1 Dec., 1901.] QUEENSLAND AGRICULTURAL JOURNAL. 571 
Science. 
ANALYSIS OF TAN-BARK. 
In March last, Mr. M. J. Gallagher, proprietor of the Kedron Tannery, 
requested the Department of Agriculture to recommend a remedy for the dis- 
agreeable smell so characteristic of colonial-tanned leather, which is a serious 
drawback the tanning industry has to contend with. Mr. Gallagher forwarded 
samples of the following tanning materials, asking that they might be analysed 
by the chemist to the Department, Mr. J. C. Briinnich. These were: Ground 
Valonia, ground Myrobolans, unground Valonia, unground Myrobolans, best 
Adelaide bark in its raw state, bark liquor No. 1, first liquor and No. 2, 
second liquor which had been used on hides in the first and last stages. Mr. 
Brinnich accordingly analysed the three liquors with the following result :— 
ott Liquors. 
A. B. ’ 
Best French. | Six Weeks Old. Very Old. 
Barkometer density ia iy oy wr 9 46° 40° 20° 
Specific gravity ... ae 45, ay 4h sie 1°0455 170388 170202 
Corresp. to Barkometer degrees +2 ~ se 45°5° 388'8° 20:2° 
Total extract in liquor, per cent. ... Fh, 11:29 9°04 4°88 
Tannin in extract + Ht ee 9:32 7°68 Nil. 
Ash of-extract rf) af ~~ “48 ‘68 ‘78 
Acetic acid free in liquor 1 for’ ap ‘108 058 014 
7} » combined withlime ,, MY a Nil. 056 108 
Lactic acid ip Pa nt Nil. ‘10 05 
Lime water test co. per 100 ce. liquor ot | ee 2032 13°5 55 
From the analyses it is shown that the specific gravity agrees with the 
Barkometer degrees ; but of how little value the latter is for judging the amount 
of tannin is strikingly shown by the third liquor, which is completely exhausted 
of all its tannin, and the 20 Barkometer are only due to impurities as colouring 
matters and a fair amount of lime salts. 
The liquors contained a smaller amount of the various micro-organisms than 
the liquors examined in April last, and the amount of acetie acid is also consi- 
derably less. The liquors are, however, still deficient in lactic acid. 
Report on Tannina Liquors anp Mareriats RECEIVED From Mr. 
J. GALLAGHER, OF THE Kepron TANNERY. 
An investigation by analyses and microscopical examination of the samples 
of tanning liquors and materials received show a rather high acidity in the 
liquors, which is chiefly due to acetic acid, whereas a predominance of lactic 
acid is desirable in soured liquor. The process of souring is entirely due to 
the action of micro-organisms ; and whereas the first liquor contained hardly 
any organisms (bot still contained a yery large amount of acid, showing that 
already fermentation must haye taken place), the second liquor contains a 
very great variety of such. The souring of the bark liquor should be a very 
slow process, at not too high a temperature, and is, like any other process of 
fermentation, influenced by the temperature, the original quality of liquors, and 
by inoculation with either favourable or unfayourable germs. A liquor which 
contains lactic acid, due to the slower lactic fermentation, produces a better, 
more supple leather, and I have no doubt also of a better odour. 
The usual test for acidity is made at tanneries with lime water, and 10 ce. 
of the tanning liquor should use from 5 to 12 ce. of lime water before a 
