The Rants, Raves, Gripes, and Prophecies of Paul R. Potts

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Fri, 26 Aug 2005 Installer VISE

Installer VISE has a good reputation as one of the best packages for building installers, but apparently that is not saying much... it is really pretty awkward to use, and the documentation is weak.

It is like writing a program in a conventional language where all the actual behavior is hidden. Like: what the conditionals actually say; how comparisons are done (what constitutes true and false); not being able to evaluate any kind of previous step for success or failure without introducing a superfluous variable test item; not being able to actually manage types and perform type coercion yourself; not being able to actually manage strings yourself... ugh.

It does supply quite a bit of behavior for you, though, which would be quite awkward if you had to write it all yourself. Oh well...

[/root/geeky/programming] permanent link

Tue, 02 Aug 2005 On Print Heads

I've written before about my experience with my HP Business Inkjet 1100D printer. I was, for the most part, quite happy with it. However, recently the black printhead failed.

The Business Inkjet design separates the ink cartridge from the print heads. One would think that this might reduce waste and cost. The ink cartridges still cost a lot of money, though. The idea was that the print heads would last much longer than the ink cartridge - thousands and thousands of pages. According to PC World, "HP estimates that the black print head will last for 16,000 pages, and the color print heads for 24,000 pages each."

Well, that didn't happen. I haven't kept a page count, but I haven't even finished a second ream of paper, and a few 25-packs or 50-packs of photo paper. I doubt I've printed more than 2,000 pages.

Now, when an ink cartridge fails, you can still print; you'll just lose a color. Of course, if this is black, that can be a big inconvenience, but ink cartridges are usually in stock at office supply chains. However, when the print head fails, you can't print a single page: the printer just refuses to do anything. I found out the hard way that because they supposedly last such a long time, the chain stores don't carry the print heads; they are a special-order item. The salesperson at Office Max was quite surprised when I brought back my print head, and tested it out in another printer. It was kaput. And just out of warranty. And my printer was completely out of commission, while I had to wait a week for the new print head to arrive.

So, I have reservations about recommending the 1100/1200 series printers. There is the irregular print area on the back of the page versus the front when duplexing. Although color photos can look pretty stunning on expensive photo paper, printing out grayscale photographs results in pictures that look greenish.

Maybe my print head failure was just an anomaly, but the cost of replacing printheads and ink cartridges is starting to add up. Are there any decent, reliable inkjet printers that produce fast and sharp text, excellent photos, and that aren't obscenely expensive to operate? The reviews of the 1200D I've seen are not encouraging -- it seems that it is not an improvement over the 1100D model, so I probably don't want to pick one up for my mom, although that was the model I was considering. I've always been an HP fan, but is it time to consider another manufacturer?

(My 1100 can duplex, but this is a feature I've rarely used, so I would not consider it an important selling point. Ethernet, however, would be welcome, since trying to share the printer with my Airport Express has led to poor results, including a lot of photo print jobs that stalled out and failed; this does not seem to be HP's fault, though).

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On Firefly

I love Firefly. I've watched all the episodes at least twice, and I'm looking forward to the release of the Firefly movie this fall.

Lately, though, I've been contemplating the show's structure, and its strengths and weaknesses as storytelling and science fiction. I'm not going to dissect the whole thing now, but one thing that has stuck in my mind is that in the world of Firefly, no accomodation is made at all to the reality of vast interstellar distances. The ship Serenity can travel between planets in a matter of a few days; I think the longest journey time they mention is a month. But there is never any mention of faster-than-light travel. It's as if Einstein was just wrong in that world. Actually, the ship never even seems to accelerate very hard -- the crew and passengers don't have acceleration couches -- so apparently they don't believe in Newton, either!

Now, I have to say, I love Kaylee and her approach to spaceship drive repair -- "that part doesn't do much anyway; you can just rip it out." I love the beautiful Firefly effect. I love the narrow escape from the Reavers in the pilot, where they ignite the engine in the atmosphere and create a huge reaction. I love that explosions in space are silent. I love the fact that most aspects of life in the Firefly world are very low-tech. Firefly is "about the strawberry" -- the Preacher's bribe to Kaylee. It is a human story of loss and longing on a harsh frontier where the amenities of old Earth are rare and valuable, and life is cheap.

