CO NH., 



000 



CO NH., 



Intense Violet. 



CO OH CO OH 



""000"^ "^000^" 



OH CO CO OH 



Yellow. Orange. 



OH CO OH OH CO OH 



000^" 000 



OH CO OH CO OH 



Orange Red. Bluish Red. 



The information gathered from these investigations has been 

 systematized to such an extent that, knowing the constitution of any 

 anthraquinone derivative, it is possible to predict with certainty the 

 effect which the introduction of one or several groups into the 

 molecule, in any of the available positions, will have on the colour 

 of the resulting substance ; or, stated in another way, if it is 

 required to produce a dye of a particular shade, it is no longer 

 necessary to make numerous experiments, for one versed in the 

 science could write down at once the formula of the dve with the 



