338 UNIVERSITY OF COLORADO STUDIES 



that recommended by Ehrlich, except that forty parts of solntion I. 

 are used instead of fifty, and no attention has been paid to the green 

 precipitates. The crucial point in our tests has always been the 

 production of a pink foam after the characteristic red ring. During 

 this period a diazo test, with objective records of the results has been 

 made on practically all of the in-patients in the medical clinic, on 

 some of them many times, and on a portion of the out-patients. 

 The number of cases examined approaches eight hundred, while the 

 number of tests made runs up into the thousands. 



A large number of chronic and a limited number of acute 

 diseases have been examined for this reaction. The method which I 

 have followed in this investigation has been to note every positive 

 diazo reaction found in the urine records during this period, and the 

 dates of tests. The clinical records of these patients were then ex- 

 amined, the diagnosis of the disease found, and the severity and 

 progress of the case considered. All other cases with similar diag- 

 noses were investigated as to diazo.- I also attempted to follow up 

 the diazo tests in each case, in order to find out the duration of the 

 reaction in the various diseases and also its prognostic worth and its 

 value in indicating complications and relapses and its association 

 with fever. Only in the cases of typhoid fever and some of the cases 

 of tuberculosis was this done to any satisfaction, since in many out- 

 patients only one test was made; in others only a few; while in 

 others the tests were days apart. 



In the accompanying table the diazo-reaction is practically 

 limited to one acute and one chronic disease — typhoid fever and 

 tuberculosis. 



In all of the cases of typhoid fever the diazo tests were made 

 almost daily from admission to the hospital till recovery. Unfortu- 

 nately, as nearly always happens, it was impossible to follow the cases 

 from the beginning, since some of them did not enter the hospital 

 till the second or even the third week of the disease. Two of the 

 three cases of typhoid fever in which diazo was negative entered the 

 hospital in the second or third week of the disease, and had very 

 light attacks. The Widal test was not made in either case. It is 



