128 MATER i A MEDIC A AND THERAPEUTICS. 



nitric acid to destroy chancres ; acetic acid, warts ; sulphuric 

 acid, some forms of malignant growths. Very dilute watery 

 solutions, sponged on the skin in fever, cool the surface by 

 evaporation, and thus act as refrigerants ; whilst watery solu- 

 tions of sulphuric acid used in this way appear to constringe 

 the tissues, and diminish the sweating of phthisis. 



Internally. In the dilute form, acids act directly upon the 

 contents of the alimentary canal, and are used in the treatment 

 of poisoning by alkalies. In every instance the free acids 

 quickly unite with bases in the digestive tract, and form neutral 

 salts. In the mouth they are stimulants and sialagogues : 

 they relieve thirst, rouse the appetite, and aid digestion by 

 increasing the flow of saliva and gastric juice, the citrates, 

 tartrates, and acetates being chiefly used for this purpose as 

 acid drinks and fruits of great variety, e.g. in fever. In the 

 stomach hydrochloric acid increases the acidity of the gastric 

 juice, and is given for this purpose during or after meals, as 

 a powerful stomachic. Carbonic acid, introduced in effervescing 

 wines and waters, has a grateful sedative action upon the 

 gastric nerves ; and in the form of champagne and effervescing 

 mixtures is a most valuable remedy in the treatment of sickness 

 with exhaustion. The other acids assist gastric digestion but 

 to a very small, possibly useless, extent. Reaching the duo- 

 denum, acids increase the acidity of the chyme and stimulate 

 the liver, pancreas, and intestinal muscles and glands. Dilute 

 nitric and nitrohydrochloric acids, given at the end of meals, 

 are therefore used as cholagogues in intestinal dyspepsia with 

 hepatic torpidity, especially in tropical cases. 



2. ACTIONS ON THE BLOOD AND THEIR USES. 



Acids render the blood less alkaline (but never acid, even 

 in poisonous doses) , by combining with part of the alkali of the 

 liquor sanguinis. No special use is made of this property. 

 Phosphoric acid increases the phosphates in the red corpuscles, 

 and is thus hsematinic. The vegetable acids, when given as 

 salts of the alkalies, have an important deoxydising effect on 

 the blood. For example, citrate of potash becomes converted 

 in the blood into carbonate of potash, carbonic acid, and 

 water, a portion, however, of the citric acid always remaining 

 unoxydised (see Potassium], thus : 2(K 3 C 6 H 5 7 ) -f- 18 (in blood) 

 = 3(K 2 C0 3 ) + 5H 2 0, + 9C0 2 . Citrates, tartrates, and acetates 

 of potash, soda, ammonia, etc., in the effervescing form, may 

 therefore be used to set free in the blood the carbonates of the 

 alkalies, which cannot be so conveniently or safely given in 

 large doses by the stomach. The vegetable acids have been 

 used in the treatment of scurvy, apparently with doubtful 



