Abstract: Disclosed herein is a process for producing 3,3-bis-(4-dimethylaminophenyl)-6-dimethylaminophthalide, which process comprises oxidizing 2-[4,4'-bis-(dimethylamino)-benzhydryl]-5-dimethylaminobenzoic acid in an aqueous solution of a mineral acid of pH of from 2.0 to 4.0 with air, oxygen or a gas containing oxygen in the presence of at least one catalyst selected from the group consisting of compounds of iron, copper, cobalt, nickel, chromium, vanadium and manganese.

Abstract: Disclosed herein are novel divinyl compounds represented by the formula (I): ##STR1## and a recording-material prepared by utilizing the divinyl compounds. The divinyl compound is in itself almost colorless, extremely stable in the atmosphere and develops rapidly blackish color by a developer. The color image given by the divinyl compound is excellent in light-resistance and moisture-resistance and the letters developed can be read by an optical letter-reading apparatus or a barcord reading apparatus.

Abstract: Disclosed herein are novel divinyl compounds represented by the formula (I): ##STR1## and a recording-material prepared by utilizing the divinyl compounds. The present divinyl compound is in itself almost colorless, extremely stable in the atmosphere and develops rapidly blakish color by a developer. The color image given by the present divinyl compound is excellect in light-resistance and moisture-resistance and the letters developed can be read by an optical letter-reading apparatus or a barcord reading apparatus.

Abstract: The chromogenic azaphthalide compounds of the invention are of the formula: ##STR1## wherein A is a pyridine ring; R.sub.1 is hydrogen atom or alkyl radicals of from one to 4 carbon atoms; X is hydrogen atom, alkyl radicals of from one to 2 carbon atoms or alkoxy radicals of from one to 2 carbon atoms; R.sub.2 is alkyl radicals of from one to 2 carbon atoms or phenyl radical; R.sub.3 is hydrogen atom or alkyl radicals of from one to 8 carbon atoms.These compounds are particularly suitable for use in providing high quality pressure- or heat-sensitive copying sheets.

Abstract: Novel chromogenic fluoran compounds of the formula: ##STR1## wherein R.sub.1 is selected from the group consisting of alkyl radicals of from five to eight carbon atoms; R.sub.2 is selected from the group consisting of alkyl radicals of from one to eight carbon atoms; R.sub.3 is selected from the group consisting of hydrogen atom and lower alkyl radicals of from one to four carbon atoms; X.sub.1 and X.sub.2 are independently selected from the group consisting of hydrogen atom and lower alkyl radicals of from one to four carbon atoms, X.sub.3 is selected from the group consisting of hydrogen atom, lower alkyl radicals of from one to four carbon atoms, halogen atoms and trifluoromethyl radical; and n is an integer of a value of 1 or 2; providing that R.sub.1 does not represent an amyl radical when R.sub.2 is selected from the group consisting of alkyl radicals of from one to five carbon atoms, X.sub.1 and X.sub.2 are each a hydrogen atom, X.sub.

Abstract: The present invention discloses a full-automatic flash welding apparatus wherein the trailing edge of the preceding strip and the leading edge of the succeeding strip are automatically accurately positioned, rigidly clamped and simultaneously cut off, the new trailing and leading edges are automatically machined and then butt welded, and thereafter the flash on the upper and lower surfaces of the joined strips is automatically removed.

Abstract: A butt welding device wherein the trailing edge of a first or preceding strip and the leading edge of a second or succeeding strip are clamped in position, simultaneously cut off, and joined together by flash butt welding and thereafter the flash and upset are removed by machining.