748 BULLETIN 82, UNITED STATB8 NATIONAL MUSEUM. 



In very intense solutions the absorption at the violet end spreads up to b and 

 unites with the third band, so that the light is entirely cut off up to b, where there 

 is a defined dark edge ; the second band is intensified and becomes black ; the first 

 band is black as before, but a paler band is added to it in continuation on its red 

 side. 



In more intense solutions the two principal bands broaden out and almost run 

 together, being separated by a narrow interval of yellow. 



The two principal bands coincide very nearly with those of turacin,' the only 

 difference being that the least refrangible band in turacin extends a little farther 

 to the green side of D than does that of pentacrinin. 



When the acid-alcohol solution is rendered alkaline by the addition of ammonia 

 the solution becomes of a bluish-green color, which shows a slight red fluorescence 

 on the concentration of sunlight in it. The spectrum is also changed. An intensely 

 black band now occupies a space on the less refrangible side of B ; on the red side 

 of D is a broad pale band, while the third band between b and F remains as 

 before, excepting that it is intensified for rather more than lialf its breadth on its 

 violet side. In very weak solutions the first and third bands remain visible after 

 the middle one is lost. 



The solution can be rendered acid or alkaline any number of times with corre- 

 sponding changes in color and spectrum. By careful addition of ammonia in small 

 quantities to the acid solution in a tall vessel one part of the solution can be ob- 

 tained green, while the remainder is still red. Thus the passage of one spectrum 

 into the other may be seen at the junction of the two solutions. As the least re- 

 frangible band of the acid spectrum fades it takes the form of a fine black line to 

 the red side of D with a fainter margin extending just over D toward the green. 

 As the ammoniacal portion of the solution is approached a dark broad band is 

 seen to extend gradually toward the red from the least refrangible acid band up to 

 the position of the least refrangible margin of the dark alkaline band in the ex- 

 treme red. The least refrangible margin of the broad band darkens as the least 

 refrangible acid band fades from view, and at length assumes the full intensity 

 of the least refrangible alkaline band. 



In a very strong solution or with weak transmitted light the broad band ap- 

 pears to extend the entire distance from the alkaline band in the extreme red to D. 

 while the entire violet and blue end of the spectrum is absorbed continuously as 

 far as b. 



By very careful neutralization of the solution a green fluid can be obtained 

 which yields both acid and alkaline spectra showing four bands. In it the ex- 

 treme red band of the alkaline solution and the intense band in the region of D 

 of the acid solution are seen of equal intensity, while the second band of the acid 

 spectrum is very faint. In the exactly neutral solution yielding four bands acid 

 and alkaline pentacrinin appear to coexist. 



' Turacin is the red or crimson coloring matter In the feathers of certain of the Musophagldee or 

 plantaiD-eaterg, a group of African birds. In solution it gives two absorption bands lilie those of oxyhsemo- 

 globln. It is said to contain about 6 per cent of copper which can not be isolated without destroying the 

 pigment. T\iracin Is said to wash out of the feathers readily during the rainy season, and also when the 

 birds bathe. 



