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��annii9takabl3- with the disturbance in the rocks caused by their upheaval into arches, but the crucial test was yet to be made in the actual location of good gas territory on this theory. During the last two years, I have submitted it to all manner of tests, both in locating and condemning gas territory, and the general re- sult has been to confirm the anticlinal theory beyond a reasonable doubt.

But while we can state with confidence that all great gas-wells are found on the anticlinal axes, the converse of this is not true ; viz.. that great gas-wells may be found on all anticlinals. In a theory of this liiml the limitations become quite as important as, or even more so than, the theory itself; and hence I have given consider- able thought to this side of the question, hav- ing formulated them into three or four general rules (which include practically all the limita- tions known to me, up to the present time, that should be placed on the statement that large gas-wells may be obtained on anticlinal folds) , as follows: —

(a) The arch in the rocks must be one of considerable magnitude ; (&) A coarse or po- rous sandstone of considerable thickness, or, if a fine-grained rock, one that would have extensive fissures, and thus in cither case ren- dered capable of acting as a reservoir for the gas, must underlie the surface at a depth of several hundred feet (five hundred to twenty- five hundred feet) ; (c) Probablj' very few or none of the grand arches along mountain ranges will be found holding gas in large quantity. since in such cases the disturbance of the strati- fication has been so profound that all the nat- ural gas generated in the past would long ago have escaped into the air through fissures that traverse all the beds. Another limitation might possibly be added, which would oonQne the area where great gas-flows may be obtained to those underlaid by a considerable thickness of bitu- minous shale.

Very fair gas-wells may also be obtained for a considerable distance dowu tlie slope from the crest of the anticlinals, provided the dip be sufficiently rapid, and especially if it be irregu- lar, or intenupted with slight crumples. And even in regions where there are no well-marked anticlinals. if the dip be somewhat rapid and irregular, rather large gas-wells may occasion- ally be found, if all other conditions are favor- able.

The reason why natural gas should collect under the aiches of the rocks is suflBeiently plain, from a consideration of its volatile na- ture. Then, too. the extensive fissuring of

B rock, which apjioars necessary to form a

��capacious reservoir for a lai^e gaa-well. would take place most readily along the anticlinals where the tension in bending would be great- est.

The geological horizon that f urnishea the best gas-reservoir in western Pennsylvania seems to be identical with the first Venango oil-sand, and hence is one of the CatskiU conglomerates. This is the gas-rock at Murraysville, Taren- tum, Washington, Wellaburg, and many other points. Some large gas-wells have been ob- tained in the subcarboniferous sandstone (Po- cono), however, and others down in the third Venango oil-sand'(Chemung). I

In Ohio, gas-flows of considerable size have j been obtained deep down in the Cincinnati limestone, while in West Virginia they have been found in the Pottsville conglomerate: hence natural gas, like oil, has a wide range through the geological column, though it is ft significant fact that it is most abundant al>ove the black elates of the Devonian.

Of the composition, probable origin, extent of gas territory in the country, and many other interesting pnlnta connected with natural gas, the necessary brevity of tliis article forbids any mention : but the writer has in preparation a more general paper on the subject, in which these and kindred questions will be disctisaed with more detail. I. C. WurtE.

��THE EFFECTS OF COLD ON UVINQ ORGANISMS.

Mr. C01.EUA.N and Professor McKendriek hav« made some remarkable eiperimenIB ' on the effect of low teiuperaturci on living organism*, partimlarlj^ microbes, using for this purpose Ehe cold- chtnery invenled bj Mr. Coteinan, which, In Its ordi> iiary working, delivers streams i>[ air cooled to ahont 80= below ;!en> (-«t° C). but by certain modlBca- tlons as low temperatures can be secured as have jret been produced In physical researcliea. The actual tempenlures in these experiments were lafaen b; an absolute alcoliol thermometer, made by NegreiU and Zambra, and checked by a special air thermometer devised by Mr. Coleman.

The experimenlB consisted In exposing for boun to low temperatures putrescible siibalaQcea in her- metically sealed tins or bottles, or in flasks plnggod with cotton wool. The tins or (las-ks were then allowed to thaw, and were fcept in a warm room, tba meao temperature of which wu about 80° F. Thar were then opened, and the cimlenls submitted to mi- croscopical examination. The geaeral result may ba stated thus: Tbe vlialit/ of micro-organisms cannot be destroyed by prolonged exposure to extreme cold. It is clear, therefore, that any hope of preserving meat bj permauently aterlllxiag it by cold must '

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