HARD WICKE ' S S CIE NCE - G O SSIP. 



These are in habit like Agarics (see figure). Most 

 frequent, B. chrysenteron ; brown and tomentose 

 above, greenish-yellow below : B. aestivalis ; pileus 

 dark brown, cracked when old, dirty white beneath : 

 and B. scaber ; much resembling it, but stipe covered 

 with fibrous scales (both species in the wood behind 

 Loughton). B. edulis, one small specimen, brownish 

 above, whitish below (when young, but when old 

 turning to a pale yellowish-green), the tubes elongated 

 and half free ; it may be known from its congeners 

 by its stem, which is elegantly reticulated. B.flavits ; 

 pileus viscid, yellowish ; hymeneal surface yellow ; 

 pores large, angular, ragged ; stem cribrose above 

 with the decurrent tubes ; not frequent. B. ekgans ; 

 hymeneal surface lemon-yellow ; of firmer substance 

 than the preceding, and with much smaller pores ; 

 one specimen ; copse below Woodford. 



Plentiful this year was another plant of the Poly- 

 pore family, of a soft, spongy, or fleshy consistence : 

 viz. Fishdina hepatica, growing upon old oak-trees. 

 Those who are unacquainted with its peculiar aspect 

 could hardly credit its strong resemblance to a piece 

 of raw bullock's liver, and still less imagine that so 

 odd-looking and unattractive a thing can be edible. 

 We had a portion of it dressed for dinner ; the odour 

 and flavour thereof were not bad, but it ate very much 

 like what stewed gutta percha might do, and there 

 was an after sensation upon the teeth and palate of 

 astringency, referable no doubt to the presence of 

 gallic acid. From a scientific point of view it is an 

 interesting fungus, because different to other Poly- 

 pores in that^the hymenium is at first papillose, but 

 when full grown the tubes are seen to be all separate 

 and distinct. 



( To be continued?) 



CHEMICAL ACTION IN ITS GEOLOGICAL 

 ASPECT. 



By T. Mellard Reade, C.E., F.G.S., &c. 



EVERY ONE is, no doubt, familiar with the fact 

 that, in boiling most water in our common 

 kettles, a white precipitate, known as "fur," forms 

 on the inside of the vessel. This is specially the case 

 with our well water, and is due to the fact that the 

 water, in its passage through the pores of the rock, 

 has dissolved and taken up, in solution, lime, in the 

 form of a carbonate, which is precipitated in the pro- 

 cess of boiling. This is not only the case with well 

 water, but, to a greater or less extent, with river water, 

 the relative amounts being due to the nature of the 

 rock forming the drainage basin of the river. We are 

 thus brought face to face with the fact that all natural 

 water contains, however clear it may seem, extraneous 

 minerals in solution, for not only do we find lime in 

 it, both in the form of a carbonate and a sulphate, 

 but also magnesia, silica, potash, soda, iron, and other 

 minerals, in more or less minute proportions. 



This may seem a very small matter, and a very weak 

 instance of " chemical action," but these very forces, 

 apparently so insignificant, have been mainly instru- 

 mental in fashioning this world of ours into its pleasing 

 alternations of mountain and valley, hill and dale. 

 But to make the importance of the fact plain, it is 

 necessary to put some figures that will give an idea of 

 the gross, as well as relative, quantity of minerals 

 removed in solution by water. It is possible, you may 

 think, that 19 grains per gallon of "solids in solu- 

 tion " is so small as to be unworthy of notice, but as 

 regards the river Thames it means, according to 

 Professor Prestwich's calculation, the removal into 

 the sea annually of 548,230 tons of saline matter, or, 

 roughly speaking, a ton a minute. 



We thus see that all rivers are carriers of invisible 

 material, and that, in addition to the mud, sand, and 

 gravel which, the most unobservant person can see, is 

 hurried along to the sea at every freshet, a slow and 

 silent transference of materials is taking place with 

 great uniformity of action, winter and summer, dry 

 weather and wet, from the land seawards. The 

 Rhine, the Rhone, and the Danube unitedly, accord- 

 ing to calculations I have made, remove annually in 

 solution over thirty-six million tons of saline matter, 

 gfc By an elaborate calculation, but a thoroughly re- 

 liable one, I have arrived at the result that the rain- 

 fall removes, in England and Wales, matter in 

 solution equal to 1 foot in thickness over the whole 

 area (in round numbers) in thirteen thousand years.* 

 But these effects of chemical action mean much 

 more, geologically, than at first sight appears, for the 

 removal of so much mineral matter in solution is, in 

 most cases, the destruction of the cementing materials 

 that hold the more insoluble particles of the rocks 

 together, and their consequent degradation. It is as 

 if the mortar of this building were dissolved out by 

 chemical action, and the loose bricks, stone, and 

 timber carried away by the first floods into the river 

 Mersey. Therefore it is clear that, in order to account 

 for geological changes of magnitude, we only require 

 time and large areas of land for the rain to act upon. 



The effects of chemical action on rocks is often 

 apparent in an objectionable and costly manner in the 

 stone used for building purposes. The decomposition 

 and crumbling away of the new red sandstone of 

 which Chester Cathedral was built is an instance, 

 and in the Shrewsbury churches the decay is very 

 apparent. The same may be said of the Permian 

 sandstone, of which a church in Coventry is com- 

 posed, while in Ludlow parish church the same action 

 may be seen on the old red sandstone. The decay 

 of these stratified rocks is largely due to their numerous 

 planes of bedding and porous nature, permitting the 

 penetration of water. Solid granite, however, not 

 possessing any stratification, weathers and decays in 



* Geological time. Presidential Address, Liverpool Geological 



Society, session 1876-77. 



