The Preparation of Demonstration Materials for the 2001 Session
by Oliver Seely Introduction
Explanations of the principles of Chemistry are incomplete without demonstrations. Pierre
Berthelot is reported to have said, "Chemistry has to be seen to be believed." Michael Faraday,
considered to be the supreme experimentalist and demonstrator of his time, well understood the
importance of demonstrations to exemplify principles of nature. J. Arthur Thomson wrote that
"[Faraday] took the greatest trouble in devising the experiments and in making sure that they
would be successful and seen by everyone. His personality, too, had an extraordinary influence.
Shortly after his death Lady Pollock, who knew him well, wrote of him: 'He was completely
master of the situation; he had his audiences at his command, as he had himself and all his
belongings; he had nothing to fret him, and he could give his eloquence full sway. It was an
irresistible eloquence, which compelled attention and insisted upon sympathy.... A pleasant vein of
humor accompanied his ardent imagination, and occasionally, not too often, relieved the tension.
He never suffered an experiment to lead him away from his theme. Every touch of his hand was a
true illustration of his argument.'"(1)
The Christmas Lectures for young people were launched by Faraday in 1826 and in the
decade
between 1851 and 1861 he participated each year. Thomson commented glowingly,(2) "[Faraday's
lectures] were in the highest degree successful in their object, to interest the young in the
principles of science in an entertaining way rather than merely to amuse them with sensational and
topical oddments of scientific information or to instruct them in textbook knowledge as in a
schoolroom." The Christmas Lectures continue today and are broadcast by the BBC. Perhaps
they will be available to chemistry teachers everywhere in the not too distant future via the same
communications channel being suggested by this paper.
Faraday did not write the published version of his lectures. They were recorded in shorthand
by a
reporter and edited by Thomson so that the reader is treated to a near-verbatim record of the
lectures, though, as lamented by Thomson, Faraday's manner has been lost. Still, some of
Faraday's style of delivery shows through in what might well have been some poking of fun at his
own intentional melodrama:
"Now, as to the shape or form of the flame. It concerns us much to know about the condition
which the matter of the candle finally assumes at the top of the wick -- where you have such
beauty and brightness as nothing but combustion or flame can produce. You have the glittering
beauty of gold and silver, and the still higher luster of jewels, like the ruby and diamond; but none
of these rival the brilliancy and beauty of flame. What diamond can shine like flame? It owes its
luster at nighttime to the very flame shining upon it. The flame shines in darkness, but the light
which the diamond has is as nothing until the flame shines upon it, when it is brilliant again. The
candle alone shines by itself, and for itself, or for those who have arranged the materials."
Offering an ongoing narrative to accompany the time Faraday wished the audience to spend in
contemplating the flame's shape and appearance suggests a keen sense of timing and purpose in
developing his theme.
Whereas the Chemical History of a Candle gives the reader insight into the
reasoning process
and techniques of demonstration by Faraday, in our own time we have been treated to several
excellent but different approaches to the art of demonstration. The first, Tested
Demonstrations, by Alyea and Dutton(3), familiar
to many of us now approaching retirement,
offers the barest "how to" instructions to a trained practitioner of the field, leaving the
embellishments and elaboration to that practitioner. The second is the comprehensive
Chemical
Demonstrations, by Bassam Shakashiri,(4) with
discussion of principle, preparation, hints for the
presentation and, where appropriate, a discussion of required calculations. The full four-volume
series is described at the Web site http://scifun.chem.wisc.edu/demoser.html.
In Chemical Demonstrations, a Sourcebook for Teachers,(5) Lee R. Summerlin and James L.
Ealy, Jr., written with the same attention to detail as the Shakashiri text, offer as well teaching tips
and questions appropriate to each demonstration.
The authors of both of the latter texts remind us that "Chemistry is not a spectator support,"
and
that demonstrations ought not to be viewed as a substitute for students working in a student
laboratory.
That experimental science is filled with unexpected occurrences gives it the potential for
entertainment as well as enlightenment. Teachers use the entertaining aspect of experimental
science to motivate their students, perhaps even at the expense of enlightenment. Henry E. Bent,
in recalling one of his worst failures in teaching: "I told the class. . . I was going to spend the
whole hour on flames and explosions; that I felt these were the most interesting experiments I
would be doing in the whole course; and that I wanted them to enjoy them."(6)
Technology and Chemical Demonstrations
Today we are treated to two advancements in technology which ought to be exploited by
practitioners of phenomenalogical disciplines like chemistry: the World Wide Web and the
increasing ease of use of video technology.
