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



of tannin."* Another authority states that sumach flourishes, 

 best in arid country. In Italy the limestone soils are considered 

 especially suitable ; the American varieties appear to be well 

 suited to sandy and clay soils as well. "The culture to be given 

 the plant is somewhat similar to that required by Indian Corn 

 (Maize)." 



The value of sumach is greatly diminished according to the 

 proportion of colouring matter it contains. With the view of 

 roughly estimating the comparative quantity in different samples,, 

 the chemist of the Department of Agriculture (Report loc. cit.) 

 adopted the following method. Of each substance to be tested lie 

 took about 5 grammes, extracted with boiling water, and made 

 the filtrate up to 150 cc. To 50 cc of this solution he added 10 cc 

 of solution of gelatine (1 in 100)f and noted the colours of the 

 precipitates, as follows : — 



Winchester, Va., mixed, collected in June gave a nearly white precipitate 

 „ „ „ July gave a decidedly yellowish- 



white precipitate. 

 ,, R. copallina, „ August gave a dirty yellow precipitate 



,, R. glabra ,, ,, gave a very dirty white ,, 



Fredericksburg, mixed, „ ,, gave a dirty yellow ,, 



Sicilian ,, ,, gave a yellowish-white ,, 



It is therefore advised that for the purpose of tanning white 

 and delicately-coloured leathers, the collection should be made in 

 June ; while for tanning dark-coloured leathers, and for dying 

 and calico printing in dark colours, where the slightly yellow 

 colour will have no injurious effect, the collection be made in July. 

 It appears that for all purposes, the sumach collected after the 

 1st of August is inferior in quality. 



I have applied the same test to the leaves of Rhus rhodanthema, 

 and the Sydney purchased Sumach referred to in this paper, with 

 the following results : — 



Rhus rhodanthema — Almost the same tint as that yielded by 

 Sumach, but a little dirty. 



Sumach — Very light buff, almost cream-coloured. 



Note. — The above colours are those obtained during the first 

 few seconds. On standing, the Sumach precipitate also becomes 

 of a dirty tint, tending to approach that of R. rhodanthema, which 

 at the same time slightly darkens. Considering all the circumstances 



* Eeportof the Department of Agriculture for 1881, Washington. Yet 

 at p. 7 of the Special Eeport on Sumach above alluded to, occurs the 

 passage : — " In cultivation of the plant, on account of its power to with- 

 stand dryness, the soil usually chosen is poor and light ; but a much larger 

 crop of leaves can be secured from strong, rich, deep soils, and it is 

 generally admitted that the product in the latter case is also better." 



f The report gives 1 in 10, evidently a misprint, as gelatine does not 

 dissolve in such a small proportion of water. 





