This section is from the book "A Treatise On Beverages or The Complete Practical Bottler", by Charles Herman Sulz. Also available from Amazon: A Treatise On Beverages.
Tartaric acid should never be used to acidify syrups or beverages colored with aniline red, as it affects and precipitates the color, so that all coloring disappears. This fact should especially be borne in mind in compounding strawberry, raspberry, etc., syrups. Tartaric acid also cannot be employed to acidify beverages that are made up with water containing carbonate or sulphate of lime or magnesia, or that is not carefully freed from these salts. It has a great inclination to combine with the latter, being a strong bibasic acid, and forms tartrate of lime or magnesia, insoluble in water and causing a precipitate, which is so oftentimes the cause of complaints in the trade. Citric acid is not as troublesome, and its combinations with lime or magnesia are soluble in water; therefore it is preferable where "hard" water is to be used. However, also in this case only pure water should be employed, as the citrates of lime and magnesia rather act as laxatives than produce the intended acidification of the beverage.