342 
SELECTED ARTICLES. 
that of oxygen will depend on the balance of affinity between 
the two, and that of oxygen for terrestrial bodies, affected by 
the tendency of the one to be a submultiple of the other; 
because in this case the attachment is more equable on all 
sides the oxygen; and as we know that the nitrogen is very 
nearly four times the oxygen, it follows that this is the exact 
ratio, from which we obtain y exactly for the specific gravity 
of oxygen; since it was shown that nitrogen is ||-. Ammonia 
in two volumes contains one of nitrogen and three of hydro- 
gen; its specific gravity was found by experiment as follows: — 
.590164 Davy; .590331 Thomson; .5912 Berzelius. The 
specific gravity of hydrogen, as derived from these separately, 
is .069368, .060479, and .07003; in these the agreement is 
very remarkable, being extremely near to i± ; Davy gives 
_ T 2__. m defect, Thomson's -^j^qq in excess; and that of 
Berzelius 25VW m excess > Dut this last chemist finds the 
specific gravity of hydrogen to be .0689 less than T \ 7 ; the 
mean of his two experiments gives .06946, which exceeds 
tW by" only jq^q-q of an unit, which agrees almost exactly 
with Dr. Thomson's direct experiment. Berzelius and Du- 
long found the specific gravity of oxygen and hydrogen to be 
as 16.014 to 1, which also is very nearly identical with the 
above. Also, Gay-Lussac found the specific gravity of steam 
to be .6235, which gives for hydrogen .0692, which again 
scarcely differs from the above at all. Nothing can be more 
satisfactory to prove that the specific gravity of hydrogen is 
UL. Muriatic acid consists of equal volumes of chlorine and 
144 t *■ 
hydrogen without condensation. Dr. Thomson found by ex- 
periment that the specific gravity of this gas is 1.2843, which 
gives for the specific gravities of chlorine 2.4992, and this 
differs from 2\ by less than the 3V00 °f an uni ^ By 
direct experiment, Dr. Thomson found the specific gravity of 
chlorine exactly 2\\ Sir H.Davy found that a cubic inch 
weighed between 76 and 77 grains: the mean gives 2.5081, 
the same as before. Carbon is of great importance, the 
specific gravity of its vapor cannot be found by direct experi- 
ment, but may be determined from its combinations. The 
specific gravity of cyanogen was found by Gay-Lussac to be 