I don't want Firefly to be Star Trek -- an unrealistic world where there is no dirt, universal socialism and abundance seems to be the order of the day (people don't even seem to use money), and there are apparently no "have-nots." Human nature seems to have irrevocably changed in the world of Star Trek -- is anyone convinced by this future? But I think it frustrates the viewer not to at least have some ready excuses available for all the various laws of physics that get left by the wayside.

On Serenity, the crew seems to have instantaneous radio communication available between planets, or while they are nearing a planet. They've got some equivalent of interstellar wi-fi. When approaching a ship or planet they can hold conversations with other people with pretty-much instantaneous response times; they don't have to wait a few minutes for the reply to come. Even the round trip from the earth to the sun would be something like 14 minutes. They don't even invoke some kind of alternate technology like "subspace."

It is as if they just compressed the universe by a factor of billions; different planets seem to be closer together than the planets of our solar system. It is 240,000 miles to the moon and takes several days to get there with Apollo technology, and even assuming drive technology we haven't invented yet, it would take a year or more to get to Mars: the distance to Mars varies from about 35 million to 260 million miles. And think of how long it has taken Pioneer just to get out to the edge of the solar system.

Maybe the magical Firefly drive can do all this: accelerate the ship far beyond lightspeed, cancel gravity and inertia, and generate cool special effects as well. That seems a little much, though.

The Serenity also has a strange habit of coming upon other ships, as they wander about in "empty space" on routes designed to avoid being detected by the Alliance. That doesn't make a whole lot of sense.

Serenity can also apparently be taken into "atmo" and landed on a planet, apparently without worrying about burning up on re-entry. But yet the ship looks like it is made of materials that are available today: steel plating, prone to rust and all that. The situation with the space shuttle now shows how tricky that kind of thing is in real life. There is one funny moment (I think it is in "Shindig") where the pilot, Wash, has to struggle to correct his entry trajectory, but when I watch this I keep thinking about how the physics don't make a lot of sense. At that speed, if he made such a dramatic error in the ship's angle of approach, they would burn up or break up before anyone had time to react. (Think space shuttle Columbia.)

That said, I still enjoy the show, and hope it can be resurrected in some form. It is ultimately about human relationships, but ignoring both Einstein and Newton without even bothering to offer a hand-waving sidestep to the laws of physics just grates on me a little; it seems insulting to the viewer. There is an especially funny line in "Objects in Space" when Zoe is speaking to Wash about River:

Wash: "Psychic, though? That sounds like something out of science fiction."

Zoe: "We live in a spaceship, dear."

Yep, they live in a spaceship, but some things are just silly!

[/root/geeky/life] permanent link

Wed, 06 Jul 2005 Handling SREC files with Ruby

Ruby is definitely one of my favorite languages, and I am far more comfortable with it than I am with Perl. It seems very expressive; very frequently, once I find the right library method, the code pretty much writes itself.

However, just like with Perl, there is more than one way to do it, so I often find myself looking for more appropriate idioms for the task at hand. There is also some question of efficiency; I'm not trying to optimize prematurely, but the program I'm working on runs slower than I'd like, and I think Ruby can do better.

To start, I'll just share one quick annoyance. The first is that there is some deficiency in handling of typing such that statements like

puts "Checksum: " + chksm

will not work; you get a run-time error (can't convert Fixnum into String)." This seems wrong; it is not very "DWIM" (do what I mean) when considered in light of Ruby's philosophy of weak "duck typing" -- if it quacks, for all practical purposes your program can treat it as a duck, or in this case a string. I bring this up because I keep getting this error -- I have a habit of forgetting to add .to_s to the variable. I'm thinking in terms of C++ iostreams, where the type is taken care of using the stream << operator.

But on to a meatier question. I want to be able to treat a string containing ASCII hex digits as an array of bytes or as a Fixnum (where I can specify the byte ordering). For example, I want to be able to turn

"DEADBEEF" into an array of unsigned integers [0xDE, 0xAD, 0xBE, 0xEF] (for purposes of generating a bytwise checksum), or into the unsigned integers 0xDEAD, 0xDEADBE, or 0xDEADBEEF (depending on the record type I'm working on).

These are the ASCII character values (exprssed in hex); 'D' is decimal 68, hex 44. Not very useful; I get 2 strings of ASCII hex out. These aren't very useful for translation, since I'd have to turn them into integers, translate them to numeric values (not just a simple offset, because the hex characters are not contiguous) and then assemble the high and low nybbles into byte values using (high << 4) + low, or some such.

