188 BACTERIOLOGICAL AND ENZYME CHEMISTRY 



solution. The precipitated albumin is carefully washed on a 

 filter pump, and finally dried in a platinum dish at a tempera- 

 ture not exceeding 100 C. It is necessary in this process to 

 use plenty of material to start with, as the losses by washing, 

 especially in the final removal of the copper, are apt to be con- 

 siderable. The preparation, however, is of much interest as 

 affording a means of obtaining albumin in a pure state and in 

 a form more convenient for investigation than that in which it 

 is commonly found. 



In the foregoing paragraphs the properties of a typical 

 albumin have been considered in some detail, apart from the 

 study of the products obtained when it is submitted to partial 

 decomposition. This study may now be followed up, keeping 

 always to the one typical substance, viz., egg-albumin. In the 

 light of the information thus obtained it will be easier to follow 

 the subsequent general description of other substances of a 

 similar nature. 



It has already been shown by qualitative examination that 

 on violently attacking albumin by such substances as strong 

 caustic soda, the presence of end products such as ammonia, 

 biuret and sulphuretted hydrogen could be detected. It is 

 obvious, however, that such a procedure gives us but little 

 information. Determinations by physical methods would 

 indicate that the molecular weight of albumin is probably 

 somewhere in the neighbourhood of 15,000. Its composition, 

 according to ultimate analysis, can be expressed within the 

 following limits : 



Carbon 50 to 55 per cent. 



Hydrogen 6'9 7'3 



Nitrogen 15 ,,19 



Oxygen 19 24 



Sulphur 0-3,, 2-4 



The information given by these figures is the same kind of 

 information that would be obtained in regard to the construe- 



