1805.] 



Proceedings of Learned Sec ie ties. 



4U 



naturally formed, and exifts in a great 

 Dumber of vegetable bodies, fuch as oak- 

 bark, galls, I'umsch, catechu, &c., com- 

 monly accompanied by exir.ft, gallic- 

 aciii, and mucilage. Recent experiments 

 have convinced Mr. H. that a I'ubftance 

 polTefling the chief charaiteriftic pioper- 

 ties of tanning may be fornied by very 

 fimpfe means, not only from vegetable, 

 but even frum mineral and animil lub- 

 flaiices. It ni.-.y be formed by expofi!)g 

 carbon to the a61ion of ni'ric acid, and 

 this is befteffe8ed when the carbon is nn- 

 combined with atiy other fubftance except- 

 ing oxvgen. 



A portion of Bovey coal was expofcd 

 to a red heat in a dole vefiel, and was then 

 reduced to powoer and digeitedwith nitiic 

 acid. Nearly the whole was converted 

 into the tannir.g fubftarce. A coal from 

 Sufl'cx, and a piece of the Surturbrand 

 from Iceland, yielded fimilar refuhs.— - 

 Deal faw-duil alio, convened fit ft into 

 chircial, and then treated in the manner 

 already defcribed, yielded a liquid which 

 copioufiy precipitated gelatine. 



Tiitfe are bur a pait of Mr. Katchett's 

 experiments. They are, however, I'u.'S- 

 cient to exhibit tlie principle, and tojiiliify 

 the conclulion, " That a fubltance very 

 analijgous to tanning, which has hitherto 

 been confidercd as one of the proximate 

 principles of vegetables, may be produced 

 by expofiiig ca'bonaceous fubftances, 

 whether vegetable, animal, or mineral, to 

 the action ol nitiic acid," 



The efficacy of this new fubftance has 

 been proved by actual pra6lice, and Mr. 

 H. has converted (kin into leather hy 

 mems of mart}-. a],, which, to |4ifcifional 

 men, muit, as he conceives, api eif extra, 

 oidinary, fuc'i as deal I'awclufl, afphal- 

 tum, tuipentine, i it-coal, wax-candk, and 

 even a piece of the fime fort of {\:.'m. — 

 Hence it is hoped that an econoniicai pro- 

 cefs may be dilcovered, {o tnat every tan- 

 ner may be enabled to prepare his leather 

 even from ttic refuie of his prefeat ma;e- 

 riaLs. 



Mr. Hatchutt's fecond paper con- 

 tains addiMonal experiments and rernarks 

 on the fime fublfance, fi'^m which it ap- 

 peTs, that three varieties of the artifici.il 

 taimint; fubftance may be fbrnied ; viz., 



1. Tiiat which is produced by th'.- ac- 

 tion of nitric ac'd upon any carhona'rroin 

 iMhffai ce, whether vegetable, animal, or 

 mineral. 



2. Tint which is formed by dirtilliiig 

 nif ic acid from common lefm, indigo, 

 dragon's -blgod, and various otlitr fub- 

 Itjiico. 



3. That which is yielded to alkohol b^ 

 common refin, elcnii, afia-foe'ida, camphor, 

 &c. after ihefe bidies have been (" me time 

 previouriy dieelted with fiilphuric acid. 



The firft variety its moft eafily forn:ed j 

 and in fome caies 100 grains of dry vege? 

 table chai coal afforded 120 of the tanning 

 fubffaace. 



The lecond variety is obtained from ^ 

 great vaiiety of vegetable bodies, bv di, 

 gelling and difliiling them with nitric 

 acid ; but it is not fo re'dily prepared a$ 

 the firif, nor in lo large proportional quan-r 

 titles. 



The third variety appears to be uni, 

 formly produced during a certain period 

 of the proce:s, but by long continuance of 

 the digell on it is dcitroyed. 



Subltances, fuch as gums, which aiiord 

 mu..h oxalic acid by treatment wiihothep 

 acids, do not yitld any of this tannino' 

 fubffance. The enerjjy of its affion on 

 gelatine and fi;in is inferior io thu of the 

 fiill variety, into which, however, jt rpay 

 be eaiily converted by nitric acid. 



Mr. TiMOTHV L.\NE, in a paper lai(i 

 before the Royal Society, ha» aneinpted 

 tn prove thit mere oxides ( f iion are not 

 niHgneticj that any inflammable fub-r 

 (lances mixed with ihem do not render 

 tliem magnetic, until they are bv heat 

 clemlciilly combined with the oxides, an4 

 that when the conibulfible fuiiffance is 

 again fc-paiated by heat, the oxides leiuriJ 

 to their unmignetic ftare. By repeated 

 experiments Mr. Lane found that hea| 

 alon; produced no magnetic effect on ihg 

 oxidi-, and thai inflimmible .matter witfi 

 lieat always rendered Lme of the particles 

 magnetic. 



Ex. I. He mixed fime oxides of iron 

 with coal in a glafs moriar, and contiivuecj 

 rubbing them together for fome time with? 

 out any m-igneiic cffc6f. The mixtijie 

 was then |)ut into a tobacco-pipe, anJ- 

 placed in the clear red- heat of a common 

 fire ; as foon as the pipe had acquired 4 

 red-he^it it was taken ouf. The mixture 

 was put cu a glazed tile to cool, and provr 

 ed highly magnetic. 



Ex. 2. He ruobed fome ox'des of iron 

 in a glal* mort'.r, with fulphur, charcoa', 

 camphor, e;her, alkohol, &c., b'lt p* 

 ongnetilm was produc'.d without a tieat 

 tquil to ab ut ih.it of boiling lead. 



Small qirtnrities <f any ipfiamrnnhle 

 m.itter in -.i red heat have a'l evi.ient ellVcl 

 on the oxidt. Hydrogen, nidt'J by a leir 

 heat, renders the ox.de mapucdc. Alko- 

 hol, if pme, has tl.e lame etftCt, 



The portion of infl linuMbie matter re. 

 qiiifirc to render a cnfjilerabie >uiantity of 



