LESSON 14.] HAIES. 41 



241. In this country, it appears that the domestics have dis- 

 covered the economic value of Deutzia, as they employ the leaves 

 with which to rub up and brighten their tin-wares a function they 

 must be very capable of per- FIQ 



forming. 



242. The quantity of Sil- 

 ica contained in the Canes, 

 especially the bamboo, is very 

 great ; in the latter it is fre- 

 quently found in the form of 

 a solid layer, between the 



joints, Called Tabasheer." Under cuticle, D. scabra. 



243. Reeds, from the large 



quantity of Silica they contain, are said, during hurricanes in warm 

 climates, to have actually caused conflagrations, by striking against 

 each other, and producing flame by friction. 



244. Silicate of potash in a vegetable sap may be mixed with ox- 

 alic acid, by which oxalate of potash and silicic acid will be pro- 

 duced, and thus the silica may be deposited in cells by this process 

 of double decomposition. 



245. When these chemical compounds meet, they mutually de- 

 compose each other in this wise : Oxygen has more affinity for potash 

 than for the acid with which it has combined to form oxalic acid ; 

 it therefore quits the acid, which is set free, and joins the potash to 

 form a new compound oxalate of potash. Then the silica has more 

 affinity for the acid liberated by the oxygen than for potash ; it com- 

 bines with it, therefore, and forms silicic acid, and thus new com- 

 pounds result. 



246. Chara translucens possesses a covering of silicic acid, which 

 could only have been formed in the manner indicated ; C. vulgaris 

 has a covering composed of silicic acid and carbonate of lime, while 

 Chara hispida has a covering of carbonate of lime alone. 



LESSON XIV. 



HAIES. 



247. Hairs are composed of one or more transparent delicate 

 cells, proceeding from the epidermis, and covered with the cuticle. 



248. Their form is very various ; some are erect, others oblique, 

 or they may lie parallel to the surface, as in the mullein. 



