CHEMlSrilY OF INSECT COLOURS. 



55 



— and treated with some or all of the following acids :* Hydro- 

 chloric (HCl) ; Nitric (HNO3) ; Sulphuric (H2SO4) ; Phosphoric 

 (H3PO4) Hydrofluosilicic (HaSiFg) ; and Oxalic (C2H2O4). 



Each experiment was made in duplicate, in order to ascertain 

 (A.), the effect of simple washing; (B.), the time effect, if any. I 

 must explain, however, that finding the process of washing 

 exceedingly tedious, owing to the large quantity of water 

 required in order to remove every trace of the acid, I had 

 modified the process to this extent, that, after a slight wash, I 

 added a drop of ammonia to neutralise the residual acid, and 

 again gave a slight wash ; this constituted in every way a great 

 improvement in the method. 



The following experiments then were made (in duplicate) : — 



V. atalanta 

 Z. JiUpendulce 

 E. jacohcecB 

 D. hella 

 C. her a 

 C. nupta 



HCl 



HNO3 



H2SO4 



H2SiF6 



H3PO4 



— 



— 



H2SO4 



H2S1F6 



— 



HCl 



HNO3 



— 



H2SiF6 



— 



HCl 



— 



— 



H2SiF6 



— 



HCl 



HNO3 



H2SO4 



HaSiFe 



— 



HCl 



HNO3 



H2SO4 



— 



— 



C2H204 



C2H204 

 C2H204 



We will take first the A. batch. These were started on 

 June 8th, treated with acid for one hour, and then washed and 

 neutralised and again washed, as above described. The follow- 

 ing are the results : — 



V. atalanta. Not the least reversion in any case. 



Z. filipendulcE. W^ g^^^ species the HNO3 specimen re- 



^.jacobcscB. mained ijerfectly yelloiu. All the others 



^' ' reverted to red. 



C. nupta. ) 



These reverted specimens were allowed to stand until July 

 25th, when the red was found still permanent in all of them (as 

 also in Deiopeia hella HCl and H2SiF6). Here, therefore, this 

 part of the experiment terminated. 



The following notes were made on the behaviour of these red 

 wings : — 



In C. nupta the reversion was the least thorough. 



In hera and jacohcece, treated with HCl, the red when re- 

 stored was not the exact natural red, but rather more cerise (or 

 in hera mauve-cerise) ; and in the case of hera this cerise tint was 

 permanent. 



All these reds dissolved a little \ (iiitpto least so), hut not in 

 HNOz more than in, e.g., HCl. 



The behaviour of atalanta red is altogether abnormal, and en- 

 tirely different from that of all the others : in which circumstance 

 we have another proof that its constitution is different from that 



• For strength of these see pp. 184, 185, of vol. xxiii. 

 I See Entom. xxiii. p. 372. 



