268 VEGETABLE SUBSTANCES. 



their cheeses without salt, by covering them with the 

 ashes of this plant. 



For the purpose of obtaining the alkali which the 

 sea-wrack contains, the plants are collected into 

 heaps, to induce a slight fermentation ; they are then 

 spread to dry in the air, and afterwards burnt to 

 ashes in a manner similar to that just described in the 

 making of barilla. The ovens in which kelp is made 

 are generally of the rudest kind, being nothing more 

 than excavations in the ground lined with rough un- 

 hewn stones. The alkali fuses, and on cooling com- 

 bines into one solid mass ; when cold it is broken up 

 with iron bars into large ponderous pieces, and in 

 that state is offered for sale, under the name of kelp. 



This is much inferior to barilla, inasmuch as it 

 contains a large portion of neutral salts, a quantity of 

 potash, and a much larger proportion of carbonaceous 

 matter than is generally found in the foreign alkali. 

 The proportion of pure soda contained in a given 

 quantity of kelp is always very small ; but it is very 

 variable in its quality, ranging in the proportion of 

 between one and eight per cent, of pure alkali. It has 

 been seen that barilla likewise varies in its quality, 

 some containing a much larger proportion of effective 

 matter than others. It is admitted on a scale of 

 duties proportionate to the quantity of pure alkali 

 which it contains. Formerly it paid one fixed duty, 

 but some years back a considerable quantity of puri- 

 fied alkali was imported from France on payment 

 of the same duty as that levied on barilla ; and Go- 

 vernment then discovered the policy of altering the 

 mode of taxing the article. In this manner the duty 

 on the pure alkali amounted to much more than 100 

 per cent, and it yielded a revenue of ,79,000 *. 



The duty on barilla has however been very recently 

 * Sir Henry Parnell on Financial Reform. 



