APPENDIX.

681

Naphthol /3 crystallises in brilliant lamellas, and melts at 122° C. Withchloride of lime it takes a yellowish colour, and the liquid, if heated, depositsyellow flocks. In solubility it agrees with the a variety. A chip of pine-woodsteeped in the aqueous solution of the naphthols, mixed with hydrochloricacid, and then exposed to sunlight, takes a green colour, which afterwardspasses into a brownish-red. The two naphthols, if treated in a dry statewith concentrated sulphuric acid, yield sulphonaphtholic acids. If sulpho-naphtholic acid a is mixed with nitric acid a red colouration appears, andbinitronaphthol (Martius’s yellow) separates.

Sulphonaphtholic acid f 3 does not give this readtion, but naphthol /3 may heconverted into binitronaphthol (3 by treating its alcoholic solution with nitricacid. The latter compound crystallises in brilliant yellow lamellae, sparinglysoluble in water, readily in alcohol, and very readily in ether and chloroform.Its solutions dye wool and silk a full, beautiful yellow.

29. Anthracen-Orange.—If binitro-anthraquinon is treated with reducingagents, such as stannite of soda, sulphuret of antimony, or sulphuret ofsodium, it is transformed into a colouring matter, the anthracen-orange ofBcettger. It is prepared as follows :—

The stannite of soda is obtained by mixing with a moderately concentratedsoda-lye a clear saturated solution of the protochloride of tin, containing aslittle free acid as possible. It is poured in a slender stream into the lye, withconstant stirring, until a slight turbidity begins to appear in the liquid. It isthen left to settle, protedted as far as possible from contadt with the air, andthe clear portion is decanted through a filter. With this the binitro-anthraquinon—washed and still damp—is drenched. A beautiful and in-tensely green liquid is immediately formed, and if boiled without interruptionanthracen-orange separates in abundance, after a short time, as flocculentpowder, of a cinnabar-red. If this colour is moistened with water, dried, andsubmitted to sublimation in a porcelain crucible placed in a sand-bath, it fusesat 235° C., and from that point to 260° it sublimes in crystals of a garnet-red,with a green metallic refledtion.

Its best solvents are acetic ether, aceton, chloroform, aldehyd, ether,alcohol, and wood-spirit. It is slightly soluble in bisulphide of carbon, but isinsoluble in petroleum and naphtha. At ordinary temperatures it dissolves insulphuric acid (full strength) without decomposition, even at a boiling heat,forming a brownish-yellow liquid, which, if largely diluted with water,depbsits a flocculent mass of a fine red colour. It dissolves also withoutdecomposition, at common temperatures, in nitric acid of specific gravity 1-2.But if heated for some time with a solution of mercuric nitrate it is trans-formed into a deep violet powder, which dissolves in ether with the samecolour. If, instead of heating the original green liquid obtained on treatingbinitro-anthraquinon with stannite of soda, it is immediately poured intodilute sulphuric acid, a flocculent reddish-brown precipitate is formed, whichif filtered, washed, and dried, and then dissolved in alcohol, leaves, afterremoval of the alc.ohol, a brown colouring matter, which dissolves in aceticether with a deep purple-red colour.

If a solution of anthracen-orange in ether is treated with nitrous acid, afine powder of a violet-brown is deposited, easily soluble not only in alcohol,but also in water, with a fine deep violet-red colour. If the dry powder isheated to about 68° C. it detonates.