c centimetres of water.

_Bases._

1. Aniline, C{6}H{5}NH{2}--93.
2. Toluidine, C{7}H{7}NH{2}--107.
3. Alpha-and beta-naphthylamine, C{10}H{7}NH{2}--143.
4. Para-or meta-nitroaniline, C{6}H{4}NO{2}NH{2}--138.
5. Nitro-para-toluidine, C{7}H{6}NO{2}NH{2}--152.
6. Amidoazobenzene (base), C{6}H{5}N:NC{6}H{4}NH{2}--197.
7. Orthoamidoazotoluol (base), C{7}H{7}N:NC{7}H{6}NH{2}--225.
8. Alpha-or beta-naphthol C{10}H{7}OH--144.

_Example of Quantities Taken._

Molecular Weight.
1. Molecule nitrite 69 grams.
2. Molecule aniline 93 "
3. Molecule hydrochloric acid 365 "
4. Molecule acetate of soda 136 "
5. Molecule of naphthol 144 "
6. Molecule caustic soda 40 "

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;