Phenomena of the Capillary Electroscope. 



87 



a tube of fine bore strong movements occurred, and 85 millims. of 

 extra height of mercury pressure was required to bring the meniscus 

 back to its original position and counterbalance the effect of the 

 current. 



Exp. 3. — 1 oz. of water and 40 grs. of potassic iodide. The direc- 

 tion of the motion of the mercurj agreed with that of the current. 

 51 millims. height of mercury pressure was required to balance the 

 influence of the current. 



Exp. 4. — 1 oz. of water and 40 grs. of potassic bromide. All the 

 results the same as those described with the chloride. The current 

 required the pressure of 82 millims. height of mercury to balance* it. 



Exp. 5. — 1 oz. of water and 40 grs. of potassic carbonate. The 

 direction of the movement of the mercury was the same as that of the 

 current. The current required 83 millims. height of mercury to 

 balance it. 



Solutions of cyanide of potassium were tried of various strengths 

 from 10 to 100 grs. per oz. of water ; the weak ones yielded feeble 

 movements in the direction of the current and the stronger ones 

 clogged the capillary tube. 



Exp. 6. — 1 oz. of water and 33 grs. of cyanide of potassium in a 

 very fine capillary. An upward current sent the mercury down a 

 long distance and out at the end of the tube. The reverse directions 

 of movement obtained with solutions of potassic cyanide compared 

 with those obtained with dilute sulphuric acid, in capillary tubes, 

 agree with those obtained with the same liquids, and a large globule 

 of mercury in an open shallow dish (see " Proc. Roy. Soc," vol. 10, 

 p. 235). 



Exp. 7. — With a solution of 40 grs. of the cyanide in 1 oz. of water, 

 the movement was more free than with 50 grs. of that salt. By pre- 

 viously passing a downward current, the commencement of motion by 

 the subsequent up-current appeared to be retarded. In another appa- 

 ratus, consisting of a column of mercury about 20 centims. total 

 height, with a long capillary surmounted by a pressure-chamber quite 

 filled with mercury, and closed by a glass plug, an upward current 

 caused the meniscus to move downwards slowly more than 25 millims., 

 and a downward one raised it about 8 or 10 millims. 



Exp. 8. — 1 oz. of water and 50 grs. of potassic cyanide. In the fine 

 part of the tube the motion of the mercury was opposite to that of the 

 current, but in the coarse part of the tube I noted that it moved in the 

 direction of the current.* When the mercury dropped from the end 

 of the capillary into this solution it formed chains of globules which, 

 when about 2 or 3 millims. high, fell over and formed a heap like a 

 pile of brambles or sticks ; the chains of globules did not break. 



* This movement requires investigation. 



