1918.] The N.Z. Journal of Science and Technology. 
3 
Preliminary Note on the Tinctorial Properties of the Genus 
Coprosma (Family Rubiaceae). 
By B. C. Aston, F.I.C. 
Although the bark of Coprosma grandijolia was examined for alkaloids 
with a negative result by Skey,* and he noted that the inner surface of the 
bark was a bright-yellow colour, the chemical examination of the colouring- 
matters of this species and the genus generally does not seem to have 
received the attention which its close relationship to the madder-plant 
(Rubia tinctorum ) of commerce would warrant. The yellow root of this 
plant, which becomes red on drying, used as a dye from very ancient times, 
is the source whence alizarin (a most important dye) was originally obtained 
The natural product is now almost entirely superseded, except for dyeing 
wool felt (which material is more easily penetrated by the natural than by 
the artificial product), by the synthetic alizarin made from the anthracene 
of coal-tar. 
From alizarin may be produced a variety of colours, especially reds 
and blues. Soluble alizarin blue is replacing indigo for some purposes, 
and is stated to be a formidable rival to that dye in wool-dyeing. 
There are at least three New Zealand species of the genus Coprosma — 
representatives of which are among the commonest and most widely dis¬ 
tributed native shrubs—the bark of which (especially that of the root) is 
of considerable tinctorial power—viz., Coprosma grandijolia , C. linariijolia, 
and C. areolata. The first has an orange-yellow, the second a bright- 
yellow, and the third a deep-brown colour. The colour is more deep the 
nearer it is to the root, and less deep towards the ends of the branches. 
The Maoris are said to have used both Coprosma grandijolia and C. robusta 
or C. lucida for producing shades of yellow in their phormium cloths, but 
the author can find no reference to a red or a blue dye obtained by the 
Natives from these plants. 
Extracts from Coprosma grandijolia dye cotton a delicate pink or red, 
and the brown inner bark of C. areolata stains the hands a persistent brown. 
The following experiment seems to show that both alizarin and purpurin, or 
some closely allied compound, are present in the bark of C. grandijolia. 
Seventy-two grams of the fresh bark of C. grandijolia from the above-ground 
portions of the plant gathered in August were allowed to lie for forty-eight 
hours, and were then steeped in water for twenty-four hours and the water 
separated. The bark was then steeped in alcohol for twenty-four hours and 
the alcohol removed by distillation. A small portion of the alcoholic extract 
gave on mixing with caustic soda (10-per-cent, solution) a brilliant purple 
coloration, becoming yellow with dilute hydrochloric acid. The acid alcoholic 
extract was shaken with ether six times, which removed all the colouring- 
matter. On evaporating the ether a crust of orange-coloured crystals was 
deposited : these under the microscope were seen to consist of a mixture of 
bright-red and yellowish clumps of acicular crystals. After drying in a 
desiccator over sulphuric acid the weight was 0*05 gram (= 0*068 per cent, 
of the wet bark). These crystals, which sublimed on the walls of a test- 
tube immersed in hot sulphuric acid, by the action of a boiling saturated 
solution of potash alum were separated into a yellowish-red fluorescent 
solution and a brown insoluble substance which gave an intense purple 
coloration with alkalies. 
* Trans. N.Z. Inst, vol. 2, 1869, p. 152. 
