URINE. 315 



colored zones, due either to the presence of indican, bile pigments or 

 to the oxidation of other organic urinary constituents, may form in 

 this test under certain conditions. These colored rings should 

 never be confounded with the white ring which alone denotes the 

 presence of albumin. 



After the administration of certain drugs a white precipitate of 

 resin acids may form at the point of contact of the two fluids and 

 may cause the observer to draw wrong conclusions. This ring, if 

 composed of resin acids, will dissolve in alcohol, whereas the albu- 

 min ring will not dissolve. 



Weinberger has recently shown that a ring closely resembling the 

 albumin ring is often obtained in urines preserved by thymol when 

 subjected to Heller's test. The ring is due to the formation of nitro- 

 sothymol and possibly nitrothymol. If the thymol is removed from 

 the urine by extraction with petroleum ether 1 previous to adding 

 nitric acid, the ring does not form. 



An instrument called the albumoscope (horismascope) has been 

 devised for use in this test and has met with considerable favor. 

 The method of using the albumoscope is described below. 



Use of the Albumoscope. This instrument is intended to facili- 

 tate the making of " ring " tests such as Heller's and Roberts'. In 

 making a test about 5 c.c. of the solution under examination is first 

 introduced into the apparatus through the larger arm and the re- 

 agent used in the particular test is then introduced through the 

 capillary arm and allowed to flow down underneath the solution 

 under examination. If a reasonable amount of care is taken there 

 is no possibility of mixing the two solutions and a definitely defined 

 white " ring " is easily obtained at the zone of contact. 



2. Roberts' Ring Test. Place 5 c.c. of Roberts' reagent 2 in a 

 test-tube, incline the tube, and, by means of a pipette, allow the 

 urine to flow slowly down the side. The liquids should stratify 

 with the formation of a white zone of precipitated albumin at the 

 point of juncture. This test is a modification of Heller's ring test 

 and is rather more satisfactory than that test, since the colored rings 

 never form and the consequent confusion is avoided. The albu- 

 moscope (see above) may also be used in making this test. 



1 Accomplished readily by gently agitating equal volumes of petroleum ether 

 and the urine under examination, for two minutes in a test-tube, before ap- 

 plying the test. 



2 Roberts' reagent is composed of I volume of concentrated HNO 3 and 5 

 volumes of a saturated solution of MgSCX. 



