320 
MR. E. H. GRIFFITHS ON THE LATENT 
TaBLeE X VII.—Comparison between REGNAULT’s Experimental Results (R.) over the 
Range 63° to 88°, with the value given by formule (R), (W), and (G,). 


















| ! | 
ite Il. III. TV. Ve VI. | VIL. | VIII. Ix. 
Experi- | 
No. - | Tempera-| mental | | 
of experi- | Tempere-| mental | (py | (wy | (G) |@)—@).|@)—(W(R)—G). 
ment. ee | 
| () | | | 
1 SoM | GEER I GRRMA IN GRR || Gaile) || @ 2) | eic8 
2 CYAGS} || Geer i) GaeHy 632°3 631°8 — Ol + 08 +13 
| 3 a SoD Ae » G28:45 1638277 25 163127 631:0 = 418} => 83} —2°6 
4, | 85:24 6286 || 632°5 | 631-5 630°7 — 39 | — 29 —2:1 
5 eSo:20he) 630577 632°5 63815 630°7 — 08 | + 0:2 +1:0 
6 8468 | 629:°9 || 632°3 le 631E2 630°5 — 24 | —13 | —06 
7 83:08 | 628°9 631:8 | 630°7 629°9 =) | = 13 in SLO) 
8 82°66 631:0 631-7 630°6 629°7 — 07 + 0-4 | +13 
9 81-03 628'8 631-2 630-0 629'1 ay = 12 | —O8 
10 80:60 627-7 631-1 629°9 | 6289 == 34) — 22 | —1:2 
11 80°37 628°8 | 631:0 629°8 628°8 — 22 =e) 0 
12 8017 | 630°2 6309 | 629°7 628°7 — 07 + 05 e115) 
13 79°55 63071 6308 | 629°5 628°5 — 07 + O07 +16 
14. | 78:28 627:0 | 630°3 | 629:0 |. 628:0 — 33 — 20 . —10 
15 76°50 628°6 | 629° | 6283 627°2 — 12 +03 | 41-4 
16 71°35 624-4 || 628-2 626'4 | 625°2 — 8Y3 — 2:0 —0°8 
17 7111 622°2 628-1 6263 |) - 625-1 — 5:9 — 41 —2:9 
18 | 70°49 626:9 | 628°0 62671 624-9 — 11 + 08 +2°0 
19 69°70 626-4 | 62772 62537 6245 | — 1:3 | + 10:7 +19 
20 | 68:01 622°5 OA || Gar 623°9) eS er tO G —1-4 
21 | 66°30 624°7 626:7 | 6245 623°2 — 20 |} + 02 +1°5 
22 | 64°34 6229 | 626-1 623°9 622°4 = i = Id) +0°5 
23 63°02 625°5 625°7 623°2 621°9 — 02 + 23 +3°6 
Sum of differences . | —49:3 —176 +52 
Mean difference . — 214) — 077 +0°23 
If we omit Experiment 23, we get 
Sum of differences . . |) —49-1 —19°9 +16 
Mean difference . | — 223) — 0°90} +0:07 











The results of the above comparison show that over the range 63° to 88° the 
formula (G) gives a closer approximation to REGNAULT’S experimental numbers than 
either of the other formule. 
The only reasonable explanation of these various coincidences which occurs to me is 
that the value of the “mean thermal unit” is practically the same as the value of the 
“thermal unit at 15° C.”* 
* Further evidence can be adduced in support of this view. In Section II. I-pointed out that if we 
express the results of the observations of Bunsen and Reenavtt, on the latent heat of fusion of 
