Homage to Gaia (47 page)

I thought about this need for a perfect separator and it occurred to me that I could use the strange properties of the metal palladium. Palladium is a precious metal rather like platinum in colour and it does not easily corrode. It is one of the so-called noble metals, favoured by jewellers and others. When it is heated to moderate temperatures round about 200° C, palladium allows hydrogen gas to flow through it as if it were no more substantial than tissue paper. To all other gases and vapours, it remains a solid piece of metal. We could use a long tube of palladium, or some alloy of palladium, and use hydrogen as the carrier gas; the hydrogen would diffuse out through the walls and leave the substances behind. This could be the basis of a most effective separator. JPL provided me with a contract and some palladium alloy
tubes and said, more or less, ‘Go home and try these and see if you can make a separator.’

This contract gave me a year of fascinating experiments. In a proper laboratory, a scientist would have set up the palladium tube in an evacuated glass vessel, and then with notebook at hand, he would have measured the flow of hydrogen through the walls of the tube at different temperatures and pressures. After this, he would repeat the measurements with the substances he wanted to separate added to the hydrogen; it would be a project taking several months to complete. In my thatched cottage laboratory at Bowerchalke, I did not have much equipment. My vacuum pump, a somewhat ancient one, was in the loft of the cottage and I could not be bothered to get it down. I was impatient to have a go and I connected the palladium alloy tubing to a variable transformer so that I could heat it to 200° C by passing an electric current along it, just as if it were the heating element of an electric fire. Then I passed hydrogen at a known rate of flow into it, with no more in mind than to see what happened. From a proper scientist’s point of view this was a terrible experiment, but I was encouraged to do it by earlier conversations with that distinguished scientist, Archer Martin. He and I agreed that it was a mistake ever to do the first experiments too carefully. One should just join up whatever one had to hand, do it, and learn from the experience before designing a proper scientific experiment. Therefore, I merely watched how much hydrogen escaped from the end of my palladium tube when it was cold and when it was hot. To do this I lit the gas escaping from the open end of the palladium tube and watched the height of the small flame of burning hydrogen. I had to use a trick here, for the flame of burning hydrogen is invisible. What I did was to make some smoke in the lab by igniting a small pile of sodium chlorate and sugar; the fine particles of sodium compounds present as smoke in the atmosphere made the flame bright yellow and clearly visible. I turned on the hydrogen with the palladium tube cold—the flow was about one cubic centimetre a second—and lit my tiny flame. Then I turned up the current through the tube until its temperature was about 200° C and, to my astonishment, the flame went completely out. The hydrogen was flowing into the tube but none was coming out, but I found that by turning up the hydrogen to 4 cubic centimetres a second I could now re-establish a tiny flame at the end of the tube. I turned off the heating current and slowly, as the tube cooled, hydrogen began to escape from the end of it and the flame grew in size to the expected height at a flow of 4 cubic
centimetres a second. To make sure I was not being fooled, I joined a short length of silicon rubber tubing to the end of the palladium tube where the flame had been and dipped this into a beaker of water so that I could see the bubbles of hydrogen escaping. When I repeated the experiment, the results were even more astonishing. At a flow of 1 cc a second, when the palladium tube was at 200° C, the hydrogen flowed back into the tube and drew water up from the beaker into the silicone tubing as if there were a vacuum inside the palladium tube. Here was hydrogen flowing into both ends of it: where was it going? This was the stuff of magic. I knew that if the tube was merely permeable to hydrogen, a little would always have flowed from the far end, but it was behaving as if the solid palladium metal were a pump. Moments like this are what make the life of a scientist worthwhile. Here was a simple experiment that any schoolboy, or schoolmaster, for that matter, could do and, more importantly, just what was needed to solve the JPL problem. I had fulfilled my contract by the very first experiment.

