702 Journal of the Department of Agriculture. 



Composition of Natal Wattle Bark. 



The first of a series of articlevS on the above sul)ject hy Mr. C. 

 Williams, B.Sc, A.R.C.S., Chemist, School of Ao-riculture. 

 Cedara, appeared in the Agricultural Journal for July, 1914, and 

 afterwards was published by the Department of Agriculture as a 

 separate bulletin (No. 59, 1914). This article dealt with the composi- 

 tion of wattle bark from trees of various ages felled in the spring 

 and early summer in the neighbourhood of Cedara, situated in the 

 midlands of Natal. 



The second article was also published as a bulletin (No. 72, 1915), 

 and contained a resumve of the results obtained in case of bark 

 stripped from trees in the same plantations during the subsequent 

 winter months. It also dealt with the tannin content of leaves and 

 twigs from wattle trees, and with the composition of the kino exuded 

 by the trees under certain conditions of growth. 



A third article by Mr. Williams has now been published as 

 Bulletin No. 1, 1920 (obtainable on application from this office), in 

 which there is summarized the results of the investigation carried 

 out on the composition of the bark of trees from plantations on the 

 north coast of Natal, in order to ascertain whether there is any 

 marked difference or not in the tannin content and maturity as com- 

 pared with trees of corresponding ages grown in the midlands. The 

 colour of the infusion from the bark has also been estimated in each 

 case and compared with the colour of other tanning materials. 



The article contains, in addition, the results of an investigation 

 conducted concerning the effect of keeping the wattle tannin liqUor 

 for a length of time, and also the effect of boiling it for some time. 

 This was carried out in order to assist extract manufacturers to find 

 out at what stages they may expect. any loss or deterioration in the 

 liquor. 



Lastly, the composition and colour of commercial samples of 

 various wattle extracts manufactured in Natal are tabulated. 



The conclusions drawn from the investigations, as described in 

 the three articles, are summarized as follow : — 



1. Mature wattle bark when being thoroughly dried under natural 

 conditions in the open air loses slightly under half its weight, on an 

 average. 



.2. In the case of wattle trees, the total amount of bark and of 

 tanning matter obtained from a tree increases fairly regularly with 

 the age, but the percentage of tanning matter was approximately the 

 same at all the ages examined from three up to seven years. 



3. The development of the trees, and the weight of bark obtained 

 per tree, are very much inferior in case of those from the coast planta- 

 tions investigated than those from the higher altitudes of the midlands 

 of Natal. The coast trees seem to mature more rapidly, and the 

 percentage of tanning matter is generally higher for trees of cor- 

 responding ages, but the total weight of tanning matter obtained per 

 tree is on the average less than half that from trees of similar age 

 in the midlands. 



4. There is a decided and continucnis decrease in the percentage 

 of tannin in the bark as Me ascend the tree. 



