496 APPENDIX. 



(46) Addition to p. 398, line 2 from bottom. Chondrin, when 

 treated with sulphuric acid, yields, according to Hoppe,* no 

 glycine, but only leucine. If sulphurous acid be passed through 

 a warm solution of chondrin, the latter is at first precipitated, 

 but afterwards undergoes decomposition with a development of 

 ammonia and the formation of leucine and other products. On 

 boiling with alkalies, chondrin is gradually decomposed with a 

 development of ammonia. On treating it with a stronger solution 

 of potash, or on fusing it with hydrated potash, there are formed 

 glycine, leucine, and other products of decomposition. (Hoppe, 

 however, could riot find tyrosine.) In the putrefaction of chondrin 

 there are formed, according to Hoppe, leucine and another crystal- 

 lisable substance, in addition to other products of decomposition. 

 On oxidation with chromic acid, it developes much prussic acid, 

 but neither formic nor acetic acid. 



Hoppe, who has more carefully analysed chondrin than any of 

 his predecessors, found 6'28 of salts in the substance in its 

 ordinary state, and only 0'68 in chondrin treated with acetic 

 acid. 



The following is his method of preparing this substance: 

 Cartilages are boiled for a short time, so as to effect the partial 

 solution of the perichondrium, and, after its removal, they are cut 

 into thin slices, macerated for some hours in cold water, and then 

 boiled in a modified Papin's digester for 45 minutes or an hour, 

 under a pressure of two or three atmospheres, by which means 

 the greatest part of the cartilaginous substance is dissolved. On 

 cooling the digester to 100, the fluid is filtered as rapidly as 

 possible, the filtrate evaporated, treated with cold water, the residue 

 again dried, pulverised, extracted with boiling alcohol, and then 

 dried at 120. To remove the inorganic salts we must precipitate 

 the solution of chondrin immediately after its first filtration \\ith 

 acetic acid, and after decanting the supernatant fluid, we must 

 treat the precipitate with water ; after the removal of the salts, it 

 is, however, somewhat difficult of solution in boiling water. 



(47) Addition to p. 453, line 7- Boussingaultf has recently 

 attempted to determine the amount of ammonia in the urine by a 

 new method, which depends upon the fact that all the ammonia 

 may be developed from dissolved ammoniacal salts when they are 

 evaporated to dryness in a vacuum with hydrated lime or carbonate 



* Journ. f. pr. Ch. Bd. 56, S. 129. 



t Ann. de Chim. et do Pliys. :i St'r. T. 29, p. 472. * 