The Web is unequaled by any earlier development in educational technology as regards the
distribution of information. Text, audio, animation and full video may be offered through this
medium. Moreover, a single offering on the Web becomes available to everyone with a
connection to it at minimal added cost in time and effort to the original author. The earlier
necessary tasks of typesetting, printing, marketing and advertising have vanished. This will have a
profound effect on the sequences of events necessary in producing new works; the creative
process itself may enjoy a greatly enhanced status to the diminishing importance of myriad
mundane interferences.
As for the use of video, the bulky video camera is a thing of the past, replaced by the
"camcorder", lightweight and often containing a cassette capable of recording an hour or more of
full motion action and audio. The ease of editing such presentations will increase markedly as the
new digital video cameras assume dominance in the marketplace. Add to that the headlong rush
by many institutions toward a greater offering of courses taught at a distance and some of us may
be treated to an unparalleled opportunity: to prepare chemical demonstrations with some
institutional assistance! Whatever else one might argue about the efficacy of Distance Education,
one impossible dream has been realized: institutions are beginning to fund fully equipped and
manned television studios. That there is a likelihood that the chickens will come home to roost in
the not too distant future and that some cost/benefit accountability might be demanded suggests
to some of us that we'd better "get it while it lasts" and to take advantage of the opportunity for
those of us who wish often to be able to record and to store some of our best demonstrations "if
only there were some support."
Material already out there
Video files can be found at hundreds if not thousands of sites on the Web. There are
doubtless
hundreds of chemistry teachers in various stages of preparation and realization of the same
objectives of this conference, that is, to offer video exemplification via the Web of chemical
principles. Two sites which ought to be viewed for a study of techniques of coverage are (1) the
University of Illinois, at http://www.chem.uiuc.edu/demos/index.html and (2) the Franklin Delano
Roosevelt High School (Hudson Valley, New York) Chemistry Class,
http://www.mhv.net/~bonagura/demos.htm.
The Illinois site offers video (without audio in some if not all cases) in two different formats
(Quick Time and Video for Windows) as well as some demonstrations using only still images.
This site is a good one to visit for another, if backhanded, reason. It points up some of the
problems still inherent with the development of communications technology on the Web. In the
Combustion of Methanol demonstration, for example, the compression used in the preparation of
the file is not compatible with my Quick Time Version 3.0 (the player which is a default on my
machine). The file is downloaded, the "slider" appears and the movie begins, but there is no
image. Bringing up the Quick Time program first and then accessing the .AVI file (finding where
the file has been cached at download time can offer a headache all its own) generates the warning
message about the incompatible compression algorithm. An imageless playback is again
experienced. However, pulling up the Windows Media Player via Programs, then Accessories,
then Multimedia, then Movie Player results in the file playing flawlessly. Since Quick Time 3.0
supercedes my version of Windows 95, it would appear that either a compression algorithm
decoder has been abandoned or changed so that there is no longer seamless receipt of the file. In
a word, there appears to be a bug in the newer version.
The site at F.D.R. High School offers links to other sites with interesting instructional
materials in
Chemistry and Physics.
During the first three discussions of the Trial Session a number of links were recommended
by participants, including the two discussed above:
What demonstrations are needed?
Any demonstration is useful which exemplifies some principle of chemistry and which is
otherwise
unavailable to the teacher who wishes to bring this principle to the attention of his or her students.
That simple demonstrations may be done before one's students in the classroom
without the infusion of elaborate technological assistance goes without saying, but even these,
when prepared for the Web become available to everyone in the world with a connection to the
Internet, including one's own students who wish to review the exemplification of some principle
demonstrated at an earlier time. Student teachers also might find video demonstrations to be
useful in learning the necessary techniques. Finally, that it is difficult or impossible to receive
permission to place on
the Web commercial offerings without prohibitively high license fees helps to focus the advantage
of moving into Web-based education where we prepare our own material.
There are four categories of demonstrations which often CANNOT be done in front of one's
students in the classroom: (1) the demonstration which may produce a fire or explosion of
sufficient size not to be safe, (2) the demonstration which produces toxic or noxious products not
certain to be carried away by the ventilation system, (3) the demonstration which requires a great
deal of time for setup and elaboration of the principle involved and (4) the demonstration which
requires equipment which cannot be brought to the lecture room.
