To Mary Stevenson
ALS: Yale University Library
Cravenstreet, Aug. 10. 61
Dear Polley,

I received yesterday my Papers. I had sent for them before to Mr. Stanley’s, but Peter found no one at home. It has however been of no Damage to me, except being so long without the Pleasure of reading your agreable little Letter that accompanied them.

We are to set out this Week for Holland, where we may possibly spend a Month, but purpose to be at home again before the Coronation. I could not go without taking Leave of you by a Line at least, when I am so many Letters in your Debt.

In yours of May 19. which I have before me, you speak of the Ease with which Salt Water may be made fresh by Distillation, supposing it to be, as I had said, that in Evaporation the Air would take up Water but not the Salt that was mix’d with it. It is true that distill’d Sea Water will not be salt, but there are other disagreable Qualities that rise with the Water in Distillation; which indeed Several besides Dr. Hales have endeavoured by sundry Means to prevent; but as yet their Methods have not been brought much into Use. I have his Pieces on the Subject, which I will leave with your Mother for your Perusal, as you may possibly make her happy a Day or two with your Company before our Return.

I have a singular Opinion on this Subject, which I will venture to communicate to you, tho’ I doubt you will rank it among my Whims. It is certain that the Skin has imbibing as well as discharging Pores; witness the Effects of a Blister Plaister, etc. I have read that a Man hired by a Physician to stand by way of Experiment in the open Air naked during a moist Night, weighed near 3 Pounds heavier in the Morning. I have often observ’d myself, that however thirsty I may have been before going into the Water to swim, I am never long so in the Water. These imbibing Pores, however, are very fine, perhaps fine enough in filtring to separate Salt from Water; for tho’ I have been soak’d by swimming, when a Boy, several Hours in the Day for several Days successively in Saltwater, I never found my Blood and Juices salted by that means, so as to make me thirsty or feel a salt Taste in my Mouth: And it is remarkable that the Flesh of Sea Fish, tho’ bred in Salt Water, is not salt. Hence I imagine, that if People at Sea, distress’d by Thirst when their fresh Water is unfortunately spent, would make Bathing-Tubs of their empty Water Casks, and filling them with Sea Water, sit in them an Hour or two each Day, they might be greatly reliev’d. Perhaps keeping their Clothes constantly wet might have an almost equal Effect; and this without Danger of catching Cold. Men do not catch Cold by wet Clothes at Sea. Damp but not wet Linnen may possibly give Colds; but no one catches Cold by Bathing, and no Clothes can be wetter than Water itself. Why damp Clothes should then occasion Colds, is a curious Question, the Discussion of which I reserve for a future Letter, or some future Conversation.

Adieu, my dear little Philosopher. Present my respectful Compliments to the good Ladies your Aunts, and to Miss Pitt; and believe me ever Your affectionate Friend and humble Servant

B Franklin

p.s. I begin to see a Rival in Dr. Hawkesworth. But, what is uncommon with Rivals, the more he likes you, and you him, the more, if possible, I shall esteem you both.
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