Why It took four weeks to write two paragraphs

I’m really under the gun. I am writing a book on how water quality instrumentation works and it is months overdue. I have a mandate from my editor that I must have a first draft complete by August. Or else…. And yet, I took 4 precious weeks without writing a single sentence and I used that time just so I could write two new paragraphs.

I threw away four good weeks because I was confused and needed to get my head on straight. There was a mystery in the principle of operation of electrochemical sensors that I just didn’t get and that hours of literature searches (okay, to be honest, Google searches) did not solve. That one question that confounded me was, in my opinion, so basic to a true understanding of electrochemical sensors that I had no right explaining how these sensors work to anyone else unless I knew the answer. To do otherwise would be a farce. So I found two books on the theory of electrodes and I read the salient chapters over and over again until the proverbial light bulb “went off.”

I have found that writing a book is like being an attorney preparing to litigate a case. A good lawyer knows ten times as much information about the case than he will ever actually have to use in court. He doesn’t consider the 90% of material that he never uses as a waste of information gathering. The fact is that this big pile of facts is what makes him an expert on the case at hand. The 10% he does use is merely the information he reveals in court to win his case. But make no mistake: Without the other 90% that never sees the light of day he is just a novice.

Okay, so what is the conundrum that baffled me? Well, instead of explaining it from the standpoint of potentiometric sensors, like an ORP probe, let me cast the problem in terms of something everyone understands—your ordinary household battery. If I want to measure the voltage of, say, a 9-volt battery I take out my handy voltmeter and connect the leads of the voltmeter to the two terminals of the battery. The red lead connects to the minus terminal and the black lead connects to the plus terminal. If the battery is still good then the voltmeter reads 9 volts.

And that’s where my confusion begins. A perfect voltmeter has an infinite resistance and draws zero current. Of course there is no perfect anything on earth so a really good voltmeter has a very high resistance (we’re talking hundreds of giga-ohms) and tiny currents (like nano-amps). And that’s a BIG problem. A battery works because chemical reactions reactions that involve the transfer of electrons occur at both electrodes. The electrons originate from the so-called oxidation reaction that occurs at the anode and travel through your electrical contraption (like a flashlight) to the cathode where the electrons are consumed by the so-called reduction reaction occurs. That flow of electrons is what we know as a current. The driving force behind the current is the voltage of the battery. But if there is no current when I connect my voltmeter then there is no chemistry and, if there is no chemistry, there can be no voltage. My voltmeter should read zero. The same chemistry and physics takes place in a pH or ORP analyzer, which also consists of an anode and a cathode in the sensor and a voltmeter to measure the probe voltage.

Here’s the answer to the conundrum: The oxidation and reduction reactions that create and consume electrons really do go on even when a voltmeter with infinite resistance is hooked up. And those reactions really do produce currents. It’s just that, in the case of a voltmeter connecting the two terminals, there are oxidation reactions that go in both directions at the anode and reduction reactions that go in both directions at the cathode. These reactions constitute currents going in opposite directions that cancel each other out. This is an equilibrium condition that is characterized by zero current. But make no mistake. That equilibrium condition still produces a voltage. This explanation of the microscopic goings on at the surface of a battery or an ORP sensor also explains other phenomena that had confused me, e.g. why an ORP sensor responds so slowly when in tap water. In other words, I received fringe benefits from all that studying.

I could explain further but that’s what my book is for. The point of my musings here is that I spent the best four weeks of my brief writing career by not writing, but by reading and thinking. I’m a better author because of that deep thought even though I wrote only about 2% of what I learned. It’s like that maxim that we all know but sometimes ignore. Don’t open your mouth unless you know what you’re talking about. To do otherwise is to—pardon my French—bullsh_t.

Gotta go. I’m more behind than ever in my book.