NOVEMBER 9, 1916] 
if not the sole, excuse that could be adduced for 
Government support of a very substantial char- 
acter to one firm only rather than helping a rela- 
tively large number of smaller concerns, which 
many now believe would have produced more 
immediately satisfactory results. 
(7) In spite of manifold difficulties much has 
been done by universities and technical institu- 
tions of the higher order to help industry. Pro- 
fessors, lecturers, and post-graduate students have 
vied with each other in endeavours to meet many 
‘demands made upon them, and their collaboration 
with manufacturers has led in many cases to 
extraordinarily gratifying results. If all 
facts could be published it would be a most agree- 
able surprise to many, who have taken an alto- 
gether too gloomy view of the possibilities of this 
collaboration. Leeds University and the Man- 
chester School of Technology have started new 
‘departments for chemical research for special 
objects, such as the study of problems in connec- 
tion with the dyestuff industry. Remarkably fine 
and eminently useful work has been carried out | 
also for the Army and Navy. A great deal more 
could have been done in that direction but for 
the aforesaid shortage of well-trained chemists, 
the relatively small number of whom are at last 
“coming into their own.” Salaries that would have 
been thought preposterously large a few years ago 
are now gladly paid. 
will tend to attract to the profession a large 
. number of suitable and able men as well as women. 
It may indeed be said that unless this takes place 
there is not much hope for the establishment and 
maintenance on an adequate scale of the dyestuffs 
and allied industries; and not only. must those 
who have to deal with the scientific and practical 
side of the industry be chemists, but what is 
equally important, the men who direct the ad- 
ministrative side of the business must also be 
well-trained chemists of business experience, or 
good business men with a chemical training. It 
is facts such as these that are appreciated far less 
than they deserve to be. But the war is teaching 
us many things, and as we have perhaps at last 
realised the importance of the work of the chemist 
in war-time, so it is just conceivable that the 
nation may in time come to realise that in peace- 
time also industrial and material progress is going 
to depend more than it ever did before on the 
successful work of the chemist. 
Ae aR. 
PRESERVATION OF NATURAL COLOUR 
IN PLANTS. 
bei long ago as 1908 Prof. J. W. H. Trail 
\J described in the Kew Bulletin a method 
which he had worked out for fixing the green 
colour in plants. By placing the plant for'a 
shorter or longer period in a boiling solution of 
copper acetate dissolved in acetic acid, a com- 
bination of the copper salt with the chlorophyll 
was formed which rendered the colour permanent 
when the specimen was exposed to the light after 
NO. 2454, VOL. 98] 
the | 
It is to be hoped that this | 
NATURE 
| about two hours. 
191 
drying or placed in a preservative solution such 
as alcohol. 
The method deserves to be more widely known 
than it seems to be among those interested in 
preparing plant specimens for exhibition in 
museums or for lecture purposes. It is essen- 
tially a method the results from which gain by 
experience ; different plants lend themselves to the 
treatment with different degrees of success, and 
require very different periods of treatment; the 
time for which it is necessary to keep the plant in 
the boiling solution varies from one minute to 
forty minutes, according to the action of the 
copper salt upon the plant. If the action is pro- 
ceeding satisfactorily, a period of one to five 
minutes should suffice; the end of the operation 
is easily judged by the colour or by treating two 
different specimens for different periods; a speci- 
men that by such comparison appears to require 
longer treatment can always be reimmersed to | 
get the desired effect. Many plants, notably the 
leaves of evergreen shrubs, are more difficult and 
generally less satisfactory in the ultimate colour, 
probably owing to the presence of mucilaginous 
or decomposition products or. tannins. These 
require long treatment varying from twenty to 
forty minutes; after the first immersion they turn 
yellowish, and then after a time the yellow 
gradually gives place to green, generally an olive- 
green. Other plants, notably Aucuba, fail en- 
tirely, as they pass from the yellow to a muddy- 
brown or black colour. 
After treatment the plants should be washed 
(like photographic prints) in running water for 
They are then dried under as 
light pressure as is compatible with keeping the 
plants from twisting, or, after shaking off as 
much water as possible, may be dried in hot 
sand. In many cases the plants are rendered so 
flaccid by boiling that sand-drying is difficult or 
impossible. Plants that have required long boil- 
ing not infrequently revert to a bad colour when 
| sand-dried. 
Young parts of plants green better than old; 
better results may be expected from “spring” 
leaves than from “autumn” leaves. 
A stock solution is made by saturating com- 
mercial strong acetic acid with powdered copper 
acetate. For treatment, dilute the stock solution 
with water in the proportion of three or four parts 
of water to one of stock solution. The solution is 
heated in a non-metallic vessel, glass beakers 
being probably the most suitable, and wooden, 
not metal, forceps should be used for manipu- 
lating the specimens. 
This method has been used at the Natural His- 
tory Museum for some time past in the prepara- 
tion of plants for exhibition purposes, and good 
results have been obtained with cryptogams as 
well as flowering plants; ferns especially give 
satisfactory results, and, as Prof. Trail has noted, 
fresh green Algzw can be successfully treated. 
Proceeding out of these investigations, experi- 
ments have been made with the object of pre- 
serving the natural colour of seaweeds or of intro- 
