208 Messrs. G. Graham and E. P. Poulton. The Alleged 



Table I shows the Effect of Increasing Amounts of /3-oxybutyric Acid, 

 Acetone and Aceto-acetic Ethyl Ester on the Determination of 

 Creatinine in Urine. 



Concentration 

 in urine, per 

 cent. 



Grammes per 

 day in 1500 c.c. 

 urine. 



Scale reading 

 in mm. 



Creatinine, 

 grm. per 100 c.c. 



Error in the 

 determination of 



creatinine, 

 grm. per 100 c.c. 



3-oxybutyric acid added to urine. 

















7 



0-116 





0-036 



0-54 



7 



-116 







1 



15 -0 



6-88 



-118 



+ -002 



2-16 



32 -4 



7-27 



0-111 



-0-005 



Acetone added to urine. 

















7 



116 





0-04 



0-6 



7 -1 



0114 



+ -002 



0-17 



2-5 



7 



0-]16 







1 



15 



7-6 



0-106 



-o-oi 



1 -6 



24 



8 "24 



0-098 



-0 018 



7 6 





12 -34 



0-066 



-0 -05 



Aceto-acetic ethyl ester added 









to urine. 









o 







7 



0-116 





°A 



1 -5 



7-2 



113 



-0 003 



0-5 



7 -5 



7-5 



(i -108 



-0 -008 



0-75 



10 -7 



8-17 



099 



-0 -017 



1 



15 



6-9 



0-117 



+ 001 



2 



30 



6-3 



0-128 



+ 012 



Acetone if added to the urine in amounts less than - 2 per cent. (Table 1) 

 does not introduce any error at all. A 1-per-cent. solution makes the colour 

 lighter than usual, while if the acetone is present in larger amounts the 

 colour becomes much lighter and it fades very rapidly on standing. As 

 acetone is excreted in urine in very small amounts the creatinine determina- 

 tions will not be affected, as a - 17-per-cent. solution caused no error. These 

 results do not agree with those of van Hoogenhuyze and Verploegh (13) and 

 Krause (16), who found that a 1-per-cent. acetone solution made the colour 

 darker, but that the error disappeared on standing. 



Aceto-acetic ethyl ester when present in small quantities produces a slight 

 lightening of the colour. Thus a O'l- and 0*75-per-cent. solution causes an 

 error in the scale reading of 0'2 and l'l mm. Larger amounts, on the other 

 hand, cause a darkening effect, but the colour becomes much redder than 

 usual, which makes it really impossible to match it with the N/2 bichromate 

 solution. These results agree with those obtained by Krause (16), Wolf 

 and Osterberg (22), and Eose (20). This experiment is not of much practical 

 importance, as the ethyl ester is never excreted in urine, but we have made 



