engineering

"pyrolysis is... complicated... by the fact... primary pyrolysis products... are... able to react among themselves... with ... from the moisture in the coal... with char or coke, or... several of these. The products... often called secondary... may differ... from the primary... Primary products can be studied... if... quench[ed]... rapidly or... [fed] directly into a suitable... instrument... [e.g.] a gas chromatograph."

"Pyrolysis of biomass, heavy petroleum fractions, , , and usually produces some amount of liquid product. Pyrolysis... without an externally added... [source] is constrained... Pyrolysis produces liquids, but leaves a residue of carbonaceous char or coke. Usually... gases also form. The... proportions of solid, liquid, and gas depend on the... feedstock and... reaction conditions."

"The organic material in oil shales requires pyrolysis to force the catagenesis of ... This can be done above ground in kilns, or underground with the shale still in place."

"Like their aliphatic counterparts, the smaller phenols are also water-soluble. Phenol... has... solubility...[≈]82 g/kg water. ...Phenols are produced in coal and wood pyrolysis. Any water used in such processes becomes contaminated with phenols (as well as other compounds) and requires processing before being released... into the environment."

"[M]easurement of the coal particles' temperature is not trivial. In many cases the temperature... must be calculated from a model. The other two experimental problems, the suppression of secondary reactions and the collection of products, depend on the reactor geometry and flow pattern..."

"We are... concerned with the evolution of tar and gases during the plastic state of coal. In this... consists of two processes in series: diffusion through the molten coal to some internal surface, that of a bubble or a pore; and transport with the bubble or through the pore to the surface of the particle. The role of preexisting pores is not well understood. ...[A] certain fraction of preexisting pores (< 60 Å) collapse during pyrolysis perhaps due to effects. Pores... 60-300 Å were preserved... but one could not distinguish preexisting pores and pores generated by the evolution of bubbles. It appears likely... the major... mass transfer occurs via bubbles while preexisting bubbles play a... minor role."

"Production of ... with [other] chemical products... involves pyrolysis, i.e. decomposition of compounds through application of heat."

"Pitch is a highly viscous residue remaining from wood pyrolysis... In the days of s, pitch was extremely valuable to seal the wood planking and for... where a tightly sticking, water-resistant material was needed."

"Flash pyrolysis poses three experimental difficulties..: (i) control and measurement of the temperature-time history of the coal particles (ii) suppression of secondary reactions (iii) quantitative collection of products."

"The groups from [wood distillation] are 1. s; formic to caproic, especially . Also, furoic, angelic, s, and valerolactone. For different woods, the total acid, calculated as acetic acid, varies between 4.3 and 6.8[%]... In vacuum distillation... formic acid may be... as high as 35[%] of the acetic acid, but in ordinary distillation at atmospheric pressure, it varies from 10-20[%] of the acetic acid. Only these two acids appear to be formed in appreciable amounts. 2. Alcohols; especially and , but also isoamyl and isobutyl alcohols, and buten-3-ol-2. The content is usually... 1.3-2[%]. 3. Esters; formed by interaction of the above acids and alcohols. 4. Ketones; ... and... its homologs... [plus] small quantities of , methyl cyclopentanone, and . The acetone is not a primary [distillation] product... but is formed secondarily from the acetic acid... homologs of acetone have a similar history. 5. Aldehydes; , , methylal and dimethyl acetal, valeric aldehyde, and methyl furfural. The pentosans are... the source of the furfural and other... homologs of furan... 6. Phenols and phenol methyl ethers [only about 1 percent of the wood distilled], mostly s of di- and tris. ...These substances come largely from the . 7. [< 0.2 percent of the total] , methyl amine, and methyl pyridine... 8. , , melene, etc. 9. es; the yields of , and vary with the maximum temperature of distillation, but at 350-400° the yields from s are about 8, 4 and 1.5[%], respectively. 10. Water; the yield... varies... 22.3-27.8[%]. 11. '. ...30-45[%] ...depending on the wood, and on the maximum temperature."

"[T]he survey of experimental results will be confined to flash pyrolysis at the exclusion of slow pyrolysis or ."

"Prompted by the need of non-petroleum-based fuels, coal research has reemerged... Pyrolysis research... has gained... momentum because of its close connection to combustion, hydropyrolysis and liquification. Spectroscopic and other instrumental techniques are... producing... information about coal structure and pyrolysis mechanisms, while modeling efforts are breaking new ground in sorting out chemical and physical phenomena... [P]ostulates and assumptions of current work provide a meaningful starting point in... theoretical descriptions of greater validity and applicability."

