On two Burning Volcanoes in Central Tartary. 157 
Nao-chay is reckoned the best. This salt is of a very penetra- 
ting nature. It is kept suspended in a stove above the fire, in 
order to dry it, and ginger is then added, for the purpose of pre- 
serving it. When exposed to the cold, or to humidity, it deli- 
quesces and is lost.” 
M. Remusat has remarked, that there are still several other 
places where the Chinese place volcanoes, of which Europeans 
have no precise knowledge. 
The existence of two volcanoes, at the distance of 400 leagues 
from the Caspian Sea, which is the nearest to them, is consider- 
ed by M. Cordier as a fact very interesting in a geological point 
of view. He regards the fact as unquestionable, and supports 
this opinion by shewing, that sal-ammoniac is almost always ^ a 
product of art, unless when it is obtained from volcanoes ; and 
is not a native salt in any country. He mentions, that, accord- 
ing to Ferrara, the lava ejected from iEtna in 1635 furnished 
considerable quantities; and that, according to Boccone and 
Borelli, the eruption of 1669 furnished prodigious quantities of 
this salt, which were embarked for different parts of Italy. In 
modern times, M. Ferrara found it abundantly in the lava of 
1763. In 1780, more than 1000 pounds were collected. The 
lava of 1792 yielded a little ; and that of 1811 gave as much 
as to supply all the manufactories and apothecaries’ shops in Si- 
cily. Sal-ammoniac is also exhaled unceasingly from the Sol- 
fatara of Pozzuola, and one of the great apertures of it has been 
wrought for several years, for the purpose of extracting the sal- 
ammoniac •[* *. 
M. Cordier terminates his observations by remarking, that 
the discovery of M. Abel Remusat gives a finishing blow to 
that hypothesis, which had for its object to explain all the vol- 
canic phenomena by the filtration of the waters of the ocean in- 
to subterraneous cavities containing burning materials, which 
serve as fuel for volcanic eruptions.” 
* That which comes from Egypt is obtained from the soot which covers the 
subterranean huts of the inhabitants. 
*1* See Brejslak’s Voyages Pkys. et Lithologique dans la Campanle, vol. ii. p. 69. 
