Abstract: A thiazine derivative, which forms a color on contact with an electron accepting material, represented by the formula (II): ##STR1## wherein A.sub.1 and A.sub.2, which may be the same or different, each represents an aryl group or a heterocyclic group and A.sub.1 and A.sub.2 may combine together to form a heterocyclic ring or a fluorene ring, the ring B represents an aromatic hydrocarbon ring or a heterocyclic ring, and Y represents a hydrogen atom, an aliphatic group, an aryl group, a heterocyclic group, an amino group, an amido group, an oxy group or a thio group, but at least one of A.sub.1 and A.sub.2 or the ring formed by the combination of A.sub.1 and A.sub.2 represents an electron donating aryl group or an electron donating heterocyclic group, and a process for preparing the thiazine derivatives represented by the formula (II) by oxidizing a thioamide derivative represented by the formula (I): ##STR2## wherein A.sub.1, A.sub.2, B and Y are as above described.

Abstract: A recording sheet comprising a support and a developer layer, which develops color images on reacting with a color former, on the support containing a dimer of the compound represented by the formula: ##STR1## wherein R.sub.1, R.sub.2 and R.sub.3 each represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, and n is 1 to 4.

Abstract: A recording method and material employing a basic color former component which changes to a colored species by an interaction with a cellulose fiber and has a molecular extinction coefficient of not less than about 100 in an ethyl alcohol solution.

Abstract: A color developer is disclosed which, when contacted with a color former, is capable of forming a distinct color, the color developer comprising a metallic compound of an aromatic carboxylic acid. Suitable metals are, for example, those of the following groups of the Periodic Table: Ib, IIa, IIIb, IVb, VIa, VIIa and VIII. A recording sheet employing the color developer is also disclosed.

Abstract: A pressure-sensitive copying paper comprising an adsorbent solid acid and a microencapsulated color former capable of forming a distinct color when reacted with the adsorbent acid coated on the same or a different surface of a support or supports, the microencapsulated color former being at least one lactone compound derived from a pyridine-carboxylic acid represented by the formula ##SPC1##Or a mixture thereof, wherein R.sub.1, R.sub.2, R.sub.3 and the partial structure ##SPC2##Are as defined hereinafter, is disclosed.

Abstract: A 1,3-dihydro-1-oxo-benzo[b]thieno[2,3-C]furan derivative represented by the following General Formula I ##SPC1##or a 1,3-dihydro-3-oxo-benzo[b]thieno[2,3-C]furan derivative represented by the following General Formula II: ##SPC2##wherein ring A represents a benzene ring or a naphthalene ring, R.sub.1 and R.sub.2 each represents an amino group, and X, Y and Z each represents a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkoxy group, an aralkoxy group, an acyloxy group, a nitro group or an amino group, useful as a color former, e.g., in a pressure sensitive copying paper.