Acidum Lacticum. Acid of Milk may be obtained, by the process termed "viscous fermentation," from Milk, the juice of the Beet, Turnip, Carrot, &c.; indeed, it is formed whenever sugar in solution of whatever kind is placed in contact with an alkaline or earthy carbonate in presence of a ferment, as, for example, the casein of milk (Pelouse). It occurs in the form of a colourless syrupy fluid of a very sour taste. Sp. Gr. 1.215. The formula of the Hydrated Acid is C6H5O5 + HO; or, considered as a Bibasic Acid, CI2H10O10 + 2 HO. The Lactates of Magnesia and Soda have been proposed as therapeutic agents by M. Petrequin.*
Med. Prop. and Action. Taken internally, Lactic Acid produces no sensible physiological effects. It is supposed to act as a digestive; and as Lactic Acid exists naturally in healthy gastric juice, it is not improbable that in cases where this acid is morbidly deficient, it may be advantageously supplied by means of this artificial product (see Dyspepsia infra). Considerable interest attaches to this acid from the experiments of Dr. Richardson, who, acting on the suggestion of Dr. Prout, that an accumulation of this acid in the system was the cause of acute Rheumatism, instituted a series of experiments, by injecting a solution into the peritoneal cavity of dogs, from which it appears that though it is not proved that Lactic Acid is the true cause of rheumatic endocarditis, yet it is certain that the acid introduced into the circulation is sufficient to produce such an endocardial condition. The subsequent observations of Moller and Rauch tend to confirm the views of Dr. Richardson; whilst those of Dr. Reyher§ throw some doubt on the correctness of the conclusions of previous observers. It is to be hoped that further investigations will be made on this interesting subject.
The Dose of Lactic Acid is fl. drru. j. - fl. drs. iij. daily, in the form of lemonade, sweetened with sugar, or made into lozenges.
In Dyspepsia, it was first introduced by Magendie, who considered that he derived great advantage from its use. Its value has also been attested by Dr. C. Handheld Jones, || who employed it chiefly in cases of irritative Dyspepsia when the digestion was painful and imperfect, and had been so for some time. He does not advise its use at the commencement of the treatment of a severe case, but only after the irritation is somewhat reduced. The dose is exv. - exx. in f ss. of water taken at meal times; it seems then to mingle with the food, and to supply one of the constituents of healthy gastric juice, which is probably imperfectly produced. Its use need not be confined to cases of Dyspepsia, but may be extended to all cases where it is desirable to improve the tone and power of the stomach. Dr. O'Connor,* who reports favourably of it in dyspeptic cases, regards it as superior to Pepsin, an opinion opposed by Mr. Squire, To obtain good effects, it is essential that the acid should be pure and of good quality, which is not generally the case with that sold in the shops.
* Ranking's Abstract, xxxvi p. 134, 1862. Med. Times, Nov. 28, 1857. Virohow's Arehiv., Bd. xx. Heft.
L and ii. p. 211.
§ Brit. and For. Med-Chir. Rev., Jan. 1862, p. 253.
|| Assoc. Med. Journ., July 14,1854.
1697. In Phosphatic Deposits, and also in those of the Oxalate of Lime in the Urine, Lactic Acid, from its solvent power over these two substances, has been resorted to, but apparently with no very marked results. Dr. Challier found that it acted as a ready solvent of Uric Acid: hence he was led to suggest its use in Lithiasis. From its power in these cases, it has been recommended in the treatment of Gout,§ but evidence of its practical utility is not adduced.