There must be a better way to do this. Here's my first try:

def make_checksum (str)
  checksum = 0
  0.step(str.length - 1, 2) { |idx|
    checksum += (str[idx].chr.hex * 16) + (str[idx + 1].chr.hex)
  return (~checksum) & 0xFF

Ugh. Look at the way I have to access the characters: str[idx] returns numeric types, not character types, which don't have a hex() method, so I have to convert them from the original characters in the string to integers, to characters, and then apply hex() to that.

Another way is to make substrings, I suppose, but it doesn't perform better, probably because it is generating a lot of extra string objects:

def make_srec_checksum (str)
  puts "make_srec_checksum; str is: " + str
  checksum = 0
  0.step(str.length - 1, 2) { |idx|
    checksum += str[idx..(idx + 1)].hex
  return (~checksum) & 0xFF

Another is that the String.unpack() method seemed from reading the documentation that it had exactly what I needed; it appeared that the "h" and "H" characters in the control string for the unpack method would be capable of unpacking ASCII hex data like DEADBEEF into byte values. That seems to be what unpack is all about. Instead, it generates ASCII hex bytes.

$ ruby -e 'puts "0123456789ABCDEF".unpack("H2" * 16)'


Not what I wanted. Most likely, there is a much better way!

It might be interesting to compare Common Lisp and Ruby implementations of my SREC tool; how concise, yet expressive, can I be in each language? This also might serve to shed some light on whether Common Lisp has fallen behind as far as libraries for typical file-handling and scripting-type tasks. More on that later.

[/root/geeky/programming/ruby] permanent link

Fri, 18 Mar 2005 The Thrice-Cursed Airport Express

The thrice-cursed Airport Express has crashed again. First, printer sharing failed, and then a few days later the shared internet connection failed. Running the Airport Admin utility revealed that the device couldn't even be found on the network. A power cycle fixed it.

I checked Apple's site and there is an update to the firmware, which will take the device from 6.1 to 6.1.1; we'll see if that offers any improvement. The AirPort 4.1 software package offered for download on the same page is apparently the same version I already have. Meanwhile, until I determine if this update helps the reliability, I can't recommend the AirPort Express to anyone.

[/root/geeky/apple] permanent link

Wed, 09 Mar 2005 In the Bunker

I recently heard an interview in which an administration insider described a political leader as follows:

That's an area where Hitler did a huge amount of harm: he actually tried to manipulate the consciences of the German people. He convinced them they had a task to do, they had to exterminate the Jews, because the Jews caused all our problems. It wasn't Hitler's own idea... it had been put forward much earlier... that they had to make a sacrifice.

And I can remember a writer... she interviewed a soldier who had been stationed in a concentration camp. He was a guard, and she asked him: Didn't you feel any pity at all... for the people you treated so badly there?

And he replied "yes, I did feel pity, but I had to overcome it. That was a sacrifice I had to make for the greater cause." And that's what happend to conscience.

After all, Hitler used to always say "You don't have to worry, any of you... you just have to do whatever I say, and I'll take responsibility." As if anyone can take charge of another person's conscience. I do think you can make someone's conscience more sensitive, or desensitize it, or manipulate it.

The longer I live, the older I get, the more I feel this burden, this feeling of guilt, because I worked for a man, and I actually like him, but he caused such terrible suffering... and the feeling that I was so unaware and so thoughtless... that I didn't notice or pay attention. That feeling has oppressed me more and more.

It seems to me that I should be angry with the child I was, that juvenile young girl, or that I can't forgive her for failing to recognize in time what horrors that monster caused. The fact that I didn't see what I was getting involved in, and above all that I just said "yes" without thinking at all... I find it hard to forgive myself for everything.

He was a crimintal -- it's just that I didn't realize it. At some point afterwards, I began to wonder if I should have seen that... and after all, apart from me there were millions who didn't see that. I mean, it's not as though everyone apart from me realized what a criminal he was. And I try to take heart from those thoughts.

And Hitler did somehow embody something monumental. At first, when I was a child, the first time I met him he probably had a kind of paternal protective attitude towards me... and that's something I had longed for. I used to envy children who could say things like "My father says so and so," or "My father thinks..." I used to think having a father must be very important. Then I started working for Hitler, and suddenly I had that sense of security, too. There really was a sense of security in that community, which cut itself off so much from the outside... I think I had a very subservient attitude toward him as a father figure.

