OF AUTS AND SCIENCES. 71 



to the constant presence of oxichloride in the preparations of this 

 compound. 



The investigation from the first has been a study of constant errors ; 

 and those who have followed us through the details will certainly allow 

 that the opinions expressed at the beginning of this paper (ou page 9) 

 were not hastily conceived, even if they do not fully agree with our 

 conclusions. In the attempts to correct or balance such errors, we have 

 found at once the chief difficulties and interest of our work, and the sec- 

 ondary results thus reached seem to us the most important fruit of the 

 whole investigation. Seeing, then, the sources of constant error we have 

 discovered, and knowing that there are others whose influence we have 

 been able to trace, although we have not been able to define them as 

 clearly as we could desire, it would be presumptuous in us to express 

 too great confidence either in the correctness of our theories or even in 

 the conclusiveness of our experimental results. Of this, however, we 

 feel assured, that more trustworthy results cannot be expected from 

 a repetition of the same processes until a more complete and accurate 

 knowledge has been acquired of the substances employed. We have 

 therefore proposed to ourselves a more thorough investigation of the 

 haloid compounds of antimony, and the first results of this investiga- 

 tion we shall shortly publish. After the requisite data have been thus 

 collected, we hope to return to the old problem with such definite 

 knowledge of the relations involved as will enable us to obtain at once 

 more sharp and decisive results than are now possible. 



During the course of this investigation, we have been successively 

 aided in the experimental work by Dr. F. A. Gooch, Mr. C. Richard- 

 son, and Mr. W. H. Melville, at the time students in this laboratory ; 

 and without their assistance we could not have accomplished the great 

 amount of labor it involved. 



Harvard College Laboratory, June \2th, 1877. 



