NAPftTHALIN COLOURS.

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When pure it is a colourless solid of peculiar smell and taste. Its specificgravity is i'i53. It melts at 79 0 C., and boils at 220° C. It is insoluble incold water, sparingly soluble in boiling water, but dissolves readily in alcohol,ether, the fatty and essential oils, and in acetic acid. It dissolves easilysulphur, phosphorus, indigo, iodine, the iodides of lead and mercury, thesulphides of arsenic, tin, and antimony, and arsenious acid.

The derivatives of naphthalen are almost innumerable, and many colouringmatters are produced by its readlions, few of which, however, have found theirway into commerce. Among the most important of its products we mentionnaphthylamine, which yields a red and a violet dye. This substance is com-

posed of—

Carbon .83'gi

Hydrogen. 7'55

Nitrogen. 8'54

lOO'OO

and has received the formula, C I0 HgN.

It is a solid body, crystallising in colourless needles, of offensive odour, andburning taste. It fuses at 50°, and sublimes at 300°. In water it is almostinsoluble, but it dissolves readily in alcohol and ether. It combines with theacids to form salts, which, on exposure to the air or to oxidising agents, takea red or violet colour.

Naphthylamine Violets.

One kind of violet resulting from the above-mentioned adlion of oxidisingagents upon the salts of naphthylamine was discovered by Piria, in 1851. Itsconstitution is unknown. The other kind is produced by the adlion of dehydro-genisers upon naphthylamine at the temperature of 200°. Their produdtiongenerally accompanies that of naphthylamine red. Neither of these violetshas yet been prepared on a large scale.

Naphthylen Diamine Violets.

These colours result from the adlion of reducing agents upon binitro-naphthalin. Troost prepares them by treating binitro-naphthalin withsulphides, cyanides, and sulpho-cyanides in presence of an alkali, which mustnot be allowed to adl before the reducing agent. The violet bodies produceddissolve in alkalies, alkaline carbonates, and alcohol, from which they areprecipitated unchanged by dilute acids.

Roussin treats binitro-naphthalin with proto-salts of tin dissolved in causticalkali. If the heat of the water-bath be applied the readtion is completewhen the temperature reaches 80°. The mixture is then thrown upon a filter,and washed as long as anything is dissolved. A violet-blue powder remainson the filter, easily soluble in alcohol and wood-spirit, and capable of dyeingfast shades.

Naphthalin Yellow.

Martius has patented the manufadlure of a yellow dye by adding analkaline nitrite to an acid solution of the hydrochlorate of naphthylamine.When a little of the liquid thus obtained gives a cherry-red with alkalies, it ismixed with a large quantity of nitric acid and boiled. The resulting acid is