304 Analyses of Boohs. [April 



witli the Ghauts, presenting, wherever the rock is unco- 

 vered, a columnar structure, and in three places, clusters 

 of columns rise up, some of which are fifty feet high and 

 twenty inches in diameter, the shafts being variously four 

 or seven sided. # 



( To he continued.) 



Article VII. 



ANALYSES OF BOOKS. 



Philosophical Transactions for 1834, Part II. 

 ( Continued from p. 226. J 



II. Intensity necessary for Electrolyzation. — In this part of the 

 paper the author demonstrates that by producing a ' current by the 

 action of sulphuric acid upon amalgamated zinc in one vessel, passing 

 it through acid in a second vessel by platinum electrodes, a current 

 may pass for a long period, but may be of so low an intensity, as to 

 fall below that degree at which the elements of water unassisted by 

 any auxiliary force capable of forming a combination with the matter 

 of electrodes, separated from each other. He found that a solution 

 of sulphate of soda can conduct a current of electricity incapable of 

 decomposing the neutral salt present ; that this salt, in a state of 

 solution, requires a particular intensity for the separation of its ele- 

 ments, and that the requisite intensity is superior to that necessary 

 for the decomposition of iodide of potassium, likewise in solution. 

 Fused chloride of lead can also conduct a current having an inten- 

 sity below that required to effect decomposition. Fused chloride of 

 silver is decomposed by a similar current. A drop of water and 

 fused nitre conducted a current without decomposition. It appears, 

 farther, that the necessary electrolytic intensity for water, is the same 

 whether it be pure, or rendered a better conductor by the addition of 

 acids, for the power of acids, alkalies, salts, and other bodies in solu- 

 tion to increase conducting power, appears to hold good only where 

 the electrolyte through which the current passes undergoes de- 

 composition. 



Currents of electricity produced by less than eight or ten series of 

 voltaic elements, can be reduced to that intensity at which water can 

 conduct them without suffering decomposition, by causing them to 

 pass through three or four vessels, in which water shall be successively 

 interposed between platinum surfaces. 



This subject is worthy of prosecution, in order to enable us to 

 arrange electrolytes in the order of their electrolytic intensities. In 

 terminating this portion of his paper, the author observes, in relation 

 to intensity generally, that when a voltaic current is produced, having 

 a certain intensity dependant upon the strength of the chemical affi- 

 nities by which that current is excited, it can decompose a particular 



* Ann. of Philosophy, vii. 309. 



