In my (ancient) memory, seems like I remember acetic acid strength is limited by it's solubility. It's about 20% when fully saturated, when crystals begin to form, and no more will dissolve. At this strength, it's called "glacial acetic acid". I think more would dissolve at higher temps, but when allowed to cool, the crystals would form and precipitate, leaving the strength of the liquid at 20%. If I'm wrong about this, someone set me straight. Thanky. Tom in Paris, TX > Somebody said they had a bottle of 99% vinegar. They probably had 9%. > It is called acetic acid when it gets above 10 or 15% and is no longer > suitable for handling in the kitchen. > > Blake in San Antonio > Mailto: blakeo@flash.net > Blake, that's me.... No the vinegar I'm speaking off wasn't for using in the kitchen I bought it for my chemical experiments I did in my early day's, and yes you can only store it in 100 % lass bottles and is very dangerous to handle, like all concentrated acid's which I had too. I even remember the price I bought it somewhere around the 1978-1980 it cost me around $40.- for only one liter, it was a big investment for a scholar that time. And I have to admit it also cost me a pair of jeans, carpet and some blisters too during one of the experiments where I wanted to make heavy smoke (but it worked, that's all I remember) Hot regards Rob