It took me some time to realize why I could find no reports of this remarkable behaviour. The permeability of palladium to hydrogen was well known and discovered in the 19
^th
century. In proper laboratories, no one would have heated a palladium tube in air. They would have placed it in a chamber and measured the leak of hydrogen gas through the walls of the tube. I tried doing this and found that the extraordinary permeability of my palladium tube vanished when another tube or vessel surrounded it. Even with a vacuum on the outside, it did not pass hydrogen anywhere near as efficiently as it did when it was simply heated in air. It dawned on me that what was happening was that the hydrogen passing through the walls of my tube encountered oxygen atoms at the surface of the palladium in the air. Now, palladium is a catalyst when hot and there must have been an instantaneous reaction between the hydrogen escaping to the surface and the oxygen of the air. This completely removed all hydrogen atoms and constituted the most powerful pump that one could imagine, and this was the explanation of its apparently magical properties. I had just what they wanted for Mars and, a few months later, with many more experiments behind me, I returned to JPL to show them what a splendid separator they had in the form of a palladium tube. When I told them my story, it was so strange that at first few believed me. They were well used to exaggeration from over-excited scientists or salesmen, and how could they tell that what I was saying was different from this? It did not help either to start talking about
magic; there is nothing that puts off a scientist more than that. But they were prepared, like the good engineers that they were, to give it a trial by experiment.

The next morning when I came in from the hotel, I found that an engineer had connected one of my palladium tubes to an old mass spectrometer that was in operation and indicated an internal vacuum of 10
⁹
torr. This is an exceedingly good vacuum (a torr is a unit of pressure used by those who work with vacuums and equal to about one thousandth of an atmosphere). He had joined the other end of the tube to a pressure gauge, a flow regulator and a hydrogen cylinder. He heated the palladium tube to 250° C and turned on the hydrogen until the gauge said twenty torr. This was the inlet pressure to my palladium tube and it was 20 thousand million times greater than that inside the mass spectrometer, but the mass spectrometer happily kept its vacuum and said that no hydrogen was flowing into it. The engineer turned up the pressure until half an atmosphere, 400 torr, registered on his gauge. Still nothing happened, and the mass spectrometer showed no hydrogen at all coming through into it. The engineer turned to me and said, ‘Your tube is blocked—there’s no way that could happen otherwise.’ So we disassembled the apparatus and tried blowing hydrogen through the cold tube but found no blockage whatever. Puzzled, the engineer joined it all up again, and repeated our test at 400 torr; with just the same result as before. Hydrogen was flowing fast into the inlet of the tube but none was coming out. The engineer was so surprised that he said, ‘Wait a minute’, and went to telephone his friends, asking them to come over and watch the experiment. Soon some scientists, space scientists, and space engineers were drifting in to the small lab to see the experiment. We next turned the pressure up to a full Earth’s atmosphere, 760 torr, and the mass spectrometer gauge stayed obstinately at 10
^-9
torr; no hydrogen was flowing into it. It was pouring in at the other end of the metal tube and literally vanishing.

It was not until we raised the pressure at the input to a 1000 torr, well above atmospheric pressure, that suddenly the mass spectrometer vacuum failed and it failed catastrophically. Reducing the flow through the palladium tube re-established once more the high vacuum inside the mass spectrometer. There was a small cheer, and from that moment on, doubts vanished. The tube, which we called a transmodulator, was to be the means of joining the gas chromatograph to the mass spectrometer that six years later went to Mars on
the Viking spacecraft. Sandy Lipsky’s original idea of a gas chromatograph/mass spectrometer combination as the ideal soil analysis experiment had been reduced to practice. We had some fun breaking the turgid rules of scientific paper writing when we described the separator in a paper in the
Journal
of
Chromatographic
Science
in 1970. Here is the opening of the paper by JE Lovelock, PG Simmonds, GR Shoemake, and S Rich:

The JPL took out a series of patents on the device. They gave me three awards for it and three plaques, which I proudly hang on the walls of my laboratory here at Coombe Mill. There has been no successful commercial exploitation of the transmodulator here on Earth. This was probably because the gas Chromatograph soon evolved to use narrow-gauge columns through which a mere wisp of gas flowed and mass spectrometers evolved with much more powerful pumps. We no longer needed the palladium transmodulator, which had served as a kind of marriage broker to bring together these two powerful instruments.

