VOL. XLV.J PHILOSOPHICAL TRANSACTIONS. 57^ 



posed by authors, and suggested by many. Thus Lemery and others tell us, 

 potash is made in Russia, and all the northern countries, only by calcining the 

 ashes in pits bricked within, and sprinkling them well with lie, till they become 

 hard and solid. But such a calcination of ashes with a lixivial salt, must render 

 them whiter, instead of black, and must further destroy the active sulphureous 

 parts of the wood, which we find in potash rightly made. So that this only 

 leaves the ashes in the state they were at first, or turns them into a kind of in- 

 dissolvable glass, as we have found on trial. 



This, and the like mistakes about the way of making potash, seem to proceed 

 from a general error concerning the nature of it ; for it is commonly supposed to 

 be only a kind of inert calx, impregnated with nothing but a lixivial salt. Some 

 such mistake seems to have frustrated all the attempts hitherto made of making 

 potash in America ; for, on trial, what they have made there was found to be no 

 better than common ashes. 



But the most general mistake about the way of making potash, seems to pro- 

 ceed from the accounts we have of making it, from glasswort, and some marine 

 plants, which are said to be easily converted to this kind of substance, in the 

 manner above mentioned. But we apprehend that the way of making it from 

 wood must be very different : for these herbs are easily reduced to ashes by a 

 small fire, that does not entirely consume their sulphureous parts, which wood 

 is not. These ashes abound with a great quantity of alkaline and some neutral 

 salts, that readily convert them to a hard and solid consistence, which wood does 

 not. They have likewise few or no terrestrial parts, to run them into an indis- 

 solvable glass, when fluxed in the fire, as happens in wood ashes. Besides, 

 these herbs have few or no sulphureous or acid parts, like most woods ; and 

 the potash made of them has few of these principles in it, like what is made of 

 wood. 



It is however generally said, if we burn our wood in a close place, as a kiln 

 in which we burn lime, or make charcoal, or a pit dug in the ground, we may 

 impregnate the ashes with the sulphureous fiames and acid parts of the wood, 

 only by the closeness of the place, or by smothering the fire in it. If at the 

 same time we impregnate them with a greater quantity of lixivial salt, it will 

 flux the whole mass, and make it run into a solid hard consistence like potash. 

 This is commonly directed to be done, by throwing fresh or green wood or 

 herbs on the others, as they are burning, before they are quite reduced to ashes, 

 or by smothering the fire, as in making charcoal ; and at the same time to 

 sprinkle the ashes, thus burnt, with a strong lye from time to time, in the 

 manner commonly practised with glasswort. 



This would be a more ready way of making potash than any of the above- 

 mentioned ; but as those who give their advice about it, have neither tried it, 



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