204 THE ENTOMOLOGIST. 



THE ACTION OF AMMONIA UPON SOME LEPIDOPTEROUS 



PIGMENTS. 



By George Coverdale. 



Two or three years back, some entomological friends induced 

 me to kill all my insects with ammonia, instead of employing 

 potassium cyanide, and I have never regretted the change I then 

 made. Nearly the first species so treated was Melanargia 

 galathea, and on opening the pill-boxes I was much surprised to 

 find every one of them of a beautiful primrose -yellow colour. In 

 a few moments the primrose-yellow had vanished and the insects 

 were of their normal white again. Evidently this phenomenon 

 was due to the volatile ammonia, so I held a specimen over the 

 bottle and instantly the primrose colour returned, only to 

 disappear again with the departure of the pungent ammoniacal 

 fumes. The reagent employed was a saturated aqueous solution 

 of ammonia, and the black pigment of the wings remained 

 unchanged throughout. 



Now here was something of great interest and well worth 

 investigation, so I determined to follow it up, and since 

 that time have never lost an opportunity for experiment or 

 study. Many of my friends are now familiar with the results 

 obtained, but as they appeared to be previously unknown to 

 all those with whom I have communicated on the subject, I 

 have though it best to place them on record. They may 

 be well known and authenticated, but to ascertain this a 

 careful search through the vast mass of the chemical and 

 microscopical literature, both of this country and the Continent, 

 would be required, and for this my spare time is quite inadequate. 

 I must therefore crave the indulgence of those who may be 

 familiar with the facts herein recorded. Naturally, the first 

 species selected for experiment was Melanargia galathea. As 

 before, ammonia gave the primrose coloration. The next 

 reagent employed was a solution of potassium hydrate, in which 

 pieces of the wing were placed, and they immediately turned 

 yellow. Other alkalies, such as solutions of sodium hydrate 

 and barium hydrate, were tried, and gave similar results, the only 

 difference being that with the fixed alkalies the primrose 

 coloration was permanent, whereas with ammonia it was neces- 

 sarily fleeting. 



