ON SOME N.S.W. TAN- SUB STANCES. 259 



I have not heard of much damage, but one fact seems worth 

 recording. From an upper window in Mr. Wiesener's workshop 

 in George Street, a pane of glass burst outwards, as if by the 

 sudden fall in the barometer relieving the pressure outside allowed 

 the air inside to expand and burst the window, a phenomenon so 

 well known in hurricane countries that they leave the door and 

 windows open. In the recent case the momentary change of 

 pressure represents a sudden weight almost like a blow of nearly 

 half an ounce on each square inch of glass, which might be 

 enough to break a large and weak pane of glass. 



SOME NEW SOUTH WALES TAN-SUBSTANCES. 

 Part Y. 



((Including an account of LowenihaVs process for the estimation 

 of tannic acid.) 



By J. H. Maiden, F.L.S., &c., Curator of the Technological 

 Museum, Sydney. 



[Read before the Royal Society of N.S.W. , October 3, 1S8S.~] 



I have already intimated that the process adopted by me for all 

 "the estimations of tannin already recorded in this Society's Journal 

 (1887) is that of Fleck. Partly because that process is of limited 

 application, I have decided to use the process (improved) of 

 Lowenthal, and as far as my experience extends, I believe that 

 that process is applicable to all Australian vegetable products. 

 Hallwachs (Dingl. Polyt. Journ., clxxx.) has instituted comparisons 

 between the various processes (Fleck's and Lowenthal's amongst 

 others) for the estimation of tannin, using materials usually 

 available to the European tanner, and the subject is so full of 

 importance that I have already commenced a series of similar 

 comparative analyses with Australia tanning materials, which 

 may perhaps be advanced sufficiently for publication next year. 



Lowenthal's Process. 

 In spite of the acceptance which this process has found 

 with European chemists, it seems strange to have to say 

 that I know of no book which describes the process in 



