lo TANNING MATTER, &Ci 



Experiments, V ^^^ effect of an) a considerable deposit was formed on 



&c.on an aiti- the filter, which was again dissolved by alcokol. Water 



ha'dng"hecha- **^"^cred the solution turbid, and a black light flaky sub- 



racter of tan- stance, which weighed 41 grains, remained upon the 



nms matter, fj^^.p^ rj^,j^^ filtrated liquor was then evaporated, and left 



a grayish-black substance, which weighed 30 grains. 



This last substance Avas highly in flammable, and when 



burned, emitted a very peculiar odour, resembling partly 



that of fat and partly that of asphaltum. It easily melted, 



and also immediately dissolved in cold alcohol, from which, 



like the resinous substances, it was precipitated by water. 



The black light flaky residuum, which weighed 41 



grains, was found to consist partly of the substance above 



mentioned and partly of coal, but the proportion of this 



last was not ascertained. 



Coagulated albumen and prepared muscular fibre were 

 also separately ex])osed to the action of sulphuric acid in 

 the manner above described, but did not afl'ord any sub- 

 stance by which gelatine could be precipitated, coal being 

 the only product which remained. 



Almost every one of the bodies which have been em- 

 I)loyed in these experiments, seem to be in some measure 

 ditterent in respect to the progressive effects produced 

 upon them by sulphuric acid; and all other circumstances 

 being similar, there appears to be a certain period of the 

 process when the production of the tanning substance has 

 arrived at its maximum, after which, a gradual diminution 

 of it takes place, and at length total destruction. These 

 eliects are produced at diflbrent periods, according to the 

 substance which may be the subject of the experiment, 

 and therefore it is impossible at present to state the utmost 

 quantity of the tanning substance which, under equal 

 circumstances, may be obtained from each of the resins, 

 balsams, kc. 



The tanning substance appears to be always the same, 

 ivhether obuined from turpentine, or common resin, or 

 from the balsams, or from asa fcietida, or camphor, or in- 

 deed from any of the bodies w hich have been enumerated; 

 its eflects on the diiferent reagents are similar ; by the 

 addition of a small portion of nitric acid, and subsequent 

 eva])oration, it is converted into that which I have called 

 IUm first variety ; or if digested with sulphuric acid, it is 



speedily 



