IIL fart of a Letter from Mr Anthony Van Leeu- 
wenhoek^ K ^ S. to John Chambcrlayne, Efq^ 
F. (1(.:S, concerning the Vitrify ed Salts of Cdcind 
Hay. 
Delft ^ March 3. 1 70 5. 
IHave received your Letter, wherein you relate that 
a great Hay rick upon Sdhbury Plaw^ after fome 
Reaking and Fermentation took fire, and was wholly 
confum'd 3 but that whereas the Afhes commonly lye 
loofe and fcatter d abroad, they were Condensed into a 
firm, but very light fubftance , and that there were 
feveral Cart-loads of it 3 whereof you carried a piece to 
the Royal Society, who judged that the fame was Vitri- 
fied and Calcin'd together by a particular Heat. When I 
had viewed a piece of the faid fubftance, which you 
were pleas'd to tranfmit to me, my Opinion was the fame 
as the Royal Society's, and I hope they will not take it 
amifs if I add my Thoughts and Obfervations thereupon : 
I imagine then that this Vitrified Matter wis moftly fixt 
Salt, which being render d Fluid by the great Heat, the 
Vapours or Moifture that rife from the Bottom of the 
Hay, or from the Particles thereof, which were not as 
yet Vitrified, had infinuated therafelves into the Fluid 
Matter, and that upon the diminution of the Heat the 
faid Vapours being Cbngealed and Imprifon'd in the Vi- 
trify 'd Matter, was the caufe of its Lightnefs 5 as we find 
by Experience, that a very fmall Particle of Moifture, 
being rarified by Heat, fills a much greater fpace than it 
did 
