Chemistry and Physios. 73 



for electrolysis is determined almost solely by these secondary 

 reactions. Evidently if the result of the secondary actions is the 

 same as it is in the case of alkali salts, the electromotive force 

 required for the decomposition will be practically the same also ; 

 thus confirming the experiments of Le Blanc and not requiring 

 us to assume the primary decomposition of the water. From 

 Shields' data, showing that a decinormal solution of sodium 

 acetate is hydrolyzed to the extent of 0"008 per cent, the author 

 calculates that the electrical conductivity of pure water at 25° is 

 0*56X10 -11 ; this conductivity being greatly diminished in the 

 presence of electrolysis. A salt of a strong acid and a strong 

 base is hydrolyzed to the extent of 1*21 X10 -4 per cent in deci- 

 normal solution, the absolute quantity hydrolyzed being nearly 

 independent of the concentration. The author has also calcu- 

 lated from the electromotive force required for the electrolytic 

 dissociation of pure water, the value of this force required to 

 develop hydrogen and hydroxyl ions from water in a liquid 

 already containing as many of these as are in normal solutions 

 of strong acids or bases. His value thus found is 0*81 volt, that 

 obtained experimentally by Le Blanc being 0*76 volt. — Zeitschr. 

 physikal. Chem., xi, 805, June, 1893. • G. f. b. 



3. On the Preparation of Chromium, Manganese an\l Uran- 

 ium in the Electric Furnace. — The electric furnace of Moissan 

 and Violle consists of a carbon vessel in which an arc from two 

 horizontal electrodes is made to act upon any substance desired. 

 This vessel is a portion of a carbon tube, of a height equal to its 

 diameter, standing on a carbon plate and covered with a disk of 

 the same material. The electrodes are also of carbon ; all the 

 carbon parts of the apparatus being prepared from powdered gas 

 carbon and tar, no boric acid being used, The carbon cylinder 

 and electrodes are enclosed in a block of lime, being supported 

 on props of magnesia and separated from the sides of the block 

 by a layer of air five millimeters thick. The dimensions of" the 

 furnace and its various parts vary according to the current which 

 is to be used and the temperature desired ; a temperature of 

 3000° being obtained without difficulty. If manganous oxide be 

 mixed with charcoal and heated by the arc given by a current of 

 300 amperes and 60 volts, the reduction is complete in five or six 

 minutes; but twelve to fifteen minutes is necessary if only 100 

 amperes and 50 volts is used. If the carbon be in excess, the 

 reduced metal contains 6 - 4 to 14'6 per cent of this substance, but 

 if the manganous oxide be in excess, only 4 or 5 per cent of car- 

 bon is contained in the metal. With a low content of carbon, 

 the metal is unaltered when exposed in open vessels; but when 

 the proportion of carbon is increased, it is attacked by moist air. 

 In water, small fragments are oxidized, hydrogen and hydro- 

 carbons being evolved. Chromium oxide mixed with carbon 

 and subjected to a current of 350 amperes at 50 volts, is reduced 

 in from 8 to 10 minutes, 100 grams of the metal being obtainable 

 at one operation. With 100 amperes and 50 volts, fifteen min- 