You know, I never had the feeling that he was conscious of pursuing criminal aims. For him they were ideals. For him they were great goals. And human life meant nothing to him in comparison. But that only became so apparent to me afterwards. You see, in the inner circle surrounding him, in his private sphere, I was shielded from the megalomaniacal projects and the barbaric measures. That was the awful thing, and that's what gave me such a shock later, when I realized what had been happening. When I started working there, I thought I was at the source of information and in fact, I was in a blind spot. It's like in an explosion, there's one place where calmness reigns. And that was the great illusion, the great, not disappointment, but lie that I had made myself believe.

The word Jew was virtually never used in everyday speech. The fact that Hitler would, at times, say something in his speeches about "international Judaism" or "the Jews," that was virtually ignored. Nobody ever raised the subject. At least, not in our presence. Actually, the only time I can remember the subject really being an issue was one evening at the Berghof when Frau von Schirach was a guest. I wasn't there at the time, I only heard about it. I was out of the room when it happened. She was on fairly cordial terms with Hitler, and she suddenly raised the subject. She told the Fuhrer directly that it was quite terrible, the way the Jews were treated in Amsterdam. They were packed into trains, she said, and it was an inhuman way to behave. It must have made him very angry, and he said to her: "Don't interfere in things you don't understand. This mawkishness and sentimentality." He really was very annoyed. He walked right out of the room and didn't return. And Frau Schirach was never invited to the Berghof again.

You couldn't discuss anything with him that was somehow sensitive or difficult. It was one aspect of him. And that was really the only time a conflict situation developed.

He didn't think in human dimensions. Humanity was never of any importance to him. It was always the concept of the superman, the nation, always this abstract image of a vast German Reich, powerful and strong. But the individual never mattered to him.

As for myself, deep in my heart, I did have some doubts, and I wondered: "Is all this absolutely right?" But then to question the situation, actually to initiate a discussion, would have taken more courage. And I think it's also the case that if you value and respect someone, you don't really want to destroy the image of that person -- you don't want to know, in fact, if disaster lies behind the facade.

I don't think he considered war a light-hearted matter. He regarded it as a terrible thing, although he never said so. For instance, whenever there were reports of air raids and people described the situation, or if I said something like: "My Fuhrer, you can't imagine how miserable it is for all those homeless people whose houses have been bombed -- it's just so terrible." He'd stop me right away and say: "I know exactly how it is, but we shall strike back. We shall take revenge, and with our new weapons everything will change. Vengeance will be ours!" He would always say that, and in particular he'd say that we would rebuild everything after the war and make it better than ever.

I think there was a general policy of denial. He never did see a city that had been badly bombed. We traveled through Germany in the special train with the blinds down, and when he reached Anhalter Station in Berlin at night the chauffeur would take the streets that weren't so badly damaged.

In the early days after the war, the past wasn't an issue, strangely enough. It wasn't a subject to be discussed in public either. And there weren't any books about it. In politics there wasn't yet the process of coming to terms with the past. Not even the Nuremberg trials started that process, the way it happened later, in the '60s. I don't know exactly why, but suddenly there were so many books. And lots of voices were raised. We heard about the SS state and then the diary of Anne Frank and there were people who had survived the whole thing. People who had resisted also spoke out. The thing that made a very strong impression on me was that after the war, the world wasn't at all the way Hitler had portrayed it and predicted it would be. Suddenly there was a spirit of freedom and especially the Americans -- I didn't get home until a year after the occuption, but especially the Americans -- turned out to be very good democrats and very helpful people. The care parcels started coming. I suddenly realized that none of it was true.

So in the early years it didn't really occur to me to come to terms with my past. Naturally all the horrors that emerged in the Nuremberg trials about the six million Jews and people of other faiths and beliefs who lost their lives -- all that struck me as very shocking. But I wasn't able at first to see the connection with my own past. I still felt somehow content that I had no personal guilt and had known nothing about it. I had no idea of the extent of what happened. But then one day I was walking past the memorial in Franz Josef Street to Sophie Scholl, a young girl who opposed Hitler, and I realized that she was the same age as me and that she was executed the same year I started working for Hitler. At that moment I really sensed that it is no excuse to be young, and that it might have been possible to find out what was going on.

