ADDITIONS AND NOTES TO VOL. I. 463 



mentioned (vol. i, p. 84) that both Wohler and Ure discovered 

 that benzoic acid was converted in the animal organism into 

 hippuric acid, and eliminated as such with the urine. The subse- 

 quent observations of Erdmann and Marchand* having shown 

 that cinnamic acid undergoes a similar metamorphosis., it became 

 a point of interest to ascertain whether the other acids homologous 

 to benzoic acid, namely, toluylic and cumic (or cuminic) acids, were 

 also transformed into hippuric acid ; but this is by no means the 

 case, as is shown by the independent investigations of Hoffmann f 

 and of Ranke.t Moreover, the acids which are homologous to it in 

 their amount of carbon and hydrogen, as salicylic acid, anisic acid, 

 and cumaric acid, pass, like those previously mentioned, in an 

 unchanged state into the urine, as was shown by Rankers experi- 

 ments. 



(19) Addition to p. 218, line 4. Scherer has found uric acid 

 in considerable quantity, as a normal constituent, in the juice of 

 the spleen. [Mr. Henry Gray (see his Prize Essay " On the 

 Structure and Use of the Spleen," London, 1854, p. 209), being 

 anxious to confirm the observations of Scherer regarding the 

 presence of uric acid and hypoxanthine in the spleen-pulp, worked 

 in one experiment on the spleens of twenty-five oxen, but wholly 

 failed in detecting either of these substances ; nor was he more 

 successful with human spleens. G. E. D.] 



(20) Addition to p. 235, line 10. Pneumic (or pulmonic) acid 

 probably belongs to this group of conjugated nitrogenous acids. 

 This acid, of which as yet we know very little, was discovered by 

 Verdeil|| in the tissue of the lungs. The minced pulmonary tissue 

 is stirred with water and exposed to strong pressure ; the decanted 

 acid fluid is heated in order to coagulate the albumen, and is then 

 filtered, neutralised with baryta-water, and evaporated to three- 

 fourths of its volume. After the removal of albuminous and some 

 other matters by sulphate of copper, and the excess of the copper 

 by sulphide of barium, we evaporate the fluid till crystals of 

 sulphate of soda are formed ; we then add a little sulphuric acid, 



* Journ. f. pr. Ch. Bd. 35, S. 307 309. 

 t Ann. d. Ch. u. Pharm. Bd. 74, S. 342. 

 + Journ. f. pr. Ch. Bd. 56, S. 3-6. 



Verhandl. d. phys.-med. Ges. zu Wurzburg. Bd. 2, S. 299. 

 || Compt. rend. T. 33, p. 604, and Traite de Chimie anatomique et physio- 

 logique. T. 2, p. 460. 