"Having fixed a pole, on a level piece of ground, and having described a circle by a cord attached to the pole, one should mark the points with pegs, where the shadow of the top of the pole touches the circle. The line joining these pegs is the West to East line. Having increased the length of the cord (which is equal to the distance of the two pegs fixed in the East West line) by itself, one should provide two slings at each end of the cord. Fix the slings on the two pegs (already fixed) stretch the cord with its mid point towards the south and fix a peg at the place, where the mid point of the cord touches the ground. He should similarly proceed towards the North. The line joining these pegs will be the South to North line."

"... Early clocks were inaccurate by as much as half an hour a day, and had to be reset frequently with the aid of a ; breakdowns were numerous. The energies of the early masters seem to have gone as much into ornamenting their clocks as into making them more precise, for the construction of human and animal automata, as well as astronomical indicators, was quite popular. Finally, in the seventeenth century, the Dutch scientist Christian Huygens created the that resulted in a vast improvement in precision. By then the clock was ingrained in the European way of thinking as the artificial model of the cyclical processes of nature, and it was ready to serve as the prototype for the mechanization of a variety of tasks that had previously been performed by hand."

"The invention of the mechanical clock, and the significant perceptual shift that attended it, provides rich and underexamined context for reading Chaucer’s works. Among social scientists it has become “textbook wisdom” that the late medieval invention of the mechanical clock transformed ideas about time."

"By a clock we understand anything characterized by a phenomenon passing periodically through identical phases so that we must assume, by the principle of sufficient reason, that all that happens in a given period is identical with all that happens in an arbitrary period."

"The simplest and perhaps earliest consisted of an earthen vessel with a small hole in the bottom. This was filled with water up to a certain mark and the water was allowed to trickle out of the hole. It would empty itself in approximately the same intervals of time. It was perhaps used for limiting the length of public speeches and the like. In fact there are quite a few references in Greek and Roman writings which would indicate this to have been a fact."

"The 1967 General Conference on Weights and Measures defined the of time, the second, based on an atomic transition—specifically, between two hyperfine levels of the ground state of cesium-133. (See Physics Today, August 1968, page 60.) Although Cs atomic clocks remain the standard, their time might be running out. Their underlying atomic transition is excited by radiation with a microwave frequency around 9 × 109 Hz, and after decades of advances, a Cs clock’s frequency can be measured with a fractional uncertainty Δν/ν0 of about one part in 1016. But clocks based on optical transitions operate at frequencies around 1014 Hz, which gives them an advantage in the push for lower uncertainty. (See the article by James Bergquist, Steven Jefferts, and David Wineland, Physics Today, March 2001, page 37.) The current record, 9.4 × 10−19, was set in 2019 by an aluminum ion–based optical atomic clock at ."

"The clock, not the steam-engine, is the key-machine of the modern industrial age. For every phase of its development the clock is both the outstanding fact and the typical symbol of the machine: even today no other machine is so ubiquitous. ... In its relationship to determinable quantities of energy, to standardization, to automatic action, and finally to its own special product, accurate timing, the clock has been the foremost machine in modern technics: and at each period it has remained in the lead: it marks a perfection toward which other machines aspire."

"We do not know when men first began to use instruments which were at all similar to modern sundials. A stone fragment in a Berlin museum is thought to be the earliest known sundial, dating from about 1500 B.C. The Bible mentions what some authorities take to have been a sundial (although the meaning is by no means certain) in the days of , king of some 700 years before Christ ... About a century later the Greek philosopher and astronomer Anaximander of is said to have introduced the sundial into Greece."

"… We are accustomed to regard as real those sense perceptions which are common to different individuals, and which therefore are, in a measure, impersonal. The natural sciences, and in particular, the most fundamental of them, physics, deals with such sense perceptions. The conception of physical bodies, in particular of rigid bodies, is a relatively constant complex of such sense perceptions. A clock is also a body, or a system, in the same sense, with the additional property that the series of events which it counts is formed of elements all of which can be regarded as equal."

"Translation in English: "Today, many in the West know nothing about Lithuania. We don't have as strong an identity as the Estonians or the Swiss. We believe that having engineering competences and positioning ourselves as an engineering country will make us distinctive and recognisable.""

