, but are of ice? What's his survival potential on the streets if he's that bad off?

I think a leak-proof body bag would be move effiicient than an ice coffin. It would be lighter, easier to handle, and not scratch up his van. I'd bury the body--at least six foot deep. The body bag plus the depth would hide the scent from dogs.

In the lake, if the body wasn't weighted down, there's a good chance it'll float after it bloats from body gases brought on by decaying tissue. It's also easier to dredge a lake than to find the exact spot of a buried body.

I still don't understand the "diamond" thing. As soon as the homeless man picks it up he'd realize it's ice.

rich said:

The body bag plus the depth would hide the scent from dogs.

Click to expand...

Actually, it wouldn't--but I could see the murderer thinking it would. I volunteer with a canine search & rescue group. Most people have no idea how little it takes of any scent for a dog to identify it. A bloodhound can smell the equivalent of a pinch of mustard in the Grand Canyon. A bodybag and six feet of dirt aren't going to faze one.

Aconite said:

Is there some reason this homeless man (even delusional) wouldn't recognize ice, and keep thinking it's a diamond despite the fact it's 1) cold, and 2) floating, which are not characteristic of diamonds, but are of ice? What's his survival potential on the streets if he's that bad off?

Click to expand...

Eh, I think you could make it believable. For example, suppose the tramp's a little delusional, and he's obsessed with finding "treasure." So every morning, he takes his home-made "metal detector" (really just a mop handle, garbage can lid, and cast-off headphones) down to the mud flats by the lake and prospects. In the last ten tears, he thinks he's found millions of dollars of Spanish doubloons, jewelery, bearer bonds, and the like -- really just flattened beer cans, plastic beach toys and litter.

So anyway, this particular morning, the tramp's out prospecting on the mud flats at the water's edge, and an early morning fisherman buzzes by out on the lake, sending some little waves rolling out over the mud flat. The tramp scampers out of the way and shakes his fist and the fisherman. He walks back down to the water's edge and... what's this? Washed up on shore, out of the water, is... Howard Hughes's wallet, and... a diamond! A huge diamond! The tramp's never seen a diamond that large. It's amazing how cold they feel.

Seem more plausible now?

---------------------------------------
Anyway. Back to the original question in the first post. I know enough about thermodynamics to know that the answer to your question would be tough to calculate. In fact, I'm gonna prescribe an experimentalist approach.

Required:
One freezer, working order.
One empty gallon milk jug.
Water dispenser.
Twelve feet rope.
One utility knife.
One large-size cooler.
One dozen individually-packaged twelve-ounce liquid containers.
Digital cronograph.
One lake with dock.
Personal bio-thermometer.

Procedure
1. Fill gallon milk jug from water dispenser. Tie knot in one end of rope; dangle rope into top of jug so knot is in the center.
2. Place gallon milk jug in freezer. Be careful of wicking action up rope.
3. Remove jug from freezer. Unchip rope. Run jug under warm water. Use utility knife to cut away jug from ice (seriously, be careful here. Ice is slippery).
4. Place ice in cooler. Fill remaining space with individually-packaged twelve-ounce liquid containers.
5. Drive to lake.
6. Insert personal bio-thermometer ("big toe") into lake. Estimate temperature. Call this temperature TL.
7. Tie rope to dock. Throw ice into lake. Note time on digital cronograph.
8. Consume liquid within individually-packaged twelve-ounce liquid containers as appropriate.
9. Occasionally check progress of ice. When ice reaches size of fist, note time on digital cronograph.
10. Drive home. Depending on consumption of dividually-packaged twelve-ounce liquid containers, you may wish to delay this step.

Calculations
1. The ice is, for the most part, 32 degrees. You've estimated the temperature of the lake (TL). The difference (TL - 32) is Delta-T.
2. To get from gallon-jug-size to fist sized requires about 3" of ice be removed from each side of the jug.
3. The time this took was, of course, the difference between your two watch readings. Call this time t.
4. So you've experimentally shown that a temperature difference of Delta-T removes 3" of ice in a time t.
5. The time taken to melt any size chunk of ice should be proportional to thickness and temperature. In other words:

t = (Constant)*(TL - 32)*(3")

Your experiment determined the constant. Now adjust the thickness and lake temperature to get what you want.

Make sense?

Andrew Jameson said:

Eh, I think you could make it believable. For example, suppose the tramp's a little delusional, and he's obsessed with finding "treasure."

Click to expand...

Yes, that (or something like it) could work. So it's clear that if you want to sell this to the reader, you have to make it plausible.

Andrew, do you think the difference in melting times between a gallon-jug-sized piece of ice exposed to warmer-than-ice water on all sides and an ice coffin exposed to water on fewer than all sides would be significant?

Aconite said:

Andrew, do you think the difference in melting times between a gallon-jug-sized piece of ice exposed to warmer-than-ice water on all sides and an ice coffin exposed to water on fewer than all sides would be significant?

Click to expand...

Well, I think the melting times would be *similar*, enough to make it plausible. What I mean is, let's suppose, just for a moment, that it takes, oh, two hours for the gallon jug blog of ice to melt down to fist size in some temperature water. And let's say that "melting down to fist size" essentially means melting off about 3" of ice from all the way around the jug.

My intuition is that, in the same temperature water, an ice coffin made from 3" walls would take about two hours to melt. An ice coffin made from 6" wall would take four hours. And so on.

Of course, that's just a first order effect. Really, I'd think that the coffin would take a little longer to melt because it's got a more compact shape. But that's offset somewhat because the coffin is *larger*, and will set up stronger localized convection currents. But that might be offset if the coffin is weighted down and sticks in the mud. But then mud will suck heat out also...

Anyway, complicated problem, which is why I think calculation would be difficult. Bottom line is that I'd be very surprised if a 3" wall ice coffin takes longer than, say, twice the time to melt as the gallon jug (and really I'd guess more like, oh, 1.3 times as long). Since we're just trying to establish plausibility, I'd think that an estimate of +/- a factor of two would be good enough.

Andrew, thanks for understanding that when I said "times" I meant "rates." Argh. Where did my brain go?