The worst qualities of the Bengal indigoes, as in all the species, are the clear blues, shading on to gray or green. This coloration denotes a great quantity of extractive matter different from the indigo brown which characterizes the red varieties, and completely inert. These indigoes are hard, dense, adhere little or none to the tongue, and do not show coppery reflections when scratched. The most skilful connoisseurs distinguish forty-three varieties of Bengal indigo. The most important are the following:— 1. _Superfine blue, light or floating_.—Color bright blue; light, friable, and spongy; adherent to the tongue, soft to the touch, showing coppery reflections when rubbed by the nail; paste uniform and pure. 2. _Fine blue_.—Like the preceding, but the color a little less vivid. 3. _Violet blue_.—A little less light and friable. Has a violet blue. 4. _Superfine violet_. 5. _Superfine purple_. 6. _Fine violet_. 7. _Good violet_. 8. _Red violet_. 9. _Ordinary violet_. 10. _Good soft red_. 11. _Good red_. 12. The indigoes, _fine coppery, good coppery, ordinary coppery, and low coppery_. _The Indigoes of Oude and Coromandel_.—These are made in the interior of Hindostan. Those of the best quality correspond to the middling Bengal indigoes, and are met with in square masses, having an even fracture, but are more difficult to break; the inferior qualities are heavy, of a sandy feel, having a blue color, bordering on green or gray, or even black; often in large squares, and covered with a slight crust or rind of a greenish color. They are the most difficult to break of all the indigoes of commerce. _Madras Indigoes_.—They have a grained fracture, and are of a cubical figure. The superior qualities have no rind. The qualities are fine blue, mixed violet blue, and ordinary. They are all lighter, and less rich in coloring matter than the Bengal indigoes. _Manilla Indigoes_.—These occur in cubical blocks, flat squares, or in irregular pieces. They are light, with a fine paste, and of a clear blue. They effervesce with acids, showing the presence of carbonate of lime incorporated in their paste. They are consequently poor in coloring material, and are hence almost exclusively used as a bluing material in washing fabrics.