Chemistry and Physics. 113 
16. On the determination of atomic weights by optical means ; 
Atprecut Scuraur.—lIf « be the index of refraction and d the density 
of a body, then Newton’s formula for the refractive power M of any sub- 
stance is by Schrauf replaced by 
A?—1 B 
M=—— + N=—, w=A+s, 
where 4 is the wave-length, N the dispersing power. 
. C’ 
Schrauf modifies the latter equation of ora to u=1+75, 
are respectively what he calls the refraction- and dispersion-equivalents. 
lh by considering light to be a vibratory motion of the atoms, he 
I proportional to ZG, 
aa; Z.is the number an nd G the ma aes of the “ physical atoms.” 
ars) or the leg asl of the 
Her parts from that of the substance entire, IMZ (To 
IM (x)=™M yes (Pars). 
For any compound of a, 8, ¢, etc., h 
Matte: enM)-+n/B(2) + te, 
Where n, n simple, entire numbers. 
_ The flowing in is a synopsis of the principal results, P are the atomic 
adopted. 
oes uncombined ; uw directly determined. 
Gas: Hydrogen, M=—0-004050 IMI—0:004050 
gen, 0:000489 0:007824 
Nitrogen, 0000602 0-008428 
Chiorine, 0:000627 0022258 
id or solid : 
Sulphur, 0-002044 0:065144 
Carbon, diamond, 0001810 0021720 ete. 
# determined by Brewster's Be of —— 
Antimony, 0°30540 
Silver, on “a 0°13631 
Merry, 0-001987 039740 ete. 
8 in combina 
Batyl -aleohol €. 'T .O=14, M=0-001474, IM~=0'109063 
‘Ethylether €;H,,@=74 — 0°001453 010757 
© as the part, and z=€ 4H, o, the above-stated value of na(O) 
Ss IM(€,H , ,=™M1(tot.) — M{(pars)—=0-100521. - 
ri of this value he now from mereury-ethyl, C,H, Hg; a = 
‘ates IME(Hz)—0-07598, while direct determination from vapor gave 
Am, Jour, Sci.—Srconp Szrres, Vou. XLIV, No. 130.—Juzr, 1867. ies 
15 see 
