LECTURES ON GEOLOGY, ,. Bu Professor SillimGn. r
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LECTURES ON GEOLOGY,

 | By Professor SillimGn. 1 SEVENTH LECrURE-MAY 1S.-Mr. Silli- ] man remarked that peat, which received a l slight notice at the previous lecture, was a most powerful antisePlic. Animal subslan. ces would remain in it unchanged fHs long period. In Great Britain two human bodies are knOwn to have been preserved by it in d state of freshness for fifty seven years. It derives its antiseptic power from tannln, a 1 vegetable matter, which is used in the making | of leather. Peat marshes may be known by (stheir tremnlOus character. They are danger. ous to be entered upon. In the time of Hen " VIII, 0f England, body of Scotch Caval- " sunk and p-rished in peat morass. Peat is in state of formation at the present time; coal is not. The crust must be preserved ] over peat beds, in order to its being produced. Holland has hardly any other fuel than this 1; it is an important compensation to New Eng- land for the absence of coal; and is not found in warm climates. .-- -raae&-f. f4

 In the coal formation there are half buried forests, especially along portions ofthe coasts of England and France. These submarine forests resemble those now growing on the earth. In respect to them, Professor Silliman said it was not important to decide whether the land had sunk or the sea has risen. one or the other occurrence being necessary to ac- count for the fact. These are mt at a@l fossil

 He said the question might be asked 1; Where the vegetables forming the coal obtain their catbon, as they had it in large measure, being composed of carbon, oxygen, and hy. drogen, with an occasional mixture of nitro gen! His answers was; that they obtain it frOmAhe sol, and the aubstances united with the soil to enrich it. Fir trees which grew high up the mountains near the line where vegetation expires, obtain carbon from the | air; that has always quantity floating in it. The breathing ofanimals, and the burning of fMe, also furnish it. Plants are known to pu- l rify ths air. by extracting from t carbon. l which is unlit for respiration. The vegetable world rcctifes the animal world. .... .l ] Anthat respects the formation of coal is mechanical. Shades are loose, incoherent kind of slate. The period of the coal forma- ton implied the existence of dry land. because 1 of the pr0fuse vegetable productions that were necessary. Fern, discovered tn the coal of Rhode Island. is exactly like that inthe mines of Europe. Coal does not exist universally. 1 It has been formed where there were islands, lagoOns, and other favorable circumstances. Bituminous coal gives out what resembles tar; anthracite yields no such matter. The cause of this difference Mr. Sillitnan supposes to be internal heat. which in one case had effected a more complete conversion than in the other. AM below the coal formation is of a marine character. r.. .,,a... .,s ..., . l..,,f Infammable gas abounds in coal mines, which was formerly very dangerous. fifty per sons having been destroyed by n single expio- sion. It would destroy life either by violence or suffocation. Sir Humphry Davy. who to the miners should he considered as an angel of mercy. removed this danger by the discoy- cry and invention of the Safety Lamp. With this. which is simply wire gauge to protect the flame from the inAammable gas. the miner can work securely in the dark caverns that were once so dangerous. MT. Silliman said the Safety Lamp was one oft the most beauti- ful donations that has ever been presented by science to the arts.

 Above the coal formation there is the same red sandstone that is below. The sand. stone is composed of the ruins of other rocks, being cOngeres of fragments, and of color derived from the metallic substance that hap. pens to unite with it. It is valuable in a-chi. lecture, and much more easily wrought than granite. through far less durable. The lec- turer said. every stone mason ought to tee a geologist, sothat hs might decide on the char acter of the materials to he used in building.

 

 ble brick. By applying little muriatic acid to the clay, and thereby producing efferves- cence. it may be known that there is lime with the clay. and that it ought not to be used. ln the middle of red sandstone gypsum end salt are deposited; also fossil remains are found which show the sandstone to be Ofthe l new or upper class. A. range of this rock runs along the Connecticut valley, commenc- ing at Greenfield in this state and terminating at New Haven, Connecticut. The Connect icut river is supposed ny many to have made a mistake at Middletown. in not following the sand stone from thence to New- Haven; but leaving it. and going on blindly to Saybrook. Selenite. beautiful form of gypsum. is found | on the great Canal. in New-YOrk. Gypsum is composed of sulphuric acid. water and lime. In Lima there are masses of salt cov- ering extensive regiHns OC country. What is called red-marl in England. is salt. No min. eral salt has been discovered in this country !; though Mr. Ellsworth, one of the COmmis. siOncrs t0 treat with the lndisns. brought a piece of sAlt from Arkansaw. which NAs giv- eH him by an Indian. In uaany places there ara fountains Ofsalt water beneath the surface. | am AAwA A~. Nw,A A~O3x