104 Odier on the Chemical composition 



fourths of their weight by the operation, the two grammes fur- 

 nishing only 0*585 gramme (9*03 grs.) of transparent matter inso- 

 luble in potassa. 



Having ascertained the presence of the different substances men- 

 tioned above in these organs, 1 was curious to enquire if they do 

 not also contain some saline matter in their composition. I there- 

 fore incinerated two grammes of elytra, previously boiled in water, 

 and consequently freed from al! soluble salts. 



Whilst burning, the elytra exhibit a character which distin- 

 guishes them from the animal substances to which they are com- 

 monly compared. They neither fuse nor swell up like horn, hair, 

 or nails; on the contrary, they remain solid as they bum .and 

 leave a coal, which retains the form of the elytrum.* Two 

 grammes afforded by incineration 001 gr. (0.1544 gr.) or 

 — 5 dth of their weight of a white ash mixed with some yellow 

 specks. This ash thrown into water and treated with muriatic 

 acid, gave no appearance of effervescence ; it therefore contains 

 no carbonate. The whole dissolved in the acid, which was dis- 

 tinctly coloured yellow. 



Ammonia gave a white precipitate with this solution, which was 

 also rendered turbid by oxalate of ammonia, Indicating the pre- 

 sence of lime, and prussiate of potassa turned it sensibly blue. 

 The ash, therefore, consisted of a mixture of phosphate of lime, 

 and a little phosphate of iron. 



Having thus ascertained in the elytra the presence of 1. albu- 

 men ; 2, extractive matter soluble in water ; 3, a brown animal 

 substance soluble in potassa, and insoluble in alcohol ; 4, a 

 coloured oil, soluble in alcohol ; 5, a peculiar matter, constitut- 

 ing |th of the weight of the elytra ; and 6, three salts, viz. car- 

 bonate of potassa, phosphate of lime, and phosphate of iron ; I 

 proceed to the particular examination of these different substances, 

 especially those of which the elytra seem to be more essentially 

 composed, and I shall then look for them in the various parts of 

 the carapace of the insects. + 



* The peculiar smell of animal matter when burnt, is not perceptible on 

 bm-ning the elytra. C. 



t Carapace. The vaulted and generally osseous covering which protects the 

 bodies of reptiles of the class chelonia, and within which they draw their head, 



