When I was a lad, I used to look at the books on my parents' shelves with a sense of wonder. I loved both reading and writing; books were the unhidden treasure of my childhood. The desire to write one, naturally, became an ambition.There was only one problem. How would I ever know enough? The process, I assumed, required the acquisition of compendious knowledge which was then distilled (a word whose full implications remained sketchy back then) into one intense volume.No one told me the truth, which is that this is not how it happens at all.The most common starting point is the combination of at least partial ignorance with raging curiosity. The acquisition of knowledge is an adventure the writer can then share with the reader; while the raging curiosity ensures that the hapless and self-doubting author doesn't give up when the going gets tough and the money runs out.Back in 1999, when I decided that a book devoted to Islay and its whiskies would be a great idea, I had little other than enthusiasm. Now it's written and published, there's still much that I don't know. But I have, along the way, discovered a lot.Including a lot that I didn't expect. The book is about much more than whisky, of course, but let's just concentrate on just one aspect of the whisky side of things for the purpose of this brief excursion: peatiness.Islay, of course, means peaty whisky for most drinkers; that's what it meant to me in 1999.I knew about ppm (or 'parts per million') phenols, the standard measurement of peatiness: Lagavulin had 35 ppm, I understood, whereas Laphroaig was on 40 ppm and Ardbeg 50 ppm. Sorted.Ha! The more I began to look into this subject, the more opaque it became.First, these figures refer to ppm in the malt - but not the spirit itself. The 'recovery rate' varies, but is rarely much more than half the original ppm, so Laphroaig's new make spirit contains around 25 ppm and Lagavulin's between 16 to 18 ppm.Not only that, but the phenols, I learned, drop away with time: the 10 year old Laphroaig contains around 10 ppm, and the 30 year old around six ppm. Distilling regimes, too, greatly influence both the recovery rate and the style of peatiness in a whisky. Caol Ila and Lagavulin, for example, both begin with identically peated malt, yet Caol Ila's new make contains 12 to 13 ppm in contrast to Lagavulin's 16 to 18 ppm, and its peatiness has an altogether different sensorial expression. (I analyse the reasons for this in the relevant chapters.)Ardbeg's purifier is why, having begun with peatier malt than Laphroaig, it ends up with about the same level of ppm in the new make. Indeed until Glenmorangie began recycling the husks by fitting a reverse jet aspirator in May 1998 it was actually lower.How, I then wondered, do you measure these famous 'parts per million'?There are, it turns out, two main methods: by colorimetric analysis and by high pressure liquid chromatography or HPLC. And - guess what? - they give different results.At higher levels, wildly different. Bruichladdich's 2003 run of Octomore malt (badged 'the peatiest in the world') was colorimetrically analysed by its maltster, Bairds of Inverness, at 76.5 ppm, but Tatlock and Thomson's HPLC analysis gave a figure of 300.5 ppm!There are even, would you believe, seven different methods of arriving at a colorimetric figure, and Tatlock & Thomson's own colorimetric figure was 129 ppm, some 52.5 ppm higher than Bairds'. Perhaps one day all analyses will be by HPLC (Port Ellen malt is still sold to colorimetric specifications) and then we will know where we stand.Or will we? The HPLC analysis is based on the seven most prominent spikes shown in the read-out. Obvious, but possibly treacherous. Your nose, you see, may pick out one of the chemicals with smaller spikes as being organoleptically more important than those with the big spikes. Even in an HPLC standardised world, in other words, we may still be measuring the wrong things.Raging curiosity, then, is a good starting point. There is, of course, no guarantee of a conclusion...