726 PHYSIOLOGICAL CHEMISTRY. 



whatever in its detection, as heat will precipitate it in most cases from 

 an acid, neutral, or sometimes even alkaline urine ; the precipitate 

 should, however, always be tested by the addition of a few drops of 

 nitric acid, and the previous addition of a few drops of acetic acid is 

 also advisable. 



Quantitative estimation of albumin. The average amount of 

 albumin present in acute cases of albuminuria is 0.1 to 0.5 per cent., 

 rarely over 1 per cent., though it may rise to 4 per cent. An 

 approximate method for the comparative estimation of albumin is to 

 precipitate it (with the precautions above given) in a graduated test- 

 tube by heat and setting aside for twelve (or, better, for twenty-four) 

 hours. At the end of that time the proportion of the coagulated 

 albumin which has collected at the bottom of the fluid is noticed. If 

 the albumin occupy one-fourth, one-sixth, one-tenth of the height of 

 the liquid, there is said to be one-fourth, one-sixth, or one-tenth of 

 albumin in the urine. If, however, at the end of twelve or twenty- 

 four hours scarcely any albumin has collected at the bottom, there is 

 said to be a trace. 



The volumes of coagulated albumin indicate the following quantities of dry 

 albumin : 



Slight turbidity indicates about 0.01 per cent. 



& of tbe tube is filled 0.05 " 



r V " " ....... 0.10 " 



j * 0.25 



I " " ....... 0.50 " 



" " ....... 1.00 " 



Complete coagulation . 2 to 3 " 



Esbach's albuminometer (Fig. 75) is a conveniently arrnnged tube for deter- 

 mining approximately the quantity of albumin. The tube is rilled with urine to 

 U, and then with the reagent to R. The reagent is a solution containing 1 

 gramme of picric acid and 2 grammes of citric acid in 100 c.c. of water. After 

 having filled the tube it is closed with a stopper, inverted twelve times, and set 

 aside for twenty-four hours. At the end of that time the albumin will have 

 settled down, when the amount pro mille in grammes may be directly read off 

 from the scale. 



Tsuchiya's reagent possesses many advantages over Esbach's, and is used in 

 the same manner. It is, Phosphotungstic acid, 1.5 grammes; hydrochloric 

 acid (concentrated), 5 c.c.; alcohol, 95 c.c. 



A better method of exactly estimating the amount of albumin is its 

 complete separation and weighing, as described below. 



Experiment 102. Acidify 100 c.c. of clear albuminous urine with acetic acid ; 

 heat to the boiling-point in a water-bath for half an hour, and filter through a 



