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THK CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



[June, 



besides llie remains of a frog, lizard, aad snake, and the bones of several 

 birds. Mr. Owen lias examined some of these remains for Mr. Lyell, and 

 recognises anion;; tliem llie /•.V;«us/»s»i/is and Tarandus priscus, both extinct 

 species, occurring in the caves of England, with the contents of which ge- 

 nerally this assemblage of fjssils from Auvergne appears to agree very 

 closely — there being a predominance, according to Messrs. Croizet, Bra- 

 vard, and I'oinel, of species not known to exist al present with an inter- 

 mixture of a few others undistiDguishable from quadrupeds now inhahiting 

 Europe. Among the land shells associated with the bones, were found 

 Cycluiloma flex"'!", I'ltiusilia rugosa, Helix hiirtensis, U. nemoralis, 11. 

 lapicitln^ and H. obvolntn — all recent, and all, with the exceptitm of the last, 

 now found in ihe immediate neighbuurhond. Mr. Lyell thinks it probable 

 that the deposit of red arjiillaceous sand under the lava containing these 

 remains, was derived cliietly from volcanic matter, which tlie eruption of 

 Tartaret threw out, and that ihe fossil animals perished by floods occasioned 

 by that outburst. That a similar Fauna continued to live iu Auvergne 

 after the latest eruptions, is inferred from the discovery of the remains of 

 many of the same group of animals — Spermophilus, Lepus, Castor, and 

 others, in the rle'ts of a lava current as modern as that of Tartaret, ob- 

 served at Aubifere, near Clermont. This Fauna, so ditferent as a whole 

 from that now living iu Europe, evidently inhabited Auvergne, when the 

 valley of the Couze had been excavated down to the same level as that 

 over which the lava of Tartaret flowed:— yet its antiquity must be ex- 

 tremely great — the gradual dying-out of species and the introduction of 

 new ones taking place, accordmg to Mr. Lyell's views, with extreme slow- 

 ness. The fact that Ihe sliells belonged ail lo living species (which possi- 

 bly might not hold good if a larger number were oblaiued) affords no pre- 

 sumption against au indefinitely remote origin as compared lo the periods 

 of history and tradition, because the lecturer has shown that the ravine of 

 the Niagara (" Travels in N. America," vol. i. ch. 2) and the Delta of the 

 Mississippi (Keports of the Brit. .A.ssoc. for 1840), both of which must have 

 required an enormous period for their lormation, are, nevertheless, posterior 

 in date to deposits full of the recent land and freshwater shells of North 

 America, associated with the remains of quadrupeds, nearly all of which 

 are now extinct. 



