Ether and Chloroform Engines.

Updated: 4 June 2009
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Ether engine; a condensing engine like a steam engine, but operated by the vapor of ether instead of by steam.

[Webster's Dictionary, 1913]

Both ether and chloroform were tried as low-boiling-point working fluids in pursuit of greater efficiency. There are many different ethers, but the bare word "ether" usually refers to the well-known anaesthetic diethyl ether, otherwise known as ethoxyethane, CH3-CH2-O-CH2-CH3. Not for the first time in this part of the museum, we are exploring the realms of organic chemistry.

Ether engines are a very specialised taste in the field of power generation. Once again we have a working fluid which is both expensive and dangerous. Ether is well-known as an anaesthetic, but it is also extremely inflammable, having a low ignition temperature and being explosive over a wide range of concentrations; from 2% to 36%. The high density of the vapour means that it tends to accumulate dangerously in low areas. The boiling point of ether is only 34.6 °C, and so from a Carnot's Law standpoint, the efficiency of any engine using ether alone would be terrible.

If this is not discouraging enough, I have just discovered a whole new hazard in the use of ether as a working fluid. Diethyl ether oxidises and polymerises in the presence of air, creating the interesting compound diethyl ether peroxide (-CH(CH3)OO-)n. This is a colorless oily liquid that is an extremely brisant (fast-exploding) and friction-sensitive explosive; less than 5 milligrams can damage chemical apparatus. The dangerous properties of ether peroxides are the reason that diethyl ether and other peroxide-forming ethers like tetrahydrofuran (THF) or ethylene glycol dimethyl ether (1,2-dimethoxyethane) are carefully avoided in industrial chemical processes.
I am certainly not an expert on ether chemistry, but continuously reboiling ether sounds like it might be a good way to generate the peroxide. Peroxides generally have higher boiling points than the compounds they come from, so if an ether mixture is heated, the peroxide can become progressively more concentrated and the risk of explosion increases rapidly.
Completely excluding oxygen from an ether cycle is not practical, especially since the ether condenser would presumably be at below atmospheric pressure, and so air would tend to leak inwards through glands, joints, etc.

The dangers of highly inflammable ether having being learnt the hard way, chloroform was also tried as a low-boiling working fluid, but without success.

Liquids that vapourise easily, when used in a stand-alone cycle, are not more efficient than water as a working fluid. Quite the reverse. See: Carnot's Law on the thermodynamics page.


EARLY BEGINNINGS

Sir Humphrey Davy suggested early in the 1800's that a volatile liquid could be boiled by exhaust steam and thus generate more power. This is called a "bottoming cycle".

The problem was studied by Ainger in 1830. So far I have found no detail of what he found out.


THE DU TREMBLAY ETHER ENGINE: 1850-56

Please note there seems to be no consensus on whether the inventor's name is spelled Du Tremblay or Du Trembley.

The first ether engine I have so far found was actually a combined water-ether steam engine, where the ether section was used as a bottoming cycle that extracted power from the heat rejected by the steam cycle. It was built in Marseilles to the design of M. Du Tremblay, under the direction of the noted French engineer François Bourdon. In 1850 the shipping line of Société Louis Arnaud, Touache Frères & Cie was founded, and they bravely chose to power their first vessel with Du Tremblay's combined steam-ether engine. It was even called the SS Du-Tremblay, indicating great confidence on the part of the owners. It was an iron schooner with an auxiliary screw driven by a steam engine of 70 nominal horse-power, though whether this figure includes the ether cycle is currently unknown. The passenger capacity was 100 souls and she could carry 230 tons of cargo, so she must have been a sizable ship, though the actual dimensions are not yet to hand.

The engine had two cylinders, one for steam and one for ether. The steam cylinder exhausted into a multi-tube condenser with ether circulating in the tubes. This sort of condenser was itself unusual for the period as conventional marine engines used a jet condenser where the steam was condensed by a spray of sea-water; the low pressures prevailing at this time making it practical to use salt water in the boilers. The ether was presumably condensed by a multi-tube condenser cooled by sea-water.
The SS Du-Tremblay was held to be successful, with fuel consumption being said to be reduced by a third. Several other marine engines were then built during the years 1852-1855 and the innovation began to attract the attention of British engineers.

Left: The Scientific American report of the loss of the La France.

Two more vessels were built at Nantes for the Atlantic service with Du Tremblay ether engines; in the Jacquard ether was tried but leakage losses were between 100 and 150 litres a day, and its use abandoned, while in the Arago it was never used.

In 1855, the Société Louis Arnaud, Touache Frères & Cie was renamed the Compagnie de Navigation Mixte (CNM). One of his ships called either La France or SS France (accounts differ) was fitted with a steam-ether engine.
On 27 September 1856, the France suffered an ether explosion and fire in the port of Bahia (on the coast of Brazil) after its first journey, and become a total loss; the company withdrew from transatlantic shipping. The incident put an abrupt end to the construction of steam-ether marine engines.

The account on the left raises an interesting point about the use of ether in hot climates. The modern figure for the boiling point of ether is 94.3 degF, and air temperatures higher than this are common in many parts of the world. This conjures up the horrifying picture of the reserve ether tanks slowly coming to the boil all by themselves. Not being constructed as pressure vessels, they would either burst or vent copiously through the relief valves (if any) and the whole vessel would fill up with clouds of ether vapour. No wonder the ship caught fire.

Whether the water in Bahia bay really reaches 100 degF I have no real idea, but it seems unlikely. Obviously if it did, condensing the ether vapour would be impossible.

