1890 Patent No. 16,666 yellow colouring matter dye, John Rudolph Geigy, Basle

Patent No. 16,666 A.D.1890 Production of a Yellow Colouring Matter or Dye

"I, John Rudolph Geigy of the firm of John Rudolph Geigy & Co. of Basle, Switzerland, Colour Manufacturers, do hereby declare the nature of this invention to be as follows: This invention relates to the production of a yellow colouring matter or dye by the action of sulphur on tetramethyldiamidothiobenzhydrol or tetramethyldiamidobenzhydrol in the presence of ammonia and muriate of amonia..."

1 page of text which has been disbound from a larger volume.

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