It was shown that all the volcanoes of the modern class of which the 

 I'uy de Tartaret is a type, were nut formed at once, for the lavas of some 

 (as for example, at Champheix, in the same valley of the Conz-;) stand at 

 a greater height above the actual river-courses and repose on ancient allu- 

 vium formed when the valleys were shallower. To allow time for the ejec- 

 tion of these numerous cones and lava-currents, of which there are several 

 hundreds in Central France, we require a long series of ages, all subse- 

 quent to the miocene period, to which another class of monuments of ante- 

 rior date are referable — as, for example, the bone-bearing alluviums alter- 

 nating with volcanic formations (pumiceous and trachytic)of fliunt Perrier, 

 lo which a distinct Fauna (of ihf genera mastodo, elephant, hippopotamus, 

 tapir, &c.) belongs. Some of the valleys cut out of the still more ancient 

 lacustrine strata were only half eroded to their present depth in the mio- 

 cene period, and were occasionally tilled up with miocene deposits and 

 afterwards re-excavated. It is possible in Auvergne to distinguish the rela- 

 tive ages of a great variety of alluviums containing the bones of terreUrial 

 quadrupeds, in consequence partly of their preservation under lavas of dif- 

 ferent ages, and partly their position on the sides of valleys which were 

 gradually deepened ; no Hood or return of the ocean having disturbed the 

 surface and mingled the fossils of one period with those of another, as has 

 hajipened in England and most parts of Europe. The oldest Fauna of 

 land quadrupeds in Auvergne, that found in a fossil state in freshwater 

 strata or marl and limestone, older than the trachyte of Mont Dor, consisted 

 of species of Paleotherium, Anoplolheriuni, Anthracotherium, Opossum, 

 &c., analogous, in great part, to those of the Paris basin, with some mio- 

 cene forms associated and belonging, according to Mr. Lyell, to an upper 

 eocene group, newer than the Parisian tertiaries, or the uppermost fresh- 

 water of the Isle of Wight. Hence it follows that the Vi\\o\e succession of 

 revolutions in the animate and inanimate creation which have occurred in 

 Central France since the land emerged, vast as they are in duration, as 

 compared to the era of the more modern volcanoes, is nevertheless, con- 

 siderably posterior to the marine clay on which Loudon is built ; — this last 

 being one of those tertiary deposits which rank as but the monumeots of 

 yesterday in the great calendar of geological chroaology. 



IMPURITIES OF WATER. 



.\t the Royal Institution, April 16, Prof. Solly delivered a lecture " On 

 the Impurities of Water ami the Mode of its Purificatiun." ' 



Mr. Solly described fresh water as the reiult of distillation from the 

 ocean. In the progress of this operation, the vapour in the first instance, 

 and the condensed liquid subsequently, must become contaminated with 

 whatever foreign matters exist in the atmosphere which receives the former, 

 and the strata of the earth on which the latter falls and through which it 

 percolates. But even at the outset of this natural chemistry there is iui- 

 l>urily. Alkaline salts, as Mr. Solly has already demonstrated, rise in 

 vapour; therefore no water which is evaporated from the sea can be pure. 

 The analysis of water is simple in theory. The gaseous or solid substances 

 cnntaiued in, or combined with it, being detected by few tests. Before, 



however, the analyst has recourse to these, he attends to the physical quali- 

 ties of the fluid — any odour, or colour, or taste, being at once indicative of 

 impurity. These impurities are eilber gaseous, organic, ot inorganic. — 1. 

 Gaseous. If common air be present in the water, it is detected by heat ; if 

 carbonic acid gas, by lime-water; sulphuretted hydrogen is discovered by 

 its odour, and by its blackening salts of lead. — 2. Inorganic iVatters. These 

 are either solid substances, as clay, held in suspension by organic matter 

 or else insoluble substances held in solution by the gas that is present in 

 the water. Thus, Carrara-water is chalk dissolved in water by Ihe excess 

 of carbon therein. There remain other inorganic substances, as common 

 salt and some salts of iron, which are essentially soluble. Besides these 

 impurities, water kept in leaden vessels often contains a trace of that metal. 

 Mr. Solly noticnd the familiar tests by which these are recognised. — 3. 

 Organic ImpuritiLS in Water are chiefly noxious by the sulphuretted hydro- 

 gen and aniuiunia which they produce, and which is usually perceptible to 

 the senses. The effects of these various impurities were next specibed. 

 Mr. Solly explained, from the principle of saponification, how water con- 

 taining salts of lime decomposes the soluble soda or potash soap, and forms 

 an insoluble lime soap, which is useless for all purposes of washing. He 

 quoted the opinion of some experimenters, that bicarbonate of lime rather 

 improved than deteriorated the utility of water for culinary purposes ; but 

 he maintained that it was injurious to the vegetation of plants, in conse- 

 quence of the deposit on their leaves which it left on being evaporated. 

