Phthalio Acid, or Anhydrid,e ; C8H604.—This is formed by strongly oxydizing naphthalene. It melts at 175° (347° F.) from boiling water, and crystallizes in plates or thick prisms. It has the same relation to benzoic acid as the latter has to benzol. When calcium phthalate is heated with quicklime to 300° (572° F.), it is converted into calcium benzoate; but, at higher temperatures, pure benzol is formed. Laurent and Casthelaz have proposed to obtain artificial benzoic acid by this reaction.
Quinizarine ; 0,41160,(OH)2.—When phenols are treated with phthalic anhydride, or when sulphuric acid, phthalic anhydride, and bydroquinone are heated together, quinizarine is formed ; it crystallizes from ether in yellowish plates, and from alcohol in deep red needles. It resembles alizarine, but gives a different absorption spectrum.
Galline ; C2d1„07.—By heating at 190°-200° (374°-392° F.), till the mass acquires a pasty con sistency, 2 parts pyrogallic acid and 1 part phthalic anhydride, the mixture turns red. It dissolves in alcohol, and, when filtered, may be precipitated with water ; this method may be used for its purification. On alum mordanted cloths, it dyes red shades resembling those of Brazil wood.
Cceruline ; C2011,007.—This is obtained by beating gallin with 20 parts sulphuric acid to 200° (392° F.); the process is terminated when a sample lieated with water gives brown flocks and a colourless solution ; the mass is then turned into a large quantity of water, and washed with boiling water. It dyes alum-mordanted fabrics a greenish colour ; and those mordanted with salts of iron, brown.
.Resoroine, OH4(CH)2, is obtained by fusing several resins ; its source is disulpho-benzolic acid, which, by fusion with caustic alkali, yields Li. mixture whence the resorcine is extracted by ether. Bindschedler and Busch give the following for its preparation :-90 kilo. fuming sulphuric atoid (80° B.), and 94 kilo. pure benzol, flow gently t,ogether through a cohobator into a cast-iron still, and are constantly agitated ; the vapours are condensed, and fall back again into the still ; at the end of two or three hours, sulpho-benzolic acid is formed. The cohobator is closed, the still is connected with a condenser, and the temperature is raised to 275° (527° F.) for about twenty minutes ; the disulpho-acid thus formed is thrown into about 2000 lit. water and boiled ; the excess of sul
phuric acid is removed by lime ; the solution contains disulpho-benzolate lime. This is converted into a soda salt, which after filtering is evaporated to dryness ; 60 kilo. are placed in a cast-iron boiler containing 150 kilo. caustic soda at 76° B. ; the whole is heated for eight or nine hours to 270° (518 FA with constant stirring. It is cooled, dissolved in 500 lit. water with hydrochloric acid in slight excess, and kept boiling ; when cool, it is filtered into copper cylinders, about 250 lit. capacity, supplied with agitating fans ; a current of ethylic ether percolates slowly through the liquid, taking up the resorcine. Tbis solution is received in an enamelled still, where the ether is evaporated and returned to the cylinders ; this is continued until all the resorcine is taken up. The resorcine remains in the still, which is finally heated to 215° (419° F.) ; the resorcine then passes over almost chemically pure.
Fluoresoine, or Resorcine-Phthaline ; C2011,206.—This is formed by fusing 100 parts resercine with 75 parts phthalic anhydride to 193° (380° F.), heating together for one hour ; on cooling, it is powdered, and is ready for use. It forms dark brown crystals, dissolving in ammonia with a red colour ; this solution exhibits, even when dilute, a most beautiful green fluorescence. It dyes silk and wool a splendid yellow. It is used principally as a source of eosine.
Eosine.—When fluorescine is heated with bromine, a substance ia produced, which, when treated with potash or soda, dried, and powdered, has a brick-red colour ; it dissolves in water, and dyes beautiful scarlet shades.
Yellowish Eosine.—To one kilo. fiuorescine, stirred into 10 lit. alcohol, is added in a gentle stream 1.1 kilo. bromine with constant agitation. This converts the fluorescine into a soluble brown oompound, which, by the further cautious addition of 1.1 kilo. bromine, is converted into a crys talline precipitate of tetra-brom-fluorescine, this is washed with a little alcohol, stirred up in warm water, and taken up vvith caustic soda or potash, taking care to avoid an alkaline reaction. The solution is evaporated, when the tetra-brom-fluereseine salt of sodium or potassium is obtained as a crystalline deliquescent powder. It dyes a fine scarlet with a yellowish tint.