Fresh Water From Seawater

The two main health problems of the Age Of Sail were scurvy and the supply of fresh or potable water; both took centuries to find a permanent fix. As late as 1962, during the Cuban missile crisis, a flotilla of Russian diesel-electric submarines in the Caribbean had plants for distilling seawater which could not even come close to keeping up with the demands of their small crews. In the unventilated heat near the equator, all the crewmen were restricted to one 3-minute fresh-water shower per week (sea-water showers made things worse, as the salt dried on the skin).

The accepted wisdom is that the ‘first’ shipboard plants for the distillation of water dated from the 18^th C, and the 1815 edition of Falconer’s Dictionary says:

Dr Lind, in 1761, discovered that sea-water, distilled without the addition of any ingredients, yielded pure fresh water… In 1763, M. Poissonnier invented a still for this purpose, and Lord Mulgrave, in his voyage towards the North Pole in 1773, has done equal justice to its practicability.

It seems that there cannot have been much development of the technology during the intervening 200 years, but at least Falconer gives us a reliable date. Or does he?

Boteler’s ‘Six Dialogues Of Sea Service’ was written during the 1630s, and contains this passage:

I find in one of our modern writers that sea water being boiled doth evaporate a dewy and watery substance and humour, the which being collected and kept together proves sweet and savoury. The which effect no doubt upon the distillation and limbecking [distilling with tubes] thereof, will prove perfect.. ..i could wish that alkl ships that are designed abroad to long voyages over large seas should be furnished with utensils proper to this purpose.

That is pretty clear: by 1640 at the latest, some masters took stills to sea with them to distill seawater – 120 years before Lind. So was Lind ‘re-discovering’ a device or technique which had been forgotten, or was he taking credit for something already widely-known among seamen, but not among the members of the Royal Society, whom Lind was addressing?

To clarify Boteler’s meaning, when he talks about ‘modern writers’ he doesn’t mean, ‘writing today’ – he is just making the distinction between classical writers – those writing in Greek and Latin – and those, more recent, writing in English. So who are the ‘modern writers’ he mentions?

I suspect he is talking about Hakluyt (Principal Navigations, 1589) and Hawkins, amongst others; Sir Richard Hawkins, son of Sir John, wrote a very wide-ranging book, published in 1593, called the ‘Observations’. In it, he says:

Our fresh water had failed us many days, by reason of our long navigation, yet with an invention I had in my ship, I easily drew out of the water of the sea a sufficient quantity of fresh water to sustain my people, with little expense of fuel. The water so distilled we found to be wholesome and nourishing.

There are two surprising elements to that passage. One is the date (1593, although he is talking about a voyage 10 years earlier) which is 230 years before Lind’s and Poissonnier’s ‘invention’. The other is the way he talks of his fresh-water still – not as a startling new invention, but as something already known about. And that is as far back as I’ve been able to trace the practice of distilling fresh water from seawater.

Mind you, the seamens' collective wisdom was far from infallible. In the account of a 1588 voyage to Africa's West coast printed in Hakluyt, the author says, It hath pleased God of his mercefull goodnesse to give me the knowledge how to preserue fresh water with little cost. Hakluyt prints in the margin, This preseruatiue is wrought by casting into an hogshead of water an handful of bay-salt, as the author told me. Hakluyt does not state how seriously he took this claim..

But one final note, to be the subject of a future piece of greater length, concerns the early use of anti-scorbutics, or cures for scurvy. Hawkins' labeling of it as 'the plague of the sea' is no exaggeration (although it was also known on land). It is due, we now know, to an absence of Vitamin C in the diet, and causes hair and teeth loss, swollen, bleeding gums, fatigue, weight loss and – if not treated with fresh fruit and vegetables – eventually, death.

It took many years, and many false starts before – in the Royal Navy, at least – in the last quarter of the 18^th century, lime- or lemon-juice was added to every seaman’s daily rations - usually in the rum or arrack, sweetened with sugar, as only sour fruit had a high vitamin C content. But how early was this known? A previous post (see below) records Captain Cook’s use of a ‘robb’ (syrup) of lime juice in 1770, but boiling the juice to make it tends to destroy the vitamin C; so the last (or the first?) word here belongs to Richard Hawkins:

..we found sour oranges and lemons the most effective remedy.