"Original in Lithuanian: "Šiandien daugelis vakariečių nežino nieko apie Lietuvą. Neturime tokio stipraus identiteto kaip estai ar šveicarai. Tikime, kad turėdami inžinerinių kompetencijų ir pozicionuodami save kaip inžinerinę šalį tapsime lengvai atpažįstamais ir išskirtiniais""

"Damascus steel actually consists of an extremely high-carbon cast steel, the best swords being forged in Iran from cakes of steel made in India and known as wootz."

"Wootz was the first high-quality steel made anywhere in the world. According to reports of travelers to the East, the Damascus swords were made by forging small cakes of steel that were manufactured in Southern India. This steel was called wootz steel. It was more than a thousand years before steel as good was made in the West."

"The salt of the was merely a means of union between the mercury and the sulphur, just as the vital spirit in man unites soul and body. It was doubtless devised to impart a triple form to the idea, in conformity with the method of the theological schoolmen."

"The mercury of a metal... represented its lustre, volatility, fusibility, and malleability; the sulphur of the metal, its colour, combustibility, affinity, and hardness."

"At a still later date [post-16th century] it was argued that exact and natural sciences proceed by induction and deduction, and occult and spiritual sciences by analogy. Following out this line of thought the alchemists produced the following remarkable trilogy:—"

"[W]hen an alchemist converted a metal into its oxide, or, as they expressed it, "made a " of it, he thought he had volatilised its mercury and fixed its sulphur. When he distilled ordinary mercury and found a solid residue in the , he called it the "sulphur" of mercury; when he found a sublimed product in the receiver (mercury bichloride), he termed it the "mercury" of mercury or "corrosive sublimate.""

"The more logical mind of Artephius Longaevus introduced a modification of this theory. He distinguished two properties in a metal—the visible and the occult. The former, comprehending its colour, lustre, extension, and other properties visible to the eye, he called its "sulphur"; the latter, comprehending its fusibility, malleability, volatility, and other properties not visible until after... special treatment, he called its "mercury.""

"Even before the appearance of The Sceptical Chemist there was a growing conviction that the old hypotheses as to the essential nature of matter were inadequate and misleading. ...[T]he four "elements" of the Peripatetics had become merged into the tria prima—the "salt," "sulphur," and "mercury"—of the Paracelsians. As the phenomena of chemical action became better known... the conception of the tria prinui, as understood by Paracelsus and his followers, was incapable of being generalised into a theory of chemistry. Becher, while clinging to the conception of three primordial substances as making up all forms of matter, changed the qualities hitherto associated with them. According to the new theory, all matter was composed of a mercurial, a vitreous, and a combustible substance or principle, in varying proportions, depending upon the nature of the particular form of matter. When a body was burnt or a metal calcined, the combustible substance—the terra pinguis of Becher—escaped."

"Before me, stretching down to the river, was the factory where a score of workers, clad in helmets and gauntlets and swathed like so many Knights Templar, travel-stained and war-worn, their visages lit up by the yellow soda flames, and their ears half-deafened with the sound of exploding —a veritable inferno—were repeating on a Gargantuan scale the little experiment first made a century ago in the cellars of this building; turning out, day and night, hundredweights of the plastic metal in place of the little pin-heads which then burst upon the astonished and delighted gaze of Davy."

"Other metals, like lead and mercury, did not appear to burn; but on heating them they gradually lost their metallic appearance, and became converted into calces. This operation was known as . In the act of burning or of calcination phlogiston was expelled. Hence metals were essentially compound: they consisted of phlogiston and a calx, the nature of which determined the character of the metal. By adding phlogiston to a calx the metal was regenerated. Thus, on heating the calx of or of with , or , or wood, metallic zinc or lead was again formed. When a candle burns, its phlogiston is transferred to the air; if burned in a limited supply of air, combustion ceases, because the air becomes saturated with phlogiston."

"The general properties and chemical activities of and sodium are so very similar that as a matter of commercial production that metal which can be most economically obtained is necessarily the one most largely manufactured, and of the two that metal is sodium. To-day, sodium is made by thousands of tons, and by a process which in principle is identical with that by which it was first made by Davy, i.e., by the of fused caustic soda."

