ORDER IV. PRISMATIC NATRON-SALT. 29 



OBSERVATIONS. 



1. The native carbonate of soda, found in the province 

 of Sukena, in Africa, consists, according to KLAPROTH, of 



Soda 37'00. 



Carbonic Acid 38-00. 



Sulphate of Soda 2-50. 



Water 22-50. 



Its composition differs considerably from that of the 

 crystallised varieties, to which the above description re- 

 fers, the composition of these being expressed, according to 

 BEHZELIUS, by Na C 2 + 20 Aq = 21-77 of Soda, 15-33. of 

 Carbonic acid, and 62-90 of Water. It is likely, therefore, 

 to belong to another, perhaps to the following species. It 

 is very soluble in water, effervesces with acids, and melts 

 easily before the blowpipe. Blue vegetable colours are 

 changed by it into green. 



2. This salt loses its water, on being exposed to a dry 

 atmosphere, and is therefore commonly met with in a 

 state of efflorescent powder on the surface of the earth, 

 on the shores of lakes, or in natural caverns. It is held 

 in solution by certain mineral waters. According to BER- 

 THOLET, it is formed in part by a decomposition of hexa- 

 hedral Rock-salt, by carbonate of lime. 



3. It occurs in considerable quantities in the plains of 

 Debreczin, in Hungary ; also in Bohemia, Italy, and seve- 

 ral other European countries, but principally in the soda 

 lakes of Egypt, and in some parts of Asia and America. 



4. Its chief employment is in the manufactures of soap. 

 It enters also the composition of glass, and is used in dye- 

 ing, washing, bleaching, &c. both in its natural state, and 

 purified by the assistance of chemical processes. 



2. PRISMATIC NATKON-SALT. 



Synonymes as above. 



Fundamental form. Scalene four-sided pyramid. 

 P- 14-1 48', 52 9', 145 52'. Vol. I.Fig.Q.Ap. 



