162 REPORT—1896. 
APPENDIX II. 
THe Capaciry ror Herat or WATER FROM 10° To 20° C. REFERRED 
vo its Capacity at 10° C. as Unity. 
— Rowland Griffiths canbe Mean 
o | 
10 1:0000 | 1:0000 1:0000 1-0000 
11 “9995 “9997 ‘9997 *9996 
12 “9990 "9994 9994 +9993 
13 “9985 “9991 “9991 “9989 
14 “9980 “9989 “9988 “9986 
15 | “9974 “9986 | “9985 “9982 
} 16 | “9969 “9983 | “9981 “9978 
| 17 “9964 | “9981 | “9979 “9975 
| 18 “9959 | “9978 } “9978 “9972 
| 19 "9954 | “9975 “9977 *9969 
| 20 | *9950 | “9973 | “9977 “9967 
(Numbers given in italics are obtained by extrapolation.) 
Nore.—If we assume the validity of the numbers in the last column, 
then any quantity of heat (Q,) expressed in terms of the capacity for 
heat of water at ¢° C. may be expressed with sufficient accuracy in terms 
of the thermal unit at 10° C. (Q,o) by means of the following formula :— 
Qio = Q, {1—-000338 (¢—10)', 
where ¢ lies between 10° and 20° C. 
Then Qo X 4:2 gives the equivalent in Joules. 
APPENDIX III. 
RECALCULATION OF THE ToTaL Heat oF WATER FROM THE EXPERIMENTS 
OF REGNAULT AND Rowianp. By W. N. Suaw. 
Tables of Thermal Data expressed in terms of Joules, 
(Pp 2 
The thermal data depending upon a thermal unit, which are, as a 
rule, included in tables of physical constants, comprise the following :— 
The variation of the specific heat of water with variation of tem- 
perature. 
Specific heats of various substances, solid, liquid, or gaseous. 
Latent heats of fusion. 
Latent heats of evaporation. 
Heat of chemical action. 
Thermal conductivities of various substances. 
The tables are mainly compiled by grouping the results obtained by a 
number of observers. Such results are only, strictly speaking, comparable 
where the scales of temperature, and the thermal units adopted for the 
reduction of the observations, are identical. With different observers 
this is only the case if very rough approximation be allowed ; but the 
experimental data communicated in the description of observations some- 
times afford the possibility of putting the results upon a better footing for 
comparison than that upon which the author’s own reductions leave them. 
Jt is clear that the auxiliary data which must be used in order to render 
the results strictly comparable, are in effect precisely those which are 
