179 



no alteration. Amongst tbe Protein-substances are classed albumin, 

 fibrin, casein, legumin, &c., and which bear the same relation to 

 each other as cellulose, starch, gum, sugar, &c. The bodies 

 belonging to each of these two series, have nearly the same 

 chemical composition and are convertible into each other, while 

 the one aeries comprises the nitrogenised compounds which pre- 

 ponderate in the animal kingdom, the other the cai-bohydrates 

 predominating in the vegetable life. These latter may be con- 

 sidered to contain as their radical the cellulose ^Ci2 Hio Oio; 

 starch having the same composition, while gum and sugar contain 

 in addition one equivalent of water. 



Mulder tried to show that those nitrogenised substances con- 

 tained also a common i-adical, which is combined in the various 

 Protein substances with varying quantities of sulphur and partly 

 also of phosphor. He named this radical Protein, and expressed 

 its composition by the formula C36 H05 N4 Oio, which demands 

 in 100: 57-29C, 6-64H, 14-85N, and 21-220. In the free 

 state, and combined with two equivalents water, ]Muldei''s Pi'O- 

 tein is obtained by dissolving any of the abovenamed matters in 

 potash-ley, boiling the solution until, by addition of an acid, 

 sulphuret of hydrogen is evolved, neutralising carefully Avith 

 acetic acid, and washing the gelatinous deposit with water. When 

 freshly precipitated it is a transparent, grey, llocky mass, which 

 becomes hard and brittle after drying, inodorous and tasteless; 

 fuses by heat, yields ammoniacal and other products, and leaves a 

 slowly, but completely combustible coal; it sinks in water, swells 

 up and resumes a gelatinous appearance; is insoluble in water, 

 alcohol, ether, oils. By continued boiling with water it is pai-- 

 tially dissolved, but at the same time altered in its pro})erties. 

 Acetic, tartaric, citric, malic and phosphoric acids dissolve it 

 readily, also diluted mineral acids; concentrated acids throw down 

 from the solution a combination of Protein and acid, insoluble in 

 the liquid. From the acid solutions the Protein is precipitated 

 by ferrocyanide and ferricyanide of potassium, tannic acid, most 

 of the metallic salts and by neutralisation with an alkali. Diluted 

 sulphuric acid colours Protein purple-i-ed on boiling. Concentrated 

 hydrochloric acid dissolves it with indigo-blue colour, the solution 

 turning black on boiling. Concentrated nitric acid colours it 

 yellow. Nitrate of mercury, containing nitrous acid, produces on 

 warming a red tinge. With sugar and sulphuric acid it assumes a 

 beautiful pur])le violet colour. 



According to recent investigations the above Protein retains 

 more than 1 per cent, of sulphur, from which it cannot be freed. 

 It is on this account that the Protein-theory has been abandoned 

 by many chemists, though, to my belief, without a just ctiuse, as 

 the proportions of the four elements C, H, N and O to each other 

 are not altered by the presence or absence of sidphur. Besides 



N 2 



