OP ARTS AND SCIENCES. 233 



Oliver W. Huntington, for the great aid he has given throughout this 

 investigation. With the help of his skill in glass-blowing I have been 

 able to secure all the connections of my gas generators with melted or 

 cement joints, except the direct connections with the globe, where india- 

 rubber could not be avoided. He has also constantly assisted my im- 

 paired eyesight in the observations with barometer and thermometer 

 on which the accuracy of the work greatly depended. I have likewise 

 been indebted to Dr. Arthur M. Comey for making the titrations 

 required, and to Mr. W. W. Bosworth for the drawings with which 

 this paper is illustrated. 



