438 M. Bccquerel on Chemico- capillary Actions. 



point of a small tube heated to redness. The crack must not be 

 allowed to become too large ; it is merely necessary that it shall 

 allow the solutions, or at any rate one of them, to enter by ca- 

 pillary attraction. 



One of the most remarkable effects is obtained by filling such 

 a cracked tube with a concentrated solution of nitrate of copper, 

 then introducing this tube into a test-glass containing a solution 

 of monosulphide of sodium which marks 12° to 15° of the areo- 

 meter, the two liquids being at the same level, so that the pres- 

 sure is the same on the two sides. By simply mixing the two 

 solutions, black sulphide of copper and nitrate of soda should be 

 formed. This, however, is by no means the case ; a short time 

 after the experiment had been arranged, a very brilliant deposit 

 of metallic copper with a crystalline texture began to be perceived. 

 Little by little the deposit increased, the crack enlarged, and the 

 tube ultimately broke. Small cylinders of copper 2 millims. in 

 diameter could then be withdrawn. 



With several other solutions of copper the effects are the same, 

 but less rapid. Similar results are also obtained with concen- 

 trated solutions of silver, lead, gold, tin, cobalt, and nickel. 



It is very difficult to obtain reduction effects with those of iron 

 and zinc. 



The author used several kinds of capillary spaces besides 

 that above mentioned — such, for instance, as the interval be- 

 tween two glass or quartz plates pressed more or less closely 

 together, the porosity of the parchment-paper used for dialysis, 

 the capillary intervals between grains of glass or of quartz, un- 

 baked porcelain or sandstone, tubes drawn out at one end. 

 The first method gave good results ; by its means the reduction 

 could be effected of gold, copper, lead, nickel, cobalt, and that of 

 platinum, which could not be accomplished by using the cracked 

 tube. 



M. Becquerel in his first memoir, after having investigated 

 the influence of the various kinds of capillary spaces, and de- 

 scribed a great number of cases of reduction effected by electro- 

 capillary, or rather chemico-capillary actions, cites instances of 

 the formation of insoluble compounds by the effect of these 

 same actions. In conclusion, he observes that there is now a 

 whole series of facts to be added to those he has observed, 

 such as the phenomena due to the properties of spongy platinum 

 and of porous bodies, to the effects of diaphragms, and those of 

 dyeing, all of which may be classed as an important part of 

 chemistry under the name of capillary chemistry. 



In his second and third memoirs M. Becquerel endeavours, 

 while increasing the number of facts, to analyze the physical 

 and chemical causes which come into play in the phenomena of 



