18V 



SOME NEW SOUTH WALES TAN-SUBSTANCES. 



Part III. 



By J. H. Maiden, F.R.G.S., Curator of the Technological Museum, 



Sydney. 



[Read before the Royal Society of N.8.W., October 5, 1887.'] 





Notes — (Second Supplement). 



1. In giving the colours of residues left after extracting with 

 water, I have generally specified "moist residue," as the colour is 

 usually more characteristic when the residue is in that state. 



2. The word " ruby " is frequently a convenient one to employ 

 in describing tan-extracts. I have used it to express the tint of 

 the well-known glass used by photographers and for ornamental 

 purposes. 



3. The tannic acids contained in the barks and kinos of 

 Eucalypts and in the barks of Acacias, have been frequently 

 examined, and, owing to slight specific differences, have been 

 designated kino-tannic acid and catechu-tannic acid respectively. 

 Some of the tannic acids yielded by other genera referred to in 

 these papers have differences more or less marked, but at present 

 I am not inclined to take upon myself the responsibility of adding 

 to the already abundant and complex nomenclature of tannins. 



4. Following a list of tan-substances given by C. T. Davis, 

 "The manufacture of Leather," lie makes the following judicious 

 remarks : — " Only a relatively small number of the many tanning 

 materials enumerated are used for tanning on a large scale. The 

 cause of this may be found partly in the conservative bias of the 

 tanners, and partly in the imperfect knowledge of the action of 

 the various tanning materials upon the skin-tissue. It requires 

 extensive study to become thoroughly conversant with the effects 

 exerted by the various tannins, and the extractive resinous 

 substances accompanying them, on the skin-tissue." To these I 

 may make the important addition, that a tanner is not to be 

 expected to take a fresh tan-substance into serious consideration, 

 unless he has some means of knowing the probable extent to which 

 it may become available for his use. Many circumstances may 

 affect a trade in any of the tan-substances alluded to in this series 

 of papers, and I express the hope that the members of this Society 

 (particularly the country ones), will kindly favour me, as 

 opportunities occur, with particulars as to the quantities available 

 in different districts, and probable cost on the spot and in Sydney. 



