<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Ad, <div><br></div><div>The vertisol you are referring to is commonly known as Mbuga or black cotton soil in physical depressions out in the "porry" of rural flat bush scub areas in much of rural East Africa. Technically is it a classed as montmorillonite clay... its instabiliy comes from the presence of a hydroxyl layer between two more stable tetrahedral layers in the overall structure. When water lubricates the hydroxyl layer, the clay expands and out goes any supporting structure. Removal of the water shrinks the mass and genrates the cacks in the process... That proves I have taken clay minerology in grad school. Another kind of appreciation of it comes when you get stuck in it 150 miles from nowhere...out in that porry...you can't even chisel it out of the wheel wells once it sets up.</div><div>On your other note about the apparent non effect of the acidity of the liquor extract on the lignin content of water saturated dung, I take it that ith the fiber intact, the dung will still be useable for briqetting...</div><div><br></div><div>Now to find the traditional and locally ubiquitos selection of aromatic plants to blend with it....</div><div><br></div><div>Dung eucalyptus briquettes anyone; a mossie repellant/ cooking fuel, right from the horse's mouth ...</div><div><br></div><div>Richard</div><div> </div><div><div><div>On Dec 7, 2010, at 5:14 PM, Anand Karve wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div>Dear Crispin,</div>
<div>the natural soil in this part of India is black in colour (it is called vertisol). It is extremely clayey. It swells when wet and contracts when it dries, producing cracks in the process. So, it is absolutely useless for any kind of construction. Our region was colonised about 2500 years ago. The soil in old human settlements shows a distinctly whitish colour. It does not expand when wet and does not crack on drying. This soil is prefered for any kind of construction work. People kept their cattle penned next to their houses. Archaeologists tell us that the vertisol gets converted into the whitish soil due to the chronic mixing with animal dung<br>
Yours</div>
<div>A.D.Karve<br></div>
<div class="gmail_quote">On Wed, Dec 8, 2010 at 8:28 AM, Crispin Pemberton-Pigott <span dir="ltr"><<a href="mailto:crispinpigott@gmail.com">crispinpigott@gmail.com</a>></span> wrote:<br>
<blockquote style="BORDER-LEFT: #ccc 1px solid; MARGIN: 0px 0px 0px 0.8ex; PADDING-LEFT: 1ex" class="gmail_quote">Dear Richard<br><br>I have seen only the original pamphlet on the clay setting method, but it<br>was definitely a PCorp publication so it should be available by now. I don't<br>
think anyone knew much about the chemistry at the time. He built houses and<br>drains around them using the method.<br><br>Regards<br>Crispin<br><br><br>-----Original Message-----<br><br>Good questions Kevin,<br><br> I am embarrassed to say that I have never pursued the issue, an admission<br>
made worse by the fact of having extolled Biogas tech widely in Tanzania<br>through most of the 70's . Question is if the bath is acid as Crispin<br>implies through his description of the mentioned peace corpsman, what<br>
effect would that have on the fiber content of the dung so essential for<br>wet process briquetting ? We would need the fibers intact.<br>As also related to Crispin's story about the use of the decanted liquid for<br>
solidifying clay: I'm just wondering Crispin; did you get any idea of the<br>thermal properties of the resulting clay-cement ? Would it in other words be<br>good for stove insulation and/or structure ?<br><br>Richard<br>
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</blockquote></div><br><br clear="all"><br>-- <br>***<br>Dr. A.D. Karve<br>President, Appropriate Rural Technology Institute (ARTI)<br><br>*Please change my email address in your records to: <a href="mailto:adkarve@gmail.com">adkarve@gmail.com</a> *<br>
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