442 ON BOMBRERITE. 



found on the margin of rivers, lakes and swamps. In many cases it is 

 found in groves also, in company with maple and other hard woods. The 

 wood is not esteemed for mechanical purposes, except in hridge and wharf- 

 building, and for piles, abutments, and ships' ground ways. It is very 

 generally cut up into boards and lathwood, the latter being exported in 

 large cpiantities to Great Britain. The wood is considered very durable 

 under water — in wharves it has been known to remain in a good state of 

 preservation for thirty years and upwards. Lloyd's committee admit it in 

 ships of the four year class for floors foothooks, top-timbers, and inside and 

 outside planking. 



The bark of the hemlock tree is greatly used by tanners, and takes the 

 place of oak bark. The bark is stripped off the tree in long slabs, and 

 answers as a substitute for boards in covering the camps or hovels used by 

 the lumbermen when engaged in the forests in lumbering pursuits. 



Wherever the hemlock and lofty pine exist, the soil, being cold and wet, 

 is not held in much esteem for agricultiu , al purposes. 



ON SOMBKERITE. 



BY DR. T. L. PHIPSON, F.C.S., 

 Member of the Chemical Society of Paris, &c. 



This mineral forms a large portion of some small islands in the Antilles 

 especially that of Sombrero Island (N. lat. 18° 35', W. long. 63° 28'), about 

 sixty miles from St. Thomas. Its composition and properties prove it 

 to be a new species, to which I have given the name Sombrerite. It 

 is remarkable by the large proportion of phosphoric acid it contains. 



Sombrerite presents itself in nature as a white, yellowish white, or 

 reddish coloured rock, having a straight fracture, and in some portions 

 a peculiar horny aspect. Its appearance is in general compact, though 

 in reality it is extremely porous. It shows no signs of crystallization 

 whatever, but appears to be an amorphous, gelatinous phosphate, that has 

 been submitted to a high temperature in contact with steam, and at a high 

 pressure. It is thought to be of comparatively recent geological origin, as 

 it encloses fossil bones (of mammalia ?), and several kinds of shells. In a 

 mineralogical point of view, Sombrerite is a compound of phosphate of 

 lime with phosphate of alumina. In some specimens a certain proportion 

 of the isomorphous oxide of iron is substituted for a corresponding 

 portion of alumina ; in others, where little or no iron is present, the 

 mineral adheres to the tongue like other aluminiferous minerals. 



Sombrerite is not phosphorescent by heat, like apatite; before the blow- 

 pipe, when moistened with sulphuric acid, it colours the flame pale green. 