The film is "Blind Spot: Hitler's Secretary." The directors include a commentary that describes Traudl Junge's later life, including the fact that she took an early retirement due to severe depression, and spent years volunteering as a reader for the blind. Shortly before the film opened, she told one of the directors "I think I'm starting to forgive myself." She died of cancer on the day of the film's premiere.

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Mon, 28 Feb 2005 Bismuth

So, we received our bismuth metal and proceeded to do some informal experiments. I call them "informal" because we did not keep strict records, form a precise hypothesis, and work hard to vary only one variable at a time. However, we did form some interesting conclusions and observations.

Experiment 1: Diamagnetism

The first thing we tried to observe was the diamagnetic effect in bismuth. The idea behind "diamagnetism" is that a magnet will induce in some materials an opposing magnetic field. We tried to observe this using a set of small but very powerful neodymium magnets. I am sorry to say that we were unable to observe any noticeable magnetic repulsion using any amount of bismuth from tiny splatter fragments to a solid ingot of perhaps 200g in mass. I am not sure why we could not observe this effect, which is supposed to be quite strong. One hypothesis is that our bismuth was not pure bismuth, but I think this is very unlikely since in all other respects (melting temperature, formation of crystals, oxidation, color tint of the oxidizing melt, and behavior when the liquid metal was dripped into water) it behaved exactly as expected). Also, it is my understanding that the bismuth would not need to be absolutely pure to show the diamagnetic effect. We will have to do a little more reading and perhaps ask some other people.


For the hot metal experiments, we made sure that we were wearing reasonably durable clothes that covered most of our skin, that we both had eye protection, and that we had a ready supply of water nearby to put out any fires, including a 32-ounce cup pre-filled and ready to go. For eye protection, I have prescription polycarbonate lenses which I judged to be adequate. Isaac put on a pair of polycarbonate sunglasses when he came near the melted metal. We used a thick cloth potholder to grab the handles of the cups, which was adequate, since the metal handles acted as heat-sinks anyway, although a silicone glove might have been provided a better grip.

Experiment 2: Melting

The second informal experiment was done to answer the question "can we melt bismuth on our stovetop?"

Our stove is a rather low-end home stove, and the oven is not very powerful, frequently doing a poor job getting the right amount of heat for baking, so I was not completely confident that we'd be able to get the metal hot enough.

Our methodology was to place 5 10-gram cylinders of the metal, as it arrived from the supplier, into a new stainless steel 3/4-cup measure. We placed this directly on the heating element and set the temperature control to 75% of the way to maximum. I was prepared to wait a while for melting to start, but Isaac noticed that the metal began melting almost immediately. So the answer was "yes." It did not even seem necessary to set the heat to maximum.

Experiment 3: Crystals

The third informal experiment was done to answer the question "can we form macroscopic bismuth crystals?"

The methodology was to melt 100 grams of bismuth and then remove the cup from the heat, allowing it to cool for several minutes without disturbing it, then pouring off the remaining melted metal into another heated cup.

We ran into complications because I had thought that we could place the hot cup on a heavy wood cutting-board in order to to allow it to cool slowly, rather than on a more heat-conductiven metal surface. The heat was too much for the wood, though, and the cutting board smoked and steamed underneath the cup. We increased the ventilation, but this was not really satisfactory. The smoke detectors did not go off, but it was at this point that Grace took the baby from the living room downstairs with her to the laundry room so that the smoke would not irritate her.

Despite this complication, after the first pour-off, we noticed visible crystals. After the bismuth and cup had cooled for several minutes, it was cool enough to try scraping some of the tiny crystals out of the cup, which I did using a wire hanger.

We broke one small crystal, about 3 millimeters across, that exhibited "hopper" structure. This was not very impressive, but it proved the concept. I threw this one back in the melted metal in the hopes of getting larger crystals on another pass. In retrospect, I should have saved it, for we were not able to get good crystal specimens after this.

The plan was to try using different cooling times to determine the cooling time which produced the most crystals. Because I was trying to find a solution to the smoke problem, we were not able to repeat the experimental conditions accurately while changing only one variable. I tried using ten layers of aluminum foil between the steel cup and the wooden board, reasoning that the foil would deflect some of the heat. This did not really solve the scorching problem; it just scorched more slowly. Moreover, the use of the foil dramatically changed the characteristics of the cooling metal. It no longer cooled first from the sides and bottom, but seemed to cool from both the top and bottom equally, so that when we attempted to pour off the remaining melted metal, it poured not from the top but from "holes" in what had become a semi-crystalline slab of brittle, oxidized bismuth. This brittle mass was clearly formed of a crystallized form of the metal, but it did not form attractive individual crystals.

