ALKALINE PLANTS. 279 



duty paid, is about 1. 14s. per cwt. ; Canada pearl- 

 ash is from 2. 2s. to 2. 5s. per cwt. 



The common fern contains a large proportion of 

 alkaline juice, which in some parts of England is con- 

 verted to useful purposes. This plant is well known 

 as growing in common and waste lands, having an 

 herbaceous, upright stalk, garnished with large 

 winged serrated leaves, and attaining to the height 

 of four or five feet. In the county of York many 

 hundreds of poor weavers work at their looms at 

 home, and when their pieces of cloth are finished take 

 them to the public mill with their own scouring 

 materials and there superintend the operation of 

 fulling. This process is intended to make the cloth 

 of a thicker and closer texture by continued beating 

 with ponderous wooden hammers, causing the stuff 

 to shrink and thus bringing the parts into more 

 intimate union ; but the desired effect will not be 

 produced unless the cloth be entirely divested of all 

 greasy matter; for this purpose an alkali is used, 

 which is generally fuller's-earth, hard soap, potash, 

 or soda. It is, however, not unusual for the poor 

 Yorkshire weavers to save the expense of any of 

 these ingredients by providing a cheaper substitute 

 in fern. They send their wives and children to an 

 adjoining common to collect this plant, which they 

 throw into the mill with the pieces of cloth, where 

 the alkaline juices are expressed and worked into the 

 cloth, and as good an effect is produced as if potash 

 or soda had been employed*. 



Some plants abound in saponaceous juices, which 

 are so easily separable from them as to be applicable 

 to the purposes of cleansing in the manner of soap. 

 There are plants growing in Arabia, which from time 

 immemorial have been thus applied. Pliny f de- 



* Parkes' Chemical Essays, 

 t Pliny, lib. xix, cap. 3. 



