A Defence of the ne'iXi Theorij of the Tides. 267 



contact with pure potassa, was found to be unmixed azote ; so 

 that 100 parts were composed of 



05 carbonic acid gas, 

 79 azote, 

 1 6 oxygen : 

 consequently the carbonic acid gas seemed to be formed at tiie 

 expense of the oxygen of the atmosphere; 5 parts in 100 being 

 supplanted by an equal volume of carbonic acidgas. The de- 

 composition of the straw, from contact witli the melted ice, ap- 

 pears to be the cause ; and the increased temperature may be 

 considered as the result of this extraordinary fermentation : 

 certainly extraordinary if the temperature at which ice is main- 

 tained be considered. The masses of ice which I have seen 

 taken from this ice-house during June last, seemed to be well 

 preserved. 



I examined, by chemical re-agents, the ice taken from this 

 ice-house, by melting the ice previously washed with distilled 

 water, and also by dissolving it in distilled vvatei\ Oxalate of 

 ammonia scarcely affected the fluid in a notable degree : the et- 

 fect was equivocal. Nitrate of silver seemed to form very deli- 

 cate silky strings; and with lime-M'ater, or caustic baryta, &c., 

 it yielded no trace of carbonic acid gas. The carbonic acid 

 gas, therefore, could not proceed from the ice. 



The ice in question was procured IVoni an adjoining pond, 

 and thrown into the ice-house in January last. In about two 

 months, it had shrunk from the wall eight inches, and this va- 

 cuity was then filled up with straw, and a covering of the same 

 thrown over it. 



A lantern let down into an adjoining weli of considerable 

 depth contiiuied to burn with undiminished flame. The ice- 

 house is in a dry sandy bank, environed with trees. 

 I have the honour to be, gentlemen. 



Yours most obediently, 



J. Murray. 



LI. A Defence of the iic'jo Theorij of the Tides. 

 Jij/ Captain Form an. 



To the Editors (f the Philosophical Ala^aziiie and Journal. 



Gentlemkn, — i^loTwrrrisTANDiNG tliere is a little asperity in 

 the styl<M>l' Mr. I lenry Rnssell's Reply to my New Theory of the 

 Tides, I am really obliged to liiin lor llie notice he has taken of 

 it; because 1 am fully jiersuatleil that the more it is discussed, 

 the more the |)iil)lic will In- convinced oI'iIk' iiller impossibility 

 of iiccounling for the rising of the tides wiliiout supposing ex- 



h 1 2 pansion 



