CHEMISTRY. 263 



Moissan has made experiments which lead him to conclude 

 that magnetic oxide of iron prepared (1) by heating ferric 

 oxide in an atmosphere of hydrogen or carbonous oxide to 

 350 or 400, or (2) by calcining the carbonate, and magnetic 

 oxide of iron obtained by decomposing water by red-hot 

 iron, or by burning iron in oxygen, are not identical, but are 

 allotropic forms of the same substance. The former has a 

 density of 4.86, the latter of 5 to 5.09 ; the former is acted 

 on by nitric acid, and becomes ferric oxide on roasting. The 

 latter is not acted on, and is unchanged by heat. 



Regnard has recorded the fact that steel ingots when 

 broken exhale a decided odor of ammonia, accompanied by 

 a slight hissing, noticeable when the ear was placed against 

 the ino-ot. On wetting the fractured surface with soap and 



O -IT" 



water, a frothing resulted, the volume of gas evolved being 

 about one cubic centimeter. The gas from one hundred in- 

 gots on analysis proved to be nearly pure hydrogen. 



Smith has proposed a new and apparently very satisfacto- 

 ry method of decomposing chromic iron for analytical pur- 

 poses by means of bromine. Fifteen centigrams of the very 

 iinely pulverized and elutriated chromite was placed in a 

 tube of hard glass; a rather large quantity of bromine water 

 was added, and ten or twelve drops of bromine, the tube 

 sealed and heated to 130 for one day, and then to 170 for 

 two days. Upon opening the tube, the residue, after wash- 

 ing, drying, and igniting, was found to be wholly soluble in 

 hydrochloric acid. The decomposition was therefore com- 

 plete. 



Riche has published a memoir upon the electrolytic deter- 

 mination of manganese, lead, copper, zinc, and nickel, and on 

 the analysis of alloys of these metals. The decomposition 

 requires the use of two or three Bunsen cells. The decom- 

 posing cell is a platinum crucible connected with the carbon 

 pole. Within this is suspended, without contact, either an 

 open cone of platinum foil or a spiral of platinum wire con- 

 nected with the zinc pole. The manganese is separated at 

 the positive electrode as dioxide, which becomes saline ox- 

 ide on calcination, and is weighed as such. Lead in an acid 

 solution, kept at 60 to 90 9 , is all precipitated on the positive 

 electrode as dioxide, which is dried at 105 to 120 and 

 weighed. Zinc is precipitated from the ammonio-sulphate 



