BISULPHIDE OF CAEBON. 213 



2.30. The greater number were under the violet 

 glass and bisulphide. 



3. Almost all were under the glass and bi- 

 sulphide. 



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» a »» • n 



"• »> » It 



October 18. 



7 A.M. „ „ „ 



8. The ants were equally divided. 



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 „ „ „ 



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 Wolet. It remained to be seen what 



