Assertion: natural coloring material | /r/HasProperty | obtained by mentioned chemical extraction
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text: It is nonetheless true that the persistent uncertainty with regard to the innocuousness on the one hand, of at least certain synthetic coloring materials, and on the other hand, of traces of solvents persisting in the natural coloring materials obtained by the above mentioned chemical extraction, in particular under pressure of public opinion and also of public authorities, gives rise to a notable regain in favor of natural coloring materials, whose manufacture does not bring into play chemical treatments.