My experiments with palladium and hydrogen gave me a clue as to what may have led astray those who thought that they had discovered ‘cold fusion’. Palladium will store as much as sixty per cent of its inner atomic space with hydrogen, and this readily happens when palladium is made the negative electrode in a watery solution. A piece of palladium filled with hydrogen is stable for a while in air, but then there is often a surge of heat as the stored hydrogen reacts suddenly and catalytically with the oxygen of the air. It was this, I think, that led to the false conclusion that cold fusion had occurred.

The most important single item that has sustained me as an independent scientist is the computer. So important has it been that I would like to digress and tell you how these wonderful devices entered my life and then changed it.

The plane from Los Angeles arrived on time and, with my small carry-on bag, I was the first of the passengers to arrive at the Customs counter. In those days, the largest plane was a Boeing 707, and Heathrow was comparatively peaceful and quiet. When asked if I had anything to declare, I said, ‘Yes, I have two small electronic items.’ I showed the Customs officer two of the early integrated circuit amplifiers. They looked like a pair of frozen black beetles, with their stiff wire legs hanging beneath. When he asked me what they were and what they were worth, I replied, ‘They are small amplifiers. They are research items given to me in America.’ He then said, ‘This is a matter for the supervisor. Hang on, I’ll give him a call.’ Within minutes, they escorted me to an office occupied by an amiable middle-aged civil servant. I showed him the chips and he asked, ‘Do you mean to tell me that these things are amplifiers. You know, like I have with my hi-fi?’ When I nodded, yes, he snorted and said, ‘Their Lordships are pissing against the wind if they think I’ll be able to stop people bringing these things in with them.’ He then helped me to fill in some forms that gave what he called Treasury direction, so that there was no Customs duty payable. It was a pleasant encounter to start the day. The chips that I had imported were early operational amplifiers made by the Fairchild Company and called
µ
A709. I needed them to control a palladium separator, which I was building for the Mars mission.

Without at the time realising it, JPL was providing me also with a priceless education in the new electronics, and not only amplifiers. Soon I was familiar with and bringing in silicon-chip electronics: logic gates, timers, and inverters. By 1970, I started one of the extravagances of my scientific life. I bought an early HP computer, a 9100B calculator. Although it was heavy, it sat easily enough on my desk. It cost over £2,000 with its peripherals, enough then to buy a small house. Its memory was made of ferrite beads strung out on a grid of wires, and it was less than one kilobyte. The programme language was only slightly removed from the fundamental binary talk of computers, but thanks to HP’s well-composed manuals, I rapidly became fluent
in it. Soon I was able to answer the problem that had plagued me over the past ten years: how does the electron capture detector work? The differential equations that describe electron capture and the behaviour of the detector were easy enough for me to write down, but they were far beyond my ability to solve analytically by ordinary mathematics. I have since childhood suffered a peculiar form of dyslexia. I cannot distinguish immediately between left and right and I reverse the order of letters in words I write. Worst of all, I have great difficulties with the manipulation of algebraic equations. I cannot instinctively tell which side is which. In spite of this, I love mathematics and have little difficulty with its concepts, only with the practical execution of them. Even this primitive computer, or calculator as they called it, was my liberation. Now I could leave it to the device to solve my equations numerically. Soon it was plotting graphs to show how and why the detector behaved so strangely. I was hooked, and as any teenager would do, I spent a sizeable proportion of what HP paid me for my advice, to buy their computers. Moore’s Law meant that every two years the computers evolved to a new desirable level and I bought a new one. It still goes on, thirty years later; soon I will be buying yet another.