INSTRUMENTATION by Ralph H. Müllet
Reluctance to develop and experiment with new techniques noted.
o our way of thinking, Dr. Hallett's Teditorial in the February issue of ANALYTICAL CHEMISTRY raises one of
the most important questions confronting analytical chemists. I t is difficult to say much more of any importance than he has done in six short paragraphs, but the general theme warrants repeated emphasis if we are to profit from its warning. When he says "Instrumenting manual methods instead of using new approaches is a weakness in chemical instrumentation" he is stating the case mildly and tactfully. In these days we are witnessing elaborate automation of some very creaky and outmoded classical methods and it is not uncommon to find several thousand dollars worth of automatic devices being applied to the performance of an essentially ten-cent technique. Our own interest in autotitrators, particularly photoelectric, began 35 years ago, but long ago we began to develop a horror for these things because some of them are beginning to resemble a launching pad for an intercontinental ballistic missile. We would indeed perk up and recover interest in these matters if someone came up with a precision of one part in a hundred thousand or could do these things in a tenth of a second, but it continues to leave us cold if an autotitrator requires 15 or 20 minutes to draw a curve and the end point has to be determined graphically or by computation, as a result of which we come up with something not much better than can be done with a beaker, buret, and stirring rod. It is strikingly obvious that the complicated and very costly analytical instruments which are worth every penny of the large sum they cost are those which started out with no immediately
N e w book available on transducers
obvious analytical use. This is true of spectrographs and spectrophotometers of all types, the mass spectrometer, x-ray de\dces, and nuclear magnetic resonance spectrometers. All of these were the developments of physicists and their progressive elaboration has always resulted in greater resolution, speed, and precision. Their great analytical importance was established without reference to classical analytical procedures. In many respects it can be said that analytical chemists brought these instruments to their high degree of excellence and performance because, as always, the analyst has respect for precision and accuracy. This is quite different from merely adding mechanical arms, legs, eyes, and ears to a simple technique. The history of technology, and to some degree of science, is replete with man's insatiate desire to mechanize things and until an original idea came along such mechanization was applied to essentially primitive methods. The oars and sculls of a galley were suggested by the fins of fish and not too much time was wasted on applying power to oars, although the sidewheeler and stern-wheeler flourished for a long time until Ericsson invented the propeller. Leonardo da Vinci, Lilienthal, and Octave Chanute made exhaustive studies of birds in flight. The use of a propeller was obvious, but its employment had to await the development of a motor with a sufficiently high ratio of horsepower to weight. Propeller design reached elegant heights as a result of advanced aerodynamic theory, but the jet has every indication of making the propeller as archaic as flapping wings. Of course, it is verv easv to sit back
and propose that we discover some radically new analytical technique. These things come along on occasion but not as frequently as one would like. It would help a great deal if we all had more time to try new things. Analytical chemistry is so important that most of us are so busy getting scientists interested in this field and keeping other people happy that the work load piles up. We get automatic equipment to lighten the burden, we manage to keep more people happy—and we learn nothing new. There is another deterrent to progress. That is the principle of applying the best resources to the problem and getting the answer and as far as new principles are concerned, it is best to let well enough alone. We have an example in our own researches wherein beta backscattering and the beta excitation of x-rays have shown numerous analytical applications. There have been two typical reactions to our work. The first was—"Why don't you buy an x-ray tube?" That is a most sensible question, but we don't happen to be in the x-ray business per se. We merely wish to find out more about the mechanisms involved and how these things may enable one to do conventional things more simply, conveniently, and cheaply. The second difficulty, and it does not worry us in the least, is the palpable evidence that all we are doing can be done much better by existing techniques. Somewhat stubbornly we recall that the first motor car could be overtaken by any horse and the Wright brothers' first plane could have been outpaced by a cyclist. With some notable exceptions, it can be said that any new technique is likely to be inferior at first to competitive VOL. 32, NO. 4, APRIL 1960
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INSTRUMENTATION methods. That it may soon outstrip these and render them obsolete is a matter of history. Despite a lifelong interest in instrumentation we are not too sure that the next great advance in analytical chemistry will involve instrumentation. We are quite certain that nothing startling will result from more extensive plumbing and hardware. Shall we be treated to something else as delightfully simple and useful to the analyst as paper chromatography or cooperative and selective bacteria?
New Book on Transducers
FUNDAMENTAL OH STRETCHING WATER BANDS RANGE: 2.50-2.65 microns
RESOLUTION: 1 cni1 (6Â)
The above curve illustrates the high resolution that users of Cary Model 14 Spectrophotometers are getting for measurements in the near-IR region. The Model 14's ability to resolve such fine structure is a feature not ordinarily found in a general purpose instrument having a wide wavelength range (1860 A-2.65 microns). In most of the ultraviolet-visible region, resolving power of the Model 14 is better than 1A. High resolving power is just one of many features that make the Model 14 so useful. A broad wavelength range, a wide choice of scanning and chart speeds, accommodation of a variety of types and sizes of sample cells, stray light of less than 1 ppm, photometric reproducibility better than .004 in absorbance even at high absorbance, and many special accessories suit the Model 14 to a wide variety of spectrophotometric problems requiring fast, accurate analyses. These and other performance features have made it the preferred recording spectrophotometer of leading research laboratories throughout the world.
Details of these benefits and complete specifications on the Model 14 are yours for the asking. Write for Data File A12-40
RECORDING SPECTROPHOTOMETERS
APPLIED
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PHYSICS
C O R P O R A T I O N · 2724 SOUTH PECK ROAD Circle No. IT H Readers' Service Card
ANALYTICAL CHEMISTRY
MONROVIA,
CALIFORNIA
A few months ago we mentioned the impending publication of an important book on instrumentation. It has now appeared—"Instrumentation in Scientific Research—Electrical Input Transducers" by Professor Kurt S. Lion of MIT (published by the McGraw-Hill Book Co., New York, 1959, ix + 324 pp., $9.50). This volume is part of a larger undertaking, the goal of which is collection, analysis, and organization of the physical methods used for experimental research or for the development of scientific or technical instruments. In five main chapters Lion discusses mechanical input transducers, temperature transducers, magnetic transducers, and electrical and radiation transducers. In the many sections in each chapter practically every known type of electrical transducer is described. Each device or principle is discussed on the basis of the physical principles involved, with just enough mathematical treatment to make the discussion precise and well defined. , It is exactly in accord with the author's conviction that "creative accomplishments in the field of research methods and instrumentation are not the result of expertness in mathematics only, nor of acrobatics in experimental techniques, but are often the consequences of a clear understanding of the physical principles or mechanisms underlying a process." Adequate but not exhaustive references are given for the various topics and there is an author and subject index. The analyst who is interested in new techniques and ideas for new instruments can find much of value in this book. It is restricted to basic principles and descriptions of how these may be applied. In it he will find no directions for making minor or trivial improvements to existing instruments but he can readily gain a broad view of transducer theory and practice. We hope that Professor Lion's further volumes will maintain the excellence of this one and that they may appear soon.
