Short Experiment Title, e.g. Charcoal
Your name here
Template for Lab Report for FYEC 175 “How did they do that? Chemistry and Early Art”
This template should be used for preparing your lab reports. The template contains
appropriate formatting for your report including fonts, font sizes, margin widths, margin
justification, line spacing, sections, footnote formats. The use of this template is not absolutely
required, but if you choose not to use this template, you are still responsible for ensuring that
your report conforms to all the requirements.
Format. To use this template start by saving a copy of this file. Rename that copy with
a logical name, say your initials and experiment title. Then open the file and simply replace the
current text in each section with your text.
You may insert figures, charts, tables, etc. at the
appropriate place in your report where you first refer to them. Do not change any of the
document parameters. Delete these instructions. Print on a high resolution printer (600 dpi or
higher).
Content. Your report should answer four questions: What did you do? What were the
results? How do explain the chemistry in modern terms? How might this work have been done
in ancient times?
Your report must include these Sections in this order:
Title
Authors
Date
Introduction
Experimental
Results
Discussion
Conclusion
References
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Short Experiment Title, e.g. Charcoal
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Title section. The title should accurately, clearly, and concisely reflect the emphasis and
content of the report. The title must be brief and grammatically correct. For example:
The Use of Charcoal in Paleolithic Parietal Art
and the Preparation of Homemade Charcoal
Author Name(s). Your name, or if this was a group project, all members of your group (don’t
include your instructor’s name). Also include your institutional affiliation, i.e. Randolph-Macon
College. Format should be first name, middle initial, last name, for example:
Elizabeth A. Fisher and John D. Thoburn, Randolph-Macon College
Introduction
The beginning of this section is marked by the section title Introduction (as above), so
do not erase that title. Replace all the text in this section with your introduction.
Although it may seem counter-intuitive, write the introduction last, i.e. after you have
write the experimental, results, discussion, and conclusion. In this section you should provide
some background for the project. You could provide some history, define important terms,
define the scope of the work. This section usually ends with a brief (one or two sentence)
description of what you will be do and/or the question you will try to answer. Your report
should include a description of how the technique might have been carried out in a previous era.
That could be done in either the introduction or the discussion. In the following example, a
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historical perspective on cave art is provided.
The historical background provides the context
for your experiments.
When amateur antiquarian Marcelino de Sautuola discovered paintings on the ceiling
and walls of the Altamira Cave in Spain in 1879, he proposed that they dated to the Paleolithic
period, based on the tools found on the cave floor, and on the depiction in the paintings of the
aurochs, an extinct species of oxen. No archaeologists believed him, though, and he died a
disillusioned man.1
Two samples of the charcoal taken from the drawings of this rhinoceros in Chauvet Cave
in France, discovered in 1994, have been dated by
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C radiometric techniques to 32,410 and
30,340 years before present.2 An area of burnt material that lay atop a calcite deposit, which in
turn lay over the charcoal drawing, was also dated to 26,000 years ago. This would appear to
refute any argument that the paintings were made in more recent times by someone who merely
picked up a piece of Aurignacian period charcoal. Confirming dates have been recovered from
collagen from bear bones found the cave.3
The black pigments of the Paleolithic drawings in Lascaux Cave in France, discovered in
1940, have been analyzed with TEM and micro-XANES.4 The results showed that some of the
drawings were made not of charcoal, but with a prepared pigment of ground manganese mixed
with clay and water, and that various rocks found at some distance from Lascaux, such as
hausmanite and groutite from the Hautes Pyrenees region, about 250 km distant, were the source
of the manganese.
Much scholarship has focused on the meaning of the Paleolithic parietal images. Henri
Breuil suggested they represented sympathetic magic intended to increase the chances of a
successful hunt.5 This theory was weakened by the study of the animal bones found in the caves,
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which did not represent the same faunal assemblage depicted by the paintings. David LewisWilliams, using ethnological comparisons with paintings of the hunter-gatherer San culture in
Namibia and Botswana, has suggested that the paintings represent hallucinatory visions
encountered in altered states of consciousness, that is, in trance.6 This theory may be supported
by the dots and web-like designs which often accompany the images of animals, since spots and
lines are reported by people who have visual disturbances similar to those which occur to people
in trance. Additional evidence for the association of the images with shamanistic rituals is the
frequent recovery of musical instruments from the caves.7
Charcoal is formed by pyrolysis of wood. At high temperature wood’s primary structural
component, cellulose, is decomposed. When wood is heated in the presence of oxygen, it burns
to give primarily water and carbon dioxide, equation (1). When wood is heated in the absence of
air, there is insufficient oxygen to oxidize the carbon. However, the internal oxygen atoms can
combine with the hydrogen atoms to form water (steam at these temperatures), leaving behind
nearly pure carbon, or charcoal.
