APPARATUS. 325 



four-drachm bottles found at almost any druggist's, say 

 with an interior calibre of one-fourth inch. Mark this 

 with a file at heights corresponding to 50, 66, 100 and 

 200 grains. This is easily accomplished with the aid of 

 the burette. The plain bottles Avithout a neck are to be 

 preferred. 



The Analysis for Urea. Take a sufficient quantity 

 of the urine, and if albumen is present clear it from the 

 same; next, pour into the measuring bottle to the 100 

 grail* mark. Transferring this to a common wineglass, 

 in a like manner measure 50 grains of the baryta solu- 

 tion ; add this to the other in the wine-glass, pour the 

 whole on a dry filter, receiving the filtrate in another 

 glass. Should the liquid come through clear, it is well ; 

 if not, it must be refiltered until it does. Three or four 

 filtrations at the most will generally accomplish the de- 

 sired end. While the filtering is in operation fill the 

 burette to the "0" mark with the standard solution. 



With the measuring pipette transfer one-half drachm 

 of the clear filtrate to a clean wineglass, adding half its 

 quantity of distilled water. Have in readiness a strip 

 of the carbonate of soda paper and a glass rod. Deliver 

 the standard solution from the burette to the filtrate as 

 long as any precipitate is distinctly seen to form, stir 

 with the rod, and place a drop from the glass in contact 

 with the paper, waiting a moment to observe the reac- 

 tion. If the paper continues white, acid again from the 

 burette, and stir again, placing a second drop on the 

 paper, and thus continue carefully until the drop trans- 

 ferred to the paper strikes a yellow color. Now look 



