FIXED ALKALIES. 



ff3 



verting the salts into pearlash, and thus extending the em- 

 ployment of it. 



The salts and pearlash contain all the soluble salts that 

 are found in ashes. M. Vauquelin, who has analyzed the 

 various kinds of potash of commerce, with reference to 

 the difference in their qualities, has obtained the following 

 results. 111*2 parts of each kind were subjected to ex- 

 periment. 



The salts and pearlash are much used in the arts : they 

 form the basis of the soft soaps, and enter into the compo- 

 sition of white glass : they are used in washing and bleach- 

 ing : they are greatly employed in coloring, metallic cast- 

 ings, the manufacture of salt-petre and alum : in short, 

 there are few manufacturing establishments, in >which 

 they are not consumed in greater or less quantities. 



Soda exists in nearly all plants which grow in a soil im- 

 pregnated with marine salt ; but all of these do not furnish 

 it equally pure, nor in the same quantity. 



The barilla (the calsola vermiculata of Linnaeus) is cul- 

 tivated in Spain for the purpose of extracting from it the 

 Alicant soda, which is one of the kinds most esteemed in 

 commerce ; in nearly all the other countries lying upon 

 the sea or upon the salt lakes, the plants growing upon 

 their coasts are burned, in order to obtain from them this 

 substance. The different kinds of soda contain different 

 quantities of alkali, according to the character of the plants 

 from which they are procured ; hence arises a great dif- 

 ference in their n^mes, prices, and uses. 



For the manufacture of soda, the marine plants are 

 gathered at the season when their vegetation has termi- 

 15* 



