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THE JOURNAL OF PHARMACOLOGY 



order to ascertain their true nature. If the uric acid ring does not appear 

 after from five to ten minutes, it may be assumed that the substance is not 

 present in increased amount, and that the quality in all probability is even 

 less than normal. As a general rule, the band appears almost at once 

 after the addition of the nitric acid, if an excessive elimination of uric acid 

 has taken place, and from the rapidity with which it appears and the 

 depth of the ring an idea may be formed of the amount present, if the 

 method has been carefully compared with one of the usual quantitative 

 methods. 



Occasionally, though rarely in the writer's experience, amounts of uric 

 acid are encountered in the urine which are truly enormous, and almost 

 immediately after the addition of the nitric acid a band of uric acid ap- 

 pears which almost tills the entire bulk of urine, and even extends to the 

 nitric acid. Upon careful examination, however, it may be seen that the 

 extension of the precipitate takes place from above downward, and not 

 from below upward, as in the case of albumin. Should both be present in 

 very large amounts at the same time, the decision, whether we are dealing 

 with uric acid, or albumin, or both, may at first appear extremely difficult. 

 The nitric acid should then be added through a pipette, and not allowed to 

 flow along the walls of the vessel. Two bands can then always be made out 

 for a lew seconds at least, the one at the zone of contact, the other separated 

 from this by an intermediary zone of practically clear urine. 



I) an increase in the amount of uric acid is observed, it should be 

 ascertained whether this increase is only relative or absolute. It will be 

 readily understood that the diagnosis of an absolute increase is only justi- 

 fiable if the amount of urine is not subnormal. The increase, so frequently 

 observed in febrile urines, is usually of a relative character, the total 

 amount of urine being subnormal. A sharp line of distinction should, fur- 

 thermore, be drawn between increased production and increased elimination. 

 It is thus not justifiable to exclude the diagnosis "uric acid diathesis" 

 when normal or even subnormal amounts arc obtained. A temporary re- 

 tention is frequently observed. 



An excess of urea is likewise quite readily discovered with the nitric 

 acid test. Every physician probably who has occasion to examine many 

 urines has observed the appearance of glistening crystals after the ad- 

 dition of the nitric acid if the specimen has been allowed to stand for a 

 lew minutes. These crystals are urea nitrate, and when formed in this 

 manner always indicate the presence of at least twenty-five grammes of 

 urea for every 1,000 c. c. of urine. When occurring in dense masses fifty 

 grammes or more are being eliminated. 



In conclusion, the nitric acid test, when applied as described, indicates 



