284 Mr Connell's Analysis of the 



shews the presence of a trace of ammonia. This reaction indi- 

 cates the existence of a minute quantity of animal matter ; and 

 it is proper to observe, as I shall afterwards have occasion to no- 

 tice more particularly, that the dark coloured limestone itself, in 

 which the coprolites are imbedded, shews a similar reaction. The 

 coprolites are soluble in dilute muriatic acid with moderate ef- 

 fervescence, leaving a residue of dark flocky matter ; and when 

 the solution is treated with ammonia, a plentiful gelatinous pre- 

 cipitate is thrown down, having all the appearance of phosphate 

 of lime. Examined in the usual way for detecting phosphoric- 

 acid by means of potassium, they afford very decided indications 

 of the presence of that acid. They also contain a little oxide of 

 iron, but no sulphur in any state of combination. Magnesia was 

 sought for both by fusion with carbonated alkalies and other ne- 

 cessary steps, in which way none was detected ; and also by 

 Berzelius's process for finding it in bones.* The ultimate 

 ignited residue got by this latter method consisted almost en- 

 tirely of siliceous and alkaline matter, with only a very minute 

 quantity of magnesia. A trace of fluoride of calcium is easily 

 detected by treating the coprolites with sulphuric acid in the 

 usual way.f Phosphate of lime and carbonate of lime are thus 

 the prevailing constituents. 



I next proceeded to ascertain the proportion of these constitu- 

 ents ; and, as it is stated by Dr Prout in his analysis of the co- 

 prolites from the lias, that the proportions appeared to differ not 

 merely in different specimens, but in different parts of the same 



* Lehrbuch, iv. 445. 



-f- In my first search for fluoric acid I merely employed the blowpipe test of fused 

 salt of phosphorus and Brazil wood paper, with the delicacy of which, the alkaline 

 reaction of the coprolites interfered. In the mean time, Dr Gkegoky and Mr 

 Walker found fluoric acid, in the usual way, in a coprolite examined by them ; 

 and I have since found that, with due precaution, it may be detected even by the 

 blowpipe test. 



