868 APPENDIX. 



2. Serum-albumin is not coagulated by being shaken up with ether ; egg-albu- 

 min is. 



3. Serum-albumin is not very readily precipitated by strong hydrochloric acid, 

 and such precipitate as does occur is readily redissolved on further addition of the 

 acid ; the exact reverse of these two features holds good for egg-albumin. 



4. Precipitated or coagulated serum-albumin is readily soluble, egg- albumin is 

 with difficulty soluble, in strong nitric acid. 



5. Egg-albumin, if injected subcutaneously or into a vein, appears unaltered in 

 the urine j 1 serum-albumin similarly injected does not thus normally pass out by the 

 kidney. 



[6. Gautier states that 10 c.c. of the following solution, added to 2 c.c. of the 

 solution to be tested, will precipitate egg-albumin but not serum-albumin : Caustic 

 soda, sp. gr. 0.7, 250 c.c. ; 1 per cent, sulphate of copper, 50 c.c. ; glacial acetic 

 acid, TOOc.c.J 



Serum-albumin is found not only in blood-serum, but also in lymph, both that 

 contained in the proper lymphatic channels and that diffused in the tissues ; in 

 chyle, milk, transudations, and many pathological fluids. 



It is this form in which albumin generally appears in the urine. 



In addition to the above, Scherer 2 has described two closely related bodies, to which he gives 

 the names paralbumin and metalbumin. The first he obtained from ovarian cysts ; its alkaline 

 solutions are remarkable for being very ropy. It seems doubtful whether this body is a proteid ; 

 it differs sensibly in composition from these. Haerlin 8 gives as its composition, O. 26.8, H. 6.9. 

 N. 12.8, C. 51.8. S. 1.7 per cent. It seems to be associated with some body like glycogen, capable of 

 being converted into a substance giving the reactions of dextrose. Metalbumin, found in a drop- 

 sical fluid, resembles the preceding, but is not precipitated by hydrochloric acid, or by acetic acid 

 and ferrocyanide of potassium ; it is precipitated, but not coagulated, by alcohol ; its solution Is 

 scarcely coagulated on boiling. 



Albumins are generally found associated with small but definite amounts of 

 saline matter. A. Schmidt* says that they may be freed from these by dialysis, 

 and that they are then not coagulated on boiling. From this it might be inferred 

 that the albumin and the saline matters were peculiarly related, and that the 

 latter played some special part during the coagulation of the former by heat. 

 Schmidt's observations, however, have not been conclusively corroborated by sub- 

 sequent observers. 



CLASS II. Derived Albumins [Albuminates]. 

 1. Acid -albumin. 



When a native albumin in solution, such as serum-albumin, is treated for some 

 little time with a dilute acid, such as hydrochloric, the properties become entirely 

 changed. The most marked changes are: (1) that the solution is no longer 

 coagulated by heat ; (2) that when the solution is carefully neutralized the whole 

 of the proteid is thrown down as a precipitate ; in other words, the serum-albumin 

 which was soluble in water, or at least in a neutral fluid containing only a small 

 quantity of neutral salts, has become converted into a substance insoluble in water 

 or in similar neutral fluids. The body into which serum-albumin thus becomes 

 converted by the action of an acid is spoken of as acid-albumin. Its characteristic 

 features are that it is insoluble in distilled water, and in neutral saline solutions, 

 such as those of spdic chloride, that it is readily soluble in dilute acids or dilute 

 alkalies, and that its solutions in acids or alkalies are not coagulated by boiling. 

 When suspended, in the undissolved state, in water, and heated to 70 C. , it be- 

 comes coagulated, and is then undistinguishable from coagulated serum-albumin, 

 or indeed from any other form of coagulated proteid. It is evident that the sub- 

 stance when in solution in a dilute acid is in a different condition from that in 

 which it is when precipitated by neutralization. If a quantity of serum- or egg- 

 albumin be treated with dilute hydrochloric acid, it will be found that the con- 

 version of the native albumin into acid-albumin is gradual ; a specimen heated 

 to 70 C. immediately after the addition of the dilute acid, will coagulate almost 

 as usual ; and another specimen taken at the same time will give hardly any 



1 Stokvis, Rech. exp. sur les Condit. pathol. de 1'Albuminurie, Bruxelles, 1867; also Lehmann, 

 Arch. f. Pathol. Anat., Bd. xxx. (1864), S. 593. 



2 Ann der Chem. und Pharm., Bd. Ixxxii., S. 135. 



8 Chem. Centralblatt, 1862, No. 56. * pfliiger's Archiv, xi. (1875), S. 1. 



