Part 24 (1/2)

While no experiments have been made to show conclusively which of these enerally used

After the boen from a tank until the pressure reaches from 20 to 25 atmospheres

The lower pressure will be sufficient in all but exceptional cases

Connection is then ed as to allow cohting systeer fro the fuse, which may effect the results The apparatus is then ready for the test

Unquestionably the bestdata is by the use of co-ordinate paper and a plotting of the data with temperatures and tiraphic representation is shown in Fig 25

[Graph: Te 25 Graphic Method of Recording Bomb Calorimeter Results]

After the bonited, readings of the temperature of the water should be taken at one h to insure a constant rate of change, and in this way deternited by co the circuit, the te considered the tenition the readings should be taken at one-half h because of the rapidity of the s only , such readings, however, being sufficiently accurate for this period The one-half nition for five er at minute intervals to deter 25 shows the results of such readings, plotted in accordance with the ested It now remains to compute the results from this plotted data

The radiation correction is first applied Probably thesuch correction is by the use of Pfaundler's nault This assu with an initial rate of radiation, as represented by the inclination of the line AB, Fig 25, and ending with a final radiation represented by the inclination of the line CD, Fig 25, that the rate of radiation for the intermediate temperatures between the points B and C are proportional to the initial and final rates That is, the rate of radiation at a point midway between B and C will be the mean between the initial and final rates; the rate of radiation at a point three-quarters of the distance between B and C would be the rate at B plus three-quarters of the difference in rates at B and C, etc This nault's in that the radiation was assunault to be in each case proportional to the difference in temperatures between the water of the calori air plus a constant found for each experinault, and the results by the two reement

Expressed as a foriven by him:

_ _ | R' - R | C = N|R + ------ (T” - T)| (19) |_ T' - T _|

Where C = correction in degree centigrade, N = number of intervals over which correction is rees per interval, R' = final radiation in degrees per interval, T = average teh which initial radiation is coe tee teh which final radiation is co 25 is as follows:

As already stated, the te just before the current is turned on, or B in Fig 25 The point C or the temperature at which combustion is presumably completed, should be taken at a point which falls ithin the established final rate of radiation, and not at the maximum temperature that the therht line deter the final radiation This is due to the fact that in certain instances local conditions will cause the ther the ti heat to the water rapidly, and at other tiht be lower than that which would be indicated were readings to be taken at intervals of less than one-half minute, _i e_, the point of maximum temperature will fall below the line deter AB, Fig 25, represents the time of initial radiation, BC the time of combustion, and CD the time of final radiation Therefore to apply Pfaundler's correction, for 25

N = 6, R = 0, R' = 01, T = 2029, T' = 2283,

2029 + 2254 + 2284 + 2288 + 2287 + 2286 T” = --------------------------------------------- = 2236 6

_ _ | 01 - 0 | C = 6|0 + -------------(2236 - 2029)| |_ 2285 - 2029 _|

= 6 008 = 048

Pfaundler's for Mr E H Peabody has devised a simpler formula hich, under proper conditions, the variation froible

It was noted throughout an extended series of calorimeter tests that the htly over oneIf this period between the ti and the maximum temperature reported was exactly one h this period would equal the radiation per one-half _ plus the radiation per one-half minute _after the h the one e of the radiation perand the radiation per minute after the maximum A plotted chart of teht lines (B, C', D) in Fig 25 Under such conditions, using the notation as in formula (19) the correction would become,

2R + 2R'

C = ------- + (N - 2)R', or R + (N - 1)R' (20) 2

This foreneralized for conditions where the maximum temperature is reached after a period of more than one minute as follows:

Let M = the nu and the h this period will be an average of the radiation for M intervals before firing and for M intervals after the maximum is recorded, or

MR + MR' M M C = ------- + (N - M)R' = - R + (N - -)R' (21) 2 2 2