42 
EDITORIAL OBSERVATIONS. 
■with avidity by the scientific world, and extensively applied. 
Some have thought that it heralds the birth of a new kind 
of terrestrial and stellar chemistry, but it remains to be proved 
that we have in it all that is necessary to demonstrate the 
whole of material existence. Doubtless a splendid and a 
wondrous field is opened up by it, and science teaches us to 
be neglectful of nothing, since the* smallest beginnings often 
eventuate in large and useful results. Speaking of it, Mr. 
Crookes says, “ Chemists can now analyse, in the most rapid 
and accurate manner, almost everything which is visible to 
the human eye. It matters not whether the body possesses 
a tangible substance or not, whether it is close at hand in a 
test-tube, or millions of miles away; if it only fulfils the 
one condition of emitting light, it is almost certain to reveal 
the secrets of its composition when submitted to the new 
development of spectrum analysis.” 
When we penned our first article on this subject, we 
combated the opinion that colour-tests were objectionable. 
We are free to confess that when we did so, we were in 
ignorance of colour-blindness being so general. We have 
since read that the late Dr. Wilson paid special attention to 
the subject of colour-blindness. The results at which he 
arrived may not, however, be familiar to all. In one year, 
we are told that he examined no fewer than 1154 persons 
with reference to their appreciation of colour, and afterwards 
many more, and that he found no smaller a proportion than 
one in fifty so blind as to be unable to distinguish between 
red and green, while one in twenty was pronounced of im¬ 
perfect power in this particular. Further, he pointed out 
the practical bearing of his researches on railway and other 
signals, suggesting as useful precautions the examination of 
signalmen as to their ability to distinguish colours, and also 
the addition of form and number to railway signals. It is 
also worthy of mention, that the colours most generally con¬ 
founded by the colour-blind have been chosen for important 
signals both by land and sea. Still we do not consider this 
a valid objection. Some persons have no ear for the sweet 
harmony of sounds : they cannot distinguish one tune from 
another. To others the most fragrant odours are offensive, 
