88 nOPINESS IX WATTLE BARK INFUSIONS, 



SUMSIARY. 



Two closely allied bacteria were isolated from ropj' infusions of wattle bark. 

 Tbey caused the mucinous fermentation of bark infusions and of synthetic media 

 containing sugar. 



Fresh infusions, of Sp.G., 1.024 and less, were made ropy by A, and of 1.048 

 and less, Ijy B. 



The bacteria exist in two phases which can bo altered at will. One jiroduces 

 a soluble slime, the other an insoluble mucus. The rojiiness Ls produced chiefly 

 by the insoluble phases. 



The utilisal)le sugars are galactose, levulose, saccharose and dextrose, the 

 non-sugars are mannit and glycerin. 



The sources of nitrogen include meat-extract, peptone, asparagin. ammonium 

 sulphate, and potassium nitrate in alkaline solution. 



The saline constituents have little influence in presence of sufficient sugar. 



A slight acidity favours the production of ropincss, the optimum ranging 

 from -|- 8° to -|- 12°. The optimum amount of tannic acid runs from 0.75 % to 

 1 %. The limiting amounts are -|-30° and 2 % of tannic acid. 



The mucus is a galactan, and is hydrolysed to galactose. 



The by-prodiK'ts from sugar are chiefly inactive lactic and acetic acids. Ethyl 

 alcohol, succinic acid and a mixture of non-volatile fatty acids are produced in 

 small amounts. In addition to these, bacterium B produces paralaetic acid. 



I have to thank Mr. F. A. Coombs for information regarding the iise of 

 wattle-bark and for obtaining the opinions of some tanners upon the occurrence 

 of ropiness. I am also indebted to Mr. "W. W. L'Estrange for nnicli valuable 

 assistance given during the course of the investigation. 



Appendix: — Opinions tijj(i)i I!op>)iess. 



Mr. F. A. Coombs, Lecturer upon Tanning in the Sydney Technical College, 

 circularised a number of master tanners asking their experieuee regarding the 

 occurrence of ropiness in wattle bark liquors, and the replies are thus summarised. 



Kopiness does occur in wattle bark liquors, but as to its frequency in barks 

 from particular places or from young or old trees no inforin%tion could be ob- 

 tained. 



It occurs in liquoi-s prepared from immature or freshly-stripped liark. 



It is met with most frequently during the Summer months, January, Febru- 

 ary, and March, but may also occur in the Spring. 



Ropiness may develop in weak or .strong liquors. 



If the liquors stand for a fairly long time without handling they may become 

 ro|iy. 



It may not be attributed to the constant use of spent colouring li(|uors, but 

 this presumes that they have been treated in some way. One tanner was definite 

 in stating that the trouble starts with the use of weak colouring liquors that 

 ought to be run away, and added tliat ixissibly some fanners, wlien strengthening 

 the six'nt li(|uor.'., let the bark ferment. 



Kopiness occurs in liquoi-s other than wattle-bark li(|Uors. 



The weak or sjjent liquors, when not run away, are either steamed, boiled, or 

 treated with disinfectant, and in these ways tlio development of ropiness in the 

 liquors is prevented. 



