47 



228. Test the specific gravity with the specific gravity 

 beads. This method has the advantage that but a small 

 amount of urine is necessary for a test. The bead which 

 floats midway in the urine indicates the specific gravity. If 

 none float midway the .specific gravity will lie between the 

 figures on the bead that floats and the figures on the bead 

 that sinks. This is ordinarily suf&cient for an approximate 

 re.sult. To obtain the exact specific gravity the beads, 

 marked respectively s, lo, 15, 20, 25, 30 euclo.sed in a tube 

 with an open bottom, are immersed in the urine. If three 

 beads float we know that the specific gravity is between 

 1. 015 and 1.020. To obtain the exact figure, add water, 

 drop by drop, to the urine, until the third bead is in a state 

 of equilibrium and only two float. If two fluid-drams (120 

 minims) of urine were taken to begin with, and 20 minims 

 of water were required to bring the third bead to the point of 

 sinking then the following ratio obtains 120: 120+20: : i5:x. 

 The value of x is found to be 1.0175, the exact specific 

 gravity of the urine. If the specific gravity is above 1.030 

 dilute the urine one-half with water and multiply the result 

 by two. 



The specific gravity of the urine of the horse ranges from 

 1.020 — 1.060; that of the ox from i.oio — 1.030; that of 

 the dog from 1.015 — 1.060. 



229. Note and record the colors of the filtered and un- 

 filtered urines, according to the chart of colors. Record 

 their specific gravities by the urinometer and beads. Record 

 also their reaction to litmus as acid, very acid or alkaline. 

 Note the great amount of mucous present in the unfiltered 

 herbivorous urine. 



XVIII. 



230. The water of the urine is derived from the food and 

 drink, a small quantity being formed in the body. 



