BISULPHIDE OF CAEBON. 213 



2. The greater number were under the violet 



glass and bisulphide. 

 2.30 „ „ „ 



3. Almost all were under the glass and bisulphide. 



The addition of the bisulphide thus caused the violet 

 glass to be distinctly preferred to the chlorate of copper. 



I then took a solution of sulphate of nickel, almost 

 •exactly the same tint as, or a shade paler than, the 

 chlorate of copper. 



At 3.45 the ants were under the violet glass and 

 bisulphide. 



4' ;j 5) JJ 



'5« 55 55 5J 



October 18. 



7 A.M. „ „ „ 



8. About half of the ants were under each. 



Here the effect was even more marked. 

 I then took some saffron 1 inch in thickness and of 

 a deep-yellow colour. 



12.45 The ants were about half under each. 



1 . Most of the ants were under the violet glass 



and bisulphide. 



1'15 55 55 55 



2. Most of the ants were under the saffron. 



Here, again, we have the same result. 



I then tried the different-coloured glasses, all of 

 "which, as I had previously found, are unmistakably 

 preferred to the violet. It remained to be seen what 



