408 COMPOUND PRODUCTS. CHAP. I. 



The ashes of the Golden Rod growing in an uncul- 

 tivated soil, and of the Bean, Ttirnsol, and Wheat,, 

 were found by Saussure to contain at least three- 

 fourths of their weight of Alkaline salts. This was 

 nearly the case also with the leaves of trees just 

 bursting from the bud. But the proportion of 

 alkaline salts is found to diminish rather than to aug- 

 ment as the parts of the plant are developed. The 

 ashes of the leaves of the Oak gathered in May 

 yielded 47 parts in the 100 of alkaline salts ; and 

 in September, only 17.* 



Uses. The utility of the alkalies, as obtained from vege- 



tables, is of the utmost importance in the arts, par- 

 ticularly in the formation of glass and of soaps. If 

 a mixture of soda or potass, and silex or sand, in 

 certain proportions, is exposed to a violent heat, the 

 ingredients are melted down into a fluid mass, 

 which is glass in a state of fusion. In this state it 

 may be moulded into almost any form at the 

 pleasure of the artist. And accordingly we find 

 that it is manufactured into a great variety of 

 utensils and instruments under the heads of flint- 

 glass, crown-glass, bottle-glass. Bottle-glass is 

 the coarsest: it is formed of soda and common 

 sand, and is used in the manufacture of the coarser 

 sort of bottles. Crown-glass is composed of soda 

 and fine sand: it is moulded into large plates for 

 the purpose of forming window-glasses and looking- 

 glasses. Fint-glass is the finest and most trans- 

 * Saussure sur la Vegetation, chap, ix, sect. iv. 



