Mixtures of two chromogenic compounds

Claim 2

A MIXTURE OF TWO COLORLESS BUT COLORABLE CHROMOGENIC COMPOUNDS WHEREIN THE FIRST CHROMOGENIC COMPOUND IS A FLUORAN COMPOUND HAVING A GENERALLY GREEN APPEARNCE AND EXHIBITING TWO LIGHT ABSORPTION PEAKS-ONE IN THE RANGE OF 400 TO 500 MILLIMICRONS AND ANOTHER IN THE RANGE OF 500 TO 650 MILLIMICRONS- IN ITS COLORED FORM AND WHEREIN THE SECOND CHROMOGENIC COMPOUND EXHIBITS A SINGLE ABSORPTION PEAK IN THE RANGE OF 500 TO 600 MILLIMICRONS IN ITS COLORED FORM;-THE MIXTURE, ADDITIONALLY, CONSISTING ESSENTIALLY OF A FIRST CHROMOGENIC COMPOUND REPRESENTED BY THE FORMULA:

Claim 3

A mixture according to claim 1 wherein said mole ratio ranges from 1:1 to 5:1.

Claim 4

A mixture according to claim 1 wherein said first chromogenic compound is: 2''-anilino-6''-diethylaminofluoran; 3''-diethylamino-7''-(N-methylanilino)fluoran; 3''-diethylamino-7''-(p-toluidino)fluoran; 3''-diethylamino-6''-methyl-7''-(p-toluidino)fluoran; 2''-anilino-6''-diethylamino-6-nitrofluoran; 2''-anilino-6''-diethylamino-5-nitrofluoran; 3''-diethylamino-7''-(N-methylanilino)-6-nitrofluoran; 3''-diethylamino-7''-(N-methylanilino)-5-nitrofluoran; 6''-diethylamino-2''-Methylaminofluoran; 2''-benzylamino-6''-diethylaminofluoran; 2''-(N-acetonyl-N-methyl)amino-6''-diethylaminofluoran; 2''-phenyacylamino-6''-diethylaminofluoran; 2''-(methoxymethyl)amino-6''-diethylaminofluoran; 2''-allylamino-6''-diethylaminofluoran; 2''-(N-carbethoxymethyl-N-methyl)amino-6''-diethylaminofluoran; 2''-N-(dimethylaminoacetamido)amino-6''-diethylaminofluoran; 2'' ,6''-bis(methylamino)fluoran; or 2'',6''-bis(diethylamino)fluoran; and said second chromogenic compound is 3,3-bis(1-ethyl-2-methyl-indol-3-yl)-phthalide; 3''-diethylamino-benzofluoran; 2''-chloro-6''-diethylamino-3''-methylfuoran; 6''-diethylaminofluoran; 2''-amino-6''-diethylaminofluoran; 2''-(o-carbamethoxy)anilino-6''-diethylaminofluoran; 6''-diethylamino-2'',3''-methylenedioxyfluoran; 6''-diethylamino-2''-thiomethylfluoran; 2''-(n-acetyl)anilino-6''-diethylaminofluoran; 2''-(n-acetyl-n-methyl)amino-6''-diethylaminofluoran; 2''-acetamido-6''-diethylaminofluoran; 9-ethylamino-spiro(12-H-benzo(a)xanthene-12,1''-phthalide); 9-diethylamino-spiro(12-H-(1)-benzopyrano(3,2,f)-quinoline-12, 1''-phthalide); or 6''-diethylamino-3''-methyl-2''-thiomethylfluoran.