374 * Scientific Intelligence. 



with 1/5 normal hydrochloric acid, and finally after removing 

 material of low specific gravity by stirring and decantation, wash- 

 ing with alcohol and ether and drying in a vacuum. The mate- 

 rial thus prepared appears to have been unusually pure, as it was 

 crystalline in character, gave analytical results very close to 

 those required by theory, and contained no graphite. The product 

 was dark gray with a tint of bronze in some cases, and very 

 brittle. Some of the larger fragments were used for hardness 

 determinations with the surprising result that this was found to 

 be only just above 3, according to the mineralogical scale. The 

 conclusion is reached, therefore, that it is not the hardness of the 

 carbide itself which causes the hardness of suddenly cooled steel, 

 but that of its solid solution in y-iron. 



The authors have determined the heat of combustion of their 

 product and have found 375*1 cal. per molecule of Fe 3 C, when 

 burnt to Fe 3 4 and C0 2 . By comparing this result with their 

 own determinations of the heat of combustion of pure iron and 

 the known value for graphitic carbon, they have calculated the 

 heat of formation as follows : 



3Fe + C = Fe 3 C — 15-1 cal. 



The compound is consequently shown to be endothermic, whereas 

 previous indirect calculations had indicated an exorthermic com- 

 bination of +8940 cal. — Berichte, xlv, 63. h. l. w. 



3. The Use of Sulphur Monochloride for Decomposing Cer- 

 tain Minerals. — The process of decomposing various minerals by 

 means of sulphur monochloride was described by Edgar F. Smith 

 in 1898. Since that time the method has been applied by various 

 other chemists. W. B. Hicks, of the University of Pennsyl- 

 vania, has recently applied this method to the decomposition of 

 fergusonite, seschynite and samarskite, which are rare-earth min- 

 erals containing columbium and tantalum. The process consists 

 in heating the finely pulverized mineral in a boat in a combustion- 

 tube in contact with the vapor of sulphur monochloride, with the 

 result that columbium, tantalum, titanium and tungsten are 

 volatilized as chlorides and may be collected in nitric acid, while 

 the rare earths, together with silica, are left behind in the boat. 

 The method appears to possess advantages over the usual methods 

 of decomposition by means of fusion with acid potassium sulphate 

 or the acid fluoride. — Jonr. Amer. Chem. Soc, xxxiii, 1492. 



H. L. W. 



4. Determination of Water. — Zekewitinoff has devised a 

 rapid and accurate method for the determination of water in 

 various substances, which is interesting on account of being 

 based on a new principle. He treats the substance, for example 

 coal or starch, in a special form of apparatus with perfectly dry 

 pyridine. This liquid is very hygroscopic and, therefore, takes 

 up the water from the substance. A proper amount of methyl 

 magnesium iodide in amyl ether solution is then added whereby 

 methane is liberated, and the volume of this gas is at once meas- 



