Applying the principles which have just been described to the dyeing of cotton, it is found that the cotton may be dyed by taking the base and preparing the diazo body, impregnating the cotton with this, and developing the colour by passing into a bath of the phenol. On the other hand, the cotton can be prepared with the phenol and the colour developed by passing into a bath of the diazotised base, and practice has shown that this latter proceeding is the best. Practically the only phenol that is used is the beta-naphthol; alpha-naphthol is occasionally used, but not often. The purer the beta-naphthol the better, especially for producing the paranitroaniline red. Various preparations of beta-naphthol have been brought out by colour makers. The process of dyeing cotton with a naphthol colour takes place in two stages, the first being the grounding or preparing with the naphthol, the second the developing with the diazotised base. Some of the effects which can be obtained from the two naphthols and various bases are given in the following table:-- Base. With beta-naphthol, gives With alpha-naphthol, gives 1. Aniline, Orange yellow; Cutch brown. 2. Paratoluidine, Full yellow orange; Cutch brown. 3. Metanitroaniline, Fiery yellowish red; Brownish orange. 4. Paranitroaniline, Bright scarlet; " " 5. Nitroparatoluidine, Orange; Very bright catechu. 6. Alpha-naphthylamine, Bluish claret red; Reddish puce. 7. Beta-naphthylamine, Turkey red; " 8. Amidoazobenzene, Red; " 9. Orthoamidoazotoluene, Yellowish claret red; " By mixing alpha-and beta-naphthols together a variety of grenat and claret reds and browns can be obtained. With regard to the fastness of the shades produced the following may be considered:-- _Fast to Soaping._ Combination of A-Naphthol with Toluidine. " " A-Naphthylamine. " " B-Naphthylamine. " " Amidoazobenzene. " B-Naphthol with Toluidine. " " Paranitroaniline. " " Nitroparatoluidine. " " B-Naphthylamine. " " A-Naphthylamine. _Moderately Fast._ Combination of A-Naphthol with Aniline. " " Paranitroaniline. " " Orthoamidoazotoluene. " B-Naphthol with Metanitroaniline. " " Amidoazobenzene. _Very Loose._