of the Corneous parts of Insects. 103 



Another gramme of the same elytra was treated several times 

 with hot alcohol : the decanted liquors being evaporated, the ex- 

 tract obtained afforded some small drops of a brown oil. Water 

 took up from it a brown extractive matter, similar to that found in 

 the aqueous solution, together with a substance sensibly alkaline 

 to the taste. This liquor, in consequence of the presence of the 

 alkali, dissolved a little fatty matter, which separated on the ad- 

 dition of muriatic acid, the acid at the same time occasioning a 

 slight effervescence. The liquid, evaporated and calcined, left a 

 salt which gave a yellow precipitate with muriate of platina, con- 

 sequently it was muriate of potassa. Hence we find in this expe- 

 riment the carbonate of potassa observed in the aqueous infusion. 

 , When the extract of the alcoholic liquor which has acted on the 

 elytra is treated with water, a brown fatty matter is left which 

 spots paper like grease, and increases its combustibility. This 

 substance has a decided smell of bile. 



Having submitted the elytra to the action of water and alcohol, 

 I wished to try that of potassa on them, which acts so powerfully 

 on all sorts of animal substances. For this purpose I took two 

 grammes (30*88 grs.) of elytra, and treated them with a hot solu. 

 tion of caustic potassa. The solution assumed a deep brown co- 

 lour. I renewed the solution several times, until it ceased to 

 have any further action on the elytra. During the action of the 

 alkali, a slight disengagement of ammonia was perceptible, as 

 happens in all solutions of animal substances in potassa. 



The alkaline solutions had a deep biown colour, as before ob- 

 served. Saturated with muriatic acid, a brown flocculent matter 

 precipitated, and collected at the bottom of the vessel. The 

 alcohol became coloured yellow brown, and left, after evapora- 

 tion, a brown fatty matter, having the odour of bile. This mat- 

 ter was the same as that extracted from the elytra by alcohol ; it 

 might perhaps be slighfy altered, as it had been dissolved, and 

 probably saponified by the potassa. The portion of the precipi- 

 tate, insoluble in alcohol, was brown and solid. It was not parti- 

 cularly examined. The elytra after the action of the potassa, be- 

 came colourless, and transparent like thin horn, without expe- 

 riencing any change in their original form. They lost nearly three 



