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 to communicate them to his Friends, and to allow them to dispose thereof, upon a hope, that equitable Readers will be ready to excuse, if hereafter they should appear also in the Treatises they belong to, since he contents to this Anticipation, but to comply with those, that think the imparting of real and practical Experiments, may do the Publick some Service, by exciteing and assisting mens Curiosity in the interim.

As for the Experiment, you saw the other day at my Lodgings, though it belongs to some Papers about Cold, that (you know) could not be Publish't, when the rest of the History came forth, and therefore was reserved for the next Edition of that Book; yet the Weather having been of late very hot, and threatning to continue so, I presume, that to give you herein compliance with your Curiosity an Account of the Main and Practical part of the Experiment, may enable you to gratify not onely the Curious among your Friends, but those of the Delicate, that are content to purchase a Coolness of Drinks at a somewhat chargeable rate.

You may remember, that the Spring before the last, I shew'd you a particular Account of a way, wherein by a certain substance obtain'd from Sal Armoniack, I could presently produce a considerable degree of Cold, and that with odd Circumstances, without the help of Snow, Ice, Niter &c. But that Experiment being difficult and costly enough, and design'd to afford men Information, not Accommodations, I afterwards tryed, what some more cheap and facile mixtures of likely Bodies with Sal Armoniack would do towards the Production of Cold, and afterwards I began to consider, whether to that purpose alone (for my first experiment was design'd to exhibite other Phænomena too) those mixtures might not without inconvenience be omitted: and I was much confirm'd in my conjecture, by an accident, which was casually related to me by a very Ingenious Physician of my acquaintance, but not to be repeated to you in few words, though he complained, he knew not what to make of it.

Among the several ways, by which I have made infrigidating Mixtures with Sal Armoniack, the most simple and facile is this: Take one pound of powder'd Sal Armoniack and about three Pints (or pounds) of Water, put the Salt into the Liquor, either altogether, if your design be to produce an intense, though Rh