406 MAEION I. NEWBIGIN. 



cence^ and the spectrum shows, in addition to the four bands of 

 chsetopterin, a new band at A 625 (see fig. 4) ; the first band 

 also tends to shift slightly to the right. There is at the same 

 time a slight precipitate of a green colour. On prolonged 

 standing with ammonia the solution loses its fluorescence, and 

 the bandsj with the exception of two in the red, tend to 

 disappear (see fig. 5). The addition of acid in excess to this 

 solution does not produce a blue colour. A more speedy and 

 certain method of attaining these results, however, is to boil 

 solutions of chsetopterin with ammonia for some time on the 

 water-bath, then evaporate to dryness, and extract the residue 

 with methylated spirit. 



Only a part of the residue is soluble, a portion remaining 

 undissolved, and being of a green colour. This is identical 

 with the precipitate already described as being formed when 

 ammonia is added to alcoholic solutions, and is apparently an 

 ammonia compound; it is insoluble in alcohol and ether. 

 After treatment with dilute acid it yields to methylated spirit 

 a solution containing a mixture of chsetopterin and its acid 

 derivative. The reason for this will be considered under the 

 action of salts on cheetopterin ; it is sufficient for the present 

 purpose to note that cheetopterin, like certain of the lipo- 

 chromes, is at least in part precipitated by ammonia, the 

 compound being insoluble in alcohol or ether. 



While heating with ammonia converts in this way a portion 

 of the cheetopterin into an ammonia compound, another portion 

 is converted into a derivative. This is present in the alcoholic 

 extract of the residue after evaporation of the alkaline solution. 

 There is usually present in addition some unaltered cheeto- 

 pterin, which can be precipitated by addition of lead acetate, 

 when the derivative remains in solution. The derivative is 

 characterised by its green colour, its peculiar spectrum con- 

 sisting of two bands in the red, one about A 650 and the other 

 at A 625 (see fig. 5), its want of fluorescence, and finally its 

 solubility in water as well as in dilute alkali. It may be 

 formed, as already indicated, by allowing alkaline solutions of 

 cheetopterin to stand for some time in the cold, but usually 



