PROTEIN. l.S 



f . Potash and protein. On the addition of protein to a concen- 

 trated solution of potash, and submitting the mixture to ebulli- 

 tion decomposition takes place, and a crystalline substance, two 

 distinct extractive matters, and formate and carbonate of am- 

 monia are produced. After the alkaline solution has been neu- 

 tralized as completely as possible by sulphuric acid ; the formic 

 acid may be removed by gentle distillation. 



On evaporating the mixture to about one third of its volume, 

 the greater part of the sulphate of potash will separate in a 

 crystalline state. 



After its removal, the fluid which is of a reddish brown 

 colour must be reduced to the consistence of an extract, and 

 then treated with boiling alcohol, which will take up everything 

 except any sulphate of potash that may have escaped previous 

 removal. As the alcoholic solution cools, erytJiroprotid is depo- 

 sited, in the form of a reddish brown extract. It is readily solu- 

 ble in water, and in boiling, but not in cold, alcohol ; and it is 

 precipitable from its aqueous solution by the salts of lead, silver, 

 and mercury, of a rose-red colour : it is also precipitable by 

 tannic acid. From an analysis of the combination of erythro- 

 protid with oxide of lead, Mulder has estimated its composition^ 

 at C,3 H, N O3. 



Subsequently to the deposition of erythroprotid, leucin se- 

 parates in a crystalline state. It occurs in brilliant plates or 

 scales, somewhat resembling cholesterin. It cranches between 

 the teeth, is inodorous and tasteless, and subKmes unchanged 



tation in tlie amount of oxidised protein must produce inflammation, -whicli may in 

 its turn determine fever. Hence also it happens that stimulating foods and drinks, 

 which quicken the respiration, or cold air, which introduces more oxygen into the 

 lungs, often give the first impidse to the development of inflammation in the organism. 

 The buff"y coat is formed when the oxides of protein predominate in the blood ; when 

 they accumulate in any particular part of the system, local inflammation is the residt. 

 In the latter case, morbid products, e.g. false membranes, &c., are evolved, which 

 are found on analysis to be in a great measure composed of oxidised protein. Now 

 inflammation must be combated by endeavouring to diminish the quantity' of the 

 tritoxide of protein, and to hinder its formation in the lungs. Venesection proves 

 antiphlogistic by directly diminishing the tritoxide of protein : increased secretion 

 of the aUmentarj' canal indirectly produces the same effect by accelerating the change 

 of substance in the body, and consequently also the consumption of a greater quan- 

 tity of protein and its oxides. 

 ' See Appendix I, Note 4. 



