LACTIC ACID

Alpha-hydroxy pro organic acid of considerable commercial importance. First prepared by Scheele in 1780 from sour milk. It occurs widely in nature, and may be prepared by the fermentation of sugar under certain conditions. It is manufactured on a commercial scale from starch corn, glucose and other substances by fermentation with a lactic acid ferment, the acid being neutralized with calcium carbonate as soon as formed, in order to prevent the solution becoming too acid, as the ferment will not grow in a liquor containing more than one-half per cent. acid. The liquor is then evaporated and filtered and the syrupy solution of calcium lactate, thus produced, decomposed with sulphuric acid. The acid occurs as a syrupy liquid, either yellowish brown or almost colorle , according to the degree of purity, having a specific gravity of about 1.24. It is soluble in water and alcohol, and has a sharp, acid taste. It is used in the tanning of leather for coloring and plumping, and for removing lime. In the textile industry, it is employed as a mordant, especially for woolen goods, to which it imparts lustre and softne . In medicine it is employed in the treatment of tuberculous ulcerations of the larynx, and to destroy diphtheritic membranes. <A recent use to which it has been put is in the preparation of baking powder. a contrivance for ascertaining the richne of milk. It generally consists of a graduated gla tube, the number of divisions, as a rule, being 100. This tube is filled with milk to the top of the graduated part, and the liquid is then allowed to stand so that the cream may separate. After a time it may be seen how many parts in a hundred the cream occupies.