of the Corneous parts of Insecls. , W^ 



This insect, according to the two last authors, feeds on leaves ; it 

 is, therefore, as to its habits in that respect, similar to the Sca- 

 rabasus melolontha, and consequently not an improper subject 

 to supply its place for the purposes of the experiments in ques- 

 tion. Before I proceed to their detail, I shall briefly mention, 

 that I found the same saline and other substances, in the ashes 

 of the insects, as are mentioned by M. Odier, with the addition 

 of a small portion of silica and magnesia, and a slight trace of 

 manganese. Their mode of burning, in contact with the atmos- 

 phere, I also found perfectly to correspond with our author's 

 statements. 



I took a certain quantity of the entire insects, previously reduc- 

 ed to a fine powder, and digested them nearly at a boiling heat in 

 a strong solution of caustic potassa, continuing the digestion for 

 several days, until the alkali had no further action on the residual 

 carapace, which was then thoroughly washed, and dried at the 

 temperature of 212° in a vessel connected with an exhausted re- 

 ceiver, containing a large surface of strong sulphuric acid. The 

 last process was continued at least 48 hours, till all traces of va- 

 pour had completely disappeared, and the carapace then immedi- 

 ately enclosed in a well stopped phial. When used, it was again 

 exposed to the heat of boiling water, to drive oflF any hygrometrical 

 moisture it might have absorbed, (of which like most other powders 

 it is extremely greedy) and weighed whilst warm. It was then suf- 

 fered to remain in the pan of the balance till it ceased to gain weight, 

 and the quantity of water so acquired deducted from that ob- 

 tained in the analysis. A further deduction was also made for the 

 incombustible matter contained in the carapace, and not separable 

 by the alkali. To be certain that it was pure, at least in the view 

 required by M. Odier, I subjected a portion to distillation in a 

 glass tube, in the neck of which a slip of moistened turmeric pa- 

 per, and another coloured blue by the juice of the Ilyacinthus non 

 scriptus, (an cxcocdingly delicate test for either acid or alkaline 

 matter) was enclosed— neither of which suffered discoloration in 

 the slightest degree. The carapace, thus prepared, was burnt in 

 gr«cn plass tubes, with proioxide of copper, having some clear 

 copper filings above the mixture, and over that a quantity of per-. 



Vol. J. a 