Add to that the reminder given us by Summerlin and Ealy, that
"[demonstrations] must always be rehearsed before class. Even if a demonstration has been
performed dozens of times, it should still be checked to ensure that all solutions are still good,"
and a resource of "canned demonstrations" freely useable for showing to one's students gains
added appeal.
The first case includes any explosive reaction: the ignition of a mixture of methanol vapor and
air
in a 5-gallon plastic water bottle, the thermite reaction, gunpowder, steel wool ignited in liquid
oxygen and many others. With recent heightened concerns about safety in the classroom and
laboratory, some chemistry teachers have abandoned one or more of these demonstrations and it
could be argued that our future chemists are poorer for not having at least some awareness of the
care required for the preparation and execution of these demonstrations and an appreciation for
the energy involved. A videotape of a natural disaster which involves a chemical reaction might
be more spectacular and meaningful than a simple laboratory demonstration. The natural event or
the laboratory demonstration AND the natural event might be more effective.
The second case would include demonstrations such as the reaction between sodium metal
and
chlorine gas to produce NaCl, the combustion of granulated steel mixed with powdered sulfur, the
dehydration of sucrose by concentrated sulfuric acid, the ammonium dichromate volcano and the
reaction between powdered aluminum and crystals of iodine. Although these demonstrations and
many others like them are done routinely in our schools, there might be circumstances where they
are not feasible.
A number of demonstrations described in the Summerlin and Ealy and Shakhashiri texts might
be
considered to fall into the third category. The Boyle's Law apparatus, the diffusion of bromine
vapor and the Preparation and Properties of Liquid Oxygen from the Shakhashiri text and
Equilibrium in the Gas Phase, the preparation of the Gerber cell and even the Iodine-Clock
Reaction (for high school teachers pressed into service as curriculum committee chairs and
textbook reviewers), from the Summerlin and Ealy texts come immediately to mind.
The fourth category predictably involves demonstrations requiring equipment either which
cannot
be lugged into the classroom or which is not on the premises. This might be because of size or
weight and it might be in another room in the science building or research laboratory. However,
the equipment might be in an industrial or government laboratory or location. Mass
spectroscope/gas
chromatographs, fluoresence spectrophotometers, atomic absorption, atomic emission
and x-ray crystallographic devices all represent important modern analytical techniques, the
principles of which are frequently discussed in textbooks but rarely observed by our beginning
students. Experiments involving isotope separation, magnetic susceptibility, neutron activation
analysis, carbon-14 dating and the determination of unit cell dimensions have not made it out of
the inner sanctum of research laboratories and into the experience of the average student.
The Purpose of this on-line Conference
The delivery of chemical demonstrations in the classroom, except in rare events, is done in
isolation. Our information for their preparation come from a variety of sources, many of them
universally available to be sure, including our own college experiences, guides and source books
such as the ones mentioned above and the occasional meeting such as the Biennial Conference on
Chemical Education in which selected colleagues demonstrate their techniques. Although we may
talk about visiting each other's classroom as a lofty principle of colleagueship and team effort in
advancing the discipline, few of us ever do it so as better to take advantage of the opportunity to
discuss technique and styles of delivery.
It is our hope that this on-line conference will offer a largely untried venue to our colleagues
to
share a typical classroom experience with the participants and in so doing to stimulate us into new
creative efforts in the presentation of chemical principles. We hope to encourage the efforts of
the naturally gifted demonstrators among us, particularly those who are unable to attend the
biennial conference of chemical educators or who might find the recorded demonstration to be a
friendlier environment than a face-to-face do-or-die encounter. We hope that this experience will
heighten our awareness of the problems confronted by all chemical educators in the execution of
demonstrations, including those constraints of the "little screen." It would be to our advantage to
see what can be done when only the simplest video equipment is available as well as what can be
accomplished when the full capability of a functioning distance education studio is available.
Finally, we hope that this conference will encourage all of us to begin to look more closely at how
we might better use digital web-based video for advancing the discipline of chemistry.
