67 



Such uniformity of structure is not unusual amongst Conifers according to 

 De Bary "Comp. Anat. Phan. and Ferns" {Juniperus communis, p. 494), but 

 E. S. Bastin and H. Trimble in their work on Coniferse (" Amer. Journ. Pharm.," 

 1896-7) show hardly such regularity in the number of plates depicting bark struc- 

 ture of certain genera of this natural order^ such as Pinus, Picea, Abies, Tsuga. 



XIX. THE TANNING VALUE OF THE CALLITRIS BARKS. 



This investigation of the barks was undertaken in the endeavour to arrive 

 at the possible economic value in this direction of the several species of Callitris 

 gro-wing in Australia and Tasmania. 



The barks of the following species have been investigated : — 



C. calcarata, from five localities in New South Wales. 



C. arenosa, ,, Northern New South Wales. 



C. glauca, ,, three localities in New South Wales. 



■C. vemicosa, „ interior of New South Wales. 



C. gracilis, ,, Rylstone, New South Wales. 



C. rhomboidea ,, Sydney, New South W'ales. 



C. Mueller i, ,, Sydney, New South Wales. 



C. robusta, ,, Western Australia. 



C. infratropica ,, Port Darwin, Northern Territory. 



C. propinqua, ,, South Australia. 



C. Tasmanica ,, Tasmania. 



The above list includes most of the Callitris; the barks of the few remaining 

 species were not available, but there is no reason to suppose that their tannins 

 would differ materially from those which' have been determined. The bark of 

 C. Macleayana is composed almost entirely of a mass of fibre, and appeared to 

 contain such a small amount of tannin, that it was not analysed. 



In many parts of the world, barks obtained from the Coniferae are extensively 

 used in the leather industries. Particularly is this the case with the bark of the 

 Hemlock (Tsuga Canadensis), a species which, both in America and in Canada, 

 is still largely used for tanning purposes, as well as for supplying the raw material 

 in the manufacture of its tanning extract. Not many years ago it formed the 

 staple material for the purpose of the tanner in America, and according to Davis, 

 (p. 118) the greater portion of the sole and heavy leathers was tanned with it. 



Professor Trimble ^" Journ. Soc. Chem. Industry," 1898, 558) publishes the 

 results of an investigation which he had undertaken on the barks of several 

 Indian trees belonging to the Coniferge, one of which, Pinus longifolia, is used for 

 tanning in that country, and which is stated to contain about 13 per cent, of 

 tannin in the air-dried bark. 



