80 ABTRACTS: APPARATUS 



possible number. The other, which might be regarded as more 

 essentially the French system, carefully records differences, whether of 

 structure or facies, and endeavors to formulate a taxonomic scheme in 

 accordance therewith. One system is based more especially upon 

 resemblances, the other upon differences. Either system when carried 

 to an extreme must involve mistakes, though knowledge as a whole 

 is more likely to be advanced by the second than by the first of these 

 systems. The author of the present volume inclines to the French 

 system, which apparently is also preferred by most of the English 

 investigators. T. L- C. 



APPARATUS. — Temperature uniformity in an electric furnace. John 

 B. Ferguson. Phys. Rev. 12: 81-94. July, 1918. 

 The problem of temperature uniformity in an electric furnace is inti- 

 mately connected with almost all investigations carried on at high 

 temperatures. For this reason it has generally been considered as a 

 part of a larger problem and has been solved to the extent demanded 

 by the requirements of the work at hand. In this paper the writer 

 presents a more general discussion of the subject, together with many 

 results obtained by him in his various investigations bearing directly 

 thereon. The production of temperature uniformity in an electrically 

 heated air column may best be done by means of three independent 

 heaters and end plugs. R. B. S. 



APPARATUS. — Thermal leakage and calorimeter design. Walter P. 

 White. Journ. Amer. Chem. Soc. 40: 379-393. February, 1918. 



The interchange of heat between a calorimeter and its environment 

 (thermal leakage) is practically proportional to their temperature 

 difference, except for the effect of evaporation and for that of convec- 

 tion, which is, for ordinary calorimetric conditions, more nearly pro- 

 portional to the square of that difference. If evaporation is suppressed 

 the advantages of a constant thermal leakage factor are obtained by 

 preventing convection. Recent investigations upon convection show 

 how this may most advantageously be done. In adiabatic work there 

 is little fear of convection, hence either very large temperature inter- 

 vals or ver}^ large air gaps can be profitably employed. Incidentally, 

 it is pointed out that the ordinary rule, that thermometric lag causes 

 no error where only one thermometer is used, deserves careful interpre- 

 tation, or else restatement, in the case of some thermochemical .de- 

 terminations. R. B. S. 



