Intravenous Injections of Living Colon Bacilli. 63 



The appearance of the homogeneous substance described and 

 its distribution naturally suggest amyloid. Attempts to produce 

 the typical staining reactions of this substance failed however, 

 possibly owing to the fact that the material had unfortunately 

 been fixed in Orth's fluid before the attempt was made. 



37 (hoi) 



The determination of amino nitrogen in urines containing glucose 



and albumin. 



By Donald D. Van Slyke. 



[From the Hospital of the Rockefeller Institute for Medical Research.] 



Albumin. — For removal of the albumin, we have found Welker's 

 aluminum hydrate method very satisfactory. For urines con- 

 taining large amounts of albumin, however, it is advisable to first 

 coagulate with heat and acetic acid; then add an equal volume of 

 the 0.5 per cent, aluminum hydrate suspension. The amino 

 nitrogen is determined in an aliquot part of the filtrate. 



Glucose. — Glucose interferes in two ways with the previously 

 described method for determining amino nitrogen in the urine. 

 If the urea is removed by treating the urine with urease, glucose 

 combines with some of the ammonia and forms small amounts of 

 an amine, which makes the results for amino nitrogen come out 

 too high. 



On the other hand, if a solution of an amino acid is concentrated 

 on the water bath with glucose, a condensation occurs, with disap- 

 pearance of amino nitrogen. 



Both difficulties are obviated as follows: The urine is kept acid 

 during action of the enzyme by the addition of three or four volumes 

 of charged C0 2 water. After the action of the enzyme is com- 

 pleted at room temperature, the glucose is removed by adding 

 sufficient copper sulphate solution to form an insoluble compound 

 containing five molecules of copper hydrate to one of glucose. 

 This compound is precipitated by the addition of a slight excess 

 of calcium hydrate. The alkaline filtrate is concentrated in a 

 vacuum, removing the ammonia, and the free amino nitrogen 

 determined. In case albumin is present in a diabetic urine, this 

 treatment removes the albumin along with the glucose. 



