This article is the transcript of a scientific paper presented in 1909. It describes the scientific methods used by the author to analyze the molecular content of a purple dye from Murex Brandaris. These methods include extraction of impurities, purifying in alcohol and ether, crystallization of the result, immersion of the powder in various solvents to discover the chemical compounds, and descriptions of the compounds involved using the organic chemistry notations. The author concludes that it would be interesting to further clarify the nature of the fresh glands in the continuing compound which, within the known indigos, has appeared similar to this substance.