160 GALVANISM. 



if a communication be made between the first and last cell, 

 by means of the hands, a strong shock will be felt, which 

 will be repeated as often as the contact is renewed. Several 

 persons, by joining hands, having first wetted them with wa- 

 ter, may receive the shock. 



The spark from a powerful galvanic battery acts upon 

 and inflames gun-powder, charcoal, cotton, and other inflam- 

 mable substances, melts all metals and disperses diamonds. 

 Fill the battery, described above, with water and nitrous 

 acid in the proportion of nine parts of water and one of 

 acid, and wipe the edges of the plates very dry ; then fasten 

 two wires to pieces of copper, which are to be put into thej 

 outer cells, and in order to hold the wires they must be sur- 

 rounded to a sufficient extent with little glass tubes. If the 

 ends of the wires be brought together on a plate of glass, a 

 spark will be perceived ; and if gun-powder be laid on the 

 glass between the points of the wires, it will be exploded. 



The galvanic battery in the laboratory of the Royal Insti- 

 tution at London consists of two hundred instruments, con- 

 nected together in regular order, each composed of ten 

 double plates arranged in cells of porcelain, and containing 

 in each plate thirty-two square inches ; so that the whole 

 number of double plates is two thousand, and the whole sur- 

 face one hundred and twenty-eight thousand square inches. 

 This battery, when the cells are filled with sixty parts of 

 water, mixed with one part of nitric acid, and one part of 

 sulphuric acid, affords a series of impressive and brilliant 

 effects. When pieces of charcoal, about one inch long and 

 one-sixth of an inch in diameter, are brought near each other, 

 a bright spark is produced, and more than half the volume 

 of charcoal becomes ignited to whiteness, and by withdraw- 

 ing the points from each other, a constant discharge takes 

 place through the heated air, in a space equal at least to four 

 inches, producing a most brilliant ascending arch of light, 

 broad and conical in form in the middle. When any sub- 

 stance is introduced into this arch, it instantly becomes ig- 

 nited ; platina melts as readily in it as wax in the flame of a 

 common candle ; fragments of diamond, and points of char- 

 coal, and plumbago, rapidly disappear, and seem to evaporate 

 in it. Such are the decomposing powers of electricity, that 

 not even insoluble compounds are capable of resisting their 

 energy ; for glass, when moistened and placed in contact 



