Scientific Intelligence — Mineralogy. 359 



mineral substance in which the crystals are imbedded — {Quarterly 

 Journal of the Geol. Society, vol. ix., No. 35, p. 24.) 



3. On the Structure of Agate ; by Theodore Giimbel. [Leon- 

 hard u. Bronn's N. Jahrb. f. Min., u.s.w., 1853, pp. 152-157.) 

 — The curious and beautiful appearances afforded by agates have 

 long made them of primary importance in mineralogical cabinets ; 

 but until of late years particular attention does not seem to have been 

 paid to the internal structure of these bodies. Dr J. Zimmerman 

 is the first, of my knowledge, who observed* that the different va- 

 rieties of quartz — as amethyst, calcedony, carnelian, jasper — formed 

 the concentric layers of the nodules, which were either hollow or 

 occupied with crystals, f 



In the Jahrbuch of the Imperial Geological Institute of Vienna 

 for 1851, J is a very interesting memoir on the interior structure of 

 agates by Prof. Dr Franz Leydolt, where he states that, on being 

 submitted to the action of fluoric acid, the amorphous portions are 

 dissolved before the crystalline layers or bands; and the agate 

 surface being thus prepared, it is made use of in printing an exact 

 copy of itself. The six beautiful plates accompanying the memoir 

 perfectly exemplify Prof. Leydolt's views, and shew, — first, that 

 the parts towards the outer surface consist of several spherules 

 variously combined, which are composed of layers of diverse cha- 

 racter ; secondly, that towards the centre of the nodule is a large 

 mass of amethystine quartz, the nucleus of the latter again being 

 formed of very small concentric spherules. 



In the Jahrbuch fur Praktische Pharmazie, Sc. 1852, is a short 

 paper of mine on the rotatory motion of matter in the amorphous 

 condition, in which I have shewn, that in a sphere of blown glass 

 the material is not homogeneous, but consists of lamellae overlying 

 one another at varying angles and confusedly distorted. As in 

 the thin pellicle of blown glass the intimate structure of the soap 

 bubble is as it were fixed, so I sought to make further researches by 

 means of experiment on molecular movement, such as can be ob- 

 served in so many instances. One of the most successful experi- 

 ments was the use of melted stearine with which very fine graphite 

 had been mixed, spangles of which easily indicated the intimate 

 motion of the mass. By this easy experiment it appears that in 

 some parts there was a strong tendency to the formation of spheres, 

 and which existed even in the interior of the larger spheres, giving 

 rise to smaller spherules. — {Quarterly Journal of the Geological 

 Society, vol. ix., No. 35, p. 259.) 



4. Scleretinite, a new Fossil Resin from the coal measures of 

 Wigan, England ; by J. W. Mallet. — Occurs in small drops or tears 

 from the size of a pea to that of a hazel nut. Brittle, with the 



* In his Taschenbuch fur Mineralogie. 



t See also Mr Hamilton's Paper on the Agate Quarries of Oberstein, Quart. 

 Journ. Geol. Soc, vol. iv., p. 215. — Transl. 

 | Vol. ii. No. 2, p. 124. 



