A SIMPLIFIED KJELDAHL METHOD FOR URINE 35 



glass tubing, with a receiver containing from 35 to 75 c.c. of 

 N/10 acid, together with water enough to make a total volume 

 of 150 c.c., and a drop or two of alizarin red. Florence flasks, 

 capacity 300 c.c. of Pyrex glass, make excellent receivers for this 

 distillation. As soon as the connection is made with the receiver 

 apply the flame again at full force but not directly under the 

 center until the acid and alkali in the flask have had time to mix. 

 The contents in the flask begin to boil almost at once and four 

 to five minutes transfers the whole of the ammonia to the receiver. 

 The contents in the receiver become heated, of course, since no 

 condenser is used, but under the conditions described the 

 temperature reached is only 65 to 70 C. 



The only precaution needed in connection with the titration 

 of the distillate (without previous cooling) is that a faint red 

 color shall be accepted as the end-point. The color will deepen 

 on cooling, and, if time permits, it is more satisfactory to cool 

 in running water before titrating. 



Remarks. While the operator is directed to make prompt 

 connections with the receiver after the alkali has been added to 

 the digestion mixture, there is in point of fact very little danger 

 of losing ammonia vapors by being unduly slow in closing the 

 mouth of the flask. Similarly when the receiver contains too 

 little acid and turns pink, there is no need of extraordinary haste 

 in adding more acid. The water, though warm, will hold con- 

 siderable free ammonia. The delivery tubes are made from glass 

 tubing, small enough to pass into the ready-made holes in rubber 

 stoppers. For the sake of flexibility the delivery tube should 

 consist of two parts connected with a short piece of rubber tubing. 

 This method is not applicable' to highly resistant materials, as 

 for example, milk; nor for urines containing much sugar. On 

 the other hand fuming sulphuric acid may be substituted for ordi- 

 nary sulphuric acid in the preparation of the hydrolyzing reagent, 

 or if 2 c.c. of fuming sulphuric acid are used in addition to 5 f c.c. 

 of the regular reagent, sugar urines are readily destroyed within 

 the regular heating period, from four to five minutes. 



Preparation of the Hydrolyzing Reagent. To 50 c.c. of 5 to 

 6 per cent copper sulphate solution add 300 c.c. of 85 per cent 

 phosphoric acid and 100 c.c. of concentrated sulphuric acid. 

 Five c.c. of this mixture are used for the destructive digestion 

 of 5 c.c. of undiluted urine. Ten per cent solution of ferric chloride 



