MORSE. — SOME MINUTE PHENOMENA OF ELECTROLYSIS. 375 



the difficulty is easily overcome. The balance loses but a small per- 

 centage of its sensitiveness when used with a heavy metal like silver 

 or copper. 



The fibres used were of quartz and about 8 cm. long. The conduct- 

 ing wires were of platinum about 0.04 mm. in diameter, and these were 

 welded to small pieces of silver wire and held fast in hooks at the end 

 of the fibres, so that the silver electrodes were presented to each other 

 at a distance of about 1.5 mm. The sensitiveness was such that a 

 0.1 mg. rider at the end of either fibre caused a deflection of more 

 than a centimeter. One of the (large) divisions of the micrometer 



Figure 3. Microcoulometer. 



eyepiece of the observing microscope corresponds to a change in weight 

 of about 0.0001 mg., and a fraction of a division is easily read. 



With this instrument the following qualitative changes were 

 noticed. 



(1) Immediately on closing the circuit a very slight decrease in the 

 weight of each electrode. This change was observed in four of six 

 experiments and must therefore be classed as doubtful until further 

 proof is obtained of its correctness. 



(2) Thereafter for several minutes an increase in the weight of each 

 electrode, the anode gaining much faster than the kathode. This 

 effect is quite certain and considerable. It is accompanied by a 

 change in color at the anode, which turns dark, and probably repre- 

 sents the formation of silver oxide or peroxide. The increase in 

 weight at the kathode is seen to be due to the deposition of silver. 



(3) From then on decrease in weight at the anode, and increase at 

 the kathode, finally approaching proportionality. 



The most important point which has been brought out in this pre- 

 liminary exploration seems to be that of the complete lack of equiva- 



