in the Magnetic Field. 277 



This form of experiment, however, is ill adapted for compar- 

 ison of the total amount of heat of chemical union within and 

 without the magnetic field, owing to the very different speeds 

 of reaction. A series of determinations made by my assistant, 

 Mr. W. S. Franklin, in which the reaction took place in a calor- 

 imeter, and the number of thermal units produced was meas- 

 ured, showed that the development of heat was always consider- 

 ably greater within the field of ihe magnet. The results of this 

 calorimetric series is given in Table II. 



Table II. — Calorimetric determination of the heat of chemical union within the 

 magnetic field. (By W. S. Franklin.) 



Mean rise of temperature, 

 Calories per gram of iron dissolved, 



Magnet not 

 acting. 



8-86 

 1035-0 



acting. 



11-03 



1288-8 



"Water value of calorimeter and contents, 583-98 C. 



Amount of iron dissolved in each reaction, 5 grams. 



Duration of the reaction, from 5 mm to 6 mm . 



The reaction during these calorimetric determinations was 

 not open to inspection as in the simpler form of experiment in 

 which the variations of temperature alone were noted, but the 

 range of temperatures within the calorimeter was such as to 

 indicate that the reaction within the field was accompanied by 

 the evolution of nitrous fumes, and outside the field by hydro- 

 gen only. Whether the amount of heat produced by a reac- 

 tion in which nitrous fumes were given off outside the field is 

 greater or less than in the corresponding form of reaction under 

 the influence of the magnet was not determined. 



II. — Experiments with Nitric Acid and Iron. 



Nitric acid was mixed in various proportions with water 

 for the purpose of finding the degree of dilution at which the 

 most rapid, uniform and complete solution of the powdered, 

 iron could be obtained. During the search for the most desir- 

 able mixture, a new and very interesting effect of the magnet 

 was accidentally discovered. Five grams of powdered iron 

 lay in the beaker close above the poles of the electro magnet, 

 which was in circuit. Some cold nitric acid was poured upon 

 the iron but the latter remained passive. Wishing to note the 

 character of the reaction, we warmed the beaker slightly, then 

 placed it upon the poles of the magnet and put a thermometer 

 into the solution to get its temperature. The bulb of the ther- 

 mometer touched the iron in process of stirring the acid, when 

 the hitherto passive mixture burst, almost explosively, into 



