The New Student's Reference Work/Acid
Ac′id, a term used in chemistry to denote a class of substances whose union with an alkali, or other base, forms salts. Strictly speaking, all acids contain hydrogen, and are, in fact, salts of hydrogen. Most of them have the following properties: they can be dissolved in water; they have a sour taste; they turn vegetable blues to red. The most common and useful inorganic or “mineral” acids are sulphuric, nitric and hydrochloric acids, which are manufactured on a very large scale. Among the organic acids are acetic acid, which gives vinegar its sour taste: citric acid, which produces the sourness in lemons; oxalic acid, which is found in sorrel and some other plants, and which in large quantities acts as a poison; malic acid, found in apples and also currants and gooseberries; tartaric acid, found in grapes and used in the manufacture of baking powder; prussic or hydrocyanic acid, a deadly poison, a small quantity of which is found in bitter almonds and in the leaves and stones of peaches. Many hundred acids are known to chemists, the greater part of which are artificial.