112 



KNO\VLEDGE 



[Fee. 1, 1886. 



percentage of ash in these plants, but will determine it 

 myself, and state the result in my next paper. 



I must here warn the reader against a fallacy usually 

 implied, though not definitely expressed in our geological 

 text books. Pictures are there shown of the calamites, 

 the sigilaria and stigmaria, the lepidodendrons, tree ferns, 

 ■ic, of the coal measures, and the reader who only learns 

 from books, without actual field-work, concludes when 

 Lyell tells him that " no less than 250 ferns have already 

 been obtained from the coal strata" ("Elements of 

 Geology," 5th edition, p. 467), that coal itself has been 

 proved to bo made of these, that ordinary coal is visibly 

 composed of such fossil vegetation, and that the pictures 

 represent fossil specimens found in the coal itself. 



This is not the case ; ordinary coal displays little or no 

 definite vegetable structure. It is true that Professor 

 Goppert found in certain samples of German coal indi- 

 cations of structure corresponding to the fossil plants 

 known as those of the coal measures, but the fossils 

 which are pictured and described in the books are those 

 found in the rocks above or below the actual coal seams, 

 not in the coal itself. Thousands of years may have 

 elapsed, must have elapsed in some cases (such as the 

 celebrated fossil tree in Cragleith quarry), between the 

 deposition of the coal itself and that of the fossil jjlants 

 in the other rocks. Great geological changes must have 

 occurred in order that pure vegetable matter, deposited 

 where it grew, should be succeeded in the same place by 

 a subaqueous deposit of sandstone, fifty or sixty or more 

 yards in thickness. All this sandstone was certainly 

 formed under water, and that water must have been 

 deeper than its own thickness. If the coal was formed 

 on the land, it must have been submerged either by a 

 great convulsion or a series of ordinary changes extend- 

 ing over a vast duration of time, before the great sand- 

 stone or shale deposit could be formed over it. 



The same reasoning applies conversely to the fossils 

 found in the rocks below the coal-seams. Many of the coal- 

 fossil specimens in our museums have come from rocks 

 that are as much as 100 ft. above or below any workable 

 coal seam. I once collected a cart-load of fine specimens 

 from the materials of a sinking in Flintishire which failed 

 to reach tlic coal. 



I do not, however, assert that vegetation correspond- 

 ing to these fossils found in the rocks have not contributed 

 to the formation of the coal itself, but that the condi- 

 tions of their deposition were quite different from that 

 of the coal seams, and that they represent only those par- 

 ticular species of plants that are capable of retaining 

 their structure under the circumstances of deposition. 

 In the rocks where these fossils occur there are ten thou- 

 sand or more i)arts of mineral matter to one of vege- 

 table matter. In the coal there are forty or fifty of 

 vegetable matter to one of mineral — less mineral matter 

 than is found, on an average, in living plants. 



Lyell struggles with this difiiculty by supposing that 

 our coal measures have " originated in the manner of 

 modern deltas." He says, "They display a vast thick- 

 ness of stratified mud and fine sand without pebbles ; and 

 in them are seen countless stems, leaves, and roots of 

 terrestrial plants, free for the most part from all inter- 

 mixture of marine remains, circumstances which imply 

 the persistency in the same region of a vast body of fresh 

 water. ' ' 



But how about the absence in the coal itself of this 

 mud and sand, the mineral sediment which makes 

 up the substance of ordinary " modern deltas " ? The 

 explanation offered by Sir Charles Lyell, who always 

 rea,sons on the sound principle of explaining the ur^ 



known by the aid of the known, is derived from 

 what actually occiirs in the valley and delta of the 

 Mississippi, where the dense growth of reeds and herbage 

 which encompasses the margins of forest-covered swamps, 

 " is such that the fluviatile waters, in jsassing through 

 them, are filtered and made to clear themselves entirely 

 before they reach the areas in which vegetable matter 

 may accumulate for centuries, forming coal if the climate 

 be favourable." 



Here he sujiposes (as he states further on) that the coal 

 was formed actually on the spot where the vegetation 

 grew ; this brings us back to the difficulty I have already 

 stated — viz., the absence of the mineral matter demanded 

 as soil for the plants. How many generations of trees 

 would be necessary to cover the ground closely together 

 so as to form a stratum only one tree deep ? How many 

 of such strata would be required to build up a coal-seam, 

 like that of South Staifordshire, thirty feet deep, seeing 

 the great condensation of original bulk which occurs? 



Mosses may grow, do grow, in peat bogs upon the dead 

 bodies of their ancestors; but forest trees and other 

 higher vegetation cannot. In tropical forests, the trees 

 that fall and the leaves that are shed vanish by slow 

 combustion and the work of microbia and insects. Their 

 carbon is converted into gaseoDS carbonic acid, and only 

 their ash remains, just mingled with a residuum of 

 humus sufficient to form an ordinary vegetable soil, 

 which, if burnt, would leave seventy, eighty, or ninety 

 per cent, of ash. 



Mr. Proctor's comments on my incidental reference to 

 phlogiston and ether seem to imply, and must convey to 

 his readers the impression, that I accept the corpuscular 

 theory of light. I reply, in order to defend myself against 

 such misunderstanding, which amounts in fact to a com- 

 plete inversion of my views. I regard the corpuscular 

 hypothesis of Newton, with its fits of easy transmission 

 or reflection, as a physical superstition one degree more 

 gross than that of the luminiferous ether, and equally 

 gratuitous. This may appear very rude, r.nd, therefore, 

 to mollify a little, I will add that my views are not 

 original, not new, not even modern. They were quaintly 

 enunciated by a great philosopher, who died when Sir 

 Isaac Newton was five years old. 



Torricelli says, " La materia altro non e che un vaso di 

 Circe incantato, il quale serve per ricettaeolo della forza, 

 e dei momenti dell' impeto " — " Matter is no other than an 

 enchanted cup of Circe, which is the receptacle of force 

 and momentum." He continues by saying that force and 

 momentum can be contained in no other receptacle than 

 the intimate substance of ordinary matter. To render 

 this a precise expression of my own views, I will translate 

 it freely into the language of modern science, when it 

 stands thus : — All the activities of matter reside itb the 

 substance of matter itself, and can be i manifested and coin- 

 mwiicatcd only by such substance. 



MODERN ANALYTICAL CHEMISTRY,* 



[GANTIC as have been the strides in 

 theoretieal chemistry since the first enun- 

 ciation of the Law of Avogadro in 1811, 

 the analytical branch of that science may, 

 we think, fairly claim to have progressed, 

 pari passji, with the hypothetical one, and 

 to have proved itself equal to any demands 

 which have so far ever been made upon it. Very worthily 



* "Select Mettiods in Chemical Analysis." By Wm. Crookes, 

 F.B.S., V.P.8.C. L'nd Edit. (London : Longmans, Green & Co. 1886.) 



