128 DEUTERO-ALBUMOSE. [BOOK II. 



The most characteristic property of hetero-albumose is the beha- 

 viour of its solutions when boiled, as well as the peculiar behaviour 

 of the undissolved body when the fluid in which it is suspended is 

 boiled. 



When hetero-albumose is suspended in water and boiled, it be- 

 comes completely insoluble in solutions of NaCl of all strengths. 

 During the process of heating the substance appears to melt, and 

 adheres in patches to the glass ; on cooling, it sets in masses, which 

 are either leathery or harder. 



Saturated solutions of hetero-albumose, containing 2 3 5 

 per cent, of NaCl, coagulate about equally, e.g. the turbidity pro- 

 duced is about the same in degree in the different cases. If, however, 

 the solutions have been diluted with from three to five times their 

 own volume of solution of pure NaCl, containing the same amount 

 of the salt as they contain, no precipitate is obtained when the 

 liquid is boiled or when it subsequently cools. The gradual addition 

 of acetic acid to these clear solutions causes, however, a turbidity, 

 which increases at first, but after a certain point disappears. Nitric 

 acid added to the fluid will now cause a fresh turbidity, which dis- 

 appears on adding a sufficient excess of acid. If to the cold solution, 

 which is clear and remains clear when boiled, strong solutions of 

 NaCl be added, a precipitate occurs which disappears, or nearly so, 

 on boiling, and reappears again on cooling. 



When to a solution of hetero-albumose only so much acetic or 

 nitric acid, respectively, is added, as will occasion a perceptible tur- 

 bidity, 'this is observed to increase as the liquid is heated, to disap- 

 pear when it is boiled, and to reappear in increased degree, when it 

 is cooled. 



Hetero-albumose, which has been suspended in water and rendered 

 insoluble by boiling the water, is found to swell and dissolve com- 

 pletely in HC1 containing between O'l and 0'2 per cent., but to be 

 almost insoluble in solutions of sodium hydrate (containing from 0'25 

 to 3 per cent, of NaHO). By its solution in hydrochloric acid the 

 coagulated substance appears to have been in part reconverted into 

 normal hetero-albumose, identical with the original substance, but in 

 part to have been changed into a substance identical with dys-albu- 

 mose. 



Acetic acid and potassium ferrocyanide render solutions of hetero- 

 albumose strongly turbid, the turbidity disappearing on adding a 

 sufficient quantity of the acid. When the reagents are added in 

 certain favourable proportions, it may be noticed that the turbidity 

 occasioned by acetic acid and potassium ferrocyanide disappears on 

 boiling the liquid, but reappears when it becomes cold. 



With copper sulphate and sodium hydrate, hetero-albumose gives 

 the biuret reaction, but it is to be noted that a very faint excess of 

 the copper salt suffices to conceal entirely the rose colour, which is 

 then covered by the well-known violet colour, characteristic of the 

 albuminous substances in solution. 



