262 Di' Da^'idson on the Bemoval of the Bitter Taste and 



land moss, but if a more speedy effect is desired, the propor- 

 tion of alkali must be increased. 



Lime may also be employed for the extraction of the bitter 

 principle. When Iceland moss is macerated with about a 

 fifth or sixth part of its weight of quick -lime, with the re- 

 quisite quantity of water to cover it, and frequent agitation 

 employed, it is deprived of its bitter principle in about a week. 

 The watery liquid acquires a deep brown colour, but it pos- 

 sesses scarcely any bitter taste, at the end of the maceration ; 

 the lime appearing to effect a partial decomposition of the 

 bitter principle. Very little of the other soluble principles of 

 the lichen seems to be dissolved, for on evaporating a portion 

 of the solution, only a small residuum was obtained. 



The Iceland moss itself is hardened in its texture, and as- 

 sumes a reddish colour, from the action of the lime. The 

 first quality, viz. the hardness, is completely removed by ma- 

 ceration in water acidulated with sulphuric acid, and the red 

 colour is diminished, though not entirely removed by it. The 

 following process may be adopted, if lime, as being cheaper 

 than potass, be employed. 



Take 112 lb. Iceland moss, 6 lb. recent quick -lime, and as 

 much water as will cover them : macerate for about a week, 

 frequently stirring during that time. After the maceration 

 has been completed, throw the moss upon a sieve or drainer, 

 having holes sufliciently large to allow the lime to pass, while 

 the lichen is left ; then pour a stream of cold water upon it, 

 until it be thoroughly washed. The lichen is afterwards to 

 be macerated in water acidulated with sulphuric acid, again 

 washed with water without sti'aining by pressm-e, and after- 

 wards dried. Quick-lime also possesses the property of re- 

 moving the lichrnous odour, to a much greater extent than 

 potass, and in this respect possesses some advantages. 



I have tried Iceland moss, deprived of its bitter princi- 

 ple by caustic potass, in the formation of bread, by making a 

 decoction of it (which, on cooling, formed a firm jelly), and 

 mixing it with wheaten flour, and it formed a perfectly sweet 

 bread, with a lichenous odour when warm, but which disap- 

 peared, to a great extent, when it was cold. The most eco- 





