354 REPoRT—1905. 
shown that the truly scientific organisation of industry includes in its scope a full 
and just consideration for the social and intellectual needs of its workers from 
highest to lowest. It augurs well, therefore, for the future of the gold industry, 
from the humane and social points of view, that its control should be more and 
more under the influence of men of scientific spirit and intellectual culture who 
we may feel assured will not forget the best traditions of their class. 
The application of science to industry requires on the part of the pioneers and 
organisers keen and persistent concentration on certain well-defined aims. Any 
wavering in these aims or any relaxation of this concentration may lead to failure 
or to only a qualified success. This necessary but narrow concentration may be a 
danger to the intellectual development of the worker, who may thereby readily 
fall into a groove and so may become even less efficient in his own particular work. 
It certainly requires some mental strength to hold fast to the well-defined practical 
aim while allowing to the attention occasiona) intervals of liberty to browse over 
the wide and pleasant fields of science. But I am certain that the acquirement of 
this double power is well worth an effort. The mental stimulus, as well as the 
new experiences garnered during the excursion, will sooner or later react favour- 
ably on the practical problems, while the earnest wrestling with these problems 
may develop powers and intuitions which will lend their own charm to the wider 
problems of science. 
Gold and Science. 
If we re-peruse the table of the elements, not now in our capacity as ‘ plain men ’ 
but as chemists, we shall certainly not select gold as of supreme interest chemically. 
Its position as chief among the noble metals, its patent of nobility, is based on its 
aloofness from common associations or attachments. Unlike the element nitrogen, 
it is mainly for itself and little if at all for its compounds, that gold is interesting, 
In it we can at our leisure study the metal rather than the element. Its colour 
and transparence, its softness and its hardness, the density as well as the extreme 
tenuity of some of its forms—such were the qualities which recommended it to 
Faraday when he desired to study the action of material particles on light. I 
should like to repeat to you in his own words the reasons he gave for this choice : 
‘Because of its comparative opacity among bodies, and yet possession of a real 
transparency; because of its development of colour both in the reflected and 
transmitted rays; because of the state of tenuity and division which it permitted 
with the preservation of its integrity as a metallic body; because of its supposed 
simplicity of character; and because known phenomena appeared to indicate that 
a mere variation in the size of its particles gave rise to a variety of resultant 
colours. Besides the waves of light are so large compared to the dimensions of 
the particles of gold which in various conditions can be subjected to a ray, that it 
seemed probable that the particles might come into effective relations to the muc 
smaller vibrations of the other particles.’ 
I may remind you that Faraday came to the conclusion that the variety in the 
colours presented by gold under various conditions is due to the size of its particles 
and their state of agyregation. Ruby glass or ruby solutions he proved are not 
true solutions, nor are they molecular diffusions of gold, but they contain the 
metal in aggregates sufliciently large to give a sensible reflection under an incident 
beam of light. Through the kindness of Sir Henry Roscoe I am able to exhibit to 
you some of the original ruby gold preparations obtained during this research, 
which were afterwards presented to him by Faraday at the Royal Institution some 
years before his death. 
By means of refined and ingenious optical methods Zigsimondy and Siedentopf 
have succeeded in making these ultra-microscopic particles visible in the micro- 
scope as diffraction discs; they have, further, counted the numer of particles per 
unit area, and have from the intensity of their reflection calculated their size. In 
ruby glass the size of the particles in different specimens was found to vary from 
4 to 791 millionths of a millimetre. No relation was found to hold between the 
colour of the particles and their absolute size. This conclusion is in direct con- 
tradiction of Faraday’s belief already referred to. Mr. J. Maxwell Garnett has 
