440 Electrkal Baths for Urea Determination [Mar. 



instead of piain tubes in order to reduce the danger of overflow and 

 loss f rom excessive ebullition. A large enamelware pan was placed 

 under the bath to retain drippings f rom tubes taken out of the bath 

 and to catch the acid in case of accidental fracture of the porcelain 

 Container. 



The latter precaution emphasized an inherent defect in the tech- 

 nic of the method. Although there were no accidents, the necessity 

 for this precaution kept Dr. Gies dissatisfied with the practica! 

 Operation of the method in spite of the convenience which the above 

 mentioned improvements afforded. It was obvious that an oil bath 

 (an alternative suggested in Benedict's first publication) would be 

 an improvement over the sulfuric acid bath, but the danger of 

 serious accidents from heating an oil bath directly over a bunsen 

 burner was even greater than that from the same treatment of a 

 sulfuric acid bath. The possibility of heating an oil bath satisfac- 

 torily on a hot plate over an electric stove appeared to offer a way 

 out of the difficulty. These conclusions did not develop in Dr. 

 Gies's consideration of the matter, however, until his personal 

 experience enforced them and, as the academic year was then about 

 to close, further attention to the matter was postponed. 



Early in the fall of 19 lo, at the beginning of my associateship 

 in this laboratory in succession to Dr. Benedict, Dr. Gies requested 

 my Cooperation in his plan of improving the technic of Benedict's 

 method, and of constructing apparatus which would facilitate the 

 safe conduct of many determinations by different workers, at the 

 same time and in various stages of the process. Together we then 

 devised the apparatus which is described below. We find that it 

 overcomes all the difficulties and embarrassments to which allusion 

 has just been made. It has steadily been giving perfect satisfaction. 



CONSTRUCTION OF THE APPARATUS 



The general character of the apparatus, as placed in working 

 order in one of our laboratory hoods, is shown by the accompany- 

 ing picture (Plate VIII). The apparatus consists of a preliminary 

 drying bath, a regulating panel, two mercury regulators, and a 

 constant temperature bath regulated between 163° and 165° C. 



The preliminary drying bath consists of a three-heat electrica! 



