CHEMICAL SCIENCE. 173 



that the animal and vegetable remains, so universally found in the 

 second and tertiary strata, might, by a chemical or electric influence 

 exerted upon the disintegrated particles of these rocks, have been the 

 cause of their aggregation. The result of numerous experiments, un- 

 dertaken since that period, has, she states, satisfactorily demonstrated, 

 that if the constituents of any mineral body, of which lime forms a part, 

 be mixed in their true proportions, (the lime used being free from car- 

 bon in any form,) and these mixed with animal and vegetable remains, 

 under circumstances of due moisture and heat, aggregation of their 

 particles will take place at periods, varying with the substances under 

 experiment, from a few minutes, to hours, weeks, and months ; and 

 those artificial aggregations (allowing for absence of time, and the in- 

 calculable amount of superincumbent pressure present in the natural 

 phenomena) come so undeniably near, in appearance and qualities, to 

 the products of nature, as to throw a totally new and interesting light 

 on some of her hitherto most mysterious operations. 



There are two problems which have justly been considered by geolo- 

 gists as among the most difficult in their science ; the one is, that the 

 nodules in strata containing fossils, particularly crustaceous relics, con- 

 tain more lime taking size for size than the intervening spaces in 

 the beds. The natural conclusion, at first sight, is, that the surplus lime 

 accrues from the osseous fabric of the organism. But investigation 

 proves that there is more lime contained in the whole nodule than this 

 will account for. Mrs. Marshall's experiments and specimens show 

 that bone or recent shell has, more than any other portion of the animal 

 frame, a power of attracting or of conde?isin g lime, while a counter 

 power is exerted by the lime of hardening or solidifying the bone. This, 

 of course, acts more powerfully and obviously when the bone and the 

 lime come in immediate contact, as in the nodules of the crustaceous 

 fossils, than in the case of the vertebrata, where the integuments in- 

 terpose like a screen. Thus, if portions of bone, or recent shells, be 

 placed in a heap of sulphate of lime, or of magnesia thoroughly free from 

 carbonic acid, with a very small proportion of vegetable matter added, 

 and the heap so prepared be kept in circumstances of moisture, the 

 parts in contact with the bone will first begin to harden or condense, 

 and this action will gradually radiate to an extent corresponding to the 

 size and form of the osseous matter, while, at the same time, the bone, 

 even the soft cellular portion, becomes hard and stone-like. The very 

 same effect is produced by and on coral ; for not only does the lime 

 harden in an extraordinary degree round the coral, but in the same 

 ratio the latter loses its dull opaque, and becomes seini-translucent. 

 AVhether " countless ages " would bring these to a perfect resemblance 

 of natural fossils, it is hard to say ; but a year and a half has sufficed 

 to render them extremely curious, and worthy of attention. The ex- 

 periments conducted with the constituents of sandstone and lias, lead 

 to the very same results, but much more slowly than in the pure lime. 



The other problem to which we allude is this : From what cause has 

 it arisen that many mineral substances, and even whole strata, are 

 found identical in the nature and proportions of their constituents, yet 

 totally different in their lithological structure ? Such is the stratum 



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