280 WJ. H. Long—Indices of Refraction of Compound Ethers. 
A+d 
2 
sin 
r~a= A 
sin a: 
where d is the observed angle of minimum deviation and A 
the refractive angle of the prism. This latter was determined 
before each observation (as the sides of the prism were formed 
of glass plates fastened by rubber bands) and varied between 
60° 2’ 30” and 60° 3’ 30”. 
In every case at least two complete sets of observations were 
made for each substance and the mean of the results, which 
was determined under diminished pressure, this latter element 
is given. In other cases the usual barometric height in Tibin- 
gen—about 735™"—is to be understood. 
METHYL FORMATE, PROPYL ACETATE. 
Bp = 32° = 87°-8-88°°2 P, 470™™ 
T A nabs aif. Fe a fi . "aiff. 
20 1°343 22 1383 
19 1°34430 00044 21 1°38404 00052 
18 13447: 43 20 1°38456 
17 1°34516 43 19 1°38507 51 
16 1°34559 43 18 1°38558 51 
15 1°34601 42 17 1°38608 50 
PROPYL FORMATE, METHYL PROPIONATE. 
r Md o_a@re. mm een 3, ° 
ABP = 61 67°°3 P, 43108 . os Bp = 19 5-80 os 
23 137604 20 1:37763 
22 137656 00052 19 1°37822 “00059 
21 1°37706 50 18 1°37875 53 
20 1°37756 50 17 1.37927 52 
19 137806 50 16 1°37980 53 
18 1°37855 49 15 1°38032 52 
17 137904 49 
IsoBuTyL FORMATE, ETHYL PROPIONATE. 
Bp = 99°-99°- = 8]°-4-82° P, 402™™ 
T. she Stel 5 ae 
22 13 20 1:384 
21 1°38693 00052 19 1°38471 "00050 
20 1°38745 52 P 18 1°385 
19 1°38796 51 17 1°38568 48 
18 5 49. 16 1:38616 4 
17 1°38893 48 15 1°38663 47 
16 1°38941 48 
