ON SOME N.S.W. TAN-SUBSTANCES. 255 



17. Stenhouse in Watts' Diet, i., 1075, gives the percentage of 

 tannic acid in coffee-berries at 3 - 5, and states that it exists in 

 combination with calcium and magnesium. " They also appear to 

 contain a larger proportion of caffetannic acid than the beans ; the 

 proportion of matter extracted by water was 38 -8 per cent." 



18. Ilex paraguayensis, St. Hil. (Aquifoliacea?). "Mate or 

 Paraguay tea" contains "little more than 6 per cent, of tannic 

 acid." 



(B.) Tannic Acid in Australian Leaves. 



1. Leaves of the following Australian plants have already been 

 examined by me with respect to their tanning properties : — Rhus 

 rhodanthema, F.v.M., page 185 ; Eremophila longifolia, F.v.M., 

 page 199 ; Polygonum plebejum, R. Br., p. 200. 



2. In addition to those noted under the species described in this 

 paper, the following notes on tannic acid in leaves of Australian 

 plants will be useful : — Eucalyptus cosmophylla, F.v.M. — " The 

 ordinarily dry leaves gave 13 per cent, of tannin according to a 

 solitary experiment ; equal to nearly 1 5 per cent, in absolutely 

 dry leaves." Decade 7 " Eucalyptographia," (Mueller). 



3. E. doratoxylon, F.v.M., 7 '01 per cent, in the dried leaves. 

 (Dec. 4, " Eucalyptographia.") 



4. "The leaves of E. leucoxylon have yielded us here from dry 

 material 9 J per cent, of Eucalypto-tannin, whereas the dry foliage 

 of Acacia pyenantha furnished as much as 15-16 per cent, of 

 Mimosa-tannic acid, and therefore still more approaches in its 

 richdom of tan-principle to the genuine Sumach-leaves of Rhus 

 coriaria. Our experiments here showed that about four weeks 

 were required to effect the tanning of cow-hides (which were used 

 on this occasion) by simple immersion in the tan-liquor, as obtained 

 by decoction, without any additions of other substances, whether 

 leaves or bark were employed, except in the case of E. Gunnii, 

 the tanning process with that species being completed in two 

 weeks, and with E. goniocalyx in three weeks. The leather 

 obtained from leaves of E. leucoxylon was grey-brown, hard and 

 tough ; that from the bark of E. Gunnii, light brown and rather 

 flexible ; that from bark of E. viminalis, E. goniocalyx, and E. 

 amygdalina reddish-brown and tough ; that from the bark of E. 

 macrorrhyncha and E. melliodora darker still than that of the 

 preceding three ; that from the bark of E. obliqua red-brown in 

 colour." (Dec. 7, " Eucalyptographia.") 



5. It will here be convenient to present the results of the 

 determinations of tan and extract in the present paper, in tabular 

 form, in order of tanning power and quantity of extractive matter. 

 Similar tables (compiled from my former papers read before the 

 Society) are also given in regard to such barks as were obtained 

 from the trees which yielded the leaves described in the present 

 paper : — 



