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.
This is a very annoying matter to the bottler, and a subject that has been frequently discussed in the trade. We are desirous of making the question clear, as far as we are able to do. Any beverage that holds some resinous matter in solution, as for instance ginger ale, will separate a slimy precipitate, if the water used contains lime or magnesia (provided no acid has been used), the resin having combined with the lime or magnesia to some kind of lime or magnesia soap. If tartaric acid has been used to acidify the syrup, this will unite with the lime, and throw down a precipitate of tartrate of lime, which is insoluble. The same happens to some extent if citric acid that was adulterated with tartaric acid has been used. Citric acid, when lime is present, forms citrate of lime, which is soluble in cold water, but the acid, and therewith the acidulous taste of the beverage, is neutralized to some degree. The salts of citrate or tartrate of magnesia are not readily soluble in water, and precipitate after some time. Therefore, in order to prevent these disagreeable occurrences, nothing but well purified, best only boiled, water should be used. A precipitate in ginger ale, even when pure water has been used, will occur, when an excess of resin is contained in the extract, that has not been sufficiently eradicated, to make the extract water soluble. Sometimes such sediments occur at intervals; the beverages may be at one time clear and bright, and another time prove the above difficulties - and still the same ingredients, and the same well-water has been used. Every rain changes the composition of the latter, as the water penetrates the earth's strata, dissolving, as we know already from Part First of this work, various minerals, and this accounts for the occasional occurrence of such sediments. Only a purification of water will remedy these changes. If pond or river water is used, which contains much nitrogenous matter, sewerage, decomposed animal and vegetable substances, the beverages generally precipitate the impurities, and assume a bad taste. If imperfectly prepared sugar coloring has been employed, and it has not been diluted and filtered before being added to syrup, the infinitesimal particles of sugar coal will precipitate in the beverage, forming a black sediment.
If glucose, instead of syrup, has been used, dextrinous matter and starch, contained in the impure substitute will separate in clouds; if any alcoholic liquid was mixed with the syrup, this separation will be even more pronounced. Glucose is favorable to fermentation. If the glucose was contaminated with sulphuric acid, this will act on resinous matter and lime similar to tartaric acid, besides being deleterious to the delicate flavors; with the lime it forms a precipitate of sulphate of lime, only slightly soluble in aqueous liquids.
By reckless charging of the fountain, marble-dust or whiting and sulphuric acid will enter the latter, and consequently the beverage, the marble-dust or whiting precipitating, and the sulphuric acid, causing the same mischief as mentioned before. Changes in the atmosphere may produce unfavorable results. Some oils are clear and transparent at a high and turbid at a low temperature, and certain oils which congeal at lower temperatures change the solutions to cloudy and thick. When the solution of cane-sugar, either by the fruit or mineral acids (to the latter we add also the sulphuric acid that enters the beverage by reckless charging), commences to be converted into invert-sugar, the beverage becomes usually cloudy, and when the modification is finished sediments occur frequently (see our explanations, page 608 and following).
If alkalines have been employed to make the extracts, etc., water soluble, they will absorb a considerable amount of resinous matter, and unless carefully removed the action of the fruit acids used to acidulate the beverages creates a slight ebullition, and there ensues turbidity and flakiness.
If clarifying powders are not carefully removed from the syrups by filtration, a precipitate in the beverage will be the consequence. If it should prove true that citric acid is a destroyer of microscopic life in water, as Dr. Langfeld has found by experiments (see page 87), and that these animalculae settle to the bottom after their death, it would furnish an explanation for some sediment where such an infected water and citric acid constitute a beverage.