"He begins by again drawing attention to the various surmises which had been made respecting the true nature of potassium and sodium. Although these substances had been isolated, and in the hands of chemists for upwards of two years, their properties were so extraordinary when compared with those of the metals in general, that many philosophers hesitated to consider them as true metals."

"[A]fter a series of revolutions in its manufacture, sodium, having been produced from time to time on a manufacturing scale by a variety of metallurgical methods involving purely thermal processes of reduction and distillation, entirely dissociated from electricity, we should have now got back to the very principle of the process which first brought the metal to light. And that this has been industrially possible is entirely owing to another of Davy's discoveries - possibly indeed the greatest of them all—Michael Faraday."

"Some of the alchemists had discovered that a metal gained, not lost, weight by . This was known as far back as the sixteenth century. It had been pointed out by Cardan and by Libavius. Sulzbach showed that such was the case with mercury. Boyle proved it in the case of tin, and Rey in that of lead. Moreover, as knowledge increased it became certain that Stahl's original conception of the principle of combustion as a ponderable substance he imagined, with Becher, that it was of the nature of an earth was not tenable. The later phlogistians were disposed to regard it as probably identical with . But even hydrogen has weight, and facts seemed to require that phlogiston, if it existed at all, should be devoid of weight."

"Although no great stress can be laid on numbers so obtained, they serve to indicate that Davy had not yet obtained the pure metal."

"It may be converted into vapour at a temperature approaching a red-heat, and may be distilled unchanged; it is a perfect conductor of electricity and an excellent conductor of heat. Its most marked difference from the common run of metals was its extraordinarily low specific gravity."

"The "basis" of soda is described as a white opaque substance of the lustre and general appearance of silver. It is soft and malleable, and is a good conductor of heat and electricity. Its specific gravity was found by flotation in a mixture of oil of sassafras and naphtha... It was found to fuse at about 180° F. (the real melting point of sodium is 197.5°). Its action on a number of substances—oxygen, , water, etc.—is then described, and its general behaviour contrasted with that of the "basis" of potash."

"It is frequently stated that Davy was enabled to isolate the metals of the alkalis because of the large and powerful voltaic battery which he had at his disposal in the Royal Institution. This is not correct. The battery he employed was of very moderate dimensions, and not by any means extraordinary in power. It was the success he thus achieved that caused the large battery, which is probably referred to, to be constructed, by special subscription, in 1809."

"The relations of the common metals to the bases of the alkalies and earths, and the gradations of resemblance between the bases of the earths and s, point out as probable a similarity in the constitution of all inflammable bodies; and there are not wanting experiments, which render their possible decomposition far from a chimerical idea."

"The whole work was done under conditions of great mental excitement. His cousin ,.. his assistant, relates that when he [Humphrey Davy] saw the minute globules of the quicksilver-like metal burst through the crust of potash and take fire, his joy knew no bounds; he actually danced about the room in ecstasy, and it was some time before he was sufficiently composed to continue his experiments. The rapidity with which he accumulated results after this first feeling of delirious delight had passed was extraordinary."

"It would seem from his description of its properties that the potassium he obtained was most probably alloyed with sodium derived from impure potash. Potassium is solid up to 143° F.; but, as Davy subsequently found, an alloy of potassium and sodium is fluid at ordinary temperatures. ...When the potassium was exposed to air its metallic lustre was immediately destroyed, and it was ultimately wholly reconverted into potash by absorption of oxygen and moisture."

"He then enters upon some general observations on the relations of the "bases" of potash and soda to other bodies."

"[T]he writings and labours of the alchemists were both extensive and important. ...[T]heir studies, although misdirected, were not... haphazard. The alchemists had a definite, and... logical, system of philosophy... [T]hey recognised—(1) the unity of matter; (2) the three principles—philosophical mercury, sulphur, and salt; (3) the four elements—fire, air, water, and earth; and (4) the seven metals—gold, silver, mercury, copper, , tin, and ."

"Before the middle of November he had obtained most of the leading facts. In a letter dated November 13th he tells W. H. Pepys—"

"He had observed that although potash when dry is a nonconductor, it readily conducts when it becomes damp by exposure to air, and in this state "fuses and decomposes by strong electrical powers.""

"The "basis" of potash at 50° F. was a soft and malleable solid with the lustre of polished silver."

"had been used to tinge glass in in the sixteenth century; but the metal was unknown till the time of Brandt, and this celebrated Swedish chemist discovered it in 1733."