Reaction before Complete Equilibrium. 69 



that all the above reactions take place with evolution or 

 absorption o£ heat. 



To get a successful experiment the following arrangements 

 proved to be necessary : — 



A. An instantaneous registration of temperature with an 

 accuracy of one or two ten-thousandths of a degree, and of 

 time to about 1/50 of a second has been made. 



B. The point of the obtained apparent equilibrium has 

 been so arranged that it differed from the real one only by 

 0°-0000i to 0°-0001. This was absolutely necessary since 

 the equations for the velocity of reaction proved to be de- 

 pendent upon the points of equilibrium. 



G. The equalization of temperature throughout the liquid, 

 thermometer, beaker, and stirrer has been made instantaneous, 

 so that the thermometer gave true indications of the tempe- 

 rature of the liquid at any moment. 



D. The amount of heat given off or taken up by the liquid, 

 &c., from the surrounding medium during the time of the 

 experiment has been made so small that it could be safely 

 neglected. 



A. The Platinum- Thermometer for Measure meat of Boiling- 

 and Freezing- point*, Solubilities, and Velocity of Reactions. 



The object of this part was to adapt the platinum-thermo- 

 meter for the special purpose of investigating freezing- and 

 boiling-points, solubilities, and the velocity of reactions. As 

 in my investigations an accuracy in the registration of the 

 thermometer of 0°'0001 or o, 0002 had to be ensured, and 

 instantaneous indications of temperature were required, the 

 chief object was to arrange the method so as to avoid the 

 necessity for the multitudinous corrections of other methods, 

 i.e. to reduce these corrections to the smallest values possible. 

 so that the aggregate error, when they are neglected, does 

 not exceed the above value of 0°-0001-0°-O002. We must 

 always bear in mind that the application of a correction 

 never completely removes the error, and that it depends upon 

 the absolute values of these corrections how far we are able 

 to ensure results of the desired degree of accuracy. 



Fig. 1 (p. 70) gives the general arrangements of the appa- 

 ratus I employ. R i> the resistance-box, containing manganin 

 coils 20 ohms (1st arm of the Wheatstone-bridge), 20 ohms 

 (2nd arm), 20, 10, 5, 3, 1, 1, 0'5 ohms (3rd arm) ; A, B, C, 

 D, </, a are terminals. A and a are connected with the 

 Callendar-Grimths compensating-loads ; C and D' — e with 

 the leads of the platinum-thermometer (4th arm of the 

 bridge). D (or d when the 0*5 ohm is not used) and D' 



