56 Analysis of the Coprolites of Birds. 



cold and hot water dissolved from the 20 grains =1*161 per 

 cent. When the cold water solution was evaporated nearly dry, 

 it was left to spontaneous evaporation over night. A beautiful 

 mass of ivhite dots were found, which were nearly all collections 

 of pearly radiations, somewhat like aggregations of sulphate of 

 alumina, surrounded by a distinct border, of which alone other 

 dots were composed, that is, dotted with rings. The boiling 

 water solution was evaporated on these dots, rings, and general 

 white film, and then the whole treated with cold water. It was 

 not all solved. A gray powder remained, soluble with efferves- 

 cence in nitric acid, and this solution afforded by evaporation 

 evidence of uric acid. The solution in cold water gave by 

 nitrate of silver, first, universal yellowness, very soon succeeded 

 by copious yellow brown flocks, which in mass appeared red 

 brown. These were exposed to light for thirty six hours ; but 

 changed not their color. Being well washed, they were divided 

 into two portions. The one gave, being heated on glass gently, 

 metallic silver — a most beautiful example — evident to the eye at 

 arm's length. The remaining portion of these brown flocks was 

 treated with nitric acid and cautiously evaporated. It began to 

 turn yellowish, and being so far evaporated as not to drop from 

 the dish, that was inverted over a vessel of pure ammonia, whose 

 vapor caused it to turn orange red, and then decidedly reddish 

 by a little heat. It was then subjected to the action of ammo- 

 nia, and reheated, when it became crimson, mottled with pur- 

 ple, no doubt purpurate of ammonia. It is not worth Avhile to 

 go into the quantitative analysis of your coprolite again. It is 

 not a matter where atomic weight is to be settled, or the exact 

 constitution of a mineral to be determined. Its ingredients 

 doubtless vary even in some portions of the same mass. The 

 result of the analysis which I have already sent you, is near 

 enough to settle the question of the presence in this substance, 

 of a large proportion of phosphate and carbonate of lime and 

 magnesia. We have proof of the presence of nric acid, of mu- 

 riate of soda, and of ammonia. The last exists probably as 

 urate, triple phosphate, and possibly muriate. It may be said 

 that I ought to have found ammonia in my solution of urates. 

 I attempted so to do. The solution remaining above the flocks 

 of urate of silver, if ammonia urate had existed, should contain 

 nitrate of ammonia. It was evaporated dry — probably no nitrate 



