370 ON THE DECOMPOSITION OF THE EARTH>« 



Tery minute films, which could not be detached by fusiottj 

 and which were instantly destroyed by exposure to air. 

 As potash I had found in my researches upon potassium^ that when 



" 1 Ui^'^ d ^ mixture of potash and the oxide of mercury, tin, or 

 was rapidly de- lead, was electrified in the Voltaic circuit, the decomposi. 

 oomposed, ^j^j^ ^^,g^g very rapid, and an amalgam, or an alloy of potas- 

 vsium was obtained; the attraction between the commoa 

 njcfals and the potassium apparently accelerating the sepa- 

 ration of the oxigen. 

 the earths were The idea that a similar kind of action might assist the de- 

 simiUur oxides composition of the alkaline earths induced me, to* electrify 

 mixtures of these bodies and the oxide of tin, of iron, of 

 load, of silver, and of mercury ; and these operations were 

 far more satisfactory than any of the others. 

 Barytes 2 p. A mixture of two thirds of barytes and one third of 



oxide of silver q^\^q yf silver very slightly moistened was electrified by iron 

 wires ; an effervescence took place at both points of con- 

 tact, and a minute quantity of a substance, possessing the 

 whiteness of silver, formed at the negative point. When 

 the iron wire to which this substance adhered was plunged 

 into water containing a little alum in solution, gas was dis- 

 engaged, which proved to be liidrogen ; and white clouds, 

 which were found to be sulphate of barytes, descended 

 from the point of the wire. 



Barytes ajid A mixture of barytes and red oxide of mercury, in the 



red oxide of 



and fifty of four inches, at this time was not more than equal to 

 that of a newly constructed apparatus of one hundred and fifty of 

 four inches. It had been made for the demonstrations in the 

 Theatre of the Royal Institution in 1803; and since that time had 

 been constantly employed in the annual courses of lectures, and 

 had served, in different parts, for the numerous experiments on the 

 decomposition of bodies by electricity, detailed in the Bakerian 

 Lectures for 1806 and 1807, and a number of the plates wer« 

 destroyed by corrosion. I mention these circumstances, because 

 many chemists have been deterred from pursuing experiments on 

 the decomposition of the alkalis and the earths, under the idea that 

 a very powerful combination was required for the effect. This, 

 however, is far from being the case ; all the experiments detailed 

 in the text may be repeated by means of a Voltaic battery, con- 

 taining from one hundred to one hundred and fifty plates of four 

 or six inches. 



s^ne 



mercury. 