I should say a few words about oxidation. We observed as we poured off, melted, and re-poured off the metal, it developed a "sheen" of various colors, most notably a vivid blue and green, as well as an oxidized, ugly "skin" of powder-gray metal, which would not melt. We were able to skim this off using the wire hanger and collect a heap of powdery oxidized bismuth. After working with the metal for a while, the cups became scarred and pocked with a yellowish oxide on the bottom, and lumps of scaly oxide on the sides, which we were unable to scrape off using the wire. At higher temperatures the liquid metal could be skimmed with the hanger, which would leave behind a clean, shiny surface, which would then immediately begin to develop a powdery-gray appearance.

This bismuth oxide, which we were not able to melt, could presumably be "reduced" using charcoal and a crucible, but we did not have an apparatus to do this, and so our shiny melted bismuth became gradually more and more contaminated with oxide. The smoke from the scorching cutting board, and possible varnish on the wire hanger, may have contributed to this contamination.

So, result was that we were able to grow at least a few small macroscopic crystals, but we were not able to successfully experiment with melting and cooling conditions or improve the results. I was not terribly disappointed by this as I was not really expecting to be able to grow large, beautiful crystals with this simple setup.

Experiment 4: Casting

A fourth informal experiment was done to answer the question "Can we cast the molten bismuth into a solid ingot using a mold made from folded aluminum foil?"

This part was very interesting. The answer was technically "yes," although with extreme reservations.

I folded a dozen layers of foil into a small box shape, and placed it on the cutting board, and poured about 100 grams of molten bismuth into the mold.

The result was somewhat startling. The combination of hot bismuth and aluminum foil immediately produced a thick black smoke, so we cleared the area and increased the ventilation. The smoke was not coming from the wood underneath, which did scorch as expected, but seemed to come the mold itself. The foil did not visibly burn, but may have either burned under the molten bismuth or have somehow allowed the bismuth itself to oxidize with some violence.

The molten bismuth did form a solid ingot, which upon cooling we were able to remove from the foil, which did not appear particularly burned. The top of the ingot was coated with a black powdery residue, which was much more difficult to remove from my fingers than the bismuth oxide. We washed and dried the ingot. Some of the aluminum foil on the bottom had stuck to the metal and could not easily be removed. We decided to melt the ingot back down and remove the foil from the melt. However, once it was melted, we were not able to find the foil, so I assume that it burned up. Our melt was now presumably contaminated with aluminum oxide, which probably would have ruled out any further crystal growth.

So, in conclusion, it was possible to use foil to form a mold and create an ingot, but the heat produced a potentially dangerous reaction, so I would not want to try this again. Powdered aluminum is used as an explosive, and aluminum is apparently too prone to oxidation to use safely for such a purpose, although I imagine that a solid piece would not produce smoke so readily. We are not certain of the toxicity of the generated smoke, but presumably it was not a good idea to be breathing it. I was glad that the baby was out of the room and that we had good ventilation.

Experiment 5: Spatters

A fifth informal experiment was done to answer the question "what happens when you drop the molten bismuth metal into water?"

We tried using several different size containers and dropping the metal in different ways, ranging from pouring individual drops into the water up close, to pouring a stream from high up.

For these experiments we used a small steel bowl on the counter, and also a large bucket on the floor. This part made it clear how important it was to have eye protection. The hot metal produced small steam explosions, which resulted in sprays of water droplets as well as occasionally very small droplets of molten or near-molten bismuth. The result was somewhat like the spatters that can happen while cooking bacon in a frying pan. I received some very minor burns on my forearms, but I had expected that this might happen, and none of the burns were severe enough to require treatment.

Pouring pure bismuth into a small container in a steady stream produced very elaborate spatter shapes that would stick together in a semi-solid "forest." Doing this raised the temperature of the water to the point where it was steaming, and produced a lot of spatter.

Dropping bismuth into the larger bucket produced at least four somewhat distinct results.

Dropping the metal from several feet produced "exploded" shapes, where it appeared that the molten metal actually splashed upon hitting the water. The shapes ranged from very thin foil-like fragments to spheres and teardrops that seemed "exploded" -- hollowed out.

Pouring the bismuth very close to the water surface resulted in elongated, needle-like shapes with points at both ends, some several inches long.

