402 



DYES AND TANS. 



[November, 1909, 



TANNING MATERIALS. 



(Prom the Report on the Work of the 

 Imperial Institute, 1908, No. 601, 

 July, 1909.) 

 Countries of Origin.— British East 

 Africa, Natal, Northern Nigeria, Gold 

 Coast, Gambia, India Portuguese East 

 Africa. 



No. of tanning materials received in 1908 .,. 16 

 „ ,, ,, reported on in 1908 ... 18 



The tanning materials examined during 

 the year belong to three groups :— 



1. Mangrove Products,— Three man- 

 grove barks, from Portuguese East 

 Africa, were found to contain 23'3, 28*3, 

 and 41'76 per cent, of tannin. The 

 samples were of special interest, because 

 No, 2, on further examination, was found 

 to contain 39'8 per cent, of tannin in the 

 inner bark, and only 8 97 per cent, in 

 the outer bark, clearly illustrating the 

 desirability of scraping the outer layers 

 off mangrove bark before shipment. A 

 mangrove bark from the Gambia was of 

 exceptional interest in yielding a very 

 light-coloured leather, but unf ortunately >t 

 it contained only 25'7 per cent, of tannin. 



The enquiry on the manufacture of 

 Indian mangrove extracts, referred to in 

 the Report for 1906-7 (p. 67), was com- 

 pleted during the year. Mangrove 

 leaves from British East Africa were 

 also examined, but proved to contain 

 too little tannin and too much salt to 

 be of value as a tannin agent. 



2. Wattle Barks.— A number of 

 enquiries have been received relating to 

 this product during the year, and infor- 

 mation has been furnished to the Govern- 

 ment of Natal respecting machinery and 

 processes for making wattle extract, 

 and also regarding the competition of 

 other tanning materials with wattle 

 bark in the United Kingdom. Six 

 samples of wattle bark were examined 

 for the Natal Government, mainly with 

 a view to ascertaining the influence of 

 the situation of a wattle plantation on 

 the bark produced. These results are 

 summarised inter alia in articles in the 

 " Bulletin of Imperial Institute," 1908, 

 VI., 157, and 417. 



Caesalpinia Pods.—" Divi-divi" pods 

 from the Gold Coast proved to be not 

 well prepared and deficient in tannin. 

 Further supplies of "teri" pods were 

 received fioni India during the year, 

 and were submitted to commercial firms 

 for trial and valuation, 



Acacia Pods. — Acacia arabica pods 

 from Northern Nigeria were found to 

 contain 26'6 per cent, of tannin. 



Full particulars regarding most of 

 these tannin materials and of others 

 investigated at the Imperial Institute 

 in recent years are given in reports and 

 articles published in the "Bulletin of 

 the Imperial Institute," 1907, V., 343, 

 1908 ; VI., 121, 167, 175, and 417. 



NATURAL DYESTUFFS. 



(From the Report on the Work of the 

 Imperial Institute, 1908, No. 601, 

 July, 1909.) 



Countries op Origin.— Northern Ni- 

 geria, Southern Nigeria, Sierra Leone, 

 India, Jamaica. 



Number of dyestuffs received in 1908 ... 17 

 ,, ,, reported on in 1908 ... 15 



Natural dyestuffs are now of so little 

 importance in commerce that their in- 

 vestigation is generally of more purely 

 scientific than practical importance. 

 There are, however, still a few natural 

 dyestuffs which for certain purposes 

 have not been entirely supplanted by 

 aniline and other artificial dyes. Among 

 the most important of these are logwood, 

 camwood, annatto, quercitron bark and 

 natural indigo, and enquiries relating 

 to, or samples of, all these products have 

 been dealt with in the course of the year. 

 There has been some revival of interest 

 in Indian indigo, chiefly on account of 

 the planting experiments with Natal- 

 Java indigo, which have been carried on 

 during the last few years in India. This 

 species furnishes a superior yield of 

 indigo, and a number of enquiries on the 

 subject were dealt with. Owing to a 

 failure in demand for Jamaica logwood, 

 enquiries were received from that island 

 as to the markets and prospects for this 

 wood in Europe, and a memorandum on 

 the subject was prepared, and enquiries 

 were placed in a position to negotiate 

 directly with consumers in this country. 



Other enquiries dealt with the method 

 of formation of the red-colouring matter 

 in camwood, the preparation and value 

 of quercitron bark, and the identifica- 

 tion of samples of saffron. 



An interesting series of materials used 

 in tanning and dyeing the native leather 

 of West Africa was received during the 

 year, and a full account of these, with 

 details of the method of using them, 

 was published in the " Bulletin of the 

 Imperial Institute," 1908, VI„ 175. 



