146 PROCEEDINGS OF THE AMERICAN ACADEMY. 



The construction of the apparatus was made with the help of 

 two grants of money from the Cyrus M. Warren Fund of the 

 American Academy of Arts and Sciences. The Chemical Depart- 

 ment of the Institute was also very generous in its support of this 

 costly research. 



Massachusetts Institute of Technology, 

 Boston, Mass., June, 1910. 



