ACIDUM SALICYLICUM. 333 



and the former is in turn broken up into salicyluric (HC 9 H 8 N0 4 ), 

 salicylic, and salicylous acids (C 7 H 6 2 ). Salicylous acid is a 

 local irritant. 



2. ACTION ON THE BLOOD AND ITS USES. 



Salicylic acid necessarily exists in the blood as the salicylate 

 of soda, being taken up with considerable rapidity. The acid 

 is possibly again liberated in part by the free carbonic acid of 

 the plasma in inflamed parts of the body, and thus exerts its 

 antiseptic action within the body ; but this is doubtful. Either 

 in the blood, or in some of the tissues, a portion unites with 

 glycocoll (just like benzoic acid), and forms salicyluric acid 

 (comparably with hippuric acid), thus : C 7 Hgp 3 + C 2 H 6 N0 2 

 (glycocoll) = H.CgH 8 N0 4 (salicyluric acid) + H ? 0. 



As regards salicin, the decomposition begun in the bowel is 

 continued in the blood. 



3. SPECIFIC ACTION AND USES. 



The action of salicylic acid and its sodium salt is identi- 

 cal in the tissues, since the former is converted into the latter. 

 A moderate dose causes increased cardiac action, flushing and 

 warmth of the surface, perspiration, a full feeling in the head, 

 tinnitus, deafness, impairment of vision, and possibly a slight fall 

 of temperature, although the nitrogenous waste is said to be 

 increased. Larger doses may cause delirium. Respiration 

 is temporarily disturbed ; the heart is depressed after the 

 primary excitation ; the vessels are relaxed, and the blood 

 pressure falls ; perspiration is increased ; the peripheral nerves, 

 both sensory and motor, are unaffected. 



All these phenomena in the healthy subject, taken 

 together, do not account for the remarkable effect of salicylates 

 upon the body temperature in pyrexia or fever. Of all anti- 

 pyretics these appear to be the most powerful, two or more 

 moderate doses (15 to 20 gr.) within one or two hours re- 

 ducing pyrexial temperatures several degrees, according to 

 the disease and the subject. It is therefore probable that the 

 salicylates act upon some pathological cause of pyrexia, possibly 

 the organisms of the specific fevers. 



Salicylate of soda is employed in two allied but distinct 

 classes of cases : 1. In pyrexia from any cause, such as typhoid 

 fever, pneumonia, pyaemia, etc., it is a simple and powerful 

 antipyretic. In this respect it is comparable with quinia ; 

 only more rapid in its action, less lasting in its effects, and 

 more depressant to the circulation. It may be given in these 

 diseases in single full doses when the temperature exceeds a 

 certain height, say 104 Fahr. 2. In acute rheumatism, salicylate 



