This section is from the book "Monograph on Flavoring Extracts With Essences, Syrups, and Colorings", by Joseph Harrop . Also available from Amazon: Monograph On Flavoring Extracts With Essences, Syrups And Colorings.
As to the use of colorings in flavoring extracts, syrups, and so forth, there can be no doubt that those of vegetable or others of harmless origin only, should be recommended and used. We are equally sure that aniline colors are often substituted.
It would appear impossible to attempt to close an effort of this kind without the addition of an appendix. While another score of years may suffice to bring order out of chaos, in the nomenclature of such a work, we feel that an effort such as this must of necessity be very imperfect.
As before stated, we have tried to illuminate the fundamental work as well as the details of formulas, and will now say that, although we think the subject of flavoring extracts and essences is capable of being well defined, in each of their particular spheres, yet the addition of colorings, acidifying solutions, and the various substances usually added in the preparation of syrups (which, so far as the druggist is directly concerned, is the particular aim of such preparations), we would observe that to classify these does appear impractical. So far as colorings go, we have placed them in a "part" by themselves, but as to acid solutions, albumen solutions, and the like, we can only throw them together, as a banker just beginning business would his small change, to be properly arranged when it shall have grown to larger proportions.