HEAT CAPACITY 
The basic theory and equipment details have been 
published previously (1) (2). An external view of the 
gold-plated beryllium-copper alloy bomb, which contains the 
sample under investigation, is shown in Figure 1. The 
apparent dullness in the lower portion of the bomb is due 
to. specular retlection of the paper on which at istsetting. 
Figure 2, a photograph of the interior gold plate, shows 
rather severe etching. In spite of this, the results appear 
to be reasonable and no failure of the bomb proper has taken 
place in Over four years of iimtermittcant use. 
The heater, which has failed once and has been re- 
placed, 25 shown in Figure 3. It consists of S00" cm of 
NichromeV wire with a resistance of about 110 ohms housed 
in an Inconel-W tube but electrically insulated from it by 
magnesium oxide insulation. The entire heater is wound 
helically on a gold-plated copper frame. The solution is 
stirred by a slave magnet housed in a monel can shown in 
the center of Figure 3. The master magnet is driven at 
300 rpm. 
Figure 4 is a photograph of the constant temperature 
oven which contains the bomb. The auxiliary equipment 
consisting of a mechanical and diffusion pump is shown in 
the foreground. Vacuum is measured by two thermocouple 
guages connected to a Hughes TGC/100 indicator and a cold 
cathode discharge gauge connected to a Hughes PGC-200 
indicator. 
A view of the potentiometers and recording system with 
several typical recordings is shown in Figure 5. 
The platinum resistance thermometer was built by Leeds 
and Northrup by placing a standard resistance element into 
a customized gold-plated copper tube. A scale drawing of 
the latter is shown in Figure 6, As shown, -the top part of 
the tubing is made of beryllium copper. Two thermometers 
have been used in the reported data. These were calibrated 
by the National Bureau of Standards. The first thermometer, 
(which eventually broke down)which was used in the study of 
NaCl, had a resistance in absolute ohms given by 
P= 25.4995" (1+ 0 200596505151 = 05 650— x tO oe) (1) 
Here, t is given in degrees Centigrade and, between 0°C and 
200°C, the precision is guaranteed to be 1 part in 5000. 
