214 
weight be fixed at 3H7, 4H7, or 5H7, silicium will still retain 
its positions as the second member of th e series Win. The chief 
properties which distinguish the elements of the series H7 n 
are their high fusing point ; their occlusive affinity for 
hydrogen ; and their passivity in the presence of ordinary 
reagents, to which iron, under peculiar conditions, forms no 
exception. In regard to their occlusive affinity for hydro- 
gen ; the relation of nitrogen to iron and palladium may 
explain the existence of the ammonium amalgam, in which 
nitrogen and hydrogen are held together in the nascent state 
by means of mercury. The formation of silicium hydride 
by electrolysis, in a manner analogous to that of the ammo- 
nium amalgam, would also indicate for silicium a similar 
occlusive affinity for hydrogen to that possessed by 
nitrogen. 
Although gold in some recent classifications of elements 
has been separated from the platinum metals, yet, in its 
primary qualities, it exhibits closer analogies with them 
than with the members of any other series, and there is no 
other place vacant in the groups which an element with the 
atomic weight and physical properties of gold would fit. 
The constant association in nature of quartz, hematite and 
specular iron ores, with gold and platinum is a fact fully 
recognised by chemical geologists,* and confirms the posi- 
tions assigned for Si, Fe, and Au, in the table as forms of 
Win. 
The remarkable resemblance which the members of the 
iron group have to one another, while their atomic weights 
are nearly if not exactly the same, has long been a subject 
of much interest to philosophical chemists, and if the views 
which I have enounced respecting the formation of ele- 
mentary species by condensation be correct, the cause of 
these resemblances admit of a possible explanation. From 
* Bishcoff’s Chemical and Physical Geology. Yol, iii., 534. Cavendish 
Soc. Works. Murchison’s Siluria. Chap, xvii., 433-439. 
