Message:

<p>[QUOTE=&quot;kaparthy, post: 1992134, member: 57463&quot;]They do compare the streak to reference streaks.&nbsp; See the Wikipedia article on Touchstones.</p><p><br /></p><p>Whether &quot;they&quot; had acids depends on who &quot;they&quot; were.&nbsp; The alchemists of the Middle Ages deserve a lot of credit.&nbsp; Nitric acid and hydrochloric acid both date to the 13th century; and the Geber processes are the ones&nbsp; sometimes still used for them today. However, sulfuric acid (vitriol) was known to the Sumerians.&nbsp; They catalogued several kinds by color - something we still do.</p><p><br /></p><p>Short of those mineral acids, the only available oxidizers were urine (usually horse urine) and vinegar.</p><p><br /></p><p>But, again, credit the alchemists.&nbsp; By distilling vinegar, you can get glacial ascetic acid.[/QUOTE]</p><p><br /></p>

Your name or email address:

Do you already have an account?

• No, create an account now.
• Yes, my password is:
• Forgot your password?

Stay logged in