THE ALUMNI JOURNAL. 



75 



the greater the proportion of sugar the more 

 rapid will be the change to yellow, and from 

 the degree of rapidity with which this change 

 in color takes place, the proportion of sugar 

 may be approximately estimated. 



Uric Acid. 



Taking o.oi per cent, as normal standard. 

 To a definite portion of the filtrate from the 

 phosphate test, add a concentrated solution of 

 nitrate of silver until the mixture becomes deep 

 gray or black, set aside for fifteen minutes; add 

 half a volume of stronger water of ammonia, set 

 aside, allow precipitate to subside, and pour off 

 as much of the clear liquid as possible ; again 

 add an equal volume of strc nger water of am- 

 monia to the residue mixture ; set aside for half 

 an hour and note bulk cf the precipitate and 

 compare it with a standard volume or bulk 

 obtained as an average from several specimens 

 containing the above amount. 



The uric acid is precipitated as silver urate. 

 If urates or free uric acid have separated as a 

 precipitate, they are re dissolved by adding a 

 slight excess of solution of caustic soda to the 

 specimen previously well shaken, diluting with 

 half a volume of water, making neutral with 

 dilute nitric acid ; then proceed to precipitate 

 the phosphoric acid as directed under phos- 

 phates. Keep the volume of the fluid double 

 that of the urine. 



Meat diet very acid by acid phosphates crys- 

 tallizes uric acid and retains the oxalate of cal- 

 cium in solution. 



Carbohydrate diet, faint acid by acid phos- 

 phates, sometimes alkaline by alkaline phos- 

 phates crystallizes oxalate calcium and retains 

 uric acid in solution. 



The acidity of the urine is reduced by the acid 

 fermentation (lactic and butyric) of the carbo- 

 hydrates, forming lactates and butyrates, which 

 like citrates and acetates when administered 

 reduce the acidity of the urine. And these acids 

 (lactic and butyric), like some of the constitu- 

 ents of meat under impaired oxidation, instead 

 of being oxidized to carbonic acid as they are 

 normally, yield intermediate products of oxida- 

 tion, as oxalic acid for example. 



With few exceptions, as the proportion of uric 

 acid increases, the indican reaction becomes 

 more intense. 



Indican. 



Jaffe's Test. 

 To concentrated hydrochloric acid (3J ) add a 



minute quantity of chlorinated lime ; then add 

 one quarter of the volume of the urine ; if the 

 chlorinated lime is added to excess the color 

 will be destroyed, if not in sufficient quantity 

 the reaction wiil be faint. With few exceptions, 

 the indican is increased as the uric acid rises in 

 proportion. 



Urobilin. 



ioo c.c. of urine, shaken with 50 c.c. ether, 

 the ether separated, evaporated without heat, 

 the residue dissolved in alcohol and examined 

 by micro -spectroscope. 



Oxalate Calcium. 



Taking 0.005 P er cent, as a normal standard. 



100 to 200 c.c. of the mine previously well 

 shaken, add from 5 to 10 c.c. of a 25 per cent, 

 solution of calcium chloride, add ammonia to 

 alkaline reaction, shake well, neutralize by 

 acetic acid, set aside for twenty-four hours; 

 separate precipitate by filtration, wash with 

 water, wash with hot solution of soda, then 

 agaiu with water, until the filtrate shows no 

 perceptiple reduction with permanganate of 

 potassium; allow to drain, dissolve the residue 

 in dilute sulphuric acid, washing the filter care. 

 fully with the dilute acid, heat the filtrate to 

 near boiling point, and titrate with ^ perman- 

 ganate : each, c.c.=o.oo54 calcium oxalate. 



Bile. 



HupperVs Method. 



To 2 ounces of urine add about 2 drachms of 

 milk of lime — shake well — separate precipitate 

 by filtration, transfer to test-tube, add alcohol 

 and concentrated sulphuric acid ; upon heating, 

 the alcohol acquires a green-yellow color. 



Phosphates. 



Taking 0.20 per cent, as a normal standard. 



Dilute the urine with an equal volume of 

 water ; to one-half ounce of the mixture add 

 two drops of a 25 per cent, solution of magne- 

 sium sulphite, then four drops of stronger 

 water of ammonia; shake well, then set aside 

 for half an hour, note bulk of the precipitate, 

 and compare it with a standard volume or bulk 

 obtained as an average from several specimens 

 containing the above proportion. 



The phosphoric acid is precipitated as amtno- 

 nio-magnesium phosphate. 



If a portion of the phosphates have separated 

 from solution in alkaline specimens, they should 

 be re-dissolved in nitric acid, then made neutral 

 by caustic soda, before proceeding as above. 



