ORIGINAL COMMUNICATIONS. 
Some Remarks upon Lieut. A Paper read before the 
Microscopical Society of Newcastle-upon-Tyne. By 
B. 8. Proctor. 
Ir can scarcely fail to have struck every microscopist that 
the white materials of everyday life, when submitted to the 
keen gaze of microscopical examination, display bright re- 
flecting surfaces and clear transmitting substance ; that black 
substances are also shining, though in a less degree and 
having less transparency ; and that the most opaque materials 
transmit more or less ight when in thin section. 
Having noticed such commonplace facts, I was led to ask 
myself— 
What is the difference in the appearance of transparent 
and opaque white powders? Are white organic materials ever 
opaque ? 
And I entered the same on a list of subjects which I keep 
for future examination. These questions had not long been 
there before they were followed by another entry. 
Are all opaque substances black when in a fine state of 
division, as copper, iron, silver, platina ? 
How far is blackness coincident with opacity and hetero- 
geneousness or division ? 
How far is whiteness coincident with transparency and 
heterogeneousness or division ? 
Is anything opaque? If not, what is the nature of the 
phenomena of proximate opacity, black, white, and coloured ? 
Having these questions entered on my list, and kept in 
my mind by occasional reference to the same, they have sug- 
gested a variety of thoughts and observations, which I now 
propose to present to you, hoping that their enunciation will 
afford you a per-centage of the interest which their elabora- 
tion has afforded myself. 
In the pursuit of physical science, we can scarcely ask our- 
selves for an explanation of any simple phenomenon without 
VOL. III.—NEW SER. M 
