180 ERYTHKITE. 



An acid, isomeric with aconitic acid, aceconitic add, 

 is produced in the form of its ethyl ether by the action 

 of sodium on ethyl bromacetate. 



SIXTH GROUP. 

 A. TETRATOMIC ALCOHOLS, C n H 2n + 2 4 . 



Erythrite (Erythrogludn, Phydte). 

 C 4 H 10 4 = C 4 H 6 (OH) 4 . 



Occurrence and preparation. Exists ready formed in 

 Protococcus vulgaris. Is formed by the decomposition 

 of erythrine (a substance contained in a number of 

 lichens, for example Roccella Montagnei) by means of 

 alkalies or alkaline earths. The lichens are exhausted 

 with milk of lime, the extract evaporated to one- 

 quarter its volume, and the lime then precipitated by 

 means of carbonic acid, and the filtrate evaporated to 

 syrupy consistence. After the addition of alcohol, 

 and after standing for some time, erythrite crystallizes 

 out, and can then be purified by recrystallization. 



Properties. Large, clear crystals, easily soluble in 

 water, difficultly soluble in cold alcohol, insoluble in 

 ether. Tastes sweet; fuses at 120, and volatilizes at 

 300, undergoing partial decomposition. When heated 

 with caustic potassa to 240, it yields oxalic acid; 

 when heated with concentrated hydriodic acid, the 

 iodide of secondary butyl alcohol (p. 69) is formed. 



Erythrite nitrate (nitroerythrite), C 4 H 6 (O.N"0 2 ) 4 , is 

 produced by treating erythrite with a mixture of 

 nitric and sulphuric acids. Large, shining, lamellar 

 crystals; fusing point, 61. Detonates under the 

 hammer. 



