( 689 ) 





















XXVI.—The Preparation and Properties of Pure Graphitoid and Adamantine 
Boron. By R. M. Morrison, D.Sc. (Edin.), and R. SypNey MarspeEn, 
B.Sc. (Edin.). 
(Read 17th June 1878.) 
In preparing a specimen of diamond boron by WOHLER and DEVILLE’s method, 
the idea struck us of substituting silver, gold, or some other metal in place of 
the aluminium. We thought that by so doing we might be able to save con- 
siderable expense if the silver would dissolve the boron; because in the case 
of aluminium the byproducts are useless, whereas in the case of silver the 
byproducts are easily reconverted into metallic silver. On making an experi- 
nent with silver in place of aluminium, we found that it did dissolve boron, 
and that on dissolving the silver away with nitric acid a slate-grey powder was 
left behind. This powder, on being examined after purification, was found to 
be boron, and to contain nothing but boron; under the microscope, it pre- 
sented a complex composition, some being transparent and some opaque,—the 
Opaque portion consisting of hexagonal prisms exactly like those of graphite ; 
the transparent portion being composed of plates and a few small tetrahedra. 
The quantity obtained was but small, so we repeated our experiment several 
times, at last obtaining sufficient to examine the properties of these crystals. 
The yield of each experiment varied considerably, owing to variations in the 
manner in which each experiment was conducted. This point we will consider 
after discussing the method of preparation. The method which we employed in 
conducting these experiments is as follows :—The silver in small lumps and the 
amorphous boron were placed in alternate layers 
in a porcelain crucible, which was fitted with a 
double lid to keep it perfectly air-tight—the one 
fitting inside the crucible and the other out- 
side—the intermediate space being filled with 
amorphous boron to prevent oxidation of the 
boron to be dissolved. Care was taken that 
the silver did not touch the sides of the cru- 
 cible, and that the mass was well packed to 
| - subsidence. This crucible was then 
Amorphous 
Boron. 
Porcelain 
Crucible, 
with double 
lid. 
Graphite 
Crucible. 

VOL. XXVIII. PART II. SR 
