94 Fossil Bones and Pseudo- Coprolites of the Crag. 



venience of reference, I have annexed a small map, which shows 

 the position of the crag along the coasts of the counties I have 

 named. By glancing at this, it will be seen, that the crag forma- 

 tion is extended over a district of country about 65 or 70 miles in 

 length by 10 miles in breadth. Only a very small portion of this 

 district, however, has as yet been examined ; the greater number 

 of fossil quarries or mines (if they may be so called) having been 

 opened in the neighbourhood of Ipswich, Brampton, Sutton, 

 Saxmundham, and Buxton. But this condition of things will not 

 exist much longer ; the eyes of the proprietor of the soil will soon 

 be opened to the sources of wealth which lie beneath its surface, 

 and in a short time — a very short time perhaps — these fossil 

 remams will be sought after as eagerly as the seams of coal with 

 which Liebig has so happily contrasted them. 



With regard to the process of analysis which was employed in 

 these examinations, it differed but slightly from that ordinarily 

 adopted. The only novelty consisted in the method of estimating 

 the fluoride of calcium. The quantitative estimation of fluorine, 

 it is well known to chemists, is accompanied by no slight diffi- 

 culty, particularly when that substance is associated with phos- 

 phoric and carbonic acid. The manner in which I proceeded to 

 effect it in the present analyses was as follows 



The finely powdered bones or coprolites, having been heated to 

 redness, were dissolved in dilute hydrochloric acid, and the solution 

 was then evaporated to dryness. The dried mass thus obtained 

 was reduced to a fine powder, and heated to from 350° to 400° F. 

 in a sand-bath, in order to expel all traces of hydrochloric acid. 

 It was afterwards repeatedly extracted with a boiling mixture of 

 alcohol and water, composed of equal parts, by measure, of 

 water and rectified spirit.* The washing was continued until the 

 liquid which passed through the filter ceased to render an acid 

 solution of nitrate of silver opalescent. The insoluble residue 

 was now heated to redness, intimately mixed with about a third 

 of its weight of pure silica, and placed in a small flask, which 

 could be weighed in a balance. To one orifice of this flask, 

 which was furnished with two tubulures, an U-shaped tube was 

 attached, containing fibres of asbestos moistened with concen- 

 trated sulphuric acid, as an absorbent of moisture. Very concen- 

 trated sulphuric acid, which had been previously boiled, was next 

 added to the mixture in the bottle, and the whole apparatus 

 weighed. Upon now exposing it tO' a proper degree of heat, 

 gaseous fluoride of silicon (S F^) was evolved, from the quan- 

 tity of which, as shown by the loss of weight sustained by the 

 apparatus after the conclusion of the experiment, the proportion 



* Fluoride of calcium is, to a certain extent, soluble in water, but is very nearly, 

 if not quite, insoluble in dilute alcohol. — T. .J. H. 



