The ABC (to Z) of Chemical Engineering

Article by Carl Schaschke CEng FIChemE

“THE stuff that cults are made of” and “Extremely funny, an ingenious plot and cracking good jokes” are two reviews of well-known books that may well be on your bookshelves. They are not, however, the reviews to be found for the Dictionary of Chemical Engineering. The dictionary is neither a ripping yarn nor a page-turner with a whodunnit. Put simply, it is a collection of words that begins with A and ends with Z.

As one of the latest additions to the Oxford Paperback Reference series, the Dictionary of Chemical Engineering is a collection of scientific and engineering terms commonly encountered in chemical engineering. With over 3,400 entries covering all aspects of chemical engineering along with terms from related disciplines, such as chemistry, physics, and mathematics, it is aimed at a general readership, students of chemical engineering and general engineering courses as well as professionals in the fields of applied chemistry, chemical technology, industrial chemistry and process engineering. It provides definitions and explanations for materials, energy balances, reactions, separations, sustainability, safety, and ethics along with concepts, laws, theories and hypotheses. Significant organisations, international legislation and biographical notes of influential scientists and engineers who have been responsible for contributing to the development of the discipline are also included, along with the definitions of many types of specialist process equipment.

Where to start?

Compiling a dictionary differs from writing any other type of book. While the entries are arranged alphabetically, contrary to popular belief, it is not written sequentially starting with A and ending in Z. Dr Samuel Johnson’s Dictionary published in 1755 was the output of nine years of work providing over 40,000 definitions to English words in common usage at the time. It wasn’t the first dictionary to be published, and there have subsequently been many updates to reflect common usage of the ever-evolving English language. Recent additions to the OED include “chillax”, “climate emergency”, and “freegan” (which is a combination of free and vegan). Perhaps the most prolific contributor was the American army surgeon, Dr William Chester (WC) Minor (1834–1920), who moved to England after serving in the Union Army during the American Civil War. A deeply troubled man and accused of murder, he was incarcerated in Broadmoor for 38 years from where he wrote and sent his many contributions.

As a source of reference, a dictionary is an evolution and not a definitive collection of all words. In the episode Ink and Incapability in the third series of the television comedy Blackadder, Dr Samuel Johnson, played by Robbie Coltrane, having proudly written his definitive collection is confronted by Edmund Blackadder (Rowan Atkinson) who unhelpfully asks: “I hope you will not object if I also offer the Doctor my most enthusiastic contrafibularitries”. While Dr Johnson hastily pens the omission to his magnum opus, Blackadder continues: “Oh, I’m sorry, Sir. I’m anaspeptic, phrasmotic, even compunctuous to have caused you such pericombobulation”. Of course, none of these words actually exist, although you can probably deduce their creative meaning. If the Dictionary of Chemical Engineering is not an exhaustive collection of terms, what words are or – perhaps more importantly – are not included?

And what does it look like?

Oxford University Press (OUP) uses a recognisable format for all of its dictionaries. So, whether you consult the Dictionary of Music, the Dictionary of Psychology or any other of its dictionaries, you will note that each entry is presented in the same recognisable way. Entries are a blend of short (up to 10 words), medium (up to 75 words) or long (300 words max). OUP provides strict instructions on how to write entries. The process of compilation involved accumulating words, preparing their definitions and, once complete, transfer to a master file. In this way, the dictionary evolves. A word tracker keeps pace of progress and consistent with English words in general usage, the most frequent first letters are the consonants C, P and S.

What makes the cut?

The sources for entries were many and various. Museums, libraries, academic and industrial experts all made contributions. Each was crafted and shaped to the required format. One contribution by an industrialist was duly corrected by an executive of the same company until it was revealed that the original source had been the CEO. Never were the stakes so high! Some words are generic and found within other OUP dictionaries. However, each entry was written specifically for the Dictionary of Chemical Engineering and therefore unique. Importantly, none of the entries came by way of internet resources such as Wikipedia. These resources are unreliable. The compilation was entirely electronic without a single page being printed during the writing or editing stages. The output, however, is a paperback distributed and sold worldwide. Seven days after publication, an illegal pirate copy appeared on the internet. Presumably, it took a week to scan the 450 pages!

Behind every entry lies its own story. The entry for Fritz Haber is short and reveals little of the person. Of course, it is widely known that he was a German chemist who, working with the engineer Carl Bosch, developed an ammonia synthesis process using nitrogen and hydrogen gas. Receiving the Nobel Prize in Chemistry in 1918, his great legacy is the development of fertilisers and transformation of the agricultural industry. What is not told so widely is the darker side of his work in developing deadly gases used in the trenches of the Great War and later a hydrogen cyanide pesticide called Zyklon B used by the Nazis. Haber’s wife, Clara, unable to reconcile herself with his work on chemical warfare committed suicide. Haber left Germany in 1933 to work at the Cavendish Laboratory. Fellow Nobel Laureate, Ernest Rutherford, publicly refused to shake Haber’s hand when they met. For the observant, this memorable event was the answer to a recent question on BBC TV’s Mastermind.

Processes and processors

The chemical processes included in the dictionary proved problematic. Many early processes have long since been superseded, and evolved into many variants often based on the use of different catalysts or operating conditions, each with their own name. Unless highly significant across an industry, these were omitted or generalised. Some have interesting origins. The Leblanc process, for example, is the manufacture of soda ash from salt that goes back to just before the Napoleonic era. In 1775, the French Academy of Sciences offered a prize for the conversion of inexpensive salt to the more highly valued soda ash. The French chemist and physician, Nicolas Leblanc (1742–1806), invented a process using sea salt and sulfuric acid. However, his winning process was confiscated by the French revolutionary government who also refused him his rightful prize money. While Napoleon later returned the plant to him in 1802, he did not receive his prize. A broken man, Leblanc committed suicide four years later. The Chemical Engineer coincidentally ran a feature on him and his process in the series Chemical Engineers Who Changed the World (

While there have been many people in the past who have been credited with pioneering chemical engineering, no living chemical engineer is featured. This is deliberate and not intended to demean the remarkable achievements of many chemical engineers living today who continue to shape and advance our profession. A chance source of biographies was gifted to me by a colleague in the process of retiring and clearing out his office. Published in 1981 as a commemoration of the 60th anniversary of the Department of Chemical Engineering at MIT, the book The Improbable Achievement provides a pen portrait of its early pioneering chemical engineers. With familiar names such as Arthur D Little, Lewis, Gilliland, Sherwood, Whitman and Hottel amongst many illustrious others, it reads as a Who’s Who, many of whom were responsible for coining terms still in use today, such as “unit operations”.

Keeping current

Updates are constant and quickly added to the online e-book version of the dictionary. An example is the recently-revised entry for kilogram, which is the SI unit of mass. Previously defined as being equal to the mass of the international platinum-iridium cylinder kept by the International Bureau of Weights and Measures at Sèvres, near Paris, France, the definition changed in May 2019 to be the equivalent mass of the energy of a photon given its frequency, via the Planck constant and is dependent on the definitions of the metre and the second. It therefore meant that other entries that depend on mass also changed.

As a collection of commonly-used, and in some cases less-commonly-used terms in chemical engineering, the dictionary provides more than a glossary of terms, yet is not encyclopaedic. Thankfully, you’ll not find made-up words from Blackadder, but it will help you distinguish between a Holley-mott and a Hortonsphere.

Article by Carl Schaschke CEng FIChemE

Dean of School of Computing, Engineering and Physical Sciences, University of the West of Scotland

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