NOGGERATH ON ACICULAR OBSIDIAN. 91 



sist of agglomerations of organic bodies either absolutely or essen- 

 tially, and which merely contain inorganic particles here and there 

 distributed amongst them. By this name however we may correctly 

 designate infusorial polishing slate, tripoli, the whole mass of polytha- 

 lamial chalk, coal, &c. Fossil shells, corals and bones are sometimes 

 indeed so far components of rocks as to form entire masses, but they 

 are generally extraneous, although often characteristic contents. 



On the other hand, the true well-defined elementary rocks 

 i^StmcMolites) are those which have no essential and original rela- 

 tion with organic existence, and only occasionally and accidentally 

 contain fossil organic bodies. 



For those rocks of organic origin which have not been subse- 

 quently modified by volcanic agency it would be both convenient 

 and definite to employ the more special name Hydrobiolite^ while 

 those, on the other hand, which have been so altered, we might call 

 Pyrobiolite, or pyrobiolitic rock, earth, or formation. And if it 

 should seem that a still further subdivision would be useful, we 

 might describe such rocks as the paper-coal (dysodil), the Bilin 

 polishing slate, mammillated slate, and other freshwater substances of 

 this kind, Hydrozoolite, while coal, &c. might be called Hydrophy- 

 tolite. So on the other hand we might designate white chalk and 

 the Sicilian marly chalk, as well as the Virginian infusorial marl, 

 Halizoolite (from its relation to marine organic life). 



It is to be hoped that after this manner the relations of rocks to 

 their organic and inorganic elements may find a more ready and 

 general expression, and that investigations which are not to the pur- 

 pose, and collision with existing theories so far as they relate merely 

 to forms of expression, may be avoided, and the principles involved 

 be soon distinctly recognised. 



D. T. A. 



2. On a capillary condition of Obsidian /row the Island of 

 OwHYHEE (Hawaii). By Professor Noggerath. 



[From Leonhaxd and Bronn's • Jahrbuch/ volume for 1846, p. 23.] 



At the meeting of the German naturalists and physicians held at 

 Nuremberg in 184-5, I received from Dr. Focke of Bremen a small 

 box marked ' Thread-like Obsidian,' with a request that 1 would bring 

 the subject before the Mineralogical Section during the meeting. 

 The substance in question had been brought in considerable quan- 

 tity from Owhyhee by Captain Wilken, and had been lorwarded by 

 M. Kind from Hamburg. 



The box contained a multitude of detached delicate needles of 

 obsidian, confusedly interspersed amongst minute nuclei of the same 

 substance. The needles or capillary fragments were of olive-green 

 colour and transparent ; they were for the most j)art about ^'j inch 

 long and of utiiform thickness, resembling human hair or swine's 

 bristles. There were however Nvith these, others not so regular in 



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