806 Notices respecting New Booh. 



lighted taper. The 3 grains of coaly matter, on being kept at a 

 ted heat in a silver crucible for some time, slowly consumed, leav- 

 ing only a residuum of -J^ of a grain, which on examination ap- 

 peared to be subcarbonate of soda, phosphate of lime, and oxide 

 of iron. 



The preceding experiments seem to show that the excrement 

 of the Boa is not very simple in its constitution. The uric acid 

 appears to enter largely into its composition ; and the facts, that 

 ammonia is evolved from it by the fixed alkalies, and that the 

 nitric solution of the excrement yields by evaporation the pur- 

 purate of ammonia, favour the idea that the volatile alkali also 

 forms one of its ingredients. It also appears to contain a minute 

 portion of subcarbonate of soda, phosphate of lime, and oxide of 

 iron. From the limited quantities of the excrement examined, it 

 would be rather premature to decide upon the products obtained 

 from its destructive distillation ; as a great part of them must ne- 

 cessarily arise from the decomposition of the uric acid in the pro- 

 cess. 



My cousin Dr. Davy, in his paper '' On the urinary Organs and 

 Secretions of some of the Amphibia*," states the solid urine of 

 serpents to consist of nearly pure uric acid; and this solid urine 

 seems closely to resemble the excrement of the Boa in its physi- 

 cal and chemical properties. But if my experiments are correct, 

 the constitution of the latter substance does not appear to be so 

 simple as that of the former ; and I am at a loss to account for the 

 differences in our results, unless thev may be referred to differences 

 in the food of the serpents. It is not, 1 presume, yet known, what 

 changes may be effected in the excrementitious matters of ani- 

 mals, by such changes in their diet as may be compatible with 

 their healthy existence. 



Cork Institution, Oct. 18, 1819. 



LI I. Notices respecting New Books. 



The Entomologist's useful Compendium; or, An Introduction to 

 the Knowledge of British Insects ; comprising the best Means 

 of obtaining r.nd preserving them, and a Description of the 

 Apparatus generally used ; together with the Genera of Linne, 

 and the modern Method of arranging the Classes Crustacea, 

 Myriapoda, Spiders, Mites and Insects, from their AfTniities and 

 Structure, according to the Views of Dr. Le;ich. Also an Ex- 

 planation of the Terms used in Entomology, a Calendar of the 

 Times of Appearance and usual Situations of nearly 3000 Species 

 of British Insects; with Instructions for collecting and fitting up 



* Philosophical Transactions 1818. 



Objects 



