Scientific Intelliyence — Geology and Mineralogy. 183 



itself will soon solve the doubts hitherto existing in the comparison 

 of the coal fossils with recent plants. 



I will merely add, that I have found quite distinctly the impres- 

 sion of the cellular cuticle of some of those plants, which, of course, 

 cannot be seen in an impression on shale, the grains of the sedimen- 

 tary matter being as large as the surface of the cells ; but on the 

 pasty mass of the coal the impression is perfect. — {American Journal 

 of Science and Arts, vol. iv., No. xii., p. 420.) 



8. Artificial Colours in Agate. — The change of colour produced 

 artificially in the agates by the workers in them at Oberstein, an 

 art learned from the Italians, and to which Mr Hamilton calls atten- 

 tion in his communication, stating his belief (referring also to the 

 labours of M. Noeggerath) that not a tew of the onyxes which have 

 come down from ancient times were thus treated, is of much interest 

 miueralogically, since it shews the very different porosity of different 

 layers in the agates, the least porous bands not being necessarily the 

 nearest to the centre, but dispersed irregularly thi-oUgh the mass. To 

 this porosity JNIr Hamilton calls attention, citing the researches of 

 M. Noeggerath, who states, that in some layers the minute hollows 

 can be seen by means of a magnifying glass ; that, while some are 

 round, others are long, and that they sometimes run into one another. 

 These hollows, Mr Hamilton considers, may form interstices between 

 the radiating crystals. By immersion for some time in honey and 

 water or olive oil, so that the pores of the agate become more or less 

 filled with a substance to be carbonised, a subsequent soaking of the 

 stone in sulphuric acid produces a difference in the tints of the agate 

 according to the porosity of the layers, the most porous becoming- 

 black, while the least porous remain white or uncoloured. By im- 

 mersion in a solution of sulphate of iron, and a subsequent heating 

 of the agate, a carnelian red is in like manner obtained for the most 

 porous layers, the iron being converted into a peroxide, while the 

 least porous layers continue unchanged in colour. It would be out 

 of place further to dwell upon the infiltration of mineral matter in 

 solution into the isolated cavities of rocks. The mode in which the 

 various minerals occur is highly interesting, as also their connection 

 with the matter filling veins and fissures in adjoining parts of the 

 same or adjacent rocks, as, for example, the filling of the fissures in 

 the red conglomerate by the same kind of siliceous matter which 

 entered into the cavities of the igneous rocks of Idal, the layers hav- 

 ing, in both cases, adjusted themselves to the surfaces on which they 

 were accumulated. — (.Sir Henry T. De la Beckers Address, delivered 

 at the Anniversary Meeting of the Geological Society of London, on 

 the 18th February 1048, p. 55.) 



9. The Coal of the Kangra Valley. — The mention of Dr Jame- 

 son's labours in the Kangra districts reminds us of the question 

 whether good coal is to bo found there. Much has been written upon 

 the subject by some of our Mofussil contempoi'aries, and we believe 



