VOL. XXXI.] PHILOSOPHICAL TRANSACTIONS. 4gQ 



A large quantity of Alkaline Salt produced hy burning Rotten Wood. By Mr, 

 Robie, of Harward College, in Cambridge, New England. N°366, p. 121. 



A white oak tree, about 2 feet diameter, is in Cambridge, of so wonderful 

 a nature, that though about a third part of it was decayed, and seemed really 

 to be rotten wood, yet this decayed part in burning would turn almost wholly 

 into a good white alkali, and it would run down into hard lumps, white and 

 clean. On tasting the lumps, it was found to be salt, and very strong. Being 

 dissolved in clean water, and decanted and evaporated without any filtration, 

 we produced a very clean white salt, exceeding in strength and whiteness any 

 to be had at the shops. 



Now though alkalis may be extracted from common ashes, yet what was pecu- 

 liar in this is, 1. That while it was burning the wood itself would melt, and 

 run down into hard lumps of salt, and none of the wood that was sound would 

 do this, but only that which was decayed; and what was most decayed, would 

 yield the greatest quantity of salt. 



2. Whereas all other alkalis of wood made thus by incineration are blackish 

 at first, and a lixivium made of them, though often filtered, will still be tinged 

 with a brown colour, occasioned by a kind of coal or ashes so inclosed, or 

 closely united to the alkali in burning, as not easily to be separated by filtration, 

 though often repeated ; yet this alkali was very white, even before solution, 

 and when dissolved, the lixivium was not in the least tinged, but clear like 

 pure water, only a very small quantity of ashes subsided to the bottom of the 

 vessel in which the solution was made. The lixivium thence decanted needed 

 no filtration, but when boiled up to dryness, the salt remained fine and 

 white. 



3. That in burning this wood, as the heat of the fire became more intense, 

 the wood, as it were, melted and clodded together in great lumps, and visibly 

 bubbled and boiled, with a hissing noise, like the frying of fat in a pan. 



4. That whereas the weight of the alkaline salt produced from other wood, 

 in the common way of incineration, is very inconsiderable, in proportion to the 

 weight of the wood producing it; yet this salt nearly equalled in weight the 

 wood from whence it was taken. 



I 5. Whereas the ashes of other wood are never so replete with salt, as that 



salt can be seen, or in the least cause the ashes to lump or clod together; yet 

 the whole of this would gather into hard and solid lumps of white salt, as 

 easily to be distinguished from ashes, though whiter, as the purest salt of tartar 

 made with nitre would be. 



6. That though from other rotten wood much less of an alkali can be pro- 



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