<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Dirk’s solution (in both senses!) is probably the easiest option. <div>Purified waters have their own acidity levels ‘built-in’ by the purification process, especially glass distilled waters (down to 4!) pH levels are fine at 6 and OK-ish down to 5 but below that and decalcification and other denaturing processes are initiated.<div><br><div apple-content-edited="true">
<div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">With all good wishes, Simon.</div><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br></div><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;">Simon Moore MIScT, RSci, FLS, ACR<br>Conservator of Natural Sciences and Cutlery Historian,<br><a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.natural-2Dhistory-2Dconservation.com&d=CwMF-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=4MOCHXngL7WVHuePwG6-KES_kObYdbtsk6_4I1-YtFE&s=8vX614A5PhRuVCNT8KEYob9_Q8r1NANmdfBxjYV-s-I&e=">www.natural-history-conservation.com</a> </div><div style="color: rgb(0, 0, 0); letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><br><br><br></div></div></div>
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<br><div><div>On 18 Oct 2016, at 15:31, Dirk Neumann <<a href="mailto:dirk.neumann@zsm.mwn.de">dirk.neumann@zsm.mwn.de</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div bgcolor="#FFFFFF" text="#000000" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;"><div class="moz-cite-prefix">Dear Nicolas,<br><br><br>it might be worth to compare the attached paper; my colleague did some tests which are summarized therein. Normal pH-paper tests will not work, you need to dilute the alcohol to get reliable measurements (see attached paper).<br><br>If your tap water is not chlorinated and pure but calciferous, you might dilute your 96% EthOH with tap water to 80%; the dilution needs to rest for at least one day, as calcium carbonate starts to precipitate; the residual carbonate in solution gives you some sort of buffer capacity.<br><br>Hope this helps<br>Dirk<br><br><br>Am 18.10.2016 um 16:00 schrieb Margraf Nicolas:<br></div><blockquote cite="mid:4DB9F0A2F0694D4BB0B6995DE22D20B4014B89F10B@nembx2.ne.ch" type="cite"><div class="WordSection1" style="page: WordSection1;"><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><span lang="EN-US">Dear all,<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Calibri, sans-serif;"><span lang="EN-US">The MHNC is a small natural history museum located in the hearth of the Jura Mountains in La Chaux-de-Fonds, Switzerland. The MHNC team is currently re-conditioning the alcohol collection, changing containers and alcohol using an 80% Ethanol solution. The team was told to check the acidity of the alcoholic solution as acidity is not good for the specimens but had trouble doing so.<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span lang="EN-US">Is a 9.6 mg/l acidity expressed as acetic acid too acidic? (12 mg/l in 96% Et-OH diluted to 4/5)<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span lang="EN-US">Additional questions:<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span lang="EN-US">The alcohol dealer was asked about the acidity of the 96% Ethanol he provides us with. The value he gave us is 12 mg/l of acidity expressed as acetic acid. We tried to calculate the pH based on that value and obtain a value of 4.23. Does that sound right?<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span lang="EN-US">We tried measuring the pH of the solution with both pH-paper and a pH-meter and found conflicting values. Is the pH-paper reading valid for an alcoholic solution? Or is the pH-meter value valid for an alcoholic solution?<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span lang="EN-US">A pH of 4.23 seems too acidic to preserve specimens so we tried to calculate the amount of Na2CO3 necessary to neutralize the 12 mg/l of CH3COOH and obtain 10.6 mg/l. Is it correct (and sufficient) to add this amount of Na2CO3 to every liter of our 96% Et-OH solution?<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span lang="EN-US">Any advice or help would be greatly appreciated.<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>Thanks,<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>Sincerely,<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>N<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>*****************************************<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>Nicolas Margraf<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>Collaborateur scientifique<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>Musée d'histoire naturelle de La Chaux-de-Fonds<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>Av. Léopold-Robert 63 - CH 2300 LA CHAUX-DE-FONDS<o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span>T +41 (0)32 967 60 71 -<span class="Apple-converted-space"> </span><a moz-do-not-send="true" href="mailto:mhnc@ne.ch" style="color: purple; text-decoration: underline;"><span style="color: blue;">mhnc@ne.ch</span></a><o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span><a class="moz-txt-link-abbreviated" href="https://urldefense.proofpoint.com/v2/url?u=http-3A__www.mhnc.ch&d=CwMD-g&c=-dg2m7zWuuDZ0MUcV7Sdqw&r=CLFZJ3fvGSmDp7xK1dNZfh6uGV_h-8NVlo3fXNoRNzI&m=awiDiMv0NtCLLz5-uNP7bpumXx_y47hSNPzjP1ztGHQ&s=j_kCUhBRpi6St_0mk54mrv-AsRO2bu6fk98EjYXHooQ&e=" style="color: purple; text-decoration: underline;">www.mhnc.ch</a><o:p></o:p></span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span> </span></div><div style="margin: 0cm 0cm 0.0001pt; font-size: 11pt; font-family: Arial, sans-serif;"><span> </span></div></div><br><fieldset class="mimeAttachmentHeader"></fieldset><br><pre wrap="">_______________________________________________
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