260 VEGETABLE SUBSTANCES. 



rally preferred by glass-makers who have made trial 

 of both these alkalis. 



Among the great variety of marine plants from 

 the ashes of which soda is obtained, are the several 

 species of glass-wort, or salsola, which yield it in great 

 abundance. The kali which grows naturally in the 

 salt marshes of England is one of this genus. 



It is an annual plant not attaining above half a 

 foot in height, having numerous branches extending 

 on every side. The leaves are short, awl-shaped, 

 and succulent, terminating in acute spines. Small 

 flowers come forth from the sides of the branches, 

 and are surrounded by short prickly leaves ; the seeds 

 which these produce come to maturity in autumn, 

 soon after which time the plant decays. 



The rosacea, a native of Tartary, is another species 

 of salsola, very similar to kali ; its flowers on their 

 first opening are rose-coloured, but soon fade. 



The tragus is indigenous to the sandy shores of 

 the south of France, Spain, and Italy. It is like- 

 wise an annual plant, and very much resembles the 

 two just mentioned, except that its leaves are longer 

 and narrower. 



The vermiculata grows naturally in Spain. This 

 has shrubby perennial stalks, which rise three or four 

 feet high. Its leaves, which are fleshy, oval, and 

 acutely pointed, grow in clusters. The flowers come 

 forth between the leaves, towards the extremity of 

 the branches ; they are so diminutive as to be 

 scarcely perceptible, except on a close inspection. 



The salsola soda has a perennial root. Its stem 

 rises with herbaceous stalks, from one to three feet 

 high ; these are without thorns, and of a reddish brown 

 colour. The leaves are long, straight, and thick, 

 adhering to the stem ; the flowers grow singly, at 

 the insertion of the leaves ; they are very small and 

 followed by capsules, each of which contains only 



