Mineralogy and Geology. 131 



I. 2-131 grains of the crystals, when heated to redness, lost 1*034 

 grs. in weight of water and ammonia. 



II. 1*940 grains gave 6 039 grs. of ammonio-chlorid of platinum 

 =0-465 grs. of ammonia. 



HI. 3*500 grains gave 10-539 grs. of phosphate of lead, which gave 

 11-786 grs. of sulphate of lead =1-854 grs. of phosphoric acid. 

 Or, in 100 parts : 



i. ii. in. 



Water, 



48-521 



• • • • 



23058 



Ammonia, j<*oo*i j 23080 .... 23-980 



Phosphoric acid, 52962 52-962 



numbers which are very nearly equivalent to 1 atom of ammonia, 1 

 atom of phosphoric acid, and \\ atoms of water. It may therefore be 

 considered as the neutral phosphate of ammonia. The excess of water 

 was doubtless caused by the moisture which remained between the in- 

 terstices of the crystals. It was therefore the same salt as that which 

 had been previously examined by Mr. Teschemacher, but which he was 

 prevented from analyzing quantitatively on account of the smallness of 

 the quantity in his possession. 



In conclusion, I should perhaps observe that the guano from which 

 the above substances were obtained was exceedingly moist, and pos- 

 sessed a strong ammoniacal smell. 



39. On the probable extent of the Flora of the Coah Formation in 

 Britain; by Dr. Hooker, (from a Memoir on the Vegetation of the 

 Carboniferous Period, in Jameson's Jour., vol. xlvi, 1848-49.)— No 

 fewer than 300 species of plants have been enumerated as belonging 

 to the Coal Flora of Great Britain ; but, whether this gives any ap- 

 proximation either to what was the amount of species at one pe- 

 riod, or even to all those which contribute to form the coal, it is impos- 

 sible to say. It need hardly be observed, that a collection of the frag- 

 ments imbedded in our most recent deposits is no index to the general 

 mass of existing vegetation, nor are the remains necessarily those of the 

 commonest plants, or even of such as would a priori be judged the 

 best suited for becoming fossilized. That hitherto unknown species do 

 exist in an available state for the botanist cannot be doubted ; they are 

 °f frequent occurrence ; but that these are not so numerous as might 

 be expected from the enormous magnitude of a coal-field, is evident 

 from the great uniformity that prevails throughout the formation. It 

 may indeed be a query, whether the number of species still to be dis- 

 covered will equal in amount that of the so-called species, which, being 

 founded on imperfect specimens, will ultimately prove to belong to 

 Previously described forms. .„ . . 



it cannot be disputed that the vegetation of the carboniferous period, 

 whether confined to the coal-veins or not, was highly luxuriant. The 

 ^ormous bulk of carbon accumulated, and the prevalence of ferns in 

 al1 the fields, and the great size to which so many soft-tissued plants 

 ?ttamed, all prove this fact. A luxuriant vegetation is, however, no 

 Ind ex to a varied one ; and as many of our modern woods, and even 

 g^at areas of tropical forests, consist of but a few spec.es greatly 

 rouluplied, so may the forests of the carboniferous period have been 

 composed of but a few Sigillaria and Lepidodendrons, sheltering an 



