336 HOW TO SEE WITH THE MICROSCOPE. 



due care, when near the complete decomposition of the 

 copper. When this shall be obtained, and the blue 

 color of the standard solution has disappeared, the sedi- 

 ment in the tube being also inclined to settle quickly, 

 the burette may be read. 



Now, to determine the amount of sugar from the 

 reading- of the burette is a simple question of the " rule 

 of three," suppose that the number marked by the bu- 

 rette to have been 228, then it follows that 228 grains 

 of the urine contained J grain of sugar; Hence 458 

 (one ounce) of the urine would contain 1 grain of sugar, 

 or, as we would say, " one grain per ounce." It may 

 be well to suggest to those who have allowed their 

 mathematics to become a little rusty, that even in solv- 

 ing proportions, simple as are the computations, that it 

 is necessary to look after one's decimal points. Thus, 

 in the above example, the expression would be 456 

 X 0.50, 4- 228 = unity. 



Use of the standard solution in the ordinary testing 

 for sugar. The practitioner will very often have occa- 

 sion to simply test for the presence of sugar, when the 

 exact amount is not necessary. In fact, after becoming 

 thoroughly familiar with the behavior of the chemicals, 

 he will be enabled to give a close guess as to quantity. 

 The urine should in all cases be cleared from albumen. 

 To merely detect the presence of sugar it is only neces- 

 sary to pour a dozen drops or so of the copper solution 

 into one of the largest test tubes (these are always bet- 

 ter when there is boiling to be done), and to add twice 

 the volume of the caustic solution. Bring- to the boil- 



