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.
Some commercial lime juice obtained in the open market has been found by analysis to contain a large proportion of sulphuric acid. It needs no explanation but common sense to decide that such an artificial product is absolutely unfit for manufacturing carbonated beverages.
Filter about half an ounce of the suspected juice through white filtering paper into a small, clean and transparent wine glass. To this is added about an equal quantity of a saturated solution of chloride of barium, and the mixture is well stirred with a glass rod. If even a trace of sulphuric acid be present, it forms the insoluble sulphate of barium, which precipitates. If the latter is collected on a filter and dried, the degree of adulteration may be ascertained. Each grain of the powder will represent about one-third of a grain of anhydrous sulphuric acid.
Lime juice is introduced in carbonated beverages at the discretion of the bottler, whose taste is his only criterion. A marked improvement is claimed by many, who are much taken with what they call the "fruity flavor" imparted by lime juice. The quantity depends upon the nature of the drink.