The Preparation of Images and Video Files
It is with more than a little trepidation that I offer the information below. As of November
1998, my knowledge of the skills required for image and video transfer to the World Wide Web
was
confined to placing a link to the occasional still image on my home page and a single Real Media
video clip I did prior to the Biennial Conference on Chemical Education in Waterloo, Ontario in
August, 1998. That video clip was prepared after I offered to organize an effort to place ALL
demonstrations done at that conference on the web to be viewed by anyone with an Internet
connection. It became immediately clear to me after this exercise that the effort required would
be herculean. Not only would video crews have to be recruited into service for the cause, but the
conversion of videotape presentations to video files showing the full demonstrations would have
resulted in files so huge as not to fit on most removable storage devices available at that time.
That exercise convinced me to write a quick e-mail message to the organizers apologizing for my
reckless hubris and asking that we delay such an ambitious project for some future conference. I
am happy to report that in little more than a year there have been some remarkable changes, both
in the availability of high density storage devices as well as video compression techniques. That is
not to say that the state of the art is without its problems, but the demonstrations available to the
trial session show what can be done at this time with far less effort than was required only a year
ago and advances which are bound to occur between now and the 2001 session will ensure that
the task will become only easier.
The CONFCHEM Trial Session on Chemical Demonstrations offers still images in JPEG
format
and video files in the RM and MPEG formats. My original intention was to encourage
participants to offer their demonstrations in a "video only" format, so as to celebrate the
immediacy of a demonstration offered by a colleague in his or her classroom. Several difficulties
appeared immediately and offered compelling arguments for expanding the presentations to text,
still images and video. The first is that all demonstrations have a lead-up of principles, a running
patter of explanation during the demonstration and finally, concluding remarks. Video files which
are meant to be downloaded would end up being prohibitively large even for viewers using
high-speed connections to the Internet. In the case of compressed files meant to be delivered by
"streaming video" (playing the file from a buffer while simultaneously downloading the rest of it
into that buffer), for delivery through a 28.8 kbaud modem, the resolution ends up being far less
than is pleasing to view some important parts of the demonstration. The lead-up to any
demonstration, the explanation of principles, the equations, the quantities, the set-up, often do not
require the use of full-motion video. In fact a student usually feels a need for extra time to think
about material being presented before the actual event and a full video presentation would force
"time certain" constraints on the presentation. Finally, the source of the videos for the trial
session came from a collection of distance education sessions held previously. They were
conveniently available, canned as it were, and ready to be converted to computer files. But the
specific segments which show the demonstration itself could not stand on their own merits
because there is not enough information fully to understand what is going on. There is still the
need for the introduction, the work-up, and some concluding remarks. Offering some text and
still images allows for those other parts of the demonstration and gives the added benefit of
superb resolution where needed at low expense in the required disk storage space.
We will here describe the process of preparing still image files and video files in the necessary
formats. At this writing the JPEG, MPEG and RM formats are commonly used on the World
Wide Web. Software and hardware to create and to display them is available from numerous
manufacturers. The products described in this short description are neither recommended nor
criticized. They are simply the ones which were used to achieve the product you see in the
demonstration pages linked to http://chemistry.csudh.edu/oliver/intro.htm.
The Preparation of Still Images
The preparation of still images in the JPEG format using a digital camera involved taking the
picture and uploading it to a PC running Windows 95. Each image was prepared at a resolution
of 100 dpi. No reformatting of images by cropping unwanted material was done. All have
height/width ratios of 4:5 in landscape mode and 5:4 in portrait mode. Image size was realized by
the necessary coding command in HTML after the image had been uploaded and stored on the
server (HEIGHT=200 WIDTH=250, for example). Each image at 100dpi resolution requires
about 50 kbytes of space. More than 20 such images can be stored easily on a 1.4 Mbyte floppy
diskette. Uploading to a server subdirectory was accomplished by means of WS_FTP95 LE,
available at http://www.ipswitch.com. It is free for non-commercial users, students and faculty of
educational institutions and government employees.
The particular digital camera used for the Trial Demonstration was an Olympus D 600L. We
picked that one specifically because it can focus as close as 12 inches in macro mode. It also can
take close-up lenses and with those its focus range decreases to 4 inches. Its zoom lens operates
at all distances. Again, we neither recommend nor criticize this camera. It is simply the one used
for the Trial Demonstration.