The purpose of this work is to prepare charcoal that can be used for drawing. Rather
than re-create the exact technology that might have been used by early cave dwellers, a modern
kiln will be used prepare charcoal. The chemistry behind the process will be explored and
charcoal drawings made from the product of this experiment.
Experimental
The next major section of your report is a description of what you did. You should
provide sufficient detail for some one to reproduce your experiments. It should be succinct but
accurate. Write the experimental section first. It is the easiest to write, especially if you have
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kept a good lab notebook. It is also the most important. Dissemination of new knowledge is the
primary goal of science. Experimental work well done will stand the test of time, even when
interpretation change in light of new experiments. The goal in science is to make sure your
results are reproducible and therefore a clear, accurate description of what you do is of the
utmost important. This section should be separated by the heading Experimental, as shown
above. The Experimental section is usually written in the passive voice. Here is an example:
Dry, fallen sticks from various species of trees were gathered from campus. After their
bark was scraped off, their weights were recorded. The sticks were then wrapped in two layers
of heavy duty aluminum foil. The packet was then placed in an electric kiln and baked at 220˚F
for 1 hour and then 580˚F for 3 hours. After cooling the sticks were re-weighed.
Results
In this section you record your observations and descriptive / numerical results. Write
this section second, after you have written the Experimental. Your observation skills will be
evaluated. If you have kept a good lab notebook, this section will write itself.
The aluminum foil was stained brown from partial decomposition of the volatile organic
materials.
The sticks lost about 75% of their weight. Soft woods tended to produce black
charcoal, while hard woods tended to produce a browner charcoal.
The charcoal sticks
manufactured by this procedure make an excellent drawing implements (accompanying figures).
Discussion
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Short Experiment Title, e.g. Charcoal
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In this section provide a chemical explanation for what happened in the experiment.
Write this section third after the experimental and results sections. Here you have free range to
cover a wider breadth of ideas, which makes this section a little more difficult to write.
Note
that the final paragraph of the example below contains some speculation on how cave dwellers
may have made charcoal. Note that a description of ancient techniques is a required part of your
report.
The pyrolysis of wood is a complicated process. At low temperatures (~212˚F) the
entrained water is driven off as steam. At higher temperatures the volatile organic components,
mostly terpenes, sesquiterpenes, and other isoprene oligomers, are driven off. As they come in
contact with the hot aluminum foil, they char and turn into the soot evident on the foil and the
kiln shelves. At still higher temperatures (<500˚F) the larger polymers (cellulose, hemicellulose,
and lignin) that make up the cells walls begins to break down into charcoal.
6n O2
OH
O
HO
O
OH
HO
O
hea t
O
OH
cellulose
(C6H10O5)n
5n CO2 + 6n H2O ( 1 )
no O2
HO
hea t
5n C
+
6n H2O
(2 )
cha rcoa l
Scheme 1. Aerobic and anaerobic high-temperature reactions of cellulose.
The electric kiln affords a highly oxidizing environment at high temperatures. These
conditions would normally convert the wood to carbon dioxide, water, and ash (equation 1 of
Scheme 1). In this experiment however the sticks were wrapped in aluminum foil, which keeps
most of the oxygen out (equation 2 of Scheme 1). What little molecular oxygen is present leads
to incomplete combustion and formation of carbon monoxide, which itself is a powerful oxidant
capable of removing bound oxygen from the cellulose.
