CHEMICAL i:.\sl> <F THK ANIMAL BODY. 1.', 



CLA II. />> :ri'-'d AUmmimt (Albtiminates). 

 \ . Acid-albumin. 



When a native iilluiniiii in solution. such as egg- or serum- 

 albumin, is treated for some little time with a dilute acid, such 

 us hydrochloric. its properties become entirely changed" The 

 :n;irU.-il changes are (1) that tin- solution is no longer eoa^- 

 ulaj_ed by lii-;it : ( _ ) that when the solution is can-fully neutral- 

 ised the whole of the proteid is thrown down as a ]>rt'ci])itatG ; in 

 other words, the serum-albumin, which was soluble in war 

 at least in a neutral fluid containing only a small |iiantity <>f 

 neutral salts, li^s become converted into a substance insoluble in 

 \vatyr "i" in similar m-ntral thuds. The Imily into which scrnni- 

 albiimin thus becomes converted by the action of an acid i< 

 spoken of a< "i-iil-ullniiiiiii. Its characteristic t'eatnn-s are that it 

 is insolultlc in distilled water, and in neutral saline solutions, 

 such asj.hose of godic chlddde. that it is readily solulde iii"dUnte 

 njMds or dilute alkalis, and that its solutions in acids or alkalis 

 ar" pot- po:nrnla^d by builing. (When suspended, in the undis- 

 solved state, in water, and heated to 75 C., it becomes coagulated^* 

 and is then undistinguishable from coagulated serum-albumin, or 

 indeed from any other form of coagulated proteid. It is evident 

 that the substance when in solution in a dilute acid is in a dif- 

 t'.'ivnt condition from that in which it is wln-n precipitated liy 

 neutralisation. It' a quantity of serum- or e^-albumiii be ti 

 with dilute hydrochloric acid.it will lie found that the eon version 

 of tin- natrve albumin into acid-albumin is gradual ; a specimen 

 heat'-d to 75 C. immediately after the addition of the dilute acid, 

 will coagulate almost Bfl usual: and another specimen taken at 

 the -;ime time, will give hardly any precipitate on neutralisation. 

 S.ime time l;iter the interval depending "ii the proportion of the 

 acid to the albumin, on temperature, and on other circumstances, 

 the coagulation will be |e88, and the neutralisation precipitate 

 will be , on^iderable. Still later tin- coagulation will be ab-ent. 

 and the whole of the proteid will be thrown down on neutrali- 

 "ii. 



i-i.iivi-r>i<'ii "f tin- native albiiinins in s,,lnti..i, int.. a.-i<l-:dl.uinin 

 l.y dilute arid- i> facilitated Iy heatiiij,-; f t'-ni|>erat un-s l.i-l.>\\ 

 at wliicli tin- albumins respe.-t ivelv n.a^idate. ' Tlie n\ i-rsmn 

 treiiidv rapiil it :i str>n^ acid is adiled tT. a <-..n. rut rated s..luti..n <-f 

 tin- ].n.tei.|; thus when a little ^la.-ial iOStlC Mid : "it., muli- 



lllted \\Ilite of ,-^ the wh-.l.- -. .| i. I i lie. lilt., a \ell-.\N t Fa II- | .11 Tell t jelly 



. .. .\kd H.I. i.xxxiv. (1- 



Arch. I:.! I 



