48 
FOSSIL NATRON. 
VIII. 
Chemical Examination of a Variety of Fossil Natron , or Na • 
five Carbonate of Soda , lately discovered in South America. 
By Amerigo Cabral de Mello. 
Fossil natron 
found in strata 
not crystal- 
line. 
Exp. 1. 
For carbonic 
acid, 
and sulphate 
of soda, 
and muriate of 
soda, 
T HE native carbonate of soda, of which I subjoin an ana- 
lysis, has lately been discovered in the vicinity of Bue- 
nos Ayres, and considerable quantities of it have been imported 
into this country. 
It occurs in compact, solid, stratified masses of from two to 
six inches thickness, deposited upon a bed of clay, strongly 
impregnated with common salt. 
It exhibits no vestiges of crystalline structure. Its masses 
are granulous, readily broken between the fingers, and of a light 
yellowish grey colour. 
It is readily soluble in water, and scarcely leaves any inso- 
luble residue. 
Experiment I. A solution of the Brazilian fossil natron, 
Containing of 100 grains of salt, after having been neutralized 
by nitric acid, lost 44*25 grains. 
2. In this solution nitrate of barytes was dropped till no farther 
cloudiness ensued. The obtained sulphate of barytes weighed 
four grains, which -are equal to 1*25 grains of sulphate of 
soda. 
3. To this fluid, from which the sulphate of barytes had 
been separated, nitrate of silver was added, till it occasioned 
no farther change in the solution. The produced muriate of 
silver, after having been dried at a heat short of its melting 
point, weighed twenty grains, indicating 9*25 grains muriate of 
soda. 
&nd water of 
crystalliza- 
tion. 
4. To learn the quantify of water of -crystallization contained 
in this salt, 100 grains of it were ignited in a platina crucible 
for one hour. The mass, which was of a porcellaneous ap- 
pearance when cold, was dissolved in a weighed quantity of 
nitric acid to ensure the complete expulsion of the carbonic 
acid contained in the salt j and from the loss of weight which 
the 100 grains of fossil natron had suffered, after having de- 
ducted 
