( HK.MK Al. BASIS OF THK ANIMAL 



>t;tt'- of transition, MI that it i> on tin- whole advisable to ;_;i\e 

 some acciiuut of th'- oldei work U well a- of tin- lnic ivet-nl. 



i,,irnti<iii "J ji' />' I r this tin- \\ \l.il\ ' lleith.- 



Hennino.-i. ' K"-s,d. 4 Hofmeister,* and I.<'\\ >hould be consulted. 

 The oeneral properties and reactions ..t th.- peptones obtained by 

 tin- aln.v.- authors may In- stated as follow.-. A- piv, -ipitate.l l.y 

 alcohol th.-y c.,u-ist of a whit ..... ' \.-llo\vi>h j.o\vdt-r. which is 



.sr,.pie and extraordinarily soluhh- in water. and in some 



11 be deliquescent 1'nle-- thorooghly dehydrated 



the ]>o\vdcr ma\ melt on tomtit- \\anniiiL: Kroni tln-ir neutral 



aqueous solutions they ;nv j.reeijiitated \\ith ditlieulty by a large 



of alcohol, bein^r unchaiiued in the ].ro.-->s and not becom- 



'adulated or insoluble by prolonged e\)H.sun- to the action of 

 the jireeijiitant. The ])recipitation occur.- with ditlieulty if at all 

 in ]>re-cncr ..f hydrochloric acid Peptones are not jTeeijiitated 

 by many of the reagents \\hich precipitate other ]>roteids, but are 

 ]ireeij.itat'Ml by taiinie acid, mercuric chloride, nitrates of mercury, 

 and by phoephotungStic and ]>hos]ihomolyhdic acids in jin-scncc of 

 hydrochloric or other mineral acids: al-o by the doul>le inlide> of 

 ].ota>sium and mercury or potas^inni and bismuth, in ]-r. 



:on^ mineral acids. A very characteristic reaction is the 



' biuret ' or jiiitk coloration which is obtained on the addition of 



of caustic soda and a inert trm-f of sulphate of copper. 



The sli^hte-t eZCeSfi of the copper salt ^ive> a violi-t coh 



is the case with all other pioteid.v whirh deepen- in tint on b(il- 



iii'_ r This biuret reaction is however now known to be yielded 



al-o by the albillll<>-es (see above). IVptolies are all 



and diflusible. 



The <littiisil.ility 'f peptones is relatirel;/ ^reat in comparison \\ith 

 that ot' otlier forms of pr..tenl- : it l- ho\\,.\ .-r iif/so/uf- />/ small \\li.-n 

 compared with that of cr\ .-tal 1 im- Mihstam-.- -uch as Miiliiini chlori<lf. 

 and licMicr thi-v mav be separated from admix. -.1 salts l.\ dial\si-. \1 

 statements as to their :ds-lute <littiisil.il it \ . a- ba-e,| on .-arli.-r state- 

 ments. mn-t however b. I \\ith caution, in view of tin- t: 



ti, ,],:,' ,iir information a- t.. the properties ,,f the true 



lias 1 ..... 11 obs.-rved that the complete separation 

 .,f p.-ptune'< from .ill";: :''! by taking ;i dvantaoe .,! the 



fa. -I that the litt.'i an all com].le(elv piecipitable b\ 

 with neutral ammonium sulphate. VtteiBU th not. 7 



I'.y means of this .liileivnce iii the behaviour of the two classes of 



1 1 'Humor's .\<-rh IM. ix 



- /.i. /; ,,l,,, s i,,i. Ckem. H.I 



" I).- l;i iiiitnn- i-t .In n'.l- j.hx -.i..l.iu'i'| ..... I' 1 -- PapttW* 

 /.i. I. ,,!,,,..., I. </,. IM III. (If 

 / 1881), S 



. ; - I , i;.| vxx. :i- 



- \\ 15,1 \MI u--.,! S.I I '.indl.d. Mlurkut.-mrd 



Ver. llri.|.-ll..-r._'. IM ni 1888 - '-'86 



