1835.] Improvements in Science. 201 



Varry describes a soluble amidine which he considers to be 

 fibrous amidine held in solution by amidine. 



Starch, he states, is therefore composed of 2*96 parts of 

 fibrous amidine, and of 97*04 parts of a soluble substance 

 which contains an insoluble matter, identical with fibrous 

 amidine, and a soluble matter or amidine. This is to the 

 soluble amidine as 60*45 to 39*55. 



Lichenine, is the name which M. Varry gives to the 

 soluble part of the lichen Islandicus, (cetraria Islandica.) 

 He prepares it in the manner indicated partly by Ber- 

 zelius, viz : allowing the lichen to remain twenty-four 

 hours in contact with water and potash of commerce, 

 in the proportion of 1 lb. lichen, 18 lbs. water, and 1 oz. 

 potash; the liquid becomes brown, the lichen is placed 

 on linen and then macerated with a new quantity of water, 

 and this is continued till it becomes bitter and alkaline. 

 The lichen is boiled with 9 lbs. of water down to §, the hot 

 solution is passed through linen, and the residue expressed. 

 Varry treats this residue twice with three times as much 

 water as the lichen employed. The jelly thus prepared 

 was dissolved in boiling water, and passed through a filter. 

 The solution was precipitated by alcohol ; the precipitate 

 re-dissolved in water at 212°, and the liquid evaporated to 

 dryness by heat. When thus obtained lichenine is yellowish 

 when dry, colourless when hydrous. It is destitute of taste 

 and smell, transparent in thin portions, and is not easily 

 pulverized. In cold water it swells, and scarcely dissolves 

 in this fluid at the ordinary temperature ; but is completely 

 soluble at 212°, and forms with it a very thick mucilage. 

 It colours iodine blue, but has not such a powerful effect as 

 an equal quantity of amidine. From its aqueous solution 

 it is precipitated by alcohol and sulphuric ether. 



Subacetate of lead precipitates it abundantly, insoluble 

 in cold water, but soluble in a few drops of acetic acid. An 

 aqueous solution becomes acid by standing, evaporated at 

 a temperature below 212°, pellicles form on the surface, 

 which are completely soluble in boiling water. 100 parts of 

 lichenine at 150°, and 250 sulphuric acid produce 93*91 parts 

 of anhydrous sugar. Nitric acid by its action on lichenine 

 produces no mucic acid ; hence, there is no arabine pre- 

 sent in it. 