 Sulphate of lime is always injurious for culinary uses, inasmuch as it in- 

 terferes with the solubility of many organic substances, as tea, &c. Hav- 

 ing briefly adverted to Ihe injury produced by the earthy impurities of 

 water when they are deposited in water-pipes, boilers of steam-vessels, 

 &c., Mr. Solly lastly suggested various methods of freeing water from the 

 impurities which he had described. Solid matters are separated by filters 

 of sand or of finely-powdered charcoal. The latter substance possesses 

 the additional property of absorbing gases : hence its use in sweetening 

 fetid waters. Carbonate of lime is decomposed by the mixture of muriate 

 of ammonia in the water which contains it. This practice has been found 

 efficacious in preventing deposits in steam-boilers. Gypsum may be thrown 

 down in the form of carbonate of lime by adding carbonate of soda. A 

 very ingenious process for Ihe same purpose was exhibited : — by filtration 

 through oxalate of baryta, sulphate of lime is entirely separated from its 

 solution. This operation may still leave a trace of the oxalate of baryta in 

 the purified water. This small contamination, however, may be entirely 

 removed by making the fluid pass through a second filter of phosphate of 

 lime. The water then becomes perfectly pure. With respect to the most 

 dangerous of all impurities — the salts of lead — Mr. Solly showed that, un- 

 less common water contain (as we understood) from g^'jj to ^^^ of its weight 

 of earthy salts — such as sulphate of lime — it ought never to be used as a 

 beverage when kept in leaden cisterns. These earthy salts protect the lead 

 from the action of the water. — Mr. Solly referred to the attempt to render 

 lead insoluble by alloying it with j|j3 of its weight of arsenic. He then 

 spoke of the signal failure of an endeavour lo protect lead from the action 

 of water by placing it in contact with zinc. The result of this experiment 

 was a vastly increased corrosion of the lead by Ihe water iu which it was 

 immersed ; which was, therefore, rendered additionally poisonous. 



VULCANIZED INDIA-RUBBER. 



At the Royal Institution, April 20,Mr. Brockedon explained " The Pre- 

 paration of InJiaruhber by Vulcanization and Conrersion." — Mr. Brocke- 

 don's ohject in this communication was to describe — 1. A mode of treating 

 india-rubber by which new properties are imparted to this substance. 2, 

 The new uses in the arts to which these acquired properties now render 

 india-rubber applicable. Vulcanization and conversion denote that combina- 

 tion of india-rubber with sulphur from which the new properties about to 

 be described result. The process of conversion consists in subiuittitig in- 

 dia-rubber to the action of bisulphuet of carban mixed with chloride of sul- 

 phur. The caoutchouc cannot, however, be penetrated by this process to 

 any depth ; and therefore it is inapplicable wlien Ihe mass to be acted on 

 is thick. The process of rulcanization, which seems to be more applic- 

 able, is the result of many experiments made by I\Ir. Hancock ; who found 

 that caoutchouc, when immersed in a bath of fused sulphur heated to 

 various temperatures, by absorbing the sulphur, assumed a carbonized ap- 

 pearance, and lastly acquired the consistency of horn. It was in the course 

 of these changes that it attained the state of vulcanization which Mr. 

 Brockedon afterwards described. The same vulcanized condition can, 

 however, be produced either by kneading the india-rubber with sulphur 

 and then exposing it to a temperature of 190°, or by dissolving the india- 

 rubber in any known solvent, as turpentine, previously chargeii with sul- 

 phur. Having thus explained the processes, Mr. Brockedon described 

 the elTect which they produced on the caoutchouc. 1. The india-rubber, 

 thus treated, remains elastic al all temperatures. In its ordinary state it is 

 quite rigid at a temperature of 4t)^. 2. Vulcanized caoutchouc is not 

 affected by any known solvents, as bisulphuret of carbon, naphtha, or tur- 

 pentine. 3. It not affected by heat short of the vulcanizing point. 4. It 

 acquires extraordinary powers of resisting compression. Thus, a cannon 

 ball was broken to pieces by being driven through a mass of vulcanized 

 caoutchouc— the caoutchouc itself exhibiting no other trace of its passage 

 than a scarcely perceptible rent. The applications of this substance appear 



