VOL. XVn.] PHILOSOPHICAL TRANSACTIONS. 4^9 



troubled, if any quantity of our precipitant were kept for some competent time 

 in it. And being gently distilled off, it left a residuum, which with a little of 

 our solution afforded a far more suddenly made and copious precipitate, than 

 had been produced with the like quality even of pump-water itself. And, 

 though I have met with rain-water that was more free from salt than any spring 

 or river-water that I remember I have examined ; yet, having for curiosity's 

 sake made trial of snow-water, this liquor, which is thought to afford the 

 lightest water of all natural ones, I manifestly found by our way of examining 

 it, not to be devoid of saltness.* 



I shall on this occasion observe, that there are many waters that are not con- 

 siderably brackish to the taste, which yet, by reason of some unheeded saltness, 

 as in most pump-waters, are more frequently, by reason of crudity, not only 

 unfit, or at best less fit for divers economical uses, as washing, boiling of some 

 meats, 8ec. but are very unwholesome ; sometimes to a degree that makes them 

 mischievous to whole communities, and perhaps nations. Of this it were to be 

 wished, that it were harder to give instances. I remember I have seen a notable 

 one in those huge and unsightly tumours about the throat, which are observed 

 by travellers to be exceedingly common, among those that inhabit the lower 

 tracts of ground that lie t>ctween the Rhaetian, Helvetian, and some other 

 neighbouring mountains ; which monstrous swellings are generally imputed to 

 the snow waters that flow from the mountains, and make the usual drink of the 

 meaner sort of people ; whence it is observed, that persons of better condition, 

 ■who drink wine more than water, are either not at all or far less troubled with 

 these disfiguring goitres,-|- as they call them. But much more notable instances 

 to our present purpose are afforded me by that great traveller M. Tavernier, 

 who, speaking of a nation of Caffres or negroes, that come sometimes to trade 

 with the Portiiguese from a remote part of Africa, informs us, " That the water 

 of their country is very bad, which is the reason that their thighs do swell, and 



• In this papier Mr. Boy4e made the beginnings of a method of examining mineral waters, which 

 has since been carried to so much perfection by Bergman, and other modern chemists. The test or 

 precipitant by which Mr. Boyle ascertained the presence of so small a proportion of sp. of salt 

 (muriatic acid) as one drop in 3000 drops of water, was nitrate of silver. The muriatic acid has so 

 strong an attraction for this mqpl (silver) that it mstantly seizes it, forming with it an almost insoltn 

 Me compound, which renders the liquor turbid or milky, and graduUy Ms to the bottotm 



t The unsightly disorder termed goitres, so frequent in the Alps and other mounlaiaous regions^ 

 consists in an enlargement of the thyroid gland. Its production has been commonly attributed to 

 the use of snow-water ; but from the accounts of some late writers, it would appear to be owing to 

 a combination of causes, such as bad air (in the valleys between the mountains, where the disorder 

 is chiefly met with) bad diet, and bad clorhing. 



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