Since the last post, I have been wandering around in the historical maze, seeing lots of strange sights and making a few surprising discoveries among the twists and turns. The signposts themselves are confusing and sometimes it seems rather this maze has led me Through the Looking Glass, or, perhaps, into a Jane Austen novel. To show you what I mean, come with me on one journey of discovery relating to my own engineering education, with a little help from Michael Faraday’s library, when he was a printer’s apprentice. Don’t worry, this trip does not get overly technical; you will not see a single equation or even have to know what some of the machinery mentioned looks like. Nothing here would be on the test, if there were a test. Just enjoy the ride.
Step back through the mists of time with me to those distant days when I was being introduced to the wondrous secrets of chemical engineering. I was immersed in an elementary class called something like “Intro to Material and Energy Balances”. This was the class which introduced us neophytes to strange, out-of-context processes, like sulfuric acid production, using impenetrable prose describing mysterious equipment like pyrite burners, dust removers, Glover towers, lead chambers, and Gay-Lussac towers, accompanied, if we were lucky, by a minimalist, sparsely-labeled, undecipherable sketch. After wading through all the information, we would be asked to calculate, in that primitive era before the dawn of apps and laptops, “the complete material and energy balances of each unit and the entire process on the basis of 100 kg of pyrites, as charged” — at least a weeks worth of number-crunching and midnight oil. In this way, we were supposed to learn the ins and outs of the First Law of Thermodynamics, how to double- and triple- check our own calculations, and how to keep track of more details than an IRS agent on a high-profile audit. In addition, we were supposed to acquire, mostly by osmosis, a great deal of mysterious jargon, seemingly unconnected to reality, as we had known it in our pre-engineering school days.
Specifically, in this class, we had an awful lot of terms describing heat and its behavior: heat capacities (mean and specific and total), specific heats, sensible heats, latent heats, and many others I am sure I have forgotten.
“But heat is heat,” I hear my teenaged self shrieking in despair. “It is energy in motion, so why complicate it unnecessarily?” All this extra terminology, even with the help of my trusty Merriam-Webster, was baffling and annoying when all I wanted to learn was engineering, not arcane technobabble.
Think about it. Sensible heat? Does heat have reasoning powers, so that it can be deemed reasonable and sensible? Will the next chapter or the next class introduce us to illogical heat? Or wild, irrational heat? Or silly, foolhardy heat? And even if these less-stable heats existed, couldn’t they all be balanced the same way, at least in the engineering sense?
And what about latent heat? Is that heat which is dormant, a sleeping giant of the thermo world? Or heat with potential, perhaps lurking, ready to spring into a full-blown conflagration if left under a pile of oily rags in the corner? Or, by stretching the definition, could it be “occult” heat? After all, certain other parts of the curriculum seemed like black magic.
However, I was way too busy to dwell on the unnecessary obfuscation of these silly terms, so I shelved my linguistic frustrations and plodded on, memorizing less-than-sensible definitions, solving the assigned problems, and, in time, simply becoming inured to the terminology. I abandoned any rebellious thoughts of a crusade to rationalize this muddle. After all, words can have special meanings in special applications. Take “unionized”: does that mean atoms with all their electrons or does it mean workers organized
Jane Haldimand Marcet
(1769 – 1858)
Fast forward a few decades, to the present, where I have just returned from a sojourn even further back in time. As part of this project (evaluating the effectiveness of historical educational experiences and how they influenced innovation), I immersed myself in the book that Michael Faraday said inspired him to study chemistry: Conversations in Chemistry by Mrs. Jane Marcet. In print on both sides of the Atlantic for nearly 50 years, in both authorized and plagiarized editions, it features twenty-six conversations between Mrs. B, a private instructor, and her two teenaged pupils, Emily and Caroline. This well-written text comprehensively covers the theory and applications of chemistry at the time, and is clearly illustrated with experiments, which might well have been carried out by the ambitious and curious students of Mrs. Marcet’s era.
My electronic copy (thank you, Project Gutenberg) is the fifth edition (1817), revised and updated from the original 1806 edition, with an additional 21st century caution against trying the experiments at home. Reading it gave me new respect for the then-prevailing caloric fluid theory of heat. Although that theory has rightfully been laid aside now, Mrs. Marcet’s explanations using the caloric theory do describe and explain the experimental evidence at hand and make useful predictions about chemical behavior. In addition, they ignited a flash of insight into my long-dormant (or latent?) freshman frustrations.
What I did not put together while concentrating on energy balances in sulfuric acid plants was that words, too, are fluid, in the sense that they change over time and place. Reading historical documents, I am finding, is like Americans and Brits talking – we all think we speak the same language, just because we use a lot of the same words, but, in fact, those words often have different meanings. Consulting contemporary dictionaries, I found that many common words have changed their meanings significantly from a mere century or two ago. With a little help from my friends (Thomas Sheridan’s 1789 dictionary and the 1828 edition of Samuel Johnson’s 1755 dictionary – courtesy of books.google.com), I have learned “industry” once meant “diligence or assiduity” not the modern “manufacturing”; “art” once meant “the power of doing something not taught by nature and instinct; a science, as the liberal arts; a trade; artfulness, skill, dexterity; cunning”, not the modern “liberal and fine arts”; and “science” once meant “knowledge; certainty grounded on demonstration; art attained by precepts or built on principles; any art or species of knowledge”.
The flash of insight from re-reading Mrs. Marcet’s descriptions of different behaviors of the caloric fluid (heat) was realizing she used the word “sensible” throughout her whole book as I would probably now use the word “tangible” or “palpable.” Sheridan and Johnson give ten meanings for “sensible”, nine of which are related to “perceptible by the senses” and the tenth of which reads almost like an afterthought: “in low conversation it has sometimes the sense of reasonable, judicious, wise.” My modern interpretation, then cited as the “low conversation” option, was the problem. Sensible heat changes the temperature of the material, and a change in temperature can be seen on a thermometer or felt, thus it is perceived by the senses of touch and vision. The latent (which meant “hidden, concealed, or secret” in the early 1800s) heat was caloric which changed the phase of the material at a constant temperature, without any “sensible” effects.
So it all makes sense now – those words “sensible” and “latent” were just archaic usages, reminders of former theories and former times, when relying on first-hand observations, including the data from all the senses, was a primary tool of scientific investigation. The terminology, therefore, makes perfect sense, in the modern sense of sense, of course. But now I am wondering what insights might await me if I re-read Sense and Sensibility with my older dictionaries by my side.
Engineering the Industrial Revolutions 