(INIMICAL BASIS OF THK ANIMAL BODY. 147 



1. jr///'.s i-i'iiction. 1 To the suspected solution a few 

 drops of very dilute sodium i; ] are 

 added, and then, drop by drop, sum.- dilute caustic soda If 

 kreatinin is prex-nt a fine but transient niliy-ivd colour is ob- 

 tained which speedily passes into yellow. If the solution is now 

 acidulated with acetic acid and \\aiined it turns at first greenish 

 and finally blue. 2 This last colour is due to the formation of 

 Prussian-blue. 8 Weyl's reaction is extremely delicate and suf- 



10 detect '0287 p. c. of kreatinin in pure solution, or '066 p. c. 

 in urine. According to Krukenberg the reaction is best obtained 

 by adding the caustic soda first and then a few drops of nm. ni- 

 trated solution of the nitro-prusside. (Juareschi recommends the 

 use of 10 p. c. solutions of the respective reagents. 4 



When applied to urine the absence of acetone should be ascer- 

 tained, since it also gives a similar ruby-red colour, but no sub- 

 sequent blue can be obtained from it, and the solution when 

 yellow turns red again on the addition of strong acetic aeid. 

 Hydantoin or methyl-hydantoin also yields the red colouration. 



2. Jaffe's reaction. 6 On the addition of an aqueous solution 

 of picric acid and a few drops of dilute caustic soda an intense 

 red colouration is produced. This suffices to detect '1 part of 



iuin in 5000 of water. Acetone alone gives a similar 

 colouration, but to a comparatively very feeble extent 



I'.v prolonged boiling of kreatinin with r'ehlinu's fluid, reduc- 

 tion takes place, but there is no simultaneous separation of cuprous 

 oxide, and it appears that kreatinin may prevent the separation 'f 

 the oxide when the reduction is due not to itself but to such a 

 substance as dextrose. 6 



7 Leucin. C,H,,NO S . [CH 8 . (CH,),CH(NH,)COOH]. 

 (a-Amido-caproic acid.) 



Is a characteristic product of the decomposition of proteids and 



gelatin whether by the action of boiling acids, caustic alkalis, or 



putrefactive influences. It occurs normally in variable amounts 



in the pancreas, spleen, t hymns, thyroid, salivary glands, liver, 



&c., and also in plants, more especially in those parts in which 



reserve materials are accumulated, such as bulbs, tub.-]>, and 



. It is also typically formed during the tryptic (pancreatie) 



lion of proteids to an extent which amounts on the average 



Ber. d. d. chem. Getell. 187 



- s.-iiuwski. /.t. /: /./M/.I/W. < '!,. n,i,.. iv. (iHso). s. m : \\. (1885), 8. 127. 



9 Krnkcnbere, \'< i/,.?,,,!. </. />//</-"/. ''>. VVnr/.lnirs:. IM. xvm. (1884), S. 5. 

 roiitiriii.'.l by SalkowBki. Cf ( '..lasanti, M.-l.-s.-h-.tt's Untert. Bd. xni. (1888), 

 Hf. 6. 



* Ann. di chim. t. difnrm - (1887), p. 195. 



i'. phyiol. Chem. Hcl. x. (ISHfi), S. 399. 



8 Worm Mull.-r. I'lliiger's Arc/,. IM. \\\ n. (1882), S. 59. 



