1918.] The N.Z. Journal of Science and Technology. 267 
* 
The author has been struck with the individuality of closely allied 
species in the matter of these colour reactions. For instance, Coprosma 
areolata and C . tenuicaulis are very similar in external characters, and are 
considered by Cheeseman to be closely allied. But the former has a cortex 
of a dark-brown colour which gives with alkalis a violet reaction, whereas 
C. tenuicaulis has a yellow cortex and gives a red colour with alkalis. 
(To be continued.) 
EXPLANATION OF SPECIMENS OF DYED WOOL (PLATE II). 
(c.c. = cubic centimetre.) 
No. 1. Coprosma grandifolia bark.—The wool was mordanted by boiling for one 
hour with potassic - bichromate solution in water of such strength that for every 
100 parts of wool there were 3 parts of K 2 Cr 2 0 7 . The wool was then taken from the 
mordanting-bath, well rinsed in cold water, and entered in the cold dye-beck consisting 
of the alkaline extract of 1 lb. of Coprosma grandifolia bark (which had been previously 
extracted by warm water three times) in 2,300 c.c. of solution (K189) made slightly 
acid, the bath being of such strength that 2 parts of bark were added to 1 part wool. 
The wool was placed in the cold beck and the temperature of the whole gradually 
raised, taking about one hour to reach the boiling-point, and then boiled for one hour. 
The wool was then taken out and thoroughly rinsed in cold water. 
No. 2. Coprosma grandifolia bark. — Single-bath process. A fresh portion of the 
same standard solution (K189) used in dyeing No. 1 specimen was used on this wool, 
the mordanting and dyeing being performed in one bath as follows : The mordant is 
first prepared by measuring off 1 c.c. of a solution of stannous chloride (made by 
dissolving 100 grams stannous chloride in 100 c.c. pure concentrated hydrochloric acid 
and 50 c.c. water) for every 10 grams of wool, diluting with water, and adding sodium- 
hydrate solution drop by drop, with constant stirring until a very slight opalescence 
becomes permanently visible. 100 c.c. of 0-5 per cent, potassic bitartrate were then 
added for every 10 grams wool, which causes a turbidity ; the whole was then diluted 
with enough water to cover the wool, which was entered and the whole boiled for half 
an hour. The wool was then taken out, and the proportion of dye solution, which 
must be only very slightly acid, was added in proportion of 4 bark to 1 wool, and the 
mordant and dye solution were boiled for ten minutes. The wool was now re-entered 
and boiled for half an hour, at the end of which time it was rinsed thoroughly in cold 
water. The success of this method depends largely on obtaining the right conditions, 
careful neutralization of the dye-beck being one of them. 
No. 3. The root and trunk bark of Coprosma areolata in small sheets as taken 
from the tree were repeatedly boiled with water, and the solutions filtered hot through 
cheesecloth and the extracts mixed and measured. A portion of the solution equal 
to 6 parts of bark for every part of wool to be dyed was measured off, and for every 
4 litres of solution 75 c.c. of strong sulphuric acid were cautiously mixed in with the 
dye, and the solution, which is at - first brown, was boiled for about fifteen minutes, or 
until the whole turns a clark-green colour with formation of a dark-green precipitate. 
The liquid is now cooled, and nearly neutralized by adding caustic-soda solution. The 
solution should not be allowed to become violet-coloured either before or after boiling. 
If it does, too much soda has been added. The wool mordanted with bichromate of 
potash as in specimen No. 1 is now entered, and boiled for one hour, when it should be 
almost a black colour. It is now thoroughly rinsed in cold water. 
No. 4. Coprosma foetidissima bark.—Extracted by dilute alkali in the same way 
as No. 1, only using a portion of the dye liquid equivalent to 1 of bark to every 1 of 
wool. The single-bath method was then used as described in No. 2. 
No. 5. Coprosma areolata bark.—Extracted as in No. 3; treated exactly as 
described in No. 2 single-bath method. 
No. 6. Coprosma lucida bark.—Extracted exactly as in No. 1. Used in the 
proportion of 1 bark to 1 wool. 
No. 7. Coprosma areolata bark.—Extracted exactly as in No. 1. Used in propor¬ 
tion of 1 bark to 1 wool. 