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The actual structure of charcoal is complex and heterogeneous. It consists primarily of
planar, layered hexagonal carbons similar to graphite, but broken into small randomly oriented
domains.8
Although we are unlikely to ever find out exactly how paleolithic artists made the
charcoal used in their cave art, we can propose several hypotheses. As mentioned above, the
decomposition of wood is a complex process and not all steps of combustion are carried to
completion. Residual charcoal pieces from a pit fire would have been sufficient quality to
produce drawings, possibly by grinding and mixing with clay binders. However, the recent
discovery of charcoal in a shell found at the Cosquer Cave in France hints that the artists may
have intentionally made charcoal under reducing conditions in a closed seashell container.
Such a method would be conceptually similar to the one used in this experiment in which the
wood was wrapped in aluminum foil. Moreover, the presence of iron and manganese oxides
originating from beyond the local environs suggests that the paintings were more than casual
drawings.
Conclusion
The simple idea behind any presentation is: “tell ‘em what you’re going to tell ‘em, tell
‘em what you told them you were going to tell ‘em, then tell them again what you told ‘em you
were gonna tell ‘em.” The point of the conclusion is to brief relate your most important points.
In this work we have demonstrated the principles that are used to prepare charcoal from
wood. The decomposition of cellulose, the primary component of wood, proceeds with the lost
of water to give nearly pure carbon (charcoal).
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Charcoal made from stick wrapped in
Short Experiment Title, e.g. Charcoal
Your name here
aluminum foil and baked in an electric kiln is an excellent material for drawing, producing
either black or black color depending on the species of wood used.
References
The Endnote section includes bibliographic references in which you site your sources. It
may also include footnotes in which peripheral and ancillary comments may be added.
Use
reference frequently, but footnotes sparingly. Be sure to use the correct format for all references,
as described in your writing manual: Hacker, Diana. A Writer’s Reference, 6th Ed. 2007. Here
are the appropriate endnotes for the Charcoal lab write-up:
1. Museo de Altamira, http://museodealtamira.mcu.es/ingles/descubrimiento.html
2. Jean-Marie Chauvet, Eliette Brunel Deschamps, Christian Hillaire, Jean Clottes (1996)
Chauvet Cave: The Discovery of the World’s Oldest Paintings; and H. Valladas, J. Clottes,
J.-M. Geneste, M. A. Garcia, M. Arnold, H. Cachier & N. Tisnérat-Labord. “Palaeolithic
paintings: Evolution of prehistoric cave art.” Nature 413, 479 (4 October 2001).
3. Herve´ Bocherens, Dorothee G. Drucker, Daniel Billiou, Jean-Michel Geneste, Johannes van
der Plicht. “Bears and
humans in Chauvet Cave (Vallon-Pont-d’Arc,Ardeche, France):
insights from stable isotopes and radiocarbon dating of bone collagen.” Journal of Human
Evolution 50 (2006) 370-376.
4. E. Chalmin, F. Farges, C. Vignaud, J. Susini, M. Menu, G. E. Brown, Jr. “Discovery of
Unusual Minerals in Paleolithic Black Pigments from Lascaux (France) and Ekain (Spain).”
13th International Conference on X-Ray Absorption Fine Structure, 2006.
5. M. Lorblanchet (1996) "Quercy, pigments des grottes ornées", Bilan scientifique 1995 (SRA
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DRAC Midi-Pyrénées), p.152-155.
6. Henri Breuil. (1952) Four Hundred Centuries of Cave Art. and J. David Lewis-Williams,
“Believing and Seeing: Symbolic Meanings in Southern San Rock Paintings” Bulletin of the
School of Oriental and African Studies, University of London, Vol. 45, No. 3 (1982), pp. 634-635.
7. Ker Than. “Stone Age Art Caves May Have Been Concert Halls” National Geographic News
July 7, 2008. http://news.nationalgeographic.com/news/2008/07/080702-cave-paintings.html
8. Rosalind E. Franklin. “The interpretation of diffuse X-ray diagrams of carbon” Acta
Crystallographa, 1950, 3, 107-121. Rosalind E. Franklin. "Crystallite growth in graphitizing
and non-graphitizing carbons”, Proceeding of the Royal Society A, 1951, 209, 196-218.
9. Jean Clottes, Jean Courtin, Luc Vanrell. “Cosquer Cave: Prehistoric Images and Medicine
under the Sea” http://www.bradshawfoundation.com/cosquer/images/26cosquer.jpg
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