IN SOME BARKS FROM BRITISH GUIANA. 



369 



Unless the tannin in the specimens examined had been diminished by 

 preventable causes, such as the trees from which they were stripped being 

 too old ; not stripping them at the proper season, that is, when the sap is 

 running freely in the tree ; and then the bark should be taken off when 

 the tree is about to be or has been felled ; and also the manner in which 

 it was saved or dried, for some barks- are neglected by allowing them 

 to get wet and then heated. 



In conclusion, I may add that the trees most suited to the climate and 

 latitude of British Guiana, and which would yield a sufficient amount of 

 tannin to render them useful as tanning materials, would seem to be some 

 of the Acacia genus, or the Divi-divi (Ccesalpina coriaria.)* 



The following Table contains the average amount per cent, of tannin 

 found by different chemists in the tanning materials examined, with the 

 authority for the same : — 

 Oak bark formation, 100 years old 





British, 50 years old 



„ age about 50 years 



55 55 •" 55 



Southampton, age about 50 years 



Coppice, picked sample 



Irish, picked sample, age 45 years 



Oak, old, white inner bark - 



55 55 55 



» young 



55 55 



55 55 



55 55 



55 55 



coloured or middle bark 

 entire bark - - 



spring-cut bark 

 Oak bark, Belgian, Popering or Plantzen - 

 „ „ „ heavy Coppice, picked 



sample 



55 55 5 5 light 



„ „ Eschurg 

 Mimosa bark - - - - 



55 55 - . - 



"Willow bark - - - - 



Willow, Leicester, white inner bark 



,, coloured or middle bark 



„ entire bark 

 Weeping - - - 



Larch bark - 



55 



55 



55 



r\ 



8-45 



C. Muller. 



13-87 



55 



8-90 



Mulligan & Dowling. 



9-76 



55 55 



6-12 



55 55 



8-80 



55 55 



1235 



55 55 



9-50 



55 _ 55 



21-00 



Cadet de Gassincourt, 



14-20 



Davy. 



15-20 



55 



4-00 



55 



6-00 



Davy & Geiger. 



22-00 



Davy. 



8-33 



Mulligan & Dowling. 



10-74 



55 55 



8-52 



55 55 



19-35 



G. Miiller. 



17-97 



Mulligan & Dowling. 



31-16 



G. Muller. 



3-95 



Mulligan & Dowling. 



16-00 



Davy. 



310 



55 



6-80 



55 



16-40 



Cadet de Gassincourt. 



3-51 



Mulligan & Dowling. 



1-60 



Davy. 



* The barks examined by my student, Mr Mulligan, were given to me in Demerara 

 by a gentleman who was attempting to establish a tannery in that country : the barks 

 were collected by his agents, and, so far as he was aware, with great care. He 

 informed me that he had tried the barks Hog-plum (Spondias lutea) and Courida 

 (Avicennia nitida, Jac.), which are stated in the ' Official Catalogue ' of the Great 

 Exhibition of 1851 to be commonly used in British Guiana for tanning, and he 

 found, from his practical experiments, that they did not contain sufficient tannin to 

 render them useful as tanning materials : he also informed me that no tannery had 

 been attempted to be established in Demerara until he started one about two years 

 ago. — E. Galloway. 



C C 



