140 MR. H. WILDE ON THE 



and a polyhasic character like that of phosphorus or 

 nitrogen^ Regnault remarked that it is easy to explain the 

 existence of the great number of silicates which nature 

 presents in well-defined and beautiful crystals, and to 

 understand the existence of the natural hydro-silicates. 



Whichever view chemists may ultimately adopt in 

 regard to the constitution of silicic acid, or whether its 

 atomic weight be fixed at 3H7, 4H7, or 5H7, silicium 

 will still retain its position as the second member of the 

 series Hyn. 



The chief properties which distinguish the elements of 

 the series liyn are their high fusing-point, their occlusive 

 affinity for hydrogen, and their passivity in the presence 

 of ordinary reagents, to which iron, under peculiar con- 

 ditions, forms no exception. In regard to their occlusive 

 affinity for hydrogen, 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 ammonium amalgam, would also 

 indicate for silicium a similar occlusive affinity for hydro- 

 gen 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 recognized by chemical geologists"^, and 



* BischofF's 'Chemical and Physical Geology,' vol. iii. p. 534. Cavendish 

 See. Works. Murchison's 'Siluria,' chap. xvii. pp. 433-439. 



