The first class include such changes as the alcoholic fermentation of sugar solutions, the acetic acid fermentation of alcohol, the lactic acid fermentation of milk sugar, and the putrefaction of animal and vegetable nitrogenous matter.
In the remedy just mentioned the salicylic acid forms the basis; but sometimes chloride of zinc or lactic acid is added to it to make it act more quickly, and these are the adjuvants.
Since Metchnikoff's introduction (see Longevity) of the use of soured milk for dietetic purposes-the lactic acid bacillus destroying pathogenic bacteria in the intestine-a great impetus has been given to the multiplication of laboratory preparations containing 'cultures of the bacillus; and in recent years much benefit to health has, in certain cases, been derived from the discovery.
Massart and Bordet, Leber, Metchnikoff and others have studied the phenomenon in leucocytes, with the result that while there is evidence of their being positively chemiotactic to the toxins of many pathogenic microbes, it is also apparent that they are negatively influenced by such substances as lactic acid.
The oxidation of the glycols led him to homologues of lactic acid, and a controversy about the constitution of the latter with H.
In 1780 he proved that the acidity of sour milk is due to what was afterwards called lactic acid; and by boiling milk sugar with nitric acid he obtained mucic acid.
It may be diminished or its increase prevented by a diet from which red meat and meat extracts are excluded, by the use of the lactic acid bacillus, by the administration of laxatives and cholagogues to regulate the bowels, and by the use of iodides and nitrites.
The Bacterium acidi lacti described by Pasteur decomposes milk sugar into lactic acid.
Although on structural grounds there should be only two hydroxypropionic acids, as a matter of fact four lactic acids are known.
Sodium amalgam or zinc and hydrochloric acid reduce it to lactic acid, whilst hydriodic acid gives propionic acid.