388 Scheerer on Isomorphism. 
Whence we may infer, first, that all the serpentines in question, 
notwithstanding their very different amount of water, give very 
nearly one and the same oxygen ratio of Si to R, as soon as we 
conceive their water to be replaced by magnesia in the proportion 
of 3H: 1Mg; and secondly, that this oxygen ratio, which from 
the mean of thirteen analyses is 100: 96-4, may, disregarding the 
trifling discordance, be put down as=1:1. This discordance 
of 3-6 per cent. is easily explained when we take into considera- 
tion the difficulty that there is in obtaining serpentine completely 
pure, and entirely free from all mechanical admixture, and how 
liable this mineral is, either by being dried at too high a temper- 
ature, or in consequence of becoming weathered, (whence it also 
takes up a small amount of carbonic acid,) to part with a small 
quantity of its water. 
From the oxygen ratio, Si: R = 1: 1, we deduce for all ser- 
pentines, the simple formula of (R]° Si, the bracket including 
the R signifying that in this member a greater or lesser portion 
of the magnesia and bases isomorphic therewith, as for instance, 
Fe, Mn, and so forth, is replaced by a corresponding quantity of 
water in the ratio here stated. This formula is however at the 
same time that of olivine, [R* Si,] with this difference merely, 
namely, that in the latter no magnesia is replaced by water. 
Hence, serpentine is to be looked upon as a hydrous olivine, or 
other words, as an olivine in which the water, as an isomorphic 
constituent, replaces a greater or less amount of the 1: 1 atomic 
bases, whence we arrive at an explanation of the known fact, 
that the crystallized serpentine from Snarum is of the same 
erystalline form as olivine. What aspasiolite is to cordierte, 
serpentine is to olivine. 
The remarkable serpentine crystals from Snarum, (some of 
which, with a corresponding width and thickness, attain the 
length of four inches and above,) have been held by some min- 
eralogists to be pseudomorphous crystals of olivine. Whoever 1s 
acquainted personally with their locality, will assuredly refuse to 
adopt this view.* 
The olivine form of these crystals, furnishes of course no direct 
proof of the conversion; it only engages us to endeavor to seek 
Jor such a proof. No such proof has hitherto been found, nel- 
ther is it probable, as I have convinced myself by a careful in- 
ee 
* Tamnau, who visited the localities some years ago, has already expressed him- 
self to that effect. See Pogg. Ann., vol. xlii, p. 462. Also, Bobert in Gaa Nor 
vegted, part i, p. 135. 