Pouring the bismuth carefully drop-by-drop resulted in a large number of small, nearly identical "teardrop" shapes. These were so remarkably uniform and attractive that I separated these out and set them aside to put in a jar for display.

In the bottom of the bucket we also collected a very fine "sand" or "grit" of dark, oxidized-looking bismuth. It is not clear whether this was solid oxide, or how it was formed. Some hypotheses include: it oxidized by the dissolved oxygen in the water itself; the hot metal actually released oxygen from the water; it was produced by the explosion within the steam bubbles; it was somehow separated from the actual bismuth metal by the dropping process.

We collected up some of the less attractive pieces, dried them, and put them back to melt again. We discovered that it was extremely important to dry the bismuth thoroughly. Some of the hollowed-out shapes still contained enough water to cause a more violent steam explosion, which blew tiny molten metal droplets everywhere. This served as a good warning; if we try to melt down more of the spatter we will bake it at a low temperature first to drive off the water and then heat it gradually to melt it to avoid this violent steam release.

Experiment 6: Casting (again)

As a final experiment, we poured some of the remaining oxidized and unattractive melted bismuth into a cup and allowed it to cool to room temperature, in another attempt to make an ingot or slab for examination later. When it was cool I was able to remove it from the cup by knocking the cup hard against the wooden cutting board.

End Products

The experiments left us with several end-products:

  1. A highly oxidized, ugly, irregular disc of bismuth combined with whatever oxides or other contaminants are present, with a powdery crust, partially yellow on the outside. I broke this into several pieces and put it into a bag. The broken edges exhibit a very shiny silicon-like appearance. The slab is extremely brittle.

  2. A badly scorched wooden cutting board. I'll save this for now in case weneed to use it again, but we will probably discard it eventually because it smells very smokey.

  3. Several "roasted" steel measuring cups. These are discolored on the outside from the heat. I scrubbed most of the oxide out with steel wool, but some remains that is too hard for me to remove. We will save these for possible use in melting down some of the spatter, or making more spatter, but they may be too contaminated to grow crystals.

  4. One more clean unused steel measuring cup. We may use this for a future attempt to grow crystals.

  5. Perhaps 300 or 400 grams of unused bismuth. We'll save this for a future experiment.

  6. Several baggies with different kinds of spatter: one with very attractive teardrop shapes, which I would like to save; one with "exploded" shapes, one with "needle" shapes, and one that is a jumble of all the rest, most of which is in the form extremely small irregular foils, lumps, crumbs, particles, and fragments.

Paul's Conclusions:

This was a fun way to get the urge out of my system to play with molten metal. Although it was more a demonstration than a formal experiment, we did learn some interesting things and it brought up some open questions for further, more formal, experimentation.

I did wind up making a couple of blunders that caused safety risks. The biggest of these were super-heating the aluminum foil, and putting spatter products that were still damp back into the melt. Fortunatley these do not seem to have caused any long-term harm, although I regret the exposure to the smoke generated by the combination of the hot bismuth and aluminum foil. The scorching of the cutting board was unfortunate but I don't believe it represented a serious risk of fire, because the wooden board was too large and flat to ignite.

Questions for Isaac:
  1. Read the chapter on bismuth in the Elmsley element book.

  2. Examine the contents of the various baggies, particularly the broken "ingot" or solid disc, and the long "needle" shapes. (Wash your hands with soap and water after handling this oxide, since it will stick to your hands).

  3. We can describe metals as ductile (bendable) or brittle (breakable). How would you describe the needle shapes? How would you describe the ingot?

  4. Can you explain the difference in color between the somewhat shiny teardrop shapes and the grayish surface of the ingot? How about the shiny broken edges of the ingot?

  5. Are the needle shapes crystallized metal? Explain. Why or why not?

  6. Is the ingot crystallized metal? Explain. If so, is it one crystal or many crystals? Can you see the crystals? Why or why not?

  7. Explain how to convert the melting temperature of bismuth from Celsius to Fahrenheit.

  8. What would you do differently if you had a chance to do more experiments with bismuth? Particularly, address how to improve safety, how to cool the molten metal without using the wooden board. Which experiment would you like to do?

  9. For the experiment you would like to do, write down the hypothesis, the planned method, the expected result, the reason the expected result would confirm the hypothesis, and an alternative explanation for the expected result that does not confirm the hypothesis.

Isaac's Conclusions:

(to be done!)

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