﻿Analysis of the Coprolites of Birds. 57 



of ammonia was decomposed. The dry mass was scraped off 

 and the powder dropped to the bottom of a test-tube and tested 

 with a drop of caustic potash warmed, and a glass rod moistened 

 with muriatic acid held at its mouth. These manipulations be- 

 ing almost simultaneous, no trace of ammonia appeared. I shall 

 not convert my period into an exclamation point ; for one would 

 hardly expect such evidence of ammonia, if it there existed. I 

 was operating on 20 grains only of coprolite, whose urate of am- 

 monia, as has been already shown, was only 01545 grs., and its 

 ammonia not quite 0015 grs., a quantity quite too small to be 

 estimated in this mode, or by a delicate nose. 



[Dr. Dana did not attempt to draw any inference from the 

 preceding results ; but at my particular request, he undertook 

 the following ingenious course of reasoning, in a letter dated 

 December 8th, 1843.— E. H.] 



1 drew no inference from the facts detailed in my last letters, 

 except that the substance I had examined was coprolite. The 

 presence of urates would not conclusively prove it the excre- 

 ments of birds. Uric acid is common to the droppings of birds 

 and of reptiles. This acid and urates are always evacuated by 

 birds, mixed with the feces, and by reptiles, sometimes accompa- 

 nied by, but never mixed with, the fecal matter. The anatomical 

 structure of the lungs, primae vise, and urinary organs of birds 

 and reptiles, lVnot less strikingly analogous than their urinary se- 

 cretions. While in reptiles this consists of uric acid almost pure, 

 being in fact the urine only, evacuated as a soft solid, at long 

 intervals of from three to six weeks, and in large serpents, in 

 masses of from three to four ounces weight — the urine of birds is 

 daily evacuated mixed with the feces. 



These facts, taken in connection with our knowledge of its 

 composition, will allow us to class your coprolite with the drop- 

 pings of birds. Let us compare its composition with the drop- 

 pings of reptiles and of carnivorous birds, which agree in con- 

 taining like portions of uric acid. The earliest observations on 

 the urine of lizards were by Schreibers, 1813. He was followed 

 in 1815 by Dr. Prout, who examined the solid excrement of the 

 boa constrictor and communicated his results to Dr. John Davy, 

 on the eve of the latter's departure for Ceylon, in 1817. Dr. Davy 

 there made extended observations on the anatomical structure 

 and urinary excretions of serpents, lizards, turtles, and tortoises, 



Vol. xlviii, No. 1.— Oct.-Dec. 1844. 8 



