284. Mr Connewx’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 muriatie 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 
Brrzevivs’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.t+ 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 Prour in his analysis of the co- 
prolites from the has, that the proportions appeared to differ not 
merely in different specimens, but in different parts of the same 
= 
* Lehrbuch, iv. 445. 
+ 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 Grecory and Mr 
Waker 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 thé 
blowpipe test. 
