PROTEIN. 173 



cent, of a calcareous salt. He endeavoured to get a purer tannate 

 by precipitating a solution of protein in acetic acid by tannin. 

 596 parts of this last salt gave 1154 of carbonic acid, and 290 of 

 water. The volumes of carbonic acid and azotic gases were to 

 each other as 58 to 5. Hence the constituents were., 



Carbon, 52-80 



Hydrogen, 5 '41 



Azote, . 10*87 



Oxygen, 30-92 



100-00 

 He represents the composition of the salt by the formula, 



C 58 H 38 Az 5 O 23 resolvable into 

 1 atom protein, C 40 H 31 Az 5 O 12 



1 atom tannin, C 18 H 5 O 9 



2 atoms water, . H 2 O 2 



C 58 H 38 Az 5 O 23 



Protein-oxide of Lead. When a solution of protein in acetic 

 acid is mixed with a lead salt, a precipitate falls, composed of 10 

 atoms protein and 1 atom oxide of lead. If there be a great ex- 

 cess of acetic acid, the precipitate is composed of 5 atoms protein 

 and 1 atom oxide of lead.* 



Sulpho-bi-proteic Acid. If we dissolve albumen in acetic acid, 

 and add dilute sulphuric acid, we obtain a flocky precipitate, which 

 may be washed with alcohol. When dried at 266 it is a com- 

 pound of protein and sulphuric acid in definite proportions. It 

 was analyzed by Mulder. 132 parts of it gave 16 of sulphate 

 of barytes. Hence 100 parts contain 4*18 of sulphuric acid. 

 51 parts gave 95*2 of carbonic acid, and 31 of water. Hence it 

 contained, 



Carbon, . . 50-90 



Hydrogen, . 6-74 



Azote, . . 15-03 



Oxygen, . . 23-15 



Sulphuric acid, . 4-18 



100-00 

 The azote was not determined ; but calculated on the supposition 



* Ann der Pharm. xxxi. p. 131. 



