UIK.MK'AL IIASIS OF TIIK ANIMAL BODY. 191 

 line crusts remains in the mother-liquors from which the tyrosiu 



lias lirrll M-parat.'d. 



Apart fn-iii its crystalline form and characteristic solubilities 

 tyrosiu may he ivadily recognised ly several well-marked 

 n-actions. 



Hi'ri'in HHH'* i-i'irtio/i. When heated with Millon's reagent so- 

 lutions of tyrosiu yi.-ld a hrilliant crimson or pink colouration 

 which, if much tymsin is present, is accompanied tinally l>y a 

 similarly coloured precipitate. Tin- test in its original form was 

 applied liy heating with a M>lutim of mercuric nitrate in presence 

 of nitrous acid. 1 



1'iriti'x /ox/inn? If tyrosin is moistened on a wateh-ojass with 

 etinci-ntrated sulphuric acid and warmed for rive or ten minutes 

 on a water kith, it turns pink, owini: to the formation of tyrosin- 

 sulphonic acid C 9 H 10 (SO,OH) NO, + 2H 8 0. Tliis is then diluted 

 with water, warmed, neutralised with kirinm < a rlion ate, and filtered 

 while, hot. The filtrate yields a violet colour on the careful addi- 

 tion i if very dilute peirhloride of iron. The colour is readil 

 stmyed hy any 6X0688 of the iron sah. :; 



Tiie remarks made mi p. 149 on the optical properties of leucin, 

 apply also to tyrosin. 4 



\Yhen tyrin i- Mihject.-d to putrefactive decomposition it yields 

 paraoxyphenylacetic acid OH . C 6 H 4 -CiL .<(( )[|.. pwaozyphenrl- 

 in-i-jiiniiif (hydropaiacomarie) acid <II . < ,.II 4 ( 'H.- ( II .' <n>n.. 

 /^-jilieiiN l]ir'>]ii<iiiii > -(hvdriicinu;iiiiir) acid (',-,11 . < II . < II . < ><>M.. 

 phenol, !',H, . OIL, and paral<n->,d CH, . C,H 4 . <ML 5 These >ul.- 

 >Jam-fs occur normally in Miiall and varialdi- amounts in uriiu- and 

 an- mcriMM-d in (ju;intity in tins excretion !>y tin- administration of 

 :\T"-in. Their presence is \\itliout dmibt cliit-tly due to j.ntrt i 



.'(c.urrin^ in the alimentary canal in corre>[>ondencc with tin- 

 facts that the bodies in question are found most markedly in the urine 

 of herl.ivora, in increased quantity in that of men under ft regetablfl 

 .nid largely disa|i]iear under the intlueiice of drills Midi ;t-> calo- 

 mel. which likens or prevents the occurrencr 'f putrefactive changes 

 in the intestine. 6 In the absence of thoe putrefactive pi. 

 ro> in when administered m not excessive amounts i> apparent!;. 

 pletely o\idi-ed and does not. as frequently stated. ^: to any 



increa~ed output of urea. 7 In large (lose.s tyro>in reappears externally 



1 I. ifhip's Ann.il. l',.i. I.XXXMI. (1S.VJ). S. 



- I.i.-t.i-'s At,,,,,!. IM i.xxxi: - L'.'H 



* For other !...< imp.. riant n-:u-tii.ns see \Vnrntrr. ' f. Pkytiol. Bd. I. 

 (1887). S. l'J4. l'.lran>/.ky. Zt f. i>h,/si,J ( t,,m. 1M. xn. (is.sS). S. 355. 



-<: Maiitliurr, I/ --'), alao Si: 



. li.l LZZXT. (1883), April-Hft. Srliul/.r. / 

 (1885). Sn l.i|i)>in:iiiii. /.'" ./. /. dum, Cettll. 1884. S. i83. 



\V-vl, Zt. f. |MM ( !,.,. ll.l. Ill I liatiinaiiii. I'-nl. lit! i\ 



S. 304. Sehottan, ///. n.i. MI. (18 - H /' d. 



li.iiiinaiiii, />'i'l. s 



Bauniai.n. /4. f } ,h<niol. Chem. IM x - 129. 



Mllt/.-M 11 Nrn.kl. /J / /.V- IM MM. 



/>;. ! 1-71 Mrii-'ger. 'A. f. /'A V W. Cl,.i. H.l u (1*7*). G 



H.'.hinann. fieri, kiln. U'orhentch. 1888. " Nrn. 43, 44. I'ol.: . -/io/. Chem 



H.I \i\ (1- 



