350 PROCEEDINGS OF THE AMERICAN ACADEMY. 



Director of the laboratory, Professor Emil Fischer, and to the President 

 of the Physikalisch-Technischen Reichsanstalt, Professor Warburg, for 

 their interest in and support of this investigation, and to Dr. Griitz- 

 macher of the Reichsanstalt for his prompt and thorough testing of 

 our thermometer. 



Summary. 



1. For the transition temperature of manganous chloride from the 

 tetrahydrate to the dihydrate the point 58.089° upon the international 

 hydrogen scale has been found. This point is probably not more than 

 0.005 degree in error. 



2. This transition temperature of manganous chloride was found to 

 be suitable for serving as a fixed point in thermometry, on account of 

 the ease of preparation of the salt and the satisfactory definiteness 

 of the transition. 



3. In this paper is described a tall transparent thermostat which 

 makes it possible to determine exactly the temperature of the whole 

 length of the thermometer. 



First CnEMiCAL Institute of the 

 University of Berlin, 

 August 1, 1907. 