The text and images in the Trial Demonstration pages were assembled using a combination of
Corel Word Perfect 7.0 wordprocessor (and storing the files in html format, as allowed by the
program) and editing the coded files by importing them as .TXT, so that all of the HTML control
symbols are visible, and making appropriate changes. Format changes were usually made by
observing other Web pages having appealing arrangements and downloading those pages, copying
the necessary lines and importing them into our files. Any HTML file can be downloaded by
holding down the SHIFT key and clicking the mouse on a link to such a file. The user is then
prompted to indicate the particular subdirectory where that file is to be stored. The preparation of still images in the JPEG format (file extension .JPG) can be executed
alternatively by scanning a photograph or slide prepared by traditional means. None of the images
you see in the Trial Session pages was prepared in this manner, though all of the pictures found at
http://chemistry.csudh.edu/oliver/labpage.htm
Twenty digital cameras were reviewed in the January 19, 1999 issue of PC Magazine: Agfa
ePhoto 780, Agfa ePhoto 1680, Casio QV-7000SX, Eastman Kodak DC210 Plus, Eastman
Kodak DC260, Epson PhotoPC 700, Fujifilm MX-500, Fujifilm MX-700, HP PhotoSmart C30,
Konica Q-M100V, Leica digilux, Nikon Coolpix 900s, Olympus D-400 Zoom, Olympus D-620L,
Ricoh RDC-4200, Ricoh RDC-4300, Sanyo VPC-X300, Sony MVC-FD71, Sony MVC-FD81
and Toshiba PDR-M1.
The Preparation of RM and MPEG Video Files
In the description which follows, the cost of software is often included. The market is
changing
so rapidly that one sees offerings on Web pages to change week by week. Some of the software
described below may be obtained at no cost if one is an educational user.
The server we use for our video files is installed in a Pentium 200 MHz central processor unit
using 64 Mbytes of RAM and running the latest version of Real Server. We don't use that
machine for anything other than the preparation and delivery of streaming video material.
RM video files are to be used with Real Media software which can be downloaded as a
full-featured program for $30 or as a limited edition at no cost from http://www.realmedia.com.
One correspondent reports to me that Real Server recently has been on sale over the Internet for
$5, but I have been unable to verify that report.
The program which creates the RM file is Real Encoder. RealEncoder has recently been
replaced
by RealProducer, available at http://www.real.com/products/tools/ for $89.95 in a basic software
bundle or as RealProducer Pro G2 for $249.
A video signal is fed into a video capture board, in our case the board was the Matrox
Millenium
II graphics accelerator board and the Matrox Rainbow Runner video capture board. These
boards have been superceded by the Matrox Marvel G200-TV, all-in-one graphics/video capture
card, available for $299 at www.matrox.com.
A large number of graphics accelerators and video capture boards, including the Matrox
products
were reviewed by PC Magazine, December 1, 1998. See www.pcmagazine.com for details.
Video files can be produced directly from live video, with a connection from the camera to
the
computer, or via a video signal already recorded and coming to the computer from a VCR. We
recommend the use of the latter approach because "start" and "stop" times are often missed and
must be repeated. Moreover, software available today has the capability of enhancing the
incoming video signal to the computer by means of and adjustment of brightness and contrast. If
one tries to input video into a computer it only makes good sense to do it in a manner that offers
some control. Live video does not allow that control.
The long and the short of it is that the video and audio signals were connected from the VCR.
The audio signal in our case was monophonic so a "Y" connector to the stereo input of the video
board was used. The user has a choice of converting an uncompressed AVI file to a compressed
RM file or doing the same using the output of a VCR. The user is led through a series of choices:
Capture audio only? Capture video? Target audience (28.8 kbaud modem to T1 line)? Nature of
signal (voice only, voice w/ background music, music with vocals or instrumental music) A choice
between "smoothest motion" or "sharpest image" must be made. The VCR is then started with
about 10 seconds lead and the "start" button is clicked with the mouse cursor at the instant when
the file is to begin. The result is a compressed .RM file stored in a location indicated by the user.
The level of compression of the vapor pressure demonstration video was from 266 Mbytes for an
AVI file to 500 kbytes for the .RM file. The RM file is a "streaming video" file. That is,
RealPlayer produces a buffer holding the first part of the file and begins to play it for viewing
while the rest of the file is coming in.
An MPEG file is usually downloaded first and then played after the whole file has been
received.
