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orders, which for about one hundred and fifty years past the English have called colds. As to Dr. Cullen's cold or catarrh a frigore, I ques

I tion whether such an one ever existed. Travelling in our severe winters, I have suffered cold sometimes to an extremity only short of freezing, but this did not make me catch cold. And, for moisture, I have been

, in the river every evening two or three hours for a fortnight together, when one would suppose I might imbibe enough of it to take cold if humidity could give it; but no such effect ever followed. Boys never get cold by swimming. Nor are people at sea, or who live at Bermudas, or St. Helena, small islands, where the air must be ever moist from the dashing and breaking of waves against their rocks on all sides, more subject to colds than those who inhabit part of a continent where the air is driest. Dampness may indeed assist in producing putridity and those miasmata which infect us with the disorder we call a cold; but of itself can never by a little addition of moisture hurt a body filled with watery fluids from head to foot. With great esteem, and sincere wishes for

your wel. fare, I am, Sir, Your most obedient humble servant,

B. FRANKLIN.

VOI. VI.

51

HH*

TO THOMAS PERCIVAL.

*

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Unwholesomeness of Manufacturing Establishments.

Moist Air not unhealthy.

West Wycombe, the Seat of Lord Le

Despencer, 25 September, 1773. DEAR SIR, I have received here your favor of the 18th, enclosing your very valuable paper of the enumeration of Manchester. Such inquiries may be as useful as they are curious, and if once made general, would greatly assist in the prudent government of a state.

The difference of deaths between one in twenty-eight at Manchester, and one in one hundred and twenty at Morton is surprising. It seems to show the unwholesomeness of the manufacturing life; owing perhaps to the confinement in small, close rooms, or in larger with numbers, or to poverty and want of necessaries, or to drinking, or to all of them. Farmers who manufacture in their own families what they have occasion for and no more, are perhaps the happiest people and the healthiest.

It is a curious remark, that moist seasons are the healthiest. The gentry of England are remarkably afraid of moisture, and of air. But seamen, who live in perpetually moist air, are always healthy, if they have good provisions. The inhabitants of Bermuda, St. Helena, and other islands far from continents, surrounded with rocks, against which the waves continually dashing, fill the air with spray and vapor, and where

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• A learned and eminent physician of Manchester, in England, and author of several valuable publications on medical and philosophical subjects. - EDITOR.

† An extract from this letter, concerning the provision made in China against famine, is printed, under the head of “ Political Economy," in Volume II. p. 381.– EDITOR.

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no wind can arrive, that does not pass over much sea, and of course bring much moisture, these people are remarkably healthy. And I have long thought, that mere moist air has no ill effect on the constitution; though air impregnated with vapors from putrid marshes is found pernicious, not from the moisture, but the putridity. It seems strange that a man, whose body is composed in great part of moist fluids, whose blood and juices are so watery, who can swallow quantities of water and small beer daily without inconvenience, should fancy that a little more or less moisture in the air should be of such importance. But we abound in absurdity and inconsistency.

Thus, though it is generally allowed that taking the air is a good thing, yet what caution against air ! What stopping of crevices!

of crevices! What wrapping up in warm clothes ! What stuffing of doors and windows! even in the midst of summer. Many London families go out once a day to take the air; three or four persons in a coach, one perhaps sick; these go three or four miles, or as many turns in Hyde Park, with the glasses both up close, all breathing over and over again the same air they brought out of town with them in the coach, with the least change possible, and rendered worse and worse every moment. And this they call taking the air. From many years' observations on myself and others, I am persuaded we are on a wrong scent in supposing moist or cold air the causes of that disorder we call a cold. Some unknown quality in the air may perhaps produce colds, as in the influenza; but generally I. apprehend they are the effect of too full living in proportion to our exercise.

Excuse, if you can, my intruding into your province, and believe me ever with sincere esteem, dear Sir, Your most obedient humble servant,

B. FRANKLIN.

FROM JOSEPH PRIESTLEY TO B. FRANKLIN.

New Experiments on Air.

Calne, 26 September, 1773. DEAR SIR, With this I return you Mr. Winthrop's letter* according to your desire, thanking you for your endeavours to serve me in America, though I find, as I was apprehensive, that the scheme would not answer. Please to return my thanks to the Professor for his candid and judicious remarks on my History of Optics, which will be much improved by them, if it should come to a second edition.

Dr. Price will have informed you, that I have resumed my experiments on air, and with a good prospect of success. Since that, I have been much more successful; but in a letter I can only confine myself to the heads of things.

The most important of the observations I have lately made is of an alkaline corresponding to my acid air, of which an account is given in what I have already printed. This I get by treating a volatile alkali in the same manner in which I before treated the spirit of salt. As soon as the liquor begins to boil, the vapor arises, and being received in a vessel filled with quicksilver continues in the form of air well condensed by cold.

I imagined that a mixture of this alkaline with acid air would make a neutral, and perhaps a common air; but, instead of that, they make a beautiful white salt, of a very curious nature. It immediately deliquesces, and even wholly disappears, upon being exposed to the open air; and if it be in a dry and deep vessel, where

; moisture cannot easily come at it, it wholly evaporates in dense white clouds, occasioning a very strong smell. This alkaline vapor, like the acid, is quickly imbibed by water, which thereby becomes spirit of sal volatile.

See above, p.

375.

Nitrous air makes this alkaline vapor turbid, and perhaps generates a different salt. But I have not yet made a tenth part of the experiments, that I propose to do with this new kind of air.

I have just found that spirit of wine yields air also, which is probably pure phlogiston, but I have not yet made one experiment with it.

If volatile alkali, liquid or solid, be exposed to nitrous air during its effervescences with common air, the vessel is presently filled with beautiful white clouds, and the salt is tinged blue. This explains the constitution of nitrous air, but I have no time for reasoning.

This experiment appears to great advantage when a vessel, no matter how large, containing the smallest portion of volatile alkali, fluid or solid, is opened in a quantity of nitrous air, for the whole is filled almost instantly with dense white clouds. Report says, that you are about to leave us, at least

, for a time. If this be true, I shall be very sorry, as it will deprive me of one of the greatest satisfactions that used to make my annual visits to London agreeable. If you should leave England before winter, I should think myself very happy in an opportunity of seeing you before your departure. As I cannot conveniently come to London, I should be particularly happy in seeing you and Sir John Pringle at my new situation, and I flatter myself that I could amuse you with some of my new experiments. If you can oblige me so far, give me a line to acquaint me with your intention, that I may be sure to be at home when you come. I am, dear Sir, yours sincerely,

JOSEPH PRIESTLEY.

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