Article from Scientific American 6th December, 1856.
Thanks to Peter Macinnis for drawing this article to my attention.

The extract below is taken from a paper read by Sir Frederick Bramwell before the Mechanical section of the British Association, and published in the Scientific American Supplement, No. 312, December 24, 1881:

"Our president alluded to the employment of ether as a means of utilizing the heat which escaped into the condenser, and gave some account of what was done by M. Du Tremblay in this direction. It so happened that I had occasion to investigate the matter at the time of Du Tremblay's experiments; very little was effected here in England, one difficulty being the excise interference with the manufacture of ether. Chloroform was used here, and it was also suggested to employ bisulphide of carbon.
In France, however, a great deal was done. Four large vessels were fitted with the ether engines, and I went over to Marseilles to see them at work. I took diagrams from these engines, and there is no doubt that, by this system, the exhaust steam from the steam cylinder, which was condensed by the application of ether to the surface of the steam condenser (producing a respectable vacuum of about 22 inches), gave an ether pressure of 15 lb on the square inch above atmosphere, and very economical results as regards fuel were obtained. The scheme was, however, abandoned from practical difficulties.
It need hardly be said that ether vapor is very difficult to deal with, and although ether is light, the vapor is extremely heavy, and if there is any leakage, it goes down into the bilges by gravitation, and being mixed with air, unless due care is taken to prevent access to the flues, there would be a constant risk of a violent explosion. In fact, it was necessary to treat the engine room in the way in which a fiery colliery would be treated. The lighting, for instance, was by lamps external to the engine room, and shining through thick plate-glass. The hand lamps were Davy's. The ether engine was a bold experiment in applied science, and one that entitles Du Tremblay's name to be preserved, and to be mentioned as it was by our president."

The passage about "the excise interference with the manufacture of ether" is most intriguing. Had ether engines been practical, this would not be the only time that the British legal system got in the way of progess; the restrictions placed on early motor cars being the most shameful and notorious example.
But why were the excise men interested in ether? Presumably because it can be drunk to produce a state of intoxication. (I once knew a chap who derived great pleasure from sniffing ether, but that is perhaps taking us a bit too far off-topic) So far I have not really got to the bottom of this influence on ether engines.


THE SUSINI ETHER ENGINE: 1893

Left: A report on Susini's ether engine.

There is no suggestion here that the ether cycle was being used as a bottoming cycle- the ether was apparently boiled by steam for safety reasons.

This is taken from the Q1 1942 issue of "Steam Car Developments and Steam Aviation", a journal run by two brothers, R H and H W Bolsover, from Whitby in England. The rest of the article included speculations on the use of alcohol as a working fluid.

Apologies for the poor image quality, this is the best I can do for the moment.


THE SHUMAN SOLAR ENGINE: 1906

Frank Shuman was an early pioneer of solar energy, like Henry Willsie. In 1906 he produced a flat-plate collector design that was similar to Willsie's sulphur dioxide system except that it employed ether as a working fluid. The performance was poor; Shuman abandoned ether for steam, and eventually built a successful solar power plant near Cairo, Egypt in 1912. Ultimately it proved not to be economically viable when imported coal became cheaper.


CHLOROFORM ENGINES
While we are on the subject of engines running on anaesthetics, we may as well look at the choloroform engine here.

The passage below comes from Scientific American, Volume 4, Issue 2, 30 September 1848:

Chloroform a substitute for Steam.
"On the twenty second of last month a committee, appointed by the Academie des Sciences Paris, went to the establishment of M C Beslay, to witness a trial of a discovery made in the application of chloroform as a motive power in machinery. It will be re-collected that the Minister of the Marine had an engine constructed for trying ether as a motive power. This engine was found to act well, and afford a considerable saving in fuel, but it was rejected on account of the inflamability of ether, which rendered it too dangerous for use in steam-vessels.
Lieutenant Lafond, of the navy, however, studied the nature of chloroform, ascertained that it was capable of producing a great motive power at a saving of 50 per cent, and that no danger is incurred. The experiment is said by our exchanges to have been completely successful. It is our opinion that it never can be successful to compete with steam. The ether engine was boasted of as being a new discovery that would revolutionise the whole science of mechanical propulsion. It has been laid on the upper shelf, and so will chloroform."

Quite the put-down, presumably based on knowledge of the poor Carnot efficiency of liquids with a low boiling point. This is a valid criticism if the engine referred to here used chloroform as the sole working fluid, as appears to be the case, but not if it was used as a bottoming cycle to improve the efficiency of a steam plant.
Note that this was apparently written before the Du Tremblay trials in 1852-55, and so implies that the ether engine caused to be constructed by the Minister of the Marine was earlier than and distinct from those built by Du Tremblay. This could use confirmation and clarification, but the information available on these engines has so far proved rather sparse.

A chloroform engine would undoubtedly be safer than an ether engine as chloroform is not flammable. However, it is poisonous, causing liver damage, which is why it was abandoned as an anaesthetic in favour of the flammable but much less toxic ether. The old and unfunny phrase "the operation was successful but the patient died" is believed refer to the unfortunates who survived surgery but succumbed later to the toxicity of chloroform. Another disadvantage of chloroform was that it sometimes caused abrupt heart failure during the induction of anaesthesia.
Anyone working with a chloroform engine would have been exposed to the inevitable leakage of the working fluid, and over time this would probably have done them no good at all.

Bibliography:

Bizarre Ships of the Nineteenth Century by John Guthrie. Hutchinson 1970.

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