Barium^ Strotitium, and Calcium. 299 



By these means the reaction was rendered more equable than it 

 could become in operating with one series more highly charged. 

 Although, under such circumstances, the reaction may, at the 

 outset, be sufficiently powerful to produce ignition, as I have of- 

 ten observed, after fifteen or twenty minutes it may become too 

 feeble in electrolyzing power to render the continuance of the 

 process in the slightest degree serviceable. Agreeably to my ex- 

 perience, as the ratio of the calcium to the mercury increases, the 

 amalgam formed becomes so much more electro-positive as to 

 balance the electro-negative influence of the voltaic current. Af- 

 ter reacting with one series of two hundred pairs, of one hun- 

 dred square inches each, for seventy minutes, I have found the 

 proportion of calcium to be only one six-hundredth of the amal- 

 gamated mass obtained. 



In this lies the great difficulty of obtaining any available quan- 

 tity of the radicals of the alkaline earths by electrolyzation ; espe- 

 cially in the case of calcium. It is easy, by a series of only fifty 

 pairs, to produce an amalgam with that metal, which, when ex- 

 posed to the air, will become covered with a pulverulent mixture 

 of lime and mercury ; but, in such case, the quantity of calcium 

 taken up by the mercury, when estimated by the resulting oxide, 

 will be found almost too small to be appreciated by weighing. 

 To increase the quantity of calcium to an available extent I have 

 found extremely difficult, since, as the process proceeds, the chem- 

 ical affinity becomes more active, while the electrolyzing power 

 becomes more feeble. 



That a change should be efiected in mercury, giving to it the 

 characteristics of an amalgam, by the addition of a six hundreth 

 part of its weight, cannot be deemed difficult to believe, when it 

 is recollected that Davy found that when, by amalgamation with 

 ammonium, a globule of mercury had expanded to five times its 

 previous bulk, it had gained, in weight, only one twelve thou- 

 sandth part.* 



As the affinity between the chlorine and the radicals of the 

 alkaline earths increases in strength with the temperature, and as 

 heat is evolved in proportion- to the energy of the voltaic action, 

 the disposition of the elements separated by electrolyzation to re- 

 unite is, in this way, promoted. Hence the necessity of refrige- 

 ration, 



* Sixty grains of mercury contained only one two hundredths of a grain. See 

 Nicholson's Journal, Vol. xxxiii, p. 213. 



