CHEMISTRY (NEW SUBSTANCES.) 



Ill 



nesium pyrophosphate and magnesium silicate 

 (asbestos), and many other substances, that the 

 most stable salts are dissociated at the tempera- 

 ture of the arc, and that it is possible to collect 

 the products of their decomposition and to study 

 them with case. He then applied his method to 

 the volatilization of the metals copper, silver, 

 platinum, aluminum, tin, gold, manganese, iron, 

 uranium, the non metals silicon and carbon, and 

 the oxides lime and magnesia, with results 

 from which he deduced the conclusions that at 

 the high temperature of the electric arc the ele- 

 ments hitherto regarded as the most refractory 

 are volatilized. The most notable compounds of 

 mineral chemistry disappear either by dissocia- 

 tion or by volatilization. Nothing remains to 

 resist these high temperatures except a series of 

 new compounds, perfectly crystalline, of an ex- 

 ceptional stability. These bodies are the metal- 

 lic borides, silicides, and especially carbides. 

 Daubree has already shown that the carbon of 

 all our present organic compounds was origi- 

 nally existent in the state of metallic carbides. 

 The electric furnace seems to reproduce the con- 

 ditions of that remote geological epoch. 



While the temperature of celestial space can 

 only be approached in the laboratory, the nearer 

 we get to it the more important physical prob- 

 lems become. Up to the present time liquid air 

 or nitrogen is the agent that has been most suc- 

 cessfully used in the investigation of this subject. 

 When liquid nitrogen is evaporated in a vacuum 

 a temperature of about 210 0. below the melt- 

 ing point of ice can be just reached, but the 

 practical working limit in such experiments is 

 about 200. This temperature is still 74 from 

 the zero, and the question now is. Can we dimin- 

 ish the distance? The zero may be defined as 

 that point of temperature at which gas particles 

 would give no pressure and have no volume. 

 The temperature at which this would take place 

 is 274 C. below the freezing point of water, an 

 estimate which is confirmed by thermo-dynam- 

 ical considerations where temperature is defined 

 apart from the properties of any particular kind 

 of matter. The only avenue of approach to this 

 point that is left seems to be the liquefaction of 

 hydrogen, the sole remaining gas which has not 

 been liquefied. The text-books, it is true, say 

 that it has been, on the ground that it has been 

 proved that compressed hydrogen when expanded 

 can yield a mist; but the attainment of real 

 liquefaction is a problem surrounded by almost 

 insurmountable difficulties. The possibility of 

 making a gas pass into the liquid state depends 

 upon our being able to get below the point of 

 temperature known as the critical point. Unless 

 this point is reached no amount of pressure can 

 force the gas into the liquid condition. The crit- 

 ical point of hydrogen is about 240 C., while 

 the lowest temperature attainable by the evapo- 

 ration of liquid air or liquid nitrogen is about 

 -200 C. The 40 or 50 lower temperature to be 

 reached can be bridged over only by construct- 

 ing a new substance which shall have a critical 

 point of 200, or about 50 lower than that of 

 nitrogen, the most volatile known liquid. Such 

 a body can be made by liquefying a gas composed 

 of hydrogen mixed with about" 10 per cent, of 

 nitrogen. This is the direction in which Prof. 

 Dewar has been lately pressing forward his in- 



vestigations, and the new results give hopes of 

 further advance. In the course of his experi- 

 ments with such a mixed gas the author has ob- 

 tained a jelly of solid nitrogen emitting hydro- 

 gen, which burns fiercely as it escapes, and* with 

 hydrogen containing from 2 to 5 per cent, of ni- 

 trogen a white solid material (solid air), along 

 with a clear liquid which is so exceedingly vola- 

 tile that it has been impossible to collect it. 

 Prof. Dewar will not declare that this liquid is 

 pure liquid hydrogen, but it is impossible to say 

 what else it can be. 



New Substances. A series of new boron com- 

 pounds containing fluorine and alcohol radicals, 

 derived from the interaction of boron fluoride 

 and alcohols, are described by M. Gosselin. The 

 mono- and difluorine compounds derived from 

 methyl and ethyl alcohol have been isolated 

 pure, and prove to be substances of great chem- 

 ical activity, affording numerous interesting 

 reactions. When boron trifluoride gas is passed 

 into methyl or ethyl alcohol, strongly cooled by 

 a freezing mixture, the gas is rapidly absorbed, 

 and the liquid becomes considerably heated. 

 The reaction occurs in equal molecular propor- 

 tions, and upon subsequent distillation of the 

 liquid product two main substances are even- 

 tually isolated. The first is the difluorine com- 

 pound, while the second is a remarkable molec- 

 ular compound of boron trifluoride with methyl 

 or ethyl ether. Difluor methyl borate distills 

 over as a colorless liquid boiling at 80 C. It 

 solidifies in the receiver in the form of long crys- 

 tals that melt at 41'5 C. The analogous ethyl 

 compound boils at 82, and the crystals melt at 

 23. The liquids fume strongly in the air, dis- 

 seminating suffocating vapors. Water decom- 

 poses them with great energy, producing boric 

 acid, fluoboric acid, and free alcohol, They are 

 insoluble in hydrocarbons, but dissolve with de- 

 composition in alcohol. The methyl compound 

 boils at 53, and is a particularly mobile and 

 strongly fuming liquid, which burns with a 

 brilliant green flame surrounded by a dense 

 white cloud. The ethyl compound is a liquid 

 of similar properties, which boils at 78. W T ater 

 decomposes both compounds with some vio- 

 lence and considerable evolution of heat. The 

 molecular compounds of boron trifluoride with 

 methyl and ethyl ether are fuming liquids, boil- 

 ing respectively at 126 and 123, which are like- 

 wise energetically decomposed by w r ater. 



Two new boron compounds diphenyl boric 

 acid and the corresponding chloride have been 

 obtained, and are described by Prof. Michaelis. 

 Phenyl boron chloride CeHsBC^, the first boron 

 compound containing a benzene radical, was 

 obtained in 1879 by Prof. Michaelis and Dr. 

 Becker. Upon bringing it in contact with 

 water a crystalline and powerful antiseptic sub- 

 stance, phenyl boric acid, C 6 H 6 B(OPI). 2 , appeared, 

 which upon being heated evolved water vapor 

 and yielded the anhydride C 6 H 6 BO. Diphenyl 

 boron chloride, (CeH^BCl, is formed when the 

 monophenyl compound is heated in a sealed 

 tube to upward of 300 C., and is separated 

 from the resultant mixture by extraction with 

 an organic solvent and distillation. It is a 

 thick colorless liquid, which fumes slightly in 

 moist air and boils at 270 C. Upon heating 

 with water it is decomposed, with formation of 