MPEG files are compressed at various levels from AVI files. The vapor pressure MPEG file is 15
Mbytes from the original 266 Mbyte AVI file. The quality of the Vapor Pressure MPEG file is
considerably better than the RM file but takes far too long to download if one is using a 28.8
kbaud modem (around 90 minutes).
The software used to create the MPEG file was Video Studio by ULEAD systems ($100),
found
at
http://www.realstore.com/videostudio/index.html or http://www.ulead.com Video Studio creates a 30 frame-per-second AVI file which may then be compressed into the
final
MPEG file. The program Ulead Video Studio 3.0 at $99, available at www.ulead.com
Linking the video files to a Web page
RealMedia or .RM files References to materials recommended by correspondents but not available to this
author:
Teaching general chemistry : a materials science companion /, Arthur B. Ellis ... [et al.].
Washington, DC : American Chemical Society, 1993. xxvii, 554 p. : ill. ; 28 cm.
Taylor, Charles Alfred. The art and science of lecture demonstration /, Charles Taylor.
Bristol,
England ; Philadelphia : Adam Hilger, c1988. xiv, 181 p. : ill. ; 22 cm.
Click here to return to the CONFCHEM Chemical Demonstrations
Introduction 1. Faraday, Michael, Chemical History of a Candle,
Thomas Y. Crowell Company, 1957
2. Ibid, p. xxvi
3. Alyea, Hubert N. and Dutton, Frederic B., Tested
Demonstrations, Journal of Chemical
Education, Easton, PA, 1969.
4. Shakhashiri, Bassam, Chemical Demonstrations, A
Handbook for Teachers of Chemistry, Vols. 1-4,
University of Wisconsin Press, 1983-1992.
5. Summerlin, Lee R., and Ealy Jr., James L. (Vols 1,2), and
Borgford, Christie L. (Vol. 2) Chemical
Demonstrations, a Sourcebook for
Teachers, Vols. 1 and 2 , American Chemical Society, 1988.
6. Ibid, Vol. 1, p. xiii
1. Univ. of Illinois - Lecture Demos
2.F.D.R. High School
Chemical Demonstrations
3. Examples of scanned Polaroid photos***Students in Quantitative Analysis Laboratory at CSU
Dominguez Hills
4.
Journal of Chemical Education Software, Chemistry Comes Alive!
5.Journal of
Chemical Education Software Index.
6.Journal of
Chemical Education Software and Chemistry Comes Alive materials.
7.UNCW Technology College,
Download Page
8. University of Missouri at
Rolla, Oxygen Bomb Calorimeter Demonstration
9. References to
many Chemical Demonstrations. Compiled at Brigham Young University.
10. Cal Poly
Pomona, Physics Lecture Demonstrations
11. A comparison of media
streaming technologies.
12. Multimedia Streaming, examples
Many Web pages today are constructed with great sophistication. Our chemical demonstration
Web pages are quite simple by comparison, but if you wish to examine their structure, use your
browser to go to http://chemistry.csudh.edu/oliver/intro.htm, scroll down to the link to the
demonstration on the vapor pressure of diethyl ether, place the mouse cursor on the link, hold the
shift key down and click the mouse. You will be prompted to choose a subdirectory to store that
HTML file. When downloaded you may examine its structure using your wordprocessor or the
Windows Notepad.
were done that way and can be viewed for comparison. All of the images you see there were
captured from Polaroid camera photos. The capture process for these images involved the use of
an HP ScanJet 4c scanner and PhotoShop 3.0 software for the creation of the files. The image
resolution is 100 dpi.
The Web page itself has a statement of the form:
(On your browser, click on "page source" in the View pull-down menu to see the actual form of
the statement below)
Click here to see the demonstration
in Real Video.
The file vaporpre.ram is a one-line file. The line in that file reads as follows:
pnm://chemistry.csudh.edu/oliver/video/vaporpre.rm
It is the file vaporpre.rm which is the actual compressed RealMedia streaming video file.
MPEG files
The Web page itself has a statement of the form:
(On your browser, click on "page source" in the View pull-down menu to see the actual form of
the statement below)
Click here to see the demonstration
in MPEG format and compatible with Windows Media
Player and Real Player Plus G2. (File size =15 MByte)
The file vaporprs.mpg is the actual video file compressed from the AVI file described above